THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 LOS ANGELES 
 
 GIFT OF 
 
 U. of Calif. 
 Berkeley
 
 MODERN STEAM TURBINES 
 
 BRITISH AND FOREIGN. 
 
 COMPRISING DESCRIPTIONS OF SOME 
 TYPICAL SYSTEMS OF CONSTRUCTION. 
 
 UNDER THE EDITORSHIP OF 
 
 ARTHUR R. LIDDELL, 
 
 Vol. I. 
 THE SCHULZ STEAM TURBINE.
 
 MODERN STEAM TURBINES. 
 
 VOL. I. 
 THE SCHULZ STEAM TURBINE.
 
 THE 
 
 SCHULZ STEAM TURBINE 
 
 FOR 
 
 LAND AND MARINE PURPOSES 
 
 With special reference to its application to War Vessels, 
 BY 
 
 MAX DIETRICH, 
 
 Marine-Oberingenieur A.D. of the German Navy, 
 
 With 43 illustrations and diagrams, and 6 tables. 
 
 NEW YORK 
 
 E. P. DUTTON AND COMPANY 
 
 31 WEST TWENTY-THIRD STREET 
 1907
 
 ALL RIGHTS RESERVED.
 
 &i e inriiig 
 Libr.r, 
 
 TJ 
 
 PREFACE. 
 
 The growing importance of the steam turbine for land 
 purposes, and still more for the propulsion of ships, has prompted 
 us to bring some of the results of British and foreign endeavours 
 in this field within the reach of interested parties. 
 
 The volumes of this series comprise descriptions of some of 
 the systems of which encouraging practical trial has been made, or 
 which, in view of the past record of their authors, have a prima 
 facie claim to be taken seriously as engineering probabilities of the 
 future. 
 
 It is clear that a new departure in practical engineering 
 must present for solution many new problems, each of which may 
 be approached in a variety of ways, and a knowledge of the successes 
 and failures of other designers who have made practical trial of this 
 or that expedient will doubtless supply hints in many directions. 
 Even untried proposals may point the way to solutions of difficult 
 questions, whether of principle or of detail. 
 
 In regard to matters of controversy between rival inventors, 
 which show themselves in some of the works in the collection, it 
 is not the intention to take sides between different engineers or 
 different schools of engineering, nor to show preference in any 
 direction, but simply to lay ex parte statements before our readers 
 
 733411
 
 with all impartiality, in the hope that mutual understanding and 
 appreciation may thereby be promoted, and that the advantages of 
 different systems may, in course of time, be combined in one good 
 standard type of engine. 
 
 It is hoped that the publication of the present series may 
 prove a timely one and may bring advantage to the engineering 
 profession. 
 
 AKTHUB E, LIDDELL. 
 
 August, 1906. 
 
 This volume is an authorised translation of "Die Dampfturbine von Scbnlz," by 
 Max Dietrich, published by C. J. E. Volckmann, of Rostock, German 1906.
 
 THE SCHULZ STEAM TURBINES. 
 
 These turbines are not only for land purposes, such as that of 
 supplying the motive power for light and power installations and 
 locomotives, but are also especially adapted for marine work, such as 
 the driving of the screw propeller. 
 
 Richard Schulz, the designer of these turbines, as Engine- 
 works Manager of the Germania Shipyard of Friedrich Krupp in 
 Kiel, has had many years of experience in the construction of engines 
 for use on land, and still more in that of marine engines. He has, 
 therefore, had ample opportunity of studying the conditions which 
 such turbines must fulfil, if they are to enter into successful com- 
 petition with the ordinary reciprocating engine. Since in the Ger- 
 mania Shipyard at Kiel not only large torpedo boats, but the very 
 largest ships of the German Navy are built, Herr Schulz has been 
 obliged to consider the suitability of the turbine for warships of every 
 possible kind. 
 
 The patents published hitherto and the designs embodied in 
 them show that both the action and the reaction principles have had 
 application, and have been developed as independently as possible. 
 Turbines on the action principle with expansion stages, in which 
 each of the working-wheels runs in a separate chamber the walls 
 of which support the guide blades, have been known for more than 
 thirty years (See "Roues et turbines a rapeur," by K. Sosnowsky, 
 Paris). The steam turbines of Bateau, Zoelly, Curtis, &c., are 
 newer constructions on the same principle ; but no types hitherto 
 known make complete use of the available motive power in this 
 case the steam ichen the work to be done is small.
 
 8 
 
 To alter the output, Zoelly simply throttled the steam. 
 Ratcau sometimes, and Curtis probably always, employed as con- 
 stant an initial pressure as possible, but devised no means of regu- 
 lating the pressure in the subsequent expansion stages. Conse- 
 quently, they failed to make full use of the steam energy, especially 
 when the output was inconsiderable. 
 
 In the new Schulz turbines, on the other hand, not only the 
 initial pressure, but the pressure in every expansion stage is so regu- 
 lated, either by hand or by some automatic device, that full use can 
 be made of the steam, even for a minimum of work. 
 
 The principal patent in this connection is the "Regulating 
 apparatus for multi-stage expansion turbines," No. 132,868; class 
 14c, of March 26th, 1901. This and the patents mentioned in the 
 specification refer to 
 
 (a) Several expansion stages, as in the designs of Rateau, 
 Zoelly, &c. 
 
 (b) Several expansion stages with subsidiary speed-expan- 
 sions, as in those of Curtis, Riedler, Stumpf, &c. 
 
 The new action turbine, of Schulz (Fig. 14) is devised chiefly 
 for use on land. It has from one to ten or even more expansion 
 stages, each of which can be amplified by one or several subsidiary 
 speed stages. In every detail of its construction this turbine shows 
 the requisite simplicity and strength. Between the fixed and the 
 rotating portions are clearance spaces of from to \ of an inch. This 
 ensures safe working. 
 
 A special valve or ring slide regulates the work done in each 
 expansion stage, so that the available boiler pressure is used to the 
 best advantage, whatever may be the output. 
 
 This condition is fulfilled likewise by the Laval turbine ; for 
 in it, whether the work done be little or much, the pressure and 
 change of temperature of the steam are utilized as completely and 
 evenly as possible.
 
 9 
 
 Schulz' action turbines can be used both for the smallest out- 
 puts of 2 or 3 horse-power and for the highest up to 15,000 horse- 
 power or more. Moreover, both high and low peripheral velocities 
 down even to 65 feet a second or less can be obtained. The number 
 of expansion stages, and especially also that of the subsidiary speed 
 stages, depends on the required peripheral velocity. The shaft 
 may be placed either vertically or horizontally. 
 
 Schulz' reaction turbine differs from the well-known Parson's 
 turbine principally in the fact that the end thrust unavoidable in this 
 sort of turbine is nullified without the employment of a grooved 
 "labyrinth piston." Schulz has solved the problem in many 
 different ways ; the contrivances for this purpose are described in 
 detail further on. 
 
 This reaction turbine is remarkable for its strength and for 
 the ease with which it can be constructed. Its length is less than 
 that of turbines of other systems; and since in spite of this the steam 
 is utilized satisfactorily, this turbine is powerful in proportion to its 
 size and weight (See the comparison between the various turbines in 
 Figs. 39 to 43). It can be employed for outputs of from 50 to 
 15,000 horse-power, or even more. 
 
 Superheating is considered an advantage in both kinds of 
 turbine. 
 
 The first problem attacked by Schulz was to make turbines 
 reversible, that is, to enable them to drive ships either forwards or 
 backwards. He laid the greatest stress on this point in his first 
 designs, which go back as far as the year 1897. Only in his later 
 plans did he pay increased attention to the other properties which 
 should be possessed by an engine for use on land or sea. The most 
 important of these is that the turbine should be economical, not only
 
 10 
 
 when its output is large, but also when the work done is moderate 
 or little. 
 
 For a marine engine, economy in the use of steam is usually 
 demanded only for motion ahead. When the engines are reversed , 
 a rapid answer of the ship to the rotation of the propeller is of more 
 importance. 
 
 The engines of warships or merchant vessels are reversed 
 when the ship is manoeuvring or is going in or out of a port, and 
 when the danger of a collision or some similar unforeseen circum- 
 stance arises. In these cases an economical use of the steam is- 
 generally not necessary, for when the engines are worked irregularly, 
 we cannot regulate the generation of steam in the boilers so that the 
 pressure is no greater than the needs of the moment require. In 
 most cases superfluous steam is formed, which must be carried off 
 to the condenser to avoid waste of fresh water. 
 
 One simple means of obtaining a reversible turbine system is- 
 to place two equal turbines on a common shaft, one for motion ahead 
 and the other for motion astern. The weight and space require- 
 ments of this system are, however, so great as to render it unsuitable 
 for a marine engine. The designers of steam turbines have often 
 supposed that they could avoid this difficulty by using a large turbine 
 for motion ahead and a small one for motion astern. Experiments 
 on such systems have, however, shown that they are, at any rate, 
 inapplicable to men of war. 
 
 The disadvantages of a go-astern engine of small output are 
 not so noticeable in smaller vessels, such as tugs or torpedo boats, 
 but in larger ships they are very much in evidence. In such cases 
 the hull answers to the propeller much too slowly, and it is a long 
 time before the ship begins to move in the direction opposite to that 
 in which she had previously been going, perhaps at a high speed. 
 This drawback is exaggerated by the fact that a turbine engine 
 is obliged to have a comparatively small screw. 
 
 If, however, vessels of any sort manoeuvre indifferently, they
 
 11 
 
 are in frequent danger of collision, while men of war lose their value 
 as fighting units. 
 
 We draw the following conclusions as to the conditions which 
 should be satisfied by a marine turbine. For motion ahead it must 
 make full use of the available energy, so as to economise coal. For 
 motion astern this is of less importance, but the turbine should be of 
 a size sufficient to affect the ship's motion promptly and effectively. 
 
 Schulz has made a number of designs to satisfy these con- 
 ditions, and has protected them by patents in Germany and else- 
 where. In these the chief consideration has been to make the go- 
 astern turbine as powerful as possible without its at the same time 
 being unreasonably extravagant in the use of steam. Although in 
 manoeuvring a large quantity of steam must be at our disposal, and 
 often some of it must be led away into the condenser or into the open 
 air, yet occasionally this superfluous steam is not available, as for 
 instance, when the engines are reversed for several minutes at a 
 time. It follows that a go-astern turbine should not use more steam 
 than would have been required during the time in which it acted for 
 motion ahead. 
 
 It is convenient to enclose the go-ahead and go-astern tur- 
 bines in a single case. Parsons also recognised this fact, and a year 
 later than Schulz he took out a patent for a go-astern reversing tur- 
 bine placed abaft of the go-ahead engine. He thereby economised 
 weight and space, but the reversing turbine had too small an output 
 and was not sufficiently accessible for inspection and repairs. 
 
 The two first Schulz turbines (Figs. 1 and 18) were turned out 
 from the Engineering Works of the Germania Shipyard at Tegel, 
 near Berlin, in the years 1898 and 1900. The improvements which 
 time has brought w r ere partly tested on these experimental turbines. 
 
 In 1901 the second of the turbines represented in Figs. 18 and 
 19 was, immediately after completion, placed in a boat of 19 tons 
 displacement and performed all its manoeuvres without a hitch. A 
 description of these turbines is given further on.
 
 12 
 
 The first turbines designed by Schulz are shown in Figs. 1 
 and 2. They were patented in April, 1898, as "Compound turbines" 
 (No. 103,879; Class 14). Many experiments on the driving of 
 screws and dynamos were made in 1899 with the radial turbine of 
 Fig. 1. Some results of these tests are given in Table I. The 
 maximum output was 51 electric horse-power, when the number of 
 revolutions was 1,700 per minute and the boiler pressure was 
 2051bs. per square inch. 
 
 Fig. i. 
 
 In the case G are one or more working wheels fastened to the 
 shaft /. These carry on their sides the working-wheel blades ar- 
 ranged in concentric rinjjs. Attached to the case are the fixed
 
 13 
 
 blades g, also concentrically arranged, which guide the steam in the 
 necessary direction to the working-wheel blades. Part T of the 
 working-wheel drives forwards : the other part, T', backwards. The 
 entry of the steam is regulated by a three-way valve. The tube V 
 leading from this opens into the steam chest a and enables the steam 
 to drive forwards. The steam finds its way to the ring of blades b r 
 lying next to the shaft /, and after going through the other rings in 
 order, finally passes through the outermost ring c and leaves the 
 case at d. Thence it passes into the condenser or to the open air. 
 The tube R, also leading from the three-way valve, opens into the 
 two steam chests e, and enables the steam to drive backwards. ID 
 
 Fig. 2. 
 
 this case also the steam passes first through the blades nearest the 
 shaft and finally, after its energy has been exhausted, leaves the case 
 at d, as before. 
 
 The end thrust is eliminated by the arrangement of two equal 
 turbines with the common steam supply for motion ahead arranged 
 between them and with separate supplies for motion astern arranged 
 at their outer sides. One of the oldest of Schulz' patents, viz., the 
 engine illustrated in Fig. 2, may here appropriately take its place.
 
 14 
 
 It is composed of a go-head turbine with axial flow and a go- 
 astern radial turbine. The working-wheel here takes the form of a 
 drum shaped like a truncated cone. The two ends of this cone 
 are closed by the plates i and i , which serve as bearings for the shaft 
 J. The case g, which supports the fixed blades, fits the shape of the 
 working parts. The rings of working- wheel blades (b to c), which 
 drive forwards, are fixed on the sloping sides of the working drum. 
 Those which drive backwards are placed on the base of the drum. 
 The design and arrangement of the steam supply may be seen in 
 the figure. The rings of blades for motion astern are of as large a 
 diameter and are situated as near the steam exit d as possible, so that 
 they may offer no resistance while the engine is driving ahead. 
 
 A disadvantage of reaction turbines is the end thrust with 
 which the steam acts on the working- wheel. In large turbines this 
 may reach very considerable values. Parsons eliminates this thrust 
 by the use of counteracting pistons, forming the well-known "laby- 
 rinth apparatus." 
 
 These increase the length of the turbine and consequently 
 waste space ; moreover they are extravagant in steam. Economy of 
 space is, however, one of the chief aims of modern builders of every 
 kind of engine, and loss of steam (though this is less important) 
 .should also be avoided. 
 
 The use of reaction turbines as marine engines necessitates 
 the employment of a large number of fixed and revolving blades, if 
 the peripheral velocity is to be sufficiently low. Marine turbines 
 must, therefore, have comparatively many more rings of blades than 
 stationary engines. It is necessary, especially for marine purposes,
 
 15 
 
 that these numerous blade rings should be divided among several 
 drums, so that the shaft may, by reason of the shortness of the indivi- 
 dual drums, be more firmly and securely mounted. Schulz' designs 
 satisfy this condition adequately and at the same time eliminate the 
 end thrust. 
 
 Schuh patented a compound steam turbine in November, 
 1900 (No. 137,792; Class 14 C ), in which two turbines are symmetri- 
 cally arranged with their end thrusts acting in opposite directions. 
 A number of rotating blades are fastened on two drums of different 
 diameters. By means of a suitable flow of steam the end thrusts of 
 these drums are opposed in such a manner that the pressure on the 
 thrust block is entirely eliminated, or at least brought within reason- 
 able limits. 
 
 Fig. 3 shows a compound turbine of this kind, in which the 
 diameters of the rings of fixed and revolving blades (as in Fig. 2) 
 
 increase in the direction of flow of the steam. Jn the patent, how- 
 ever, provision is also made for the case in which the rings of the 
 high and low pressure turbines respectively are of equal diameter. 
 
 In Fig. 3 the high-pressure turbine with the smaller blade 
 rings is denoted by the letter a, the low pressure turbine with larger 
 rings by 6. Both revolving drums are enclosed in a common case d
 
 16 
 
 and are fixed to the shaft c. The steam enters the turbine at e, and 
 after passing through the fixed and revolving blades of the high 
 pressure engine, is regulated by the valve g. Tt then goes through 
 the connecting pipe / arid the tube It, finds its way at h into the low 
 pressure turbine, and is led away at i into the condenser or into the 
 open air. In a and b the steam flows in opposite directions. 
 
 The fixed blades in a and b are placed in such a way that both 
 a and b drive in the same direction. The valve g at the mouth of the 
 pipe / regulates the pressure of the steam as it leaves a. In this way 
 the resultant end thrust on the thrust block n can be altered within 
 certain limits. 
 
 As in Fig. 2, the moveable reversing blades are fastened to the 
 base of the low-pressure working drum and the fixed blades to the 
 corresponding cover of the case. The steam for reversing enters 
 through the pipe m , and in this case also reaches the smallest of the 
 concentric rings of fixed blades first. The steam, as in the case of 
 direct rotation, leaves at i, close to the outermost ring. 
 
 This radial go-astern turbine can also be replaced by a shorter 
 axial engine, as is shown in a diagram in the patent specification. 
 
 Compound turbines are composed of two or more turbine- 
 drums, whose rotating parts are placed in separate cases, and sit 
 either on a single shaft or on several distinct shafts. Of the many 
 combinations which are given in the before-mentioned patent No. 
 137, v 02, v\e shall mention only two. 
 
 Fig. 4 shows four turbine-drums a, b, u, v, placed on a single 
 shaft. The arrows show the direction of the driving steam and 
 
 Fig. 4.
 
 17 
 
 hence the directions of the corresponding end thrusts. We see that 
 a,b, and u give an end thrust to the shaft in a direction opposite to 
 that given by v. 
 
 In Fig. 5 the drums are divided between two shafts. Here 
 we see an arrangement in which the smaller turbines a and b act on 
 one shaft, the larger ones and v on the other. The distribution of 
 the steam flow necessary to counteract end thrust is clear from the 
 figure. 
 
 In this diagram only the grouping of the four drums is new. 
 Monsieur Tournaire (as is well known) had as early as 1853 described 
 in detail a method in which several turbines, worked one after another 
 by a flow of steam, can be made to drive several shafts simultaneously. 
 
 In stationary turbines the end thrust should, of course, be 
 abolished as completely as possible. In marine engines, on the 
 other hand, the end thrust should be adjusted by a suitable choice oi 
 the diameter of the revolving parts, so as just to counterbalance the 
 thrust of the screw. When the ship is going ahead, this screw thrust 
 is towards the bow, so that the turbine thrust should be of equal 
 amount, but should act in the direction of the stern.
 
 18 
 
 For better regulation of the axial thrust the use of manometers 
 on suitable parts of the high and low pressure engine cases is advan- 
 tageous. When the pressures of the steam in the two turbines are 
 known, the end thrust may be determined. The difference of pres- 
 sure and hence the thrust may be altered to some small extent by the 
 valve g (Fig. 3). 
 
 Another design patented in July 1901, (No. 135,937; Class 
 14c) also aims at the abolition of end thrust. Two such turbines are 
 represented in Figs. 6 and 7. 
 
 Fig. 6 shows a longitudinal section of a turbine rotating in a 
 single direction only. It is admirably suited for use 011 land. The 
 flow is partly radial and partly axial. The axial portion of the 
 rotating parts is denoted by a, and the radial by 6. The case e is 
 
 Fig. 6.
 
 19 
 
 closed by the covers x and y. The radial portion of the revolving 
 blades is placed in a ring-shaped extension of the case, and here also 
 is the steam chest z for the entering steam. The cover y carries the 
 chest /, through which the steam exhausts. The direction of flow of 
 ihe steam is shown by arrows. 
 
 Fig. 7 shows a section through a turbine with radial and 
 .axial flow, which is reversible. For direct motion this turbine 
 
 Fig. 7. 
 
 "has two axial drums, a larger and a smaller, denoted by 1 and 2 
 respectively. The rotating apparatus a 6 for reversing is, a,s in 
 Fig. 6, partly axial and partly radial. 
 
 In the turbine of Fig. 6, and in the reversing portion of Fig. 7, 
 the steam is divided on its entrance into the case and passes at the same 
 lime through the radial (6) and the axial (a) parts of the common
 
 20 
 
 rotation rings. Both a and b give an end thrust towards the right , 
 but the steam flowing against the back of the flange-like part b before 
 its entrance into a, gives a thrust towards the left. This latter may 
 be regulated at pleasure so, for instance, as exactly to counter- 
 balance the thrust to the right. 
 
 In eliminating the end thrust, the chief consideration is, in 
 the go-ahead turbine, the difference of pressure in 1 and 2 in the 
 reversing turbine the breadth of the flange placed on the drum wall 
 of b. 
 
 After solving the problem of the design of a turbine which 
 should fulfil the necessary conditions of ease of reversal and elimina- 
 tion of end thrust, Scliulz turned his attention to the question of 
 economy. 
 
 Steam turbines with several blade rings work economically 
 only while they are giving the largest possible output under maxi- 
 mum boiler pressure. 
 
 The cross section of the steam passage is generally calculated 
 to suit the greatest output, and the steam is led into the first blade 
 ring at as high pressure as possible. When the steam goes through 
 the other rings its pressure gradually diminishes till the condenser is 
 reached, when, provided the energy be well utilised, it becomes com- 
 paratively small. 
 
 If a smaller output be demanded from the turbine with its 
 steam passages formed as above, it becomes necessary to resort to 
 throttling. By this, however, the steam loses its pressure to a con- 
 siderable extent even before it reaches the first ring, and economy 
 is thereby sacrificed. To meet this objection, Scliulz devised means
 
 21 
 
 of varying the cross section of the steam pipes in each separate ring 
 of blades. The entry of the steam to the revolving parts is thereby 
 so regulated with reference to the desired output, that the full boiler 
 pressure is employed, whatever may be the rate of working. This is 
 effected by the placing of a ring-slide valve before each ring of guide 
 blades or before a portion of the ring (German Patent No. 132,868; 
 Class 14c; March, 1901). 
 
 By altering the position of this valve we can leave free a 
 varying number of holes in the fixed rings for the passage of the 
 steam to the rotating parts. In Fig. 8 the individual fixed rings are 
 stationary, but the ring slides, while arranged for simultaneous ad- 
 justment by a common lever, can on occasion be moved separately. 
 The same regulation of the steam may also be obtained by the moving 
 of the individual blade rings relatively to their ring-slide valves.
 
 22 
 
 There is no essential alteration in the operation of the steam 
 when the rings of guide blades are made moveable, either separately 
 or simultaneously, instead of the ring slides. 
 
 Fig. 8 shows a section of a turbine constructed in this manner, 
 In Figs. 9 to 12 the above-mentioned adjustments are depicted. 
 
 The action turbine of Fig. 8 has axial flow and is provided 
 with five expansion stages. Each of these has three subsidiary 
 
 Fig. 9. 
 
 speeds. The case (6) has a greater diameter at the steam exit 
 than at the entrance, but the working- wheels all have the same 
 mean diameter. 
 
 The five wheels (3) are fastened to the common shaft (1), 
 which is supported by the covers (4 and 5) at the ends of the turbine. 
 Each wheel bears three revolving blade rings (2), corresponding 
 with the speed stages. The first fixed blade ring of each stage is ad- 
 justable, and is placed on the corresponding partition wall. The two 
 others are formed of blades (15) arranged in ring fashion round the
 
 inner periphery of the case. On the cover (4) is the chest for the 
 introduction of the steam ; on the cover (5) is the chest for its exit. 
 The direction of the steam flow is shown by arrows. The different 
 expansion stages are formed by the partition walls (7) (Fig. 9). 
 They reach nearly to the shaft, and the clearance space being so 
 small, no appreciable loss of steam can there take place. The ring 
 slide (8) and the corresponding adjustments are represented in 
 Fi<r. 10. 
 
 Fig. 10. 
 
 Fig. 11 is an expansion drawing, showing the relative posi- 
 tions of the holes in one of the ring slides and in the corresponding 
 partition wall when the output is at a maximum and when it is at a 
 minimum respectively. 
 
 As shown in Fig. 10, the ring slide carries on the upper part 
 of its circumference a number of tcoth (9), fitting into the toothed 
 wheel (10), which can rotate about the axis (11). The slide valve is 
 moved by the adjusting-lever (12), and its position is given by the
 
 24 
 
 scale (13). The divisions through which the axis (11) is moved are 
 denoted by 14. The adjusting apparatus on the partition is shown 
 in Fig 9. The adjusting-rod (16) and the spindle (11) pass through 
 ordinary stuffing boxes. 
 
 Fig. 11. 
 
 In this turbine the partitions have 28 entrance holes or nozzle- 
 like channels placed at equal intervals and having the same cross- 
 section. The ring slides have also 28 openings which, though alike 
 in each quadrant, vary in size and distance apart. In Fig. 11 two 
 such quadrants are shown developed on to a plane. 
 
 The distances between the openings are so chosen that in the 
 extreme position all the seven st?am holes arc open and the corres- 
 ponding expansion stage in question undergoes complete impinge- 
 ment. If the valve be moved in the direction shown by the arrows, 
 the holes on the left of each quadrant are closed. If the valve be 
 moved further still, into the position shown in the lower half of Fig.
 
 25 
 
 11 , the steam only enters through one hole in each quadrant. Hence 
 .a turn of the lever 12 through one division always opens or closes 
 four holes. 
 
 By means of the partition walls and ring slides of Figs. 9 and 
 10 we may, therefore, obtain either a complete or a partial flow of 
 steam. We can, however, partially cut the steam off by another 
 method, as is evident from Fig. 12. This latter device has the advan- 
 tage that the steam from leading channels or nozzles, which are 
 .arranged close to one another, is directed against the work ing- wheel 
 in question in a single stream. 
 
 Fig. 12. 
 
 If the ring slide is to be worked automatically, the lever (12) 
 is connected with a powerful governor. The partitions are adjust- 
 able separately, as before stated. We are, therefore, able to regulate 
 the width of the steam passage in each partition and hence for each 
 expansion stage separately. If, for example, all the holes are open, 
 we can by moving one or other of the partitions, increase the pres- 
 sure of the steam leaving the corresponding expansion stage, and 
 O secure the best economy for the desired output.
 
 W Grade. 
 
 2nd Grade 
 
 10th Grade 
 
 Measurements in Mm. 
 (i Mm.=o'03937 ins.) 
 
 Fig. 18.
 
 27 
 
 Fig. 13 shows the construction of the ring slides and parti- 
 tions, and their positions in the turbine. The openings in them are 
 also shown in detail. 
 
 To prevent the steam from passing along the shaft from one 
 expansion stage to the next, the corresponding borings in the walls- 
 are edged with saw-like teeth. The steam vortices and the friction 
 so caused reduce the loss of steam considerably. In addition, a 
 special packing-ring is provided at each partition. 
 
 The advantages of Schulz' new designs have been already 
 recognised by many German firms, who are now building turbines 
 on his system. 
 
 A larger type for outputs of from 500 to 800 horse-power and 
 2,000 revolutions per minute, is given in Fig. 14 This turbine has- 
 four expansion stages, each w r ith two subsidiary speed stages. In 
 regard to the division into pressure and speed stages, every other 
 possible variation of these may here be made. Also, the steam flow 
 may be either axial or radial, and may be partial in some of the 
 stages and complete in others. An example of a radial turbine of 
 three expansion stages and three subsidiary speed stages, with special 
 regulating apparatus and radial flow, is shown in a diagram of the 
 above-mentioned patent No. 132,868. The preference, however, in 
 this case given to axial flow. 
 
 In the turbine of Fig. 14, the driving steam is sent through 
 the fixed and moving blades very effectively. The widths of the 
 holes and the number of these in the various partitions, as well as 
 the number of expansion and speed stages, are in all cases adjusted
 
 to the requirements in regard to available boiler pressure, number of 
 revolutions per minute, c. 
 
 Fig. 8 shows a similar turbine with five expansion stages, 
 <?ach having three speed stages. 
 
 The action turbine in Fig. 14 is designed for a stationary 
 plant. It will, however, serve just as well for warships and mer- 
 chant vessels. It will give both large and small outputs with high 
 or low peripheral velocities, and will work at the highest pressures. 
 It should be especially noticed that the efficiency of these turbines is 
 not sensibly diminished even when the output and peripheral velocity 
 are small. It is only necessary that, with due consideration to the 
 conditions in each case, the expansion stages be fairly numerous. 
 Under all circumstances, however, Schulz' action turbines will not 
 need more than the minimum number of blades and wheels usually 
 adopted for the purpose in hand, so that the cost of construction is 
 not excessive. 
 
 In the turbine shown in section (Fig. 14) the regulation of the 
 steam in the first expansion stage is effected by a number of small 
 stop valves. In the other expansion stages the steam supply is con- 
 trolled by ring slides, which are placed immediately in front of the 
 groups of nozzles in the partitions (see Fig. 12). Thus the cross- 
 section of the steam passages is suited to the work required. The ring 
 slides may be adjusted by a cogged wheel system, by worm gearing, 
 or by levers. The governor is placed on the free shaft wheel near 
 the stop-valve and the apparatus for moving the ring slides ; these 
 latter are adjusted by a very simple device. The governor can be 
 arranged so as to adjust both the ring slides and the stop valves, or 
 it may be made to act only on the latter. 
 
 The turbine can be divided horizontally into equal halves. 
 It is made of cast iron or cast steel, or, in very small engines, of 
 bronze. The guide wheels or partitions are made of the same
 
 80 
 
 material, and are placed steam-tight in the case. The working- 
 wheels are of steel, accurately turned on the lathe and well balanced. 
 The revolving blades are of delta-metal , and are strongly and simply 
 attached to the wheel ring by a specially contrived method. Com- 
 paratively wide clearance spaces are left between the fixed and the 
 rotating parts, and even when highly superheated steam is em- 
 ployed, no trouble due to the rubbing of the blades against each other 
 or to such like causes can arise. 
 
 Measurements in Mm. 
 (i Mm. 0-03937 ins.) 
 
 Fig. 15. 
 
 Fig. 15 shows the method of attaching the fixed and moving 
 blades in the older turbines of the year 1900. These were dove- 
 tailed into suitable grooves and fixed firmly by a special method
 
 Fig. 16. 
 
 Measurements in Mm. 
 (i Mm. =0-03937 ins). 
 
 Fig. 17.
 
 Such fixing is not effected in the more modern types by the caulking 
 tight of the distance pieces, since it is difficult in this case to avoid a, 
 twisting of the hlades. Besides, if the positions of the blades be 
 altered they cannot be recovered. 
 
 Here also we see the saw-like grooves, which create vortices 
 in the axially flowing steam. These tend to prevent loss at the 
 clearance space between the case and the guide blades and between 
 the latter and the working- wheel. In recent times, however, less 
 stress has been laid on this point. The labyrinth apparatus closes 
 the shaft at its exit from the case. 
 
 In Figs. 16 and 17 are shown the constructions of the older 
 labyrinth stuffing boxes, which closed the shaft of the Schulz tur- 
 bine. These stuffing boxes are extended for a considerable distance 
 along the shaft, so as to make the path of the steam in the labyrinth 
 as long as may be. Fig. 16 shows one of these stuffing boxes, in 
 which the labyrinth is formed by two cylindrical castings fitting into 
 each other with rings screwed to them. The inner casting is 
 fastened to the shaft by means of an arrangement of screws, placed 
 axially. The labyrinths may be thus regulated, so that the spaces 
 left on one side of the rings are as little as 7 lo inch, while those 
 left on the other side are comparatively larger and can serve as steam- 
 chambers. 
 
 Fig. 17 also shows a packing of Schulz' design. Here the 
 stuffing box is composed of a number of well-fitting rings. All these 
 are placed on a common cylindrical casting and are kept in place 
 by a ring at the end. The labyrinths are here formed by the peculiar 
 cross section of the individual rings. Schulz' new labyrinths differ 
 from these types chiefly in the shape of the rings screwed to the 
 casting. 
 
 As in all action turbines, the steam pressure in each expansion 
 stage is the same on both sides of each working-wheel. A consider- 
 able end thrust, such as we find in multi-stage reaction turbines is
 
 34 
 
 in this case impossible. Counteracting pistons and similar devices 
 can, therefore, be dispensed with. 
 
 We see, then, that the new Schulz turbines satisfy all require- 
 ments; they are reliable in working, simple in design, and very 
 economical in use of steam, employing the full available pressure 
 for every variation in the output. 
 
 Many crucial experiments have been made on the two steam 
 turbines mentioned on page 11 (Figs. 1, 18, and 19), which were 
 built in the works of the Germania in Teg el. The second, especially, 
 has been repeatedly tested, both in the workshops and in a boat of 
 19 tons displacement on Lake Tegel, near Berlin. This experi- 
 mental boat was built principally to test the manoeuvring powers of 
 ihe new turbines. In December, 1901, soon after the engine was 
 placed in the boat, it was inspected by His Excellency Admiral ron 
 Tirpitz, Secretary of State for the German Admiralty, and went 
 through all its manoeuvres without a hitch. 
 
 This turbine is shown in Figs. 18 and 19. Fig. 18, which 
 shows the external appearance of the turbine, is reproduced from a 
 photograph taken in the experimental room of the workshop. On 
 the high pressure case may be seen the adjusting appliances for the 
 partitions (Fig. 9). ' Within certain limits, these regulate the steam 
 pressure in the various expansion stages. Mention may also here 
 be made of an indicator appliance, which enables graphic repre- 
 sentation to be made of the pressure in the various expansion stages. 
 In Figs. 21 to 24, several diagrams of this kind are shown.
 
 36 
 
 The apparatus required for this purpose consists of an indicator 
 stop-cock to which a large number of tubes (in this case 15) are 
 attached (see Fig. 20). In Fig. 18 three of these cocks are visible. 
 With each expansion .stage of the turbine one of them communicates 
 by means of a narrow pipe, so that, when its cone is turned SUm- 
 
 g. 20. 
 
 ciently and a simultaneous rotation of the indicating paper cylinder 
 is made, the curves shown in Figs. 21 and 22 are described. The 
 three diagrams of Fig. 22 show that, even when the cross-section 
 of the steam passages is reduced to a sixth of its original size, the full 
 available pressure is employed in the first expansion stage. The 
 abrupt fall of pressure noticeable especially in Fig. 22, II. and III., 
 is due to the temporary throttling of the steam passages in the expan- 
 sion stages in question.
 
 37 
 
 Indicator Diagram, December, 1900. 
 Revolutions per minute=2050. 
 
 i"= 18-67 Ibs. 
 per sq. in. 
 
 Fig. 21.
 
 Indicator Diagram, January 22nd, 1901. 
 
 t\t\3\+\s\e\r\8\\io\it\n\a\Vf\ 
 
 1 Atmosphere=14-7061bs. per sq. in. 
 Fig. 22. 
 
 Grades i-io 
 
 are given J passage. 
 
 1310 revolutions. 
 
 Grades 1,5, and 10" 
 
 are given J passage, 
 
 1440 revolutions. 
 
 Grade i 
 
 is given J passage. 
 1440 revolutions.
 
 39 
 
 Figs. 23 and 24 show the advantages of placing an indicator 
 on a turbine, just as do Figs. 21 and 22. They were drawn from the 
 pressure curves of the high and low r pressure turbines when mounted 
 in the boat and being driven at a diminishing speed. In one case 
 only six passages were open to the steam ; in the other 30. The 
 diagrams show plainly how the pressure diminishes in the different 
 expansion stages as the speed decreases, and it is noticeable that, aa 
 the output becomes smaller, one expansion stage after another at the 
 exit end of the low-pressure turbine ceases to contribute anything to 
 the work done. 
 
 In Fig. 23 six steam passages are open. Of the 30 expansion 
 stages 25 are still in use when the number of revolutions is 890 per 
 minute ; 22 are employed when the number is 770 ; while only 19 are 
 working when the number is as low as 300. 
 
 Fig. 19 gives in section the marine turbine of Fig. 18. The 
 high and low pressure turbines are those given in the patent No. 
 132,868 ; the go-astern engine is that published in the patent specifi- 
 cation No. 135 ,937 (see Figs. 6 and 8) . The details of the design are 
 shown in Figs. 8 to 17. 
 
 The direct turbines of this engine are axial ; the go-astern tur- 
 bine is both axial and radial. The high pressure engine is, for the 
 most part , an action turbine ; in the low-pressure and go-astern 
 engines the reaction principle is employed. The end thrust is elimi- 
 nated by the methods already described. 
 
 The turbine of Fig. 18 is here illustrated in a tenth of its natural 
 size. It weighs, with mountings and fittings, only a little over a 
 ton, and since its output is 230 horse-power, its weight per horse- 
 power is only about 11 Ibs. The case is made of cast iron and ii 
 divided horizontally. The working-wheels are of steel and the 
 blades of the well-known delta-metal. The boat used to test this 
 engine was 59 feet long by 9ft. 3ins. broad, and had a mean draught 
 of 4ft. Sins. The diameters of the various propellers (which were
 
 JO 
 
 r f 
 
 
 Q .9
 
 -11 
 
 d 
 
 CS 4 
 
 I- 1 
 
 -*-> r i ' ^ 
 
 O M 
 
 b g' s 
 
 ll- 
 
 I i 
 
 H
 
 42 
 
 Fig. 25.
 
 49 
 
 Fig. 26.
 
 44 
 
 used both singly and in pairs during the test) varied from 12 to 16 
 inches, while the number of revolutions per minute varied from 1,000 
 to 2,200. The greatest speed was more than 13 knots, the highest 
 average over the measured mile on Lake Tegel being 12'35 knots. 
 No vibration was felt even at the highest obtainable speed. The 
 boat manoeuvred satisfactorily, and the engines worked perfectly 
 throughout the trials. 
 
 The results obtained in the test are given in Table III. 
 
 The economy of this comparatively small turbine may be 
 gathered from the curves of Figs. 25 and 26. Especially at speeds 
 above 11 knots a comparatively low consumption of fuel is noticeable. 
 The abscissae in Fig. 25 represent numbers of revolutions ; these 
 range from 1,000 to 2,500 per minute. In Fig. 26 the abscissae give 
 the number of knots per hour. 
 
 Curve 1 gives the number of revolutions per minute. 
 
 Curves 2 and 3 give the mean peripheral velocities of the first 
 and last working-wheels of the turbine. 
 
 Curve 4 gives the speed of the boat in knots. 
 
 Curve 5 gives the screw-thrust when the boat is moored and 
 the engine is driving ahead. 
 
 Curve 6 gives the same when the engine is driving astern. 
 
 Curve 7 gives the corresponding thrust when the boat is 
 moving. 
 
 Curves 8 and 9 give the work done by the screw when the boat 
 is stationary and when it is in motion respectively. 
 
 Curves 10 and 12 give the steam consumption per hour. 
 
 Curves 11 and 13 give the steam consumption per horse-powei 
 per hour.
 
 45 
 
 The excess pressure of the driving steam at this trial varied 
 approximately from 200 to 213 Ibs. per square inch. The super- 
 heating of the steam was generally about 160 to 180 cleg. F. ; in 
 some cases, however, it amounted to more than 780 deg. F. The 
 vacuum was never more than 9'4 Ibs. per square inch. A better 
 vacuum could not be obtained, owing to the insufficient output of the 
 air-pump. 
 
 When the comparatively small peripheral velocities of the 
 first and last turbine wheels (100 and 165 feet a second) are con- 
 sidered, the results shown by Table III. and by the curves in Figs. 
 25 and 26 must be considered excellent. With an output of 195 
 horse-power and a speed of 2,200 revolutions per minute, only 22 Ibs. 
 of steam per horse-power per hour were used, in spite of the bad 
 vacuum of 9'4 Ibs. per square inch. The brake trials in the Tegel 
 workshop during June, 1901, in which a higher vacuum was at 
 disposal, gave an appreciably larger output. In fact, for every extra. 
 Ib. per square inch in the vacuum, the turbine gave respectively 
 13'0, 13'7, and 15'1 extra horse-power when the numbers of revolu- 
 tions per minute were 2,000, 2,200, and 2,600. Allowing for this, 
 we get an additional output of 240 horse-power when the number of 
 revolutions is 2,200 per minute, while the steam consumed per hour 
 for each horse-power of output is 17'8 Ibs., instead of 22 Ibs. (see 
 Table IV.) 
 
 The steam used during these experiments in the various auxi- 
 liary engines was led into the low-pressure turbine, so that its energy 
 could be completely utilised. The steam consumption in these 
 auxiliary engines is not included ; it was found by special investiga- 
 tions to be about 880 Ibs. per hour. The economy of the turbine is 
 considerably increased if this steam is also reckoned, as in the curves- 
 of Figs. 25 and 26, where the steam consumption for the subsidiary 
 engines is denoted by the shaded portion. 
 
 According to the latest trials of the "Turbinia," fitted with 
 large Parsons turbines, the steam consumption with the highest out- 
 put of 1 ,600 to 1 ,700 horse-power is about 20 Ibs. per horse-power per
 
 46 
 
 hour. It must be noticed, however, that these turbines are appre 
 ciably larger than the Schulz turbines under discussion. Moreover, 
 according to page 193 of "Engineering, 1 ' August 1st, 1903, the 
 velocities of the steam in the first and last blade rings of the Parsons 
 turbine were 150 and 280 feet per second respectively, the number 
 of revolutions being 2,200 and 3,000 a minute. The velocity in the 
 Schulz turbine, on the other hand, was only 100 to 165 feet per 
 second, when the output and speed of revolution were at their 
 maxima. 
 
 The results of Table I. apply to the turbine of Fig. 1 : those of 
 Tables II., Ill, and IV. to the turbine of Figs. 18 and 19. 
 
 TABLE I. 
 EXPERIMENTAL TURBINE No. 1 DRIVING A DYNAMO. 1899. 
 
 Number of Experiment. 
 Boiler pressure .. .. .. .. .. .. 
 
 12345 
 Excess pressures in atmospheres, 
 
 15 15 11 7-4 5-2 
 
 Steam pressure in entrance chamber .. .. 
 Pressure behind first expansion stage 
 Pressure in passage from 1st to 2nd turbine 
 Pressure in middle expansion stage of 2nd turbine. . 
 Number of revolutions per minute .. 
 (Voltage 
 10 1 Current in Amperes 
 (Kilowatts 
 Output l Electric Horsepower 
 
 12 12 10-5 7 5 
 9 8-9 7-8 4-8 3-5 
 2 2 1-9 1-15 0-7 
 0-25 0-25 0-2 
 1700 1400 1200 980 800 
 150 160 100 80 75 
 250 170 200 110 70 
 37-5 27-2 20 S'S 5-25 
 51 37 27-2 11-97 7-14 
 
 The steam turbine weighs, with all the mountings and fittings, about 12 cwts.
 
 
 
 
 2 
 
 s 
 
 
 5 
 
 <h 
 
 00 
 
 ?> 
 
 i 
 
 
 - 1 
 
 
 
 
 
 t 
 6 
 
 5 
 
 o 
 6 
 
 t~ 
 
 6 
 
 | 
 
 
 
 
 ep 
 
 o 
 
 t- 
 
 o 
 
 i 
 
 
 
 2 
 
 o 
 
 
 
 
 o 
 
 s 
 
 j 
 
 to 
 
 
 o 
 
 t- 
 
 
 
 
 
 i 
 
 '& 
 
 
 
 1 
 
 05 
 
 
 
 at 
 
 I 
 
 
 *o 
 
 i 
 
 i 
 
 
 
 iN 
 t~ 
 
 i 
 
 g 
 
 e* 
 
 2 
 
 " 1 
 
 
 
 g 
 
 6 
 
 r- 
 
 s 
 
 
 
 g 
 
 8 
 
 6 
 
 1 
 
 a 
 
 eS 
 
 
 
 
 
 <M 
 
 CO 
 
 T* 
 
 U3 
 
 co 
 
 9 
 
 QQ 
 
 
 
 
 CO 
 
 CT 
 
 5! 
 
 t- 
 t- 
 
 o 
 
 aj 
 
 - 1 
 
 s 
 
 o 
 
 ? 
 
 o 
 
 <?> 
 
 
 
 t- 
 
 6 
 
 *n 
 
 <M 
 t~ 
 
 6 
 
 t~ 
 
 6 
 
 1 
 
 
 9 
 
 CJ 
 
 
 
 <P 
 
 9 
 
 9 
 
 op 
 
 
 o 
 cb 
 10 
 
 CO 
 
 2 
 
 N 
 
 CO 
 
 o 
 
 to 
 
 06 
 
 st 
 
 a. 
 
 - i 
 
 1 
 
 t~ 
 
 cc 
 
 t- 
 
 o 
 
 CO 
 
 t^ 
 
 6 
 
 i 
 
 
 
 f- 
 
 6 
 
 t^ 
 6 
 
 1 
 
 
 2 
 
 d 
 
 1 
 
 <? 
 
 00 
 
 CM 
 
 C5 
 
 >. 
 t'< 
 
 
 \O 
 
 s 
 
 o 
 
 g 
 
 8 
 
 
 
 tp 
 
 "* 
 
 
 ~ _ 
 
 ' 
 
 8 
 
 
 
 O 
 
 1 
 
 6 
 
 8 
 
 t- 
 
 
 
 I 
 
 
 
 
 i 
 ><j 
 
 
 9 
 
 g 
 
 co 
 
 s 
 
 ^f 
 CO 
 
 
 
 
 
 -* 
 
 2 
 
 05 
 
 
 
 1O 
 
 g 
 
 
 
 
 >O 
 
 a 
 
 - 1 
 
 6 
 
 05 
 
 F 
 
 
 
 t- 
 
 6 
 
 t- 
 
 6 
 
 
 i 
 
 
 
 | 
 
 JO 
 
 8 
 
 o 
 
 
 s 
 
 a 
 
 No. of Experiment. 
 No. of Revolutions per Minute. 
 
 Pressure behind main turbine 
 ,, in condenser . . 
 Horse-power . . 
 
 Pressure behind main turbine 
 in condenser .. 
 Horse-power . . 
 
 Pressure behind main turbine 
 ,, in condenser 
 Horse-power . . . . 
 
 Pressure behind main turbine 
 ,, in condenser . . 
 Horse-power 
 
 Pressure behind main turbine 
 ,, in condenser 
 Horse-power .. 
 
 Pressure behind main turbine 
 .. in condenser 
 Horse-power . . 
 
 '$ 
 
 J3 
 
 be 
 "S 
 ^ 
 
 a 
 2 
 
 .5 
 
 3 
 H 
 
 autSua jo jnoaj 
 n; 9jnBS9j,j 
 
 t- 
 
 C3 
 
 1-1 
 
 CO 
 
 'O 
 
 o 

 
 TABLE III. 
 
 EXPEPIJIENT IN THE BOAT WITH TuBHINK No. 2. 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 C 
 
 7 
 
 8 
 
 9 
 
 10 
 
 11 
 
 1-2 
 
 13 
 
 ii 
 
 Mean peri- 
 pheral velocity 
 in feet per 
 second 
 
 Boat's 
 speed 
 in 
 kncts. 
 
 Screw thrust in cwts. 
 
 Output of 
 screw in 
 horse-power 
 
 Hourly consumption of steam 
 in Ibs. 
 
 of I of 
 first ! last 
 
 when stationary 
 
 when 
 
 when 
 station- 
 
 when 
 mov- 
 
 when stationary] when moving 
 
 
 per 1 
 
 per 
 
 
 
 
 
 for- 
 
 back- 
 
 moving 
 
 ary. 
 
 ing. 
 
 Total 
 
 horse- j Total. 
 
 horse- 
 
 
 turbine wheel. 
 
 
 wards. 
 
 wards. 
 
 
 
 
 
 power. ] 
 
 power. 
 
 1000 
 
 46-2 
 
 73-8 
 
 7-4 
 
 7'G 
 
 7-6 | 6-8 
 
 33-7 
 
 28-5 
 
 2380 
 
 70 ! 1950 
 
 68 
 
 1400 
 
 G47 
 
 103-3 
 
 9-1 
 
 13-0 12-1 
 
 10-9 
 
 82-1 
 
 69 
 
 3700 
 
 45 
 
 2730 
 
 40 
 
 1800 
 
 83-1 
 
 132-8 
 
 10-7 
 
 18-5 
 
 16-9 
 
 15-4 
 
 1504 
 
 126-5 
 
 5070 
 
 34 
 
 3500 
 
 27 
 
 2200 
 
 101-6 
 
 102-4 
 
 12-35 
 
 
 
 20-1 
 
 
 195 
 
 
 
 4300 
 
 22 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2300 
 
 
 
 12-6 
 
 
 
 21-2 
 
 
 211 
 
 
 
 4500 
 
 21 
 
 2400 
 
 110-9 
 
 177-2 
 
 13 
 
 
 
 22-4 
 
 
 228 
 
 
 
 4G70 20-5 
 
 Vacuum = 5 of an atmosphere. 
 
 TABLE IV. 
 
 
 l 
 
 9 
 
 12 
 
 13 
 
 per square in. 
 
 No. of Revolutions 
 
 Effective Horse- 
 
 Steam 
 
 Consumption in Ibs 
 
 
 per minute. 
 
 power. 
 
 per hour. 
 
 per horse-power. 
 
 9-4 
 
 
 195 
 
 
 22 
 
 
 2,200 
 
 
 4,300 
 
 
 12-8 
 
 
 240 
 
 
 17-8
 
 49 
 
 After the experiments with the above-mentioned boat had 
 been carried through successfully, Schulz turned his attention to 
 the construction of an engine suitable for all men-of-war, including 
 battleships, cruisers, and torpedo boats. 
 
 Merchant ships, whether they be cargo, passenger, or mail 
 boats, steam steadily at their highest possible speed, except, foi 
 instance, when the weather is rough or foggy. The construction of 
 turbines for such vessels, therefore, offers no special difficulties. With 
 men-of-war the case is very different ; their engines must always be 
 prepared to develop their utmost power, but this output is required 
 but seldom, and then only for short spaces of time. Moreover, in 
 warships it is demanded that the consumption of fuel in proportion 
 to horse-power be the most economical when the output is small or 
 moderate, say from T V to ? of its maximum value. 
 
 The multi-stage marine turbines constructed by Parsons and 
 Rateau use appreciably more coal in proportion to the output when 
 the latter is small, than when it is large. On the well-known sea- 
 going torpedo-boats, "Viper" and "Cobra," the consumption of fuel 
 for small outputs was nearly twice as great as in the sister-ships, 
 "Albatross" c., which were fitted with reciprocating engines. 
 
 Rateau and Parsons before him have combined reciprocating 
 engines with large-sized turbines for use when only a small output is 
 required. Parsons, however, has gone back to pure turbine engines. 
 The steam consumption on the German sea-going torpedo-boat, 
 "S 125," fitted with Parsons' turbines, cannot even yet be accurately 
 determined, the air-pump having at the first series of trials, proved 
 unsatisfactory. Several months were then wasted while the latter 
 was being replaced, and since other mishaps have meanwhile inter- 
 vened to delay the trial trips, it may be still some time before the 
 coal consumption is determined. However, it is fairly evident from 
 the reports on the first trials, that the above-mentioned conditions 
 will not be satisfactorily fulfilled by this engine. 
 
 D
 
 50 
 
 Schulz has now patented another marine turbine (No. 
 160,863; Class 65a ; April 23rd, 1901), which is shown in Figs. 27 
 and 28. This plant is arranged for a single shaft only. In ships- 
 with several screws it is proposed to use one of these engines for each 
 shaft. 
 
 In front of the main turbine a number of turbine wheels are 
 placed, which can also be separated into groups. The steam is cut 
 off from these when the output is large, so as to prevent them from. 
 
 Go-asten 
 Turbine. 
 
 Disconnectable 
 Auxiliary Turbines. 
 
 Fig. '27. 
 
 sharing in the work. The smaller the output, the larger is the 
 number of auxiliary turbines which contribute their share to the 
 work done. When the output is at its smallest, the steam passes 
 through the stop-valve 1 into the turbine d, the remaining stop- valves 
 3,5, 7, being then closed, and the exit valves 2,4,6 opened. When 
 the output is larger, the smallest turbine d is cut off by the closing of 
 the stop-valves 1 and 2, and the steam passes by the valve 3 into the
 
 51 
 
 second turbine c. On further increase of the work the turbine c is 
 also cut off by the closing of the valves 3 and 4 ; and when the output 
 is at its maximum, all the valves 1 to 7 are closed, so that the steam 
 only enters the main turbine a. 
 
 By this arrangement an increasing number of turbines contri- 
 bute their share of work as the output diminishes, so that, owing to 
 the increasing number of expansions, the difference of steam pres- 
 sure in two successive expansion stages is always very small. The 
 initial pressure may, therefore, be so high that the difference between 
 the pressures at the entrance and exit passages respectively of the 
 engine always maintains its maximum value. 
 
 Fig. 28. 
 
 If, then, the auxiliary turbines be of suitable size, the full 
 energy of the steam is utilized, whatever may be the speed, and due 
 economy is observed. 
 
 It is indifferent whether the whole apparatus is enclosed in a 
 single case or whether each separate turbine has its own cover. 
 
 Fig. 28 shows a section of this compound engine. The 
 rotating wheels 1 to 4 are placed on the common shaft 15, and work 
 directly ; the wheel 5 is for motion astern. To regulate the end
 
 52 
 
 thrust the steam flows in opposite directions through the largest 
 turbines (4) and the smaller ones (1, 2, 3). The main stop-valve 7 
 allows the steam for forwards motion to flow through the pipe 10 
 and the valve 11, through the pipes 10 and 19 and the 
 valve 30, or through the pipes 10, 19, and 25, and the 
 valve 26, into the various turbines. The steam for reversing passes 
 through the pipes 8 and 9. The pipe 29 allows steam to pass from 
 turbine 1 to turbine 2. The circular passages, 18, 23, 24, 27, and 12, 
 serve as chests for the steam before its entrance into the various tur- 
 bines ; the passages, 28, 31, 21, and 13, serve as exit chests. The 
 steam is led to the condenser through the pipe 13. 
 
 The Parsons turbine is at present the most popular for marine 
 purposes. It is, therefore, of interest to compare this engine with 
 the Schulz turbine, especially as lawsuits have been brought by the 
 former engineer against the latter for infringement of patent. These 
 lawsuits were decided in favour of the defendant. 
 
 The plaintiff relied chiefly on the English patent, 11,223/97, 
 with which the German patent No. 103,559 corresponds. He 
 maintained that Schulz' arrangement had been already protected by 
 this patent and that consequently Schulz' patent No. 160,863 (Figs. 
 27 and 28) was invalid. 
 
 Parsons' arrangement in the patent No. 103,559 is shown in 
 Pigs. 29, 30, and 31. Though he has made many laborious and costly 
 experiments to get a low steam consumption in both low and high 
 outputs, he has failed, and Schulz was the first to obtain a satis- 
 factory solution of the problem. Parsons subsequently followed in 
 the path already trodden by Schulz.
 
 53 
 
 In Parsons' attack en Schulz' system (Figs. 27 and 28) atten- 
 tion was first called to an article by the naval engineer, Herr 
 Grauert, in the Marine- Rundschau, of January, 1904. Notice was 
 also taken of Grauert's remarks in "Steam Turbines," by Dr. A. 
 Stodola, relating to the economy of steam necessary for warships. 
 
 Fig. 29. 
 
 Now in this article we read : 
 
 "For constant output, the fuel burnt per horse-power is appre- 
 ciably higher at low rates of revolution. If, however, the output 
 and speed of rotation fall simultaneously, the consumption of steam 
 is altered but little."
 
 Fig. 10.
 
 55 
 
 The first of these two statements would be intelligible only if 
 it were, under normal circumstances, possible for the output of a 
 marine engine to remain constant when the speed altered. More- 
 over, it is easily proved that, when output and speed diminish, the 
 fuel consumption, so far from being lessened, is very considerably 
 increased. 
 
 Grauert's diagram is reproduced in Fig. 32. 
 
 Now we must not suppose that in the production of this diagram 
 three equal turbines of 1,500 horse-power were used, working on a 
 single shaft parallel to the boiler. For to use a second and a third 
 engine of 1,500 horse-power directly the required output exceeded 
 1,500 and 3,000 horse-power respectively would be too extravagant a 
 method to be of any practical use. 
 
 . 31. 
 
 The experimental trials on which Grauert's diagram was 
 based were, no doubt, made on a normal stationary Parsons turbine, 
 in which it was possible to alter the rate of revolution without change 
 of output. A very similar diagram is found on page 37 of a paper 
 circulated by Parsons' representatives, "The steam turbines of 
 Brown, Boveri, and Parsons for stationary and marine engines."
 
 CONSUMfTtON Of STEAM n* H P'ei HOVK > * 
 
 (f ffe * 2-2 Let) 
 Fig. 32.
 
 S7 
 
 The curve given here for light load is that used in Grauerfs diagram. 
 It is only applicable to marine engines with uncoupled shafts, and is- 
 worthless for trials of steam consumption on marine engines, so that 
 on this ground also we assume that a stationary Parsons turbine is- 
 ref erred to. If this assumption be correct, the conclusions drawn 
 from the diagram are of value only when applied to the driving of 
 stationary engines, and not in the case of marine engines working at 
 markedly varying speeds. 
 
 In ships' turbines it is impossible to maintain constant output 
 with varying speed of revolution. In such engines the output varies 
 as the cube of the speed of rotation ; for example, if the speed be 
 halved, the output will have only an eighth of its former value. 
 
 Now the diagram shows four outputs of a single turbine for 
 speeds of revolution differing but little from each other. To arrive- 
 at a satisfactory conclusion we must consider the lower speeds also. 
 The diagram, however, has a very different aspect when it is ex- 
 tended so as to cover the smallest ordinary speeds as well as the 
 higher ones. 
 
 It is usual to take 40 % of the maximum for the lowest speed 
 ordinarily employed. Since we may suppose the speed roughly 
 proportional to the number of revolutions in a given time, the limits- 
 to be considered lie between 600 and 240 rotations per minute. 
 
 Now, in a marine engine the output (as mentioned before) 
 varies approximately as the cube of the number of revolutions per 
 minute, and the 600 revolutions per minute necessary for the maxi- 
 mum output of 4,500 horse-power with a steam consumption of 
 73,000 Ibs. an hour (about IG'l Ibs. per horse-power per hour), being 
 taken as a basis, the consumptions for other outputs work out as- 
 given in Table V., here following. We assume that in the diagram 
 an ordinate of 1 mm. represents an hourly use of 1,100 Ibs., or a, 
 consumption per horse-power per hour of I'l Ibs.
 
 58 
 TABLE V. 
 
 Output in horse-power. 
 
 No. of revolutions per 
 minute 
 
 600 
 
 Steam con 
 Per hour. 
 
 sumption. 
 
 Per horse-power 
 per hour. 
 
 4,500 
 
 73,0:0 
 
 16-1 
 
 3,000 
 
 522 
 
 51,800 
 
 17-3 
 
 1,590 
 
 5G2 
 
 415 
 300 
 
 3G,400 
 28,800 
 
 24-2 
 4-2-3 
 
 288 
 
 240 
 
 18,700 
 
 64-S 
 
 Grauert's diagram reproduced in Fig. 32 was extended with 
 the help of this table. The curves thereby added show clearly the 
 great difference of output and corresponding fuel consumption in 
 one and the same turbine for greater and smaller speeds. 
 
 The trials on the well-known "Turbinia," constructed at the 
 Parsons works, have given similar results. Prof. E wing has col- 
 lected these at the instance of the Marine Steam Turbine Company. 
 They were published in a paper read by Parsons before the Institu- 
 tion of Naral Architects on June 26th, 1903, and are given, amongst 
 other matters, on page 185 of the "Marine Engineer" for 1903. 
 Table VI. contains these results. 
 
 TABLE VI. 
 
 Output in horse-power 
 referred to the resistance 
 of the ship. 
 
 *r>,Wi in ' S'eam consumption per 
 knits horse-power per hour 
 in )bs. in kg. 
 
 Steam pressure per 
 square inch 
 in Ibs. in aim. 
 
 98n 
 
 on 
 
 23-7 13-0 
 
 1G2 ll'O 
 
 704 
 
 28 
 
 33-0 15-0 
 
 129 8-75 
 
 325 
 
 20 
 
 41-9 19-0 
 
 72 4-9 
 
 184 
 
 in 
 
 52-5 23-8 
 
 47 3-2 
 
 90 
 
 13 
 
 68-3 31-0 
 
 29 2-0 
 
 31 10 88-2 40-0 
 
 13 0-9
 
 . ( 7 ATAt.= /+ . ?JLBS. f* S tN. ) 
 
 Fig. 33.
 
 60 
 
 In the last column of this table is given the initial pressure 
 of the steam at its entrance into the turbine. We see that when the 
 output is at its minimum the steam must be throttled below atmos- 
 pheric pressure before it finds its way into the engine. This explains 
 the great losses of steam sustained by these turbines as their output 
 diminishes. Fig. 33 gives the results of Table VI. in graphical form. 
 Comparison of Figs. 32 and 33 show r s the similarity of the two- 
 Parsons turbines, and proves that when they are used for ships the 
 steam consumption increases considerably as the work done per 
 horse-power per hour diminishes. 
 
 It is now quite evident without further explanation, why the 
 torpedo-boat destroyers "Viper" and "Cobra" consume nearly twice 
 as much fuel on an ordinary voyage as their sister-ships "Albatross," 
 &c., which are fitted with reciprocating engines. The turbines of 
 the "Viper" and "Cobra" are shown in Fig. 30 (Fig. 2 of the patent 
 Xo. 103,559). Since it was mainly on this patent that Parsons relied 
 in his lawsuit against Schuh, it is sufficiently shown that it is not by 
 this method that we can solve the problem of securing the same 
 economy with small outputs as with large ones. 
 
 Parsons also has recognised the fact that the arrangement of 
 his patent Xo. 103,559 cannot bring much success. This is evident 
 from the circumstance that he had recourse to reciprocating engines 
 for slow speeds. This system was protected in the English patent 
 16,551/1900, but also proved a failure. The German Naval Adminis- 
 tration, for example, was averse to a composite system, and Parson t 
 then had recourse to detachable turbines en the Schidz pattern. 
 
 S chitl z had patented his system in England on April 23rd , 
 1901. Soon after the publication of the patent specification 
 (8,378/1901), Parsons, on August 7th, 1902, brought out the Eng- 
 lish patent 17,391/1902, which relied on the principle of small detach- 
 able turbines for ordinary voyages, similar to those in Scliulz' pre- 
 vious patent, 8387/190]. Parsons' only alteration was the intro- 
 duction of additional steam into the individual turbines, by which he
 
 61 
 
 obtained a better graduation of the output while sacrificing the 
 advantage of greater economy. 
 
 It is true that Parsons described in his patent, and fitted in the 
 German torpedo-boat " S 125," and in the English cruiser" Amethyst," 
 a system in which the smallest turbine is cut off during fast voyages 
 
 Turbines 
 
 for 
 Full Power 
 
 Disconnectable 
 
 Auxiliary Turbines 
 
 for Low Powers. 
 
 Fig 34. 
 
 and the steam led directly into the second turbine (Fig. 37). In 
 this he followed the Schulz system. He failed, however, to notice that, 
 owing to the distribution of auxiliary turbines adopted, the outer 
 shafts communicated very unequal amounts of energy to their screws, 
 and that, consequently, the system is quite unsuited for marine 
 purposes.
 
 62 
 
 These considerations quite dispose of Parsons 1 statement,, 
 that he had by the method of his former patent No. 103,559, practi- 
 cally solved the difficulties arising from the varying rates of speed at 
 which marine turbines must work. This will be still clearer if we- 
 submit the specification of the patent to a searching examination. 
 
 Fig. 35. 
 
 We can only obtain the maximum economy with a turbine r 
 or with a combination of turbines, when the expansion of the steam 
 from the boiler to the condenser has a considerable range, and when 
 the current in the turbine flows without discontinuous changes of 
 pressure. For this purpose we must give a suitable succession of 
 cross-sections to the passages by which the steam is led from its 
 entrance into the first turbine to its exit into the condenser. To-
 
 68 
 
 emphasize the difference between Schulz' and Parsons 1 turbines, we 
 reproduce a number of diagrams in which, for the sake of clearness , 
 all the turbines of the plant are placed side by side. The diagrams- 
 are only intended to show the variation of pressure as the steam 
 passes through the turbines, and make no claim to accuracy in detail. 
 
 Fiji. 36. 
 
 From Fig. 34 it is quite clear that Schulz' system satisfies the above- 
 mentioned conditions. As we pass from the maximum output to a, 
 lesser one and so down to the minimum, we are continually adding 
 smaller and smaller turbines. In all cases the steam passes at its- 
 boiler pressure into the foremost of the additional turbines, and 
 undergoes a continuous and complete expansion as it passes through 
 passages of continuously increasing cross-section.
 
 64 
 
 Now we cannot construct a turbine plant in such a manner that 
 .at every speed all the working- wheels contribute to the expansion 
 of the steam. It is usual to secure the most favourable case when 
 the output is at its maximum, as is apparent from the diagrams. As 
 the output is lessened, an increasing number of turbines at the con- 
 denser end cease to share in the work. This is, however, inevitable, 
 and does not affect the general principle, that increase in the number 
 of turbines should accompany decrease of output. 
 
 Parsons has attempted to secure an economical use of fuel ;it 
 till speeds by a redistribution of the turbines, but has only actually 
 attained this in those cases which in Figs. 35 and 36 are num- 
 bered I, VI, and VIII. All the remaining arrangements fail to 
 secure a continuous expansion of the steam. It is apparent from the 
 patent specification that Parsons also, for small outputs, sends the 
 steam through all the turbines one after another, but it appears that 
 for larqe outputs he also sends it through all the turbines by a route 
 that is several times as long. If we consider first of all the method of 
 Fig. 35, we see that, on plotting the fall of pressure, we get a normal 
 curve only when all the eight turbines are placed in series. In II. 
 the turbines B and D hardly contribute any share to the output, 
 while between A' and B' and also between C ; and D' we have an 
 exceptionally large fall of pressure without any corresponding per- 
 formance of work. Fig. 36 shows the decrease of pressure due to the 
 arrangement of Fig. 30 (Fig. 2 of Parsons' patent). This is the 
 system fitted on the "Viper" and "Cobra." If we assume that the 
 turbines work satisfactorily when connected in parallel (Fig. 36, 
 VI.), this can no longer be the case when all four of them are con- 
 nected in series to suit small outputs. The turbines A and D then 
 -do hardly any work a fact which explains the large coal consump- 
 tion of these vessels. Consideration must, moreover, be given to the 
 above-mentioned inequality in the distribution of the work. 
 
 Similarly, Figs. 36, VIII, IX, and X, prove that the system 
 of Fig. 31 (Fig. 3 of the patent specification) is economical only when 
 Jthe turbines are connected in series.
 
 65 
 
 Except, then, in the case of the distributions I, VI, and 
 VIII we cannot obtain a gradual fall of pressure by any of the 
 methods of the patent No. 103,559. The steam passages leading 
 from the boiler to the condenser will not have properly graduated 
 cross-sections, and the division of work among the screw shafts will 
 be so uneven, that the distribution methods described in the patent 
 specification cannot possibly produce a plant that will be economical 
 at all speeds. 
 
 For the principal turbines of a plant on the Schulz system 
 (Fig 34) intended to drive a large-sized man-of-war, from 60 to 90 
 working- wheel blade-rings are necessary. The number of rings in 
 the auxiliary turbines depends on the smallest output required. In 
 most cases a distinctly larger number of rings is necessary for the 
 auxiliary than for the main turbines. If we have found the number 
 of blade-rings required in the principal turbines, and also the number 
 in the other turbines suitable for the smallest reasonable speed of 
 working, we can evidently get every possible speed that lies between 
 the maximum and minimum limits. We have only to determine 
 how best to group the blade-rings of the auxiliary turbines so that 
 the various speeds may be obtained with the greatest economy. 
 
 In Fig. 34 is shown an arrangement of this kind with three 
 detachable turbines. For the smallest output all three groups of 
 blades are employed. The steam passes through each in turn, then 
 through the main turbine, and so on, into the condenser. It may 
 happen that the steam has expanded completely before it has passed 
 the last blade-ring. This last ring will then turn in the vacuum 
 without performing work, but the slight disadvantage connected 
 therewith is inevitable
 
 66 
 
 If a greater output be required, the first auxiliary turbine is 
 cut off, and the steam enters the second one. For still higher out- 
 puts only one auxiliary turbine is used, and for the maximum only 
 the main turbine. 
 
 By this means we can get the best result at every intermediate 
 speed, provided we know how to determine the total number of rings 
 necessary for the smallest output required, and how to divide them 
 properly into the various groups. 
 
 If, now, an output having the highest possible economy be 
 desired for only one or two given speeds besides the maximum, it is 
 natural to apply the Schulz system only so as to satisfy these require- 
 
 Fig. 37. 
 
 ments and to pay no attention to the intermediate outputs. This, 
 however, in no way detracts from the merits of the new method of 
 working, the inventor of which is Schulz. 
 
 It is, moreover, a matter of complete indifference, whether his 
 auxiliary turbines are mounted on the same shaft as the main tur- 
 bine, or whether they are distributed over several different shafts and 
 connected by pipes of greater length. Schulz has given due con- 
 sideration to such arrangements, and has applied for further patents.
 
 67 
 
 After the publication of Schulz' new system, Parsons, as 
 mentioned above, employed similar arrangements. For instance, 
 in a French torpedo-boat he placed a turbine for ordinary voyages in 
 front of the main turbine, and in the English cruiser "Amethyst" 
 and the German torpedo-boat "S 125" he built a similar auxiliary 
 turbine in front of the main turbine of each of the outer shafts. 
 
 Fig. 37 shows this arrangement. The two auxiliary turbines 
 are denoted by 1 and 2 : the three main turbines by 3,4,4. When 
 the output is at a minimum, the steam goes from 1, through 2, to 3. 
 Then it is divided and passes through 4 and 4. If a larger output be 
 required, Parsons, following Schulz' method, cuts out 1, and sends 
 the steam directly into 2, and thence, by way of 3, to 4 and 4. 
 
 Fig. 38. 
 
 For turbine plants with four screw shafts, Parsons solves the 
 problem in a similar manner. Fig. 38 shows the system adopted on 
 the small German cruiser "Lubeck." The usual voyage speeds of 
 this vessel are 11 and 19J knots per hour, corresponding with out- 
 puts of 1,400 and 7,000 horse-power respectively. 
 
 When the smaller speed is required, the steam passes first 
 into the auxiliary turbines 1 and 2, placed on the two inner shafts in 
 front of the corresponding main turbines. On leaving 2 it is divided 
 and passes through the main turbines 3 and 4 on one side of the ship 
 and 3' and 4' on the other side. For high speeds and for some of
 
 68 
 
 the intermediate ones 1 and 2 are cut off, and the steam passes 
 directly into 3 and 3'. 
 
 In all these cases, Schulz' new principle of detachable turbines 
 is adopted, but only to a limited and, therefore, imperfect extent. 
 
 Moreover, both the plants of Figs. 37 and 38 give rise to un- 
 even and asymmetrical distributions of the work amongst the shafts. 
 Besides, in the system of Fig. 38 the central partition-wall of the 
 ship is pierced three times by steam pipes, including one pipe for the 
 go-astern engine. This interdependence of their two sides is cer- 
 tainly unfavourable for the working of the engines. 
 
 We have shown that m Schulz' Marine Turbine (Patent No. 
 168,863), there is a continuous fall of pressure and, therefore, a per- 
 fect use of the available energy under all possible circumstances. In 
 Parsons' system, on the other hand, this is only true for certain 
 special cases. Schulz' method certainly gives the surest solution of 
 the problems connected with the turbine engines of war and mer- 
 chant vessels. 
 
 When the output of a reciprocating engine alters, the economy 
 does the same, for it diminishes with diminishing output. The 
 same is true in steam turbine engines also. 
 
 Machines for stationary plant almost invariably work at speeds 
 bearing constant ratios to the different outputs. These ratios vary 
 within narrow limits, being mostly either 1 : 2 or 1 : 4. On this 
 speed of working the economy of stationary engines chiefly depends. 
 The case is different with marine engines, and especially with those 
 of men-of-war. Here the speed may vary from the maximum down 
 to the 1/1 5th part of it,
 
 69 
 
 In steam turbines the cross-section of the steam passages is 
 made just large enough for the highest output, i.e. , for the maximum 
 consumption of steam. When the work to be done is smaller, these 
 passages are much too large. Since a resort to throttling is here 
 necessary, the steam pressure in the first expansion stage must fall 
 abruptly, and waste of energy is always the result. Now Schuh 
 has. above all things, secured the maximum of efficiency at different 
 speeds by dividing the whole turbine complex into detachable por- 
 tions and by passing the steam into these various turbines in such a 
 manner that a state of expansion is always present. When the out- 
 put decreases, an increased number of turbines or turbine drums come 
 into play. For the minimum of work all the turbines share in the 
 propulsion. 
 
 The paradoxical nature of the arrangement makes it the less 
 surprising that this device should have escaped the notice of the 
 earlier designers of marine turbines, Parsons and Rateau. Schuh 
 was the first to perceive that here was the means of obtaining a 
 steady fall of pressure. 
 
 Now it is in general true, that every turbine makes the maxi- 
 mum use of the energy supplied to it only at one particular peripheral 
 velocity and rate of steam flow. Schulz has accordingly chosen the 
 number of expansion sta.ges, the blading, and the cross-section of 
 the steam passages in the individual turbines to suit a certain mean 
 speed of flow. Since the elasticity of the steam has also to be con- 
 sidered, the loss of economy is very slight, even if the rate of flow 
 vary within small limits. The number of auxiliary turbines neces- 
 sary for maximum economy during manoeuvres can only be deter- 
 mined by experience. 
 
 The Schulz turbine works at every speed with nearly constant 
 boiler pressure. If its speed is to be reduced, the number of the 
 auxiliary expansion stages is increased and the rate of flow of the 
 steam becomes smaller, because the latter has to go through turbine?
 
 71 
 
 with passages of small cross-section before it passes into the main 
 turbine on its way to the condenser. The speed of the turbine 
 decreases as the number of the expansion stages is increased, and 
 extravagance in fuel is thus avoided. 
 
 Now, it is impossible to secure an absolutely perfect use of 
 steam at every speed. 
 
 If, for example, the main turbine be so designed that the 
 steam will , at the highest output , already have reached the condenser 
 pressure at its exit from the last expansion stage, it is inevitable that, 
 when all the auxiliary turbines are used, the last blade rings of the 
 main turbine should rotate without performing work. 
 
 In fact, the condenser pressure is attained before the steam 
 leaves the main turbine ; for it is impossible so to arrange the blading 
 and the cross-sections of the passages that all requirements are satis- 
 fied at both high and low pressures. If, at the smallest output of the 
 plant, the last few expansion grades be ineffective, the uselessly 
 revolving hindmost blade rings waste work in unnecessary ventila- 
 tion, and the amount of this must be deducted from the effective 
 output of the engine. The loss is, however, small, owing to the 
 fact that the condenser pressure is always low, and it also becomes 
 less as the rate of steam consumption diminishes. 
 
 We have shown that the Schulz turbine system possesses the 
 following essential advantages for marine use : 
 
 1. The maximum of economy at all speeds. 
 
 2. High pressure of the steam on its entrance into the tur- 
 bine at every speed.
 
 72 
 
 3. Powerful and prompt action in reversing. 
 
 4. The regulation of the end thrust exerted on the shaft by 
 the steam and by the propeller respectively. 
 
 5. The combination of action and reaction turbines in one 
 system. 
 
 6. The division of the whole plant into several detachable 
 portions, so that a steady expansion of the steam is always attained. 
 
 7. The simple and convenient arrangement of the various 
 valves. 
 
 8. An even distribution of the work over the different shafts. 
 
 9. Economy in space and weight in comparison with other 
 systems (Figs. 39 to 43.). 
 
 In Figs. 39 to 43 a comparison is made between the space re- 
 quirements of the best known turbine systems. The diagrams show 
 the plans and elevations of these turbines on a scale of 1 to 100. The 
 outputs range approximately from 500 to 600 horse-power in the 
 cases of Curtis' turbine and Schulz* reaction turbine from 500 to 
 800 horse-power. The speeds of revolution are from 2,000 to 3,000 per 
 minute. This comparison shows that the Schulz turbine econo- 
 mizes space to a considerably greater degree than do those of the 
 other systems. 
 
 The patent specifications bear reference to the further 
 development of the action turbines, as well as of 
 the reaction turbines on the Schulz system and to the distribution of 
 the turbines, in a compound engine, over several shafts.
 
 73 
 
 In this, special attention is paid to the simplicity and con- 
 venience of the levers which control the cutting off of the various 
 auxiliary turbines during manoauvres. 
 
 Unlike many other inventions on the domain of steam tur- 
 bines, the Schulz system has a firm foundation in the extensive 
 practical experience of its designer. It is to be greatly desired that 
 these turbines be soon brought into competition with those of other 
 types ; their success will then not be long delayed.
 
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