ORNIA AGRICULTURAL INSION SERVICE ULAR 139 SEPT., 1947 ELECTRIC ign^i John B. Dobie F AGRICULTURE FORNIA • BERKELEY The Electric Hay Hoist Offers Many Advantages over the Old Method of Hoisting by Horse or Tractor: • It is faster to operate and easier to handle. • It is safer, because the man with the trip rope is usually in complete command of the operation; fewer signals between workers are necessary. It offers more positive control of the hoisting system. • It is inexpensive to operate, since its low power consump- tion of i to 2 kilowatt hours per hour averages approxi- mately 3 cents an hour. • It frees the tractor operator to go for another load— if a buck rake is used, and if the haul is less than a half mile- while the man at the hay fork hoists the first load into the barn. • It eliminates the need of a long driveway on which to pull the cable. • It is a compact unit, and can be used for other hoisting jobs around the farm. This publication is the seventeenth in a series reporting results of investigations conducted by the California Agricultural Experi- ment Station in cooperation with the California Committee on the Relation of Electricity to Agriculture. THE ELECTRIC HAY HOIST JOHN B. DOBIE 1 The electric hay hoist efficiently replaces the horse or tractor in elevating hay into the barn or onto a haystack. Its use is increasing, for it is fast, safe, simple in mechanism and operation, and reasonable in first cost and operating cost. It is a labor-saving device which frees the horse or tractor for use else- where in the haying operation. The hoist can be used in either small or large haying operations, with long hay or baled hay, but it has little place in a chopped-hay type of operation. The many farmers who continue to harvest and handle long hay, either by choice or through necessity, can use it to ad- vantage. The Hoist Has Three Primary Parts The hoist consists primarily of a drum, a clutch, and a power unit. The drum is a cylinder, 6 to 9 inches in diameter, 15 to 24 inches long, with flanges on each end 16 to 20 inches in diameter. The drum should hold about 50 feet more cable or rope than is required to run the length of the barn, plus double the height of the hay track from the ground. The rope or cable is wound on the drum, which is driven by belt, gear, or chain from the power unit through a clutch. A friction clutch— usually a cone or a band type— is used, since the drum must be free to rotate during the pullback operation. Cone clutches are nor- mally hardwood blocks which engage by friction against steel. Four to six hardwood blocks fit against the cone-shaped steel surface on the end of the drum, the blocks being forced against the steel by a handle-and-cam arrange- ment. The band type of clutch utilizes an internal ring faced with asbestos brake lining. To drive the drum, the ring is expanded, forcing the lining against a steel outer ring attached to the flange on one end of the drum. Most hoists have some form of brake to hold the drum in an emergency, or where the particular hoisting operation may require holding the load sta- tionary in midair. This brake is usually an external brake band operating through friction with the outer surface of one of the end flanges of the drum. It may be either automatic or manual, but the manual type is more positive in action than the automatic. A hoist may be equipped with a pullback drum for returning the fork or slings to the load. This is a small auxiliary drum, 3 to 5 inches in diameter and the same length as the hoisting drum— 15 to 24 inches— with flanges 8 to 12 inches in diameter. The same type of clutch is used on this as on the main drum, except that it may be designed for a lighter load. The auxiliary drum is mounted parallel to the other drum, is driven from the same gear, but 1 Associate in the Experiment Station, Division of Agricultural Engineering. [3] 4 CALIFORNIA AGRICULTURAL EXTENSION CIRCULAR 139 requires an additional handle for its control. This drum must be capable of holding as much pullback rope as needed to extend the length of the hay track. Another attachment sometimes used is an anti-backlash device. This usually consists of a small brake band attached to a lever which is controlled by the tension on the hoisting cable or rope. When this cable is under tension, either in hoisting or during the pullback, the brake is held off the drum. As soon as the tension is released, the brake drops onto the flange of the drum and stops the drum. This action prevents the cable from unwinding and becoming tangled. A multiple V-belt drive of four B-section or three C-section belts is recom- mended for electric-motor-driven hoists. The belts may run on a flat pulley on the hoist shaft. A flat belt may be used, but it is more likely to slip, espe- cially when subjected to a heavy load. Slipping may be quite serious if the hoist is not provided with a brake of sufficient capacity to handle any emer- gency. The rope speed, when hoisting, should be 100 to 150 feet per minute. The hoist must have a capacity of 1,200 to 1,500 pounds lift on a double line. A 6-inch hoisting drum should turn about 64 revolutions per minute. The speed of the rope on the return may be 175 to 200 feet per minute. Types of Hoists Used Most Often Single-Drum Hoist. This type consists only of the hoisting drum, with either a counterweight or a manual-type pullback for returning the hay carrier to the end of the track. The unit usually has a clutch and a brake to improve its operation, except for the reversible-direction hoist, on which the clutch and sometimes the brake are eliminated. The counterweight pullback system is described in more detail in a later paragraph. This system provides an automatic return of the hay carrier and fork to the outer end of the hay-carrier track, when the hoist clutch is dis- engaged or the drum is rotating backward. It does not have sufficient power to return the carrier and fork until after the load of hay has been dropped. It acts against the hoist only when the load is traveling along the carrier track, and is controlled by the hoist lever, operating when the lever is placed in the neutral position. The single-drum hoist with a counterweight pullback is a very satisfactory combination. For barns less than 50 feet in length, the cable is sometimes hand-pulled back by the trip rope. However, this practice defeats the purpose of the electric hoist in that it slows down the operating cycle and does not eliminate the most tedious part of the old method of hoisting by tractor or horses— pulling back the cable by hand. This hoisting drum and manual-type pullback com- bination is the simplest and most inexpensive of all installations, but is also the least satisfactory. Double-Drum Hoist. This type hoist, pictured on the cover, is commonly made commercially. Here, the safety guards, which are essential, have been ELECTRIC HAY HOIST 5 removed temporarily. The double-drum hoist includes both the hoisting and return drums and the clutches, plus either a manual or an automatic brake. It is a popular hoist, having the advantage of positive pullback which, in turn, provides positive control in either direction regardless of the position of the load. It has the disadvantage of an extra rope in the working area for pullback. Operation of this unit requires the handling of two levers, or of two ropes if controlled from the point of loading of the fork. When the fork is being returned to the load, difficulty is sometimes experienced in handling both the ropes and the fork. Reversible Hoist Used for Special Work This type of hoist, whose increased cost totals approximately $200 to $250, is seldom used; then, only for special applications requiring reversible direc- tion due to loading during both hoisting and return. It is found in various forms among home-made hoists, one of the most satisfactory of which is a drum connected direct to a speed-reducing gear three-phase electric motor. This is a compact unit which may be mounted in an out-of-the-way place in the barn and controlled electrically by push button. The push button is con- nected through a reversing switch, enabling the operator to control remotely the direction of rotation of the hoist drum. For a 6-inch diameter drum and TRACK SUPPORT PULLEY HOIST CABLE PULLBACK CABLE Fig. 1.— Cable hookup with counterweight pullback for putting hay into barn. CALIFORNIA AGRICULTURAL EXTENSION CIRCULAR 139 TRACK SUPPORT "At I S^> r, TO HOIST o WEIGHT •HOIST CABLE PULL BACK CABLE Fig. 2.— Cable hookup with counterweight pullback for removing hay from barn. a motor speed of 1,750 revolutions per minute, the gear reduction must be about 27 to 1 to obtain a minimum cable speed of 100 feet per minute. Ex- perience has proved that this gear reduction, plus the friction of the carrier pulley, is nearly sufficient to hold a load of 1,000 pounds of hay suspended in midair. Thus, a brake is not necessary with this unit. A counterweight pullback is necessary with the reversible hoist, which must rotate in reverse direction for the pullback to operate. After the carrier reaches the end of the track, the hay fork is sufficiently heavy to descend to the ground by gravity when the hoist is rotating backward. One advantage of this system is the ease with which the cable hookup may be reversed to take hay out of the barn. It is also useful in serving a long barn with a hay door at each end. By locating the hoist in the top center of the barn, one unit will handle both ends of the barn. Figure 1 shows the cable arrangement for putting hay into the barn. Figure 2 indicates the changes in cables to remove hay from the barn. How the Cable Is Installed The cable hookup, an example of which is shown in figure 3, is much the same as that used for any other method of hoisting by cable. The cable con- nections of the hay carrier and to the pulley at the far end of the hay track, are the same as those normally used. From the hay carrier, the cable is con- ELECTRIC HAY HOIST 7 nected through a sheave at the far end of the hay-carrier track, across to one side of the barn mow, back along that side of the mow, and down to the hoist. At each turn, the cable is run through a sheave or a snatch block. The last sheave must be in line with the center of the hoist drum to prevent the cable from running off the drum. Cables should be located so -that they will not be above the working area of the hay mow or stack except directly under the hay track. The greater strength of cable, for its size, makes it preferable to rope for hoisting. hay S£^SAR«'£R Hay ****** Fig. 3.— Barn showing arrangement of cables for electric hay hoist. The pullback rope may be attached either to the hay carrier or to the hay fork, although the former is usually preferred. When attached to the hay carrier, the pullback rope is fastened to the hay carrier and is threaded through a sheave hung at the extreme outer end of the hay-track support and from there to the pullback. If a pullback drum is being used, another block is usually necessary to guide the rope onto the drum. This block must be so located that the rope will be held out of the way of an incoming load of hay. In some cases this may be provided by a stake driven into the ground. Since the stress on the pullback is relatively low, rope may be used. This hookup returns the carrier to the end of the hay track and from there, the fork descends to the ground by gravity. When the return rope is fastened to the hay fork, the sheave at the end of the hay-carrier-track support is eliminated. The rope runs directly from the hay fork to the snatch block and then to the hoist. This system returns the 8 CALIFORNIA AGRICULTURAL EXTENSION CIRCULAR 139 hay carrier to the end of the hay track and then pulls the fork to the ground. Two disadvantages tend to limit the use of this system: first, the pullback rope drags on the hay door of the barn, causing undue wear of the rope; and second, any fouling of this line during the hoisting period will result in a direct downward pull on the hay fork, causing the fork to dump unexpectedly. For hoists mounted in the peak of the barn roof, the hoisting cable is con- nected directly from the hay carrier to the hoist drum. For the return of the carrier and the hay fork, a counterweight-type pullback must be used. As previously mentioned, this type of carrier return may also be used in place of the pullback drum on other types of hoists. It is a complete cable hookup, independent of the hoist, in which the cable is connected to the hay carrier and through the sheave at the extreme outer end of the hay-track support. From there it goes to a vertical block-and-tackle arrangement, shown in figure i, in which the top multiple block is stationary and the lower pulley is sus- pended and weighted. The vertical pulley arrangement must contain slightly more rope in its extended position than the length of the hay-carrier track. In an extremely long or low barn, more sheaves may have to be added to the blocks, increasing the number of turns of rope. The vertical pulley arrange- ment may be located out of the way in a corner of the barn, under the over- hang of the roof at the end of the barn, or in a near-by tree. The weight varies in size with the friction in the hoisting cable system and the length of the barn, and is just sufficient to pull the hay carrier back to the end of the hay track when the hay fork is empty. This plan depends on gravity for return of the fork from the carrier to the ground. Use an Electric Motor for Power The electric motor is the most satisfactory power unit for a hay hoist. Either a single-phase or a three-phase electric motor is satisfactory, but the three- phase motor is preferred. Most hoists require a two- or three-horsepower motor, although some may take five horsepower. Motor sizes are recommended by the manufacturers of all commercial hoists. A reversing switch is used with a three-phase motor for the reversible hoist previously described. A magnetic thermal overload switch is recommended for all hoists. If the hoist is mounted permanently, the switch and motor should be wired in rigid conduit, with proper size wire for the particular installation. Where the hoist is to be used in several locations, the hoist, motor, and switch should be mounted on a solid frame and should be moved as a unit. A plug-in re- ceptacle should be wired to each location where the hoist may be used. The motor switch may then have a heavy cord and plug to facilitate connecting at each location. For the reversible-type hoist, the switch should be mounted near the motor and a permanent line run in rigid conduit to the end of the barn near the hay door. An extension cord, with push-button control, may then be connected when the hoist is in use. ELECTRIC HAY HOIST 9 Power consumption for a three-horsepower hoist will not exceed 2 kilowatt hours per hour of- operation, which, at an average cost of 2 cents per kilowatt hour, will be a maximum of 4 cents per hour of operation. Locate the Hoist to Meet Specific Need The location of the hoist with respect to the barn varies with each installa- tion. An arrangement such as is shown in figure 3 is usually satisfactory. Here, the hoist is located near the hay-door end of the barn to facilitate operation. In this way, the man operating the fork or the slings can also operate the hoist. To save steps, the hoist handles may be operated remotely by ropes through pulleys. Remote control requires an automatic brake for safety. Where the manual-type brake is used, the operator should be within reach of the hoist in order to operate the brake when necessary. For use in more than one location or for other types of lifting, it is best to mount the hoist and motor on a heavy frame which may be moved as a unit. This frame may then be fastened down in any location needed, and, if de- sired, may be mounted on wheels. Since the hoist is subject to a considerable amount of strain while in operation, it must be fastened securely. When the hoist is to be used in one location only, it should be mounted permanently to a solid base capable of withstanding the pull of the load on the hoisting cable. Under these circumstances, the hoist and power unit should be located inside the barn, if possible, where they will be protected from the weather. Hoists controlled by electric push button are often mounted on a platform which is suspended from the barn-roof framing to a position just below the hay-carrier track. Hoists so controlled must be located beyond the farthest point to which a load of hay may be carried on the track. How to Operate the Hoist When hay is hauled to the barn with buck rakes, slides, or dump trucks, the hay-fork operator works on the ground. He has the choice of operating the hoist by ropes or by walking back and forth between the hoist and the point of loading of the hay fork. If slings are used, so that a large load may be picked up by the hoist, fewer trips are necessary, and direct hand operation may be preferable. When hay forks are used, smaller loads are hoisted each time, and more trips are necessary. To reduce footwork, ropes are used to control the hoist handles. In using hay forks, the operator often finds it necessary to guide the fork, as tension is taken up in the cable, but this cannot be done if he is at the hoist. It is usually more satisfactory to use one or more ropes to control the hoist since their installation does not keep the operator from manipulating the hoist directly. Figure 4 shows a load of hay being hoisted into the barn, with ropes being used to operate the hoist. 10 CALIFORNIA AGRICULTURAL EXTENSION CIRCULAR 139 Fig. 4.— Hay being hoisted into barn with electric hoist. ELECTRIC HAY HOIST 11 The cycle of operation consists of setting the fork, hoisting the hay into the barn, dumping the load, and returning the fork to the ground. The time re- quired to complete this cycle varies with the type of fork used; there is a considerable amount of variation in fork-setting time. With a loose-tined grapple fork, the fork-setting time is about equal to the time required to complete the rest of the cycle. The Jackson or the harpoon-type forks cut the fork-setting time in half. However, when hay is very dry, these forks will not pick up so much per trip, and therefore require more trips per wagon load. When one man is working alone from the top of a wagon load of hay, the hoist must be operated by ropes. However, since the driver of the wagon or truck is usually idle while the hay is being unloaded, he can assume direct operation of the hoist and, in this way, speed up the entire process. The Jack- son fork or the harpoon fork is easier to handle on top of the load than the other types of forks. Maintenance Is Simple but Important After the clutch is worn in and the usual adjustments are made, there is little to be done in maintaining a hoist in good operating condition. The hoist bearings will require frequent lubrication, and the bearings in the elec- tric motor should be checked for oil supply. An occasional check should be made to keep all bolts tight and to maintain proper belt tension. The motor and hoist should be kept reasonably free from loose hay or other material which might hinder proper operation. Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914. B. H. Crocheron, Director, California Agricultural Extension Service. 10m-9,'47(A5032)