Patent GB-479600-A (GB)
Title: Improvements in or relating to conveying apparatus
IPC: B66B9/10
Filed: 1936-08-06
Abstract: 479,600. Ammunition hoists. GENERAL HYDRAULIC CO. Aug. 6, 1936. No. 21649. Convention date, Aug. 10, 1935. [Class 92 (i)] [Also in Group XXX] A conveyer system for ammunition comprises loading and unloading platforms spaced from one another, means for driving the conveyor in either direction, and means responsive to the presence or absence of loads at said loading and unloading stations for controlling the starting and stopping of the conveyer. In the construction shown in Figs. 1 and 2 an endless hoisting chain C having load platforms or steps 2 is driven with a step-by-step motion by an hydraulic motor 3 through a shaft S, the motor being stopped automatically as soon as the chain has moved through the distance from one load step to the next. Upper and lower unloading points B, A are provided, and the chain may be driven in either direction so as to raise or lower shells 22 or other loads. The motor 3 is driven by a pump 5 through a control valve unit 4, the direction of rotation being controlled by a hand lever 7, and the starting and stopping by two valve levers 8, 9 respectively connected by rods 13, 10. to levers 14, 12 adapted to be engaged by the loads 22 at the loading points A, B. The control valves are so arranged that the motor 3 can only be started if one of the levers 12, 14 is pressed " in " by a load at the corresponding point B or A and the other lever is " out,", i.e. there is no load at the corresponding point ; further, even then the motor can only be started in the direction which takes the load at A or B, as the case may be, to the other point B or A. If there are loads at both A and B, or if there is no load at either A or B the motor cannot start. A load can only be placed on the step or platform 2 at A if pivoted guards 17 are moved aside, preferably by a pedal 23. This movement also actuates two levers 21 which grip a stop 16 on the valve rod 13 and hold it in neutral position so that the motor cannot be started. The load can then be placed on the step and the lever 14 pressed " in," spring connections 15 permitting the lever to move without actuating the rod 13. When the pedal is released the guards 17 return to their normal position and the levers 21 release the stop 16, so that the springs 15 are free to move the rod 13, and the motor is started if lever 12 is out " and the lever 7 is in the left-hand or " hoist '' position. In the construction shown in Fig. 3 the connection between the levers 12, 14 and the control valve unit 4a is electrical. A variable-delivery pump 5a is connected to the motor 3a by a pipe 6a passing through an automatic stop valve 32 and the control unit 4a having a valve 35 actuated by a hand lever 7a. The hoisting shaft Sa driven by the motor carries cams 30, 31 which respectively control a slowing-down valve 37 and a stop valve 32. The load-actuated levers 12, 14 operate switches 46, 47 connected by a changeover switch 48 operated by the hand lever 7a, those switches being in series in the circuit of a solenoid 49 controlling the valve 32. When the solenoid is energized a lever 50 is moved away from the cam 31 and the valve 32 allows liquid to pass from the pump 5a to the control or reversing valve 35. It will be seen that the solenoid circuit can only be completed to start the hydraulic motor if one lever (say) 12 is " out," the other 14 is " in," and the switch 48 is moved by the reversing lever 7a to the position corresponding to the correct direction of rotation for the motor. When the motor has been started the lever 12 (or 14) is released and the solenoid circuit broken so that the lever 50 is released and rests on the cam 31. As soon as the cam completes one revolution a lug 51 on the lever 50 falls into a notch on the cam and the valve 32 stops the motor. The hoisting shaft carries a self-sustaining device comprising a freewheel 42 and a normallyapplied brake 41 ; when it is being driven in the lower direction the reversing valve 35 admits pressure liquid through pipes 45, 44 to a cylinder 43 which releases the brakes during lowering. The cam 30 operates a valve 37 controlling the return flow of the liquid from the motor to the tank and is arranged so that it partially closes the valve at the beginning and end of each hoisting and lowering operation. This results in an increase in pressure in the pipe 6a and a cylinder 99 so that a piston in the cylinder is depressed against a spring 40 and shortens the stroke of the pump.