Patent GB-1044013-A (GB)
Title: Hydraulically driven industrial truck
Inventor: MARCO ROBERT FRANK DE
IPC: B66F9/075
Filed: 1963-04-03
Abstract: 1,044,013. Hydraulic transmission of power. HEIFRED CORPORATION. April 3, 1963, No. 13195/63. Headings F2C and F2D. [Also in Division B7] An industrial truck has a single batterydriven electric motor 26 driving a pair of hydraulic pumps supplying liquid to the individual hydraulic motors of the driving wheels 32 and to fork-lifting and mast-tilting rams. In a first embodiment, Fig. 1, provided with castor wheels 60, the reversible wheel driving motors 45, 45a are connected to individual variable capacity pumps 27, 27a for steering, whereas in a second embodiment, Fig. 12, the driving motors 170, 170a are connected in parallel to one variable capacity pump 162, the other services being supplied by a second pump 163 which may be connected in parallel with pump 162 to provide an increased vehicle speed. The second vehicle is steered by a pair of wheels 152 connected by chain 158 and sprockets 159, 157 to steering wheel 153. The capacities of the motors 45, 45a, 170 and 170a although normally non-variable, may be altered when service requirements are changed. 1st embodiment, arrangement.-Electric motor 26 (Fig. 9), drives two identical pumps 27, 27a of which the one, 27, connected to the righthand wheel only will be described below. The outlet ports 70 of the pump are connected through line 75 and reversing valve 76, controlled by solenoids 84, 85, to driving wheel motor 45. Line 75 communicates through line 86 with brake release cylinder 52 to release brake 48 against the force of spring 51 when the electric motor is operating, but before the vehicle has started to move. Pump outlets 71 normally communicate through line 90 with manual valves 92, 93 controlling the forklifting cylinder 18 and mast-tilting cylinders 13 but a valve 100 controlled by solenoid 101 is provided to connect the outlets 71 through check valve 103 with line 75 to provide an overdrive speed for the motors 45. Should the pressure in line 75 become excessive, pressure switch 105 operates solenoid 101 to disconnect line 75 from outlets 71. Drive control.-The output of the pump 27 (Fig. 6), is controlled by the vertical position of a slider 111 movable in the vertical arm 112 of control member 113. Follower 114 of the slider is movable in slot 115 of link 116, which is pivoted at 117 to fixed arm 118 and has a follower 136 engaging slot 132 in cam-plate 131. Slot 132 has a portion 134 of constant radius from pivot 131b and a portion 133 of increasing and then decreasing radius arranged so that on rotation of steering wheel 125 from a straight ahead position when follower 136 is at the right-hand end of slot portion 134 camplate rotates anti-clockwise, rotating link 116 clockwise and moving slider 111 downwards to the zero pump delivery position when the radius of slot portion 133 is at its maximum and block 128, below steering wheel 125, closes switch 141 to actuate solenoid-controlled valve 76 to reverse motor 27 and then on further steering wheel rotation the radius of slot portion 133 decreases to increase the pump output again but in the reverse direction. Motor 27a is similarly controlled but the cam-plate slot is arranged so that when follower 136 is on the constant radius slot portion follower 136a is on the varying radius slot portion and vice versa and switch 143 closes when follower 136a is in the zero output position. Forward movement of control lever 121 which is connected to control member 113, from the zero output position of the pumps first closes switch 123, starting the electric motor to release the brakes and then increases the output to its maximum. Reversing lever 145 is provided to reverse both valves 76, 76a together. 2nd embodiment.-The output of hydraulic pump 162 for the wheels is controlled by rockable pedal 169 connected to dash-pot 214. Pedal 215, after initial movement which closes an electric switch for moving valve 179 (Fig. 13), to reverse drive position, moves with pedal 169 to control the reverse drive. When steering wheel 153 is moved to its extreme left-hand turn position solenoids 183 and 189 are both actuated to reverse the left-hand motor 170a and when the other extreme is reached solenoid 189 only is actuated to reverse motor 170.