| 摘要 |
<p>1,139,453. Variable-speed transmissions. LEWIS-SHEPARD CO. 31 May, 1966 [2 June, 1965], No. 24111/66. Headings F2C, F2D and F2L. A hydrostatic transmission is used to accelerate a material handling truck to its running speed, whereupon an electric motor, which may be that employed to drive the hydrostatic transmission or an independent motor, drives the truck directly and the hydrostatic transmission is unloaded. As shown in Figs. 1, 2, an electric motor 12 drives a variable displacement pump 20 supplying a motor 18 through a reversing valve 36, and the electric motor is connectible to the output means by an electromagnetically operated clutch 14. The pump 20 is controlled by a pedal (62) which when fully depressed closes a switch energizing the clutch 14 and actuating a valve 72 unloading the pump 20. The electric motor also drives a pump 22 actuating the material handling equipment under the control of valves 24, 26, 28. During hydrostatic drive, if the motor 18 over-runs the pump the braking effect is limited by a valve 86. The reversing valve 36 is controlled by a manual control which also determines the direction of rotation of the electric motor. In a modification (Fig. 5), an electric motor (110) drives a split flow pump (108) having a variable delivery side connected to an hydraulic motor (100) connectible by a clutch (106) with the output shaft (104) of an electric motor (102). When a pedal which controls valving determining the flow from the pump is fully depressed the clutch (106) is disengaged and the electric motor (102) is energized. A constant delivery side of the pump (108) controls ancillary devices. A reversing valve (136) and a reverse control for the electric motor (102) are conjointly controlled by a manual control (142).</p> |
