| 摘要 |
1,269,653. Lift trucks. DSO BALKANCAR. 22 April, 1969 [24 April, 1968], No. 20596/69. Heading B8H. [Also in Divisions F1 and F2] An hydraulic unit for use in the control of an electric lift truck (not shown) comprises an hydraulic distributer 18 with a single-acting section 21 connected to a lifting cylinder 23 and three double-acting sections 24, 25, 26 respectively connected to double acting cylinders 33, 34 and an hydraulic motor 35 which may be used for tilting or advancing the lifting gear or driving interchangeable attachments. Two pumps 1, 2 coupled to an electric motor 3 supply oil from a tank 4 to lines 7, 8. Valves 13, 15 are mechanically coupled respectively to sections 21, 25. The distributer 18 comprises a normally closed safety valve 18<SP>1</SP> and a by-pass valve 18<SP>11</SP>. When all the sections 21, 24, 25, 26 are inoperative a small portion of the oil entering the distributer 18 passes through a throttle T and all the sections 26, 25, 24, 21 to the tank 4, the pressure difference generated acting to open the by-pass valve 18<SP>11</SP> to return oil to the tank 4. On actuation of one or more of the sections the flow through the throttle is blocked and the by-pass valve 18<SP>11</SP> closes. On actuation of the sections 24, 26 the pumps 1,2 respectively supply oil to lines 7, 8 but the oil from the pump 2 passes through lines 12, 14, 16 and the open valves 13, 15 to the tank 4. On actuation of section 21 or section 25 in one of the most extreme positions, either valve 15 or 13 closes the oil path therethrough and the oil from the pump 2 passes through line 9, non-return valve 10 and line 11 to line 17 to join the oil from the pump 1. |
