GB615834A - Improvements in or relating to lifting jacks for motor vehicles - Google Patents

Abstract

615,834. Vehicle jacking devices. HOLT, W. Aug. 14, 1946, No. 24082. [Class 79 (iii)] [Also in Group XXX] A hydraulic jack which may be permenently hinged to a motor vehicle and has means for supplying compressed air to the jack reservoir to cause the liquid therein to raise the plunger, has a safety valve 33 mounted on the reservoir chamber. A compressed air pipe is connected to the jack at 16 and the air passes through a three-way tap 18, when in the second position, into the reservoir 4. Ports 7 and 9 connect the reservoir with the cylinder 3 through a valve chamber 8 housing a cone valve 11 which, under the control of a manually operated screw threaded spindle 12, determines the passage of oil. The upward movement of the plunger 20 is limited by the enlarged end 24 striking the annular shoulder 25. When the plunger has reached its limit the spindle 12 is turned to seat the valve and retain the oil in the chamber 8 and the tap is turned to the first position to cut-off the supply of compressed air. To lower the jack the cone valve is unseated to permit slow escape of oil and the tap is turned to the third position to allow escape of air. The device can also be used inverted. It may be movable and adapted to be clipped out of the way on the vehicle, or it may be permanently secured or hinged to the vehicle.