GB588779A - Jack - Google Patents

Abstract

588,779. Jacks. PAGE, H. E. March 6, 1945, No. 5573. Convention date, March 6, 1944. [Class 78 (iii)] A hydraulic jack provided with a load lifting piston 30, Fig. 2, reciprocally mounted in a main cylinder 10 which is supplied by a pump 45 with pressure fluid for raising the piston, includes lever means 70 so mechanically associated with the work piston and the pump operating member as to mechanically move the piston quickly into engagement .with the load, whereupon the continued movement of the piston to lift the load takes place hydraulically by the pressure fluid forced into said main cylinder. The operating handle journalled into the boss 68 reciprocates arm 70 and spring 78 to press collar 75 against piston 30 in order to raise the latter. At the same time the operating handle depresses arm 69 and piston 45 to force oil through passageway 50 and valve 61 to chamber 47. Additional oil flows from reservoir R through passageway 82. When the piston pad 32 contacts the work the latter continues to be raised solely hydraulically. The piston is released by screwing member 85 to open valve 61 and to allow oil to flow back to reservoir R. Collar 75 is kept in position by an additional spring (not shown) which is attached to the base. Piston 30 has. threaded core 31 for extension purposes. In the modification, Fig. 5, the operating handle 106 fulcrummed in piston 103 at 107 actuates collar 120 through rod 115. Piston 100 is also actuated but valve 61 is of such strength that no oil passes from chamber 46 (flowing only from' reservoir R) until the pad 32 contacts the work when valve 61 will yield and the consequent elevation will be carried out hydraulically. The fulcrum point 107 rises and the front opening is covered by flexible rubber covering 110. Collar 120 may be formed of resilient leaves, and rod 115 with a lower portion fitted with a spring that will yield at a predetermined compressive pressure so that overloading is avoided.