GB442148A - Improvements in or relating to lifting jacks - Google Patents

Abstract

442,148. Lifting-jacks. LAKE, A. E., 113, Dunmow Road, Bishop's Stortford, Hertfordshire. Aug. 2, 1934, No. 22515. [Class 78 (iii)] A lever-jack, especially suitable for vehicles and of the type in which a beam such as D, to which a crutch L is pivoted at L<1>, is guided in a wheeled frame A<1>, for example by roller bearings B, and is pivoted intermediate its ends to beam links such as K<2> pivoted to the frame at K<3>, is characterized by (1) the provision of secondary crutch-supporting links M<1> forming a jointed parallelogram support which prevents undue tipping or tilting of the crutch and (2) the provision of a bent beam so that when the jack is fully lowered, the pivot L<1> lies below the pivot K<4>, while K<4> lies between the pivots K<3> and B but at a higher level. To elevate the crutch the bearings B are moved along their channelled guides by screw, hydraulic, or ratchet-mechanism, the form shown, comprising a thrusting pawl J carried by a hand-operated lever H pivoted at H<1>. A retaining pawl G is pivoted on the frame. Both pawls engage a guided ratchet bar E carried by the shaft of the roller bearing. Reversing-mechanism may be incorporated to permit controlled lowering of the load. The wheels of the frame may be mounted as castors, while the actual crutch may be a member mounted slidably in the member L.