Improved Jack for Load Tests: Japanese Modifications to the Standard Type

IN carrying out load tests on aeroplanes at the Aeronautical Research Institute at Tokyo, the ordinary motor‐car type of jack used was found to have certain disadvantages liable to lead to overstressing of the spars in the destruction test and possible reversal of stress in the elastic test. Certain modifications to the jack used, which has a capacity of 2,720 k.g. (5,800 lb.) and a stroke of 20 centimetres (7? in.), were therefore made, which are described in the Institute's Report No. 78, July 1932. As these seem likely to be of general interest they are reproduced here. The jack's mechanism was altered somewhat by inserting a long steel rod and a universal coupling between the revolving handle and the jack itself, thus enabling the operator to work it without noise and with considerable free play for the handle so that he could work from any angle. Furthermore, the joint between the rod and the universal coupling, and that between the handle and the rod, are made readily detachable to prevent injury to the operator should destruction of the tested object cause upsetting of the jack.