From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Operation and multiple disadvantages of a vehicle jacking system.
| Identifier | ExFiles\Box 26\3\ Scan118 | |
| Date | 21th January 1932 | |
| -2- the pistons are forced downwards out of the cylinders, the ends of the pistons having round metal pads come into contact with the ground and further pumping lifts the axle clear of the ground. To let the car off the jacks, the distributor tap is turned to the off position which allows the oil in the jacks to return to the reservoir firstly due to the weight of the car on the jack pistons and after the car is on the ground again by the action of a spring in each cylinder which returns the piston to its starting position. The system is quite easy to operate, requiring only moderate effort to jack up a car. The first time we jacked up the car, very slight rolling bent the brackets which hold the jacks to the rear axle allowing the jacks to assume an alarmingly large angle from the vertical. We wrote to the makers who sent us strengthened brackets, these have been fitted but the rolling test has not again been applied as the method of clamping the jacks to the axle is so bad that one is sure something must bend. The method of clamping the jacks to the front axle is also very poor, if one side is jacked up only the brackets can be see to twist. To be satisfactorily secure the whole jack would have to be redesigned. Oil leaks very badly from one of the jacks each time it is operated. This system has several other disadvantages :- (1) It is necessary to maintain a correct level of oil in the reservoir, Lockheed special brake oil is used. (2) There are a great number of oil pipes and connections distributed all over the chassis; a leak from which pipe system renders the jacks inoperative.. (3) It is a system which cannot be fitted to a chassis before the body is fitted because of mounting the distribution box in the most convenient place. (4) We should expect the pistons themselves to leak after considerable service, (one leaks badly already). (5) The jacks when fitted to the front axle look ugly and necessitate two holes being cut in the front apron to accommodate them. (6) The system is costly to fit up and the parts are not well made. | ||