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).
Issues with hydraulic jacks, including pads sinking into the ground and brake linkage problems when the vehicle is lifted.
| Identifier | ExFiles\Box 91\1\ scan0339 | |
| Date | 21th June 1936 | |
| +300a GRY{Shadwell Grylls}- /4s. 81 HOTEL DE FRANCE, CHATEAUROUX. Indre. France. GWH{George W. Hancock - Head Chateauroux}/HFH{Hoppy F. Hamilton}/6/JAB. 21st June 1936. To. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} 32. EX. Hydraulic Jacks. During the run of the 19.6.36, we had to change a rear wheel on the road. We found that due to the weight of the car, the Jack pads sink a good inch into the tarmac surface. There is no doubt that they would sink further on softer ground. We suggest that the pads be made at least another inch in diameter to avoid this happening, for if the pads sink too far it makes the removal of the wheels difficult, as they only clear the ground by a small amount. We have also found that if the front of the car is jacked up, the geometry of the brake linkages is such that, as the wish bones drop the front brakes are pulled on. Although it is possible to remove the wheel, it is impossible to rotate the wheel or drum when investigating troubles which necessitate this. It is possible however, to do this if only one jack is used, i.e. worked by hand so as to lift one side at a time, but it seems a pity to have to go to this trouble when a perfectly good set of hydraulic jacks are fitted. It also follows that on full rebound, the brakes would be pulled on, probably momentarily locking the front wheels. ------------ H.F. Hamilton. GWH{George W. Hancock - Head Chateauroux}/HFH.{Hoppy F. Hamilton} | ||