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).
Comparing the hydraulic Jackall system with the mechanical D.W.S. four-wheel jacking system.
| Identifier | ExFiles\Box 26\3\ Scan090 | |
| Date | 3rd December 1931 | |
| Y3117. To Sg.{Arthur F. Sidgreaves - MD} FROM Hs{Lord Ernest Hives - Chair}/Lid{A. J. Lidsey} c. to C. Hm.{Capt. W. Hallam - Head Repairs} c. to EV.{Ivan Evernden - coachwork} Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}6/MA.3.12.31. re. FOUR WHEEL JACKING SYSTEMS. We have taken one of our cars to S. Smith and Sons in order that it may be fitted up with Jackall Hydraulic Jacks. This scheme of course is hydraulic and although very attractive we can forsee possible failures due to such things as broken oil pipes, leaky connections and vavles. In addition to the Jackall system we have made enquiries concerning the D.W.S. scheme. This is entirely mechanical and is on the same principal as the Jenks jack which we tried some little time ago, it is however a very much better article and is exceedingly well made. In view of the necessity for a jacking scheme on present day cars (with rear and front aprons) we think it well worth while to obtain a set, we think we may prefer them to Jackall. The D.W.S. scheme has several advantages over Jackell:- D.W.S. Jackell (1) Price (to us). £6-10-0 (approx) £11-7-0 (2) Fitting 10-0 £4-4-0 (3) Unsprung Weight 40lbs. (approx) 60lbs. (approx) We understand that the D.W.S. people are developing their system under Government instruction for use on armoured cars, and in a modified form for aircraft. The system is manufactured by Donald Sessions Co. Ltd., 906 Harrow Road Willesden. If you agree we will obtain a set. Hs{Lord Ernest Hives - Chair}/Lid{A. J. Lidsey} | ||