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).
Phantom III hydraulic jack pump leakage, comparing pump types and recommending modifications.
| Identifier | ExFiles\Box 139\1\ scan0166 | |
| Date | 15th June 1936 | |
| To By.{R.W. Bailey - Chief Engineer} c. to E.{Mr Elliott - Chief Engineer} c. to Mx.{John H Maddocks - Chief Proving Officer} Phantom III Sessions Hydraulic Jacks. Owing to trouble experienced by Mx.{John H Maddocks - Chief Proving Officer} of leakage of the top cap of these jacks if the system is overloaded by continuing pumping after the car is fully raised, we have taken some measurements of the pressures obtainable. We had previously found on 36-EX that it was impossible to damage the system by overload. We have found that there are three kinds of pump in existence. On continuing to pump after the jacks are extended results were obtained as follows :- 36-EX Pump, port type, 3/4" dia. piston - max. pressure obtainable, 3000 lbs/sq.in. 37-EX Pump (obtained from production some time ago), port type with valve, 9/16" dia. piston - max. pressure obtainable, 3700 lbs/sq.in. Latest production pump, valve type with no ports in casting, 9/16" piston - max. pressure obtainable 5000 lbs/sq.in. During these tests the cap on one front jack leaked copiously at 3600 lbs/sq.in. and soon after tightening would not subsequently hold 3000 lbs/sq.in. We recommend - and E.{Mr Elliott - Chief Engineer} is in agreement - that no further chassis be fitted with valve type pumps, and that all pumps be altered to the early 3/4" bore port type before cars reach customers. We think probably that if the pumps are returned to Sessions they can be modified to the early type. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||