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).
Page 2 of a report detailing a 5-piston central valve arrangement with diagrams.
| Identifier | Morton\M20.1\ img003 | |
| Date | 1st April 1924 guessed | |
| (2) As you will remember the central valve is in equil- ibrium and should take practically no force to move. It only needs to move it up or down to uncover inlet and exhaust ports. I found considerable difficulty in finding a satisfactory valve arrangement, hence the 5 pistons. The scheme is doub-le acting, and everything is symmetrical it will be noted. The middle piston of the valve by moving up or down admits oil (pressure) into the annulus below and above it. The oil passes through the holes shewn at A.{Mr Adams} into the space under or above the main piston, and endeavours to make it (the big piston) follow the valve. At the same time the valve piston at the extreme ends open the opposite space to the exhaust. [Diagram A] Leather. Exhaust. Inlet piston. Centre of length. This piston only separates the pressure. It will be seen that the main piston has a waist:- [Diagram B] Shaft to outside passing through packed gland. Main motor piston. Lever about 1.6". Force available with 2 1/4" piston 1" hollow rod with 10 lbs. oil pressure is 40 lbs. The stroke is .8" to 1". | ||