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).
Oil pressure in the operating cylinder and the sticking of the change speed valve.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan274 | |
| Date | 17th September 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. Expl. No. The pressure recorded with the valve in the REFd-position is no doubt due to the restricted port area, and the difference between the pressures obtained at the mid-position with the piston at different end of the cylinder is explained by a slight asymmetry in casting of the admission ports. (5) MAXIMUM OIL PRESSURE OBTAINABLE IN OPERATING CYL. As fitting stronger springs to the toggle was contemplated we required to know what pressures could be obtained in the cylinder at normal working temperatures. The toggle was therefore fixed in the high gear position, and the change speed valve set to change from high to low gear position. The pressure in the scavenger pump circuit rose to a max. of 150 lbs/sq.in., at which pressure the valve was lifting from its seat against the spring and oil was flowing freely from the front end of the valve. It was noticed that the change speed valve started to leak oil at 10 lbs/sq.in. These results show that ample pressure is available for the working of the toggle with 20% stronger springs. (6) STICKING OF CHANGE SPEED VALVE. When turning over the change speed valve with the engin running slowly in readiness for gear changing, it was noticed the the valve seemed to stick in the mid-position, and considerable effort was required to turn it further. This is undesirable since with a series of long springy rods between the operator and the valve it might be impossible for the former to operate the gear. Furthermore, when the valve had reached the sticking position, the operator might be deluded into the contd :- | ||