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).
Modifications to the oil relay ignition governor, focusing on piston sticking issues.
| Identifier | WestWitteringFiles\M\2April1925-June1925\ Scan22 | |
| Date | 1st April 1925 | |
| R.R. 493A (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}1/LG21.4.25. OIL RELAY IGNITION GOVERNOR. We should like to recapitulate the modifications which have been made to this unit since it was first produced experimentally. Sticking of Inner Pistons E.72503. This was a frequent occurence initially and various clearances from .001 to .007" were tried on the small inner piston. It was found that .007" clearance could be used without loss of efficiency but this clearance was considered too great on account of the quantity of oil which passed the piston at higher temperatures. The clearance for production was therefore fixed at .004" which is the minimum to ensure reasonable immunity from sticking due to fine particles of foreign matter which pass the filter. Experiments were then carried out to determine whether it would be possible to exclude foreign matter from the control valve by reducing the mesh of the filter gauze. It was found that if fine dust was introduced directly into the oil pipe to the relay it would pass even 100 mesh gauze when the oil was cold and cause the small inner piston to hold even with .004" clearance. It was considered impractical to go to a finer gauze than this with a filter of the present area. In practice, sticking of the relay on the road due to dirt in the oil has been an exceptional occurrence, and has always taken place shortly after the car has been assembled. It can therefore be attributed to foreign matter left contd :- | ||