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).
Test results for various gear and pump casing configurations, measuring priming times under different conditions.
| Identifier | ExFiles\Box 149\2\ scan0144 | |
| Date | 12th February 1937 | |
| -4- (8a) As above but with air gap (splined gear) between bush flange and counterbore in casing filled with solder. This air gap (.015" x .100" deep) by-passes the splined gear teeth from suction to pressure side, thus causing the failure to prime readily. All Aluminium casings have this fault. Test A.{Mr Adams} 70 M.P.H. 15 secs @ 500 R.P.M. (Average temp.) 25 (Hot). Test B. 3 secs. This pump now only makes two attempts when building up pressure, the second being final. (6b) Straight gears in Alum., casing with air gap between bush flange and counterbore, closed with solder. Test A.{Mr Adams} 70 MP.H. 2 secs. @ 500 R.P.M. Test B. 1 second. (1a) 22° Helical gears in Alum. casing with air gap between bush flange and counterbore, closed with solder. Test A.{Mr Adams} 70 M.P.H. 3 secs @ 500 R.P.M. (Hot) Test B. 1 second. (1b) 22° Helical gears in Alum. casing with small bush fitted to splined gear; duplicating idle gear bush even to clearance round periphery. This in effect is sealing the air gap with both gears, but will increase wear from thrust. Test A.{Mr Adams} 70 M.P.H. 3 secs. @ 500 R.P.M. Test B. 3 seconds. (1c) 22° Helical gears in Alum. casing with modified bush and limit of .0015" such as can be produced and adhered to according to the Tool Dept. Test A.{Mr Adams} 70 M.P.H. 2 secs. @ 500 R.P.M. (cold) 6 (hot) Test B. 3 seconds. continued | ||