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 report comparing the performance of straight and helical gears in aluminium and brass casings.
| Identifier | ExFiles\Box 149\2\ scan0143 | |
| Date | 12th February 1937 | |
| -3- From these figures it was obvious that the trouble lay in the casings and not the gears. To prove this still further, we had a pair of straight gears fitted to an Alum. casing; which was machined to suit. (6) STRAIGHT gears in Aluminium casing. Test A.{Mr Adams} 70 M.P.H. 15 secs @ 1000 R.P.M. 2 mins @ 500 Test B. 15 seconds. (6a) The suction pipe was then carried 3/4" above the ceiling of the pump with no appreciable difference. Both the aluminium and Brass casings were then compared. Width and length dimensions were duplicated and tested without improvement. The ports on the brass casing are located in the ceiling whereas on the aluminium they are central. With this in view, an aluminium case was plugged and the ports redrilled, to enter the interior near the ceiling; thus increasing the volume of oil retained round the gears. (7) 22° Helical gears in aluminium casing; ports redrilled 3/8" higher but only 3/8" diameter. Test A.{Mr Adams} 70 M.P.H. 30 secs. @ 1000 R.P.M. (no difference) Test B. 45 seconds (worse than originally) (7a) As above but with oil release slot machined in ceiling on pressure side as in brass casing. No appreciable difference in result. (8?) Brown & Sharps special straight gears. (30° obliquity, involute) in aluminium casing. Test A.{Mr Adams} 70 M.P.H. 20 secs. @ 1000 R.P.M. 5 mins. @ 500 Test B. 20 seconds. Gears rattle continuously @ 500/2500 R.P.M. It was noticeable with this pump, that two attempts were shown on the gauge before registering finally at the third; even at 1000 R.P.M. | ||