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).
Suggestions for higher indirect gear ratios for a Bensport 20/25 gearbox.
| Identifier | ExFiles\Box 179b\1\ img282 | |
| Date | 24th January 1933 | |
| HS{Lord Ernest Hives - Chair}/RM.{William Robotham - Chief Engineer} ) FROM HDY.{William Hardy} C.c. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} Er. DA.{Bernard Day - Chassis Design} ORIGINAL HDY{William Hardy}1/H24.1.33. X4853 BENSPORT GEAR RATIOS. As requested by HS{Lord Ernest Hives - Chair}/RM.{William Robotham - Chief Engineer} we send suggestions - shown on B. sch. 3658. herewith - for higher indirect/gear ratios for the standard 20/25. box fitted to the first Bensport. We gather from experimental reports on this car that the axle ratio is about 4 to 1., giving 90 MPH. at 4500 RPM. With this axle we calculate that we can have a first speed of .36 and still climb 1 in 3 with four persons in the car. This is a 20% increase of 1st. speed. We have raised 2nd. by the same amount, but 3rd. will not, in our opinion, stand more than about 10% increase. We then get existing gearbox ratios .73, .43, and .3. increased to .8, .57, and .36. Existing speeds at 4500 RPM. are 90., 65., 43., and 27., which become 90., 72., 51., and 32. We shall be sending higher indirect ratios for the Bensport box to suit a 4 1/4 axle ratio. In this case it will only be necessary to raise the constant mesh ratio. HS{Lord Ernest Hives - Chair}/RM{William Robotham - Chief Engineer} We shall now let you have details for all the altered parts BV/Cgh{W Clough} HDY{William Hardy} | ||