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).
Clearance between engaging teeth for helical second-speed gears on various car models.
| Identifier | ExFiles\Box 179b\1\ img264 | |
| Date | 14th January 1933 | |
| HS.{Lord Ernest Hives - Chair} ) FROM HDY.{William Hardy} BY.{R.W. Bailey - Chief Engineer} ) C to SC. WOR.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} ORIGINAL HDY{William Hardy}2/M14.1.33. X4027 X4553 HELICAL SECOND SPEED GEARS. CLEARANCE BETWEEN ENGAGING TEETH. We understand that the Expl. Dept. have asked for more movement of the change gear lever before the 2nd. speed engaging teeth come into contact, as there has been a complaint by Sales about this feature on the Derby helical 2nd. speed for Phantom. The tooth clearance on our print of the Derby EX. 92yl scales .100, the standard box has .140, and our helical 2nd. .150, so there does not appear to be any need for alteration to what we are suggesting on the Phantom. Our sch. for the 20/25. has .125 clearance against the standard .140. If this reduction is thought to be of importance we suggest reducing the width of the 1st. speed wheel by .050 and making the clearances for 2nd. and 1st. .150, and the travel for 2nd. speed .550 (an extra .025 is desirable anyhow) and for 1st. speed .900. The clearance on the helical 2nd. for Peregrine is the same as for the straight tooth box - .125 - and cannot easily be increased. In the case of the Bensport there is a greater change gear leverage in 1st. and 2nd. than on the other cars, and the .125 clearance will represent more at the lever handle than on the other cars. * PINION UNALTERED HDY.{William Hardy} [Signature] | ||