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).
Improvements and issues with the front wheel braking system.
| Identifier | ExFiles\Box 5\3\ 03-page146 | |
| Date | 5th June 1925 | |
| To Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to CJ. Wor.{Arthur Wormald - General Works Manager} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} SECRET. INDIA. FRONT WHEEL BRAKING. X.5940 X.5370 There have been some arbitrary rules on the multi-plication power of the servo. I can only think that the standard should be that if we have a 3" lever actuating we ought to take the torque delivered by the servo at the same radius. The amount this ought to be in my opinion is 1 to 1., but as the travel of the servo is twice the angle of the oper-ating levers, the servo will then be doing twice as much braking as the direct foot. This is not what we want. The total braking will be in proportion to 3 times the direct braking, either in travel, clearance, or power. We seem to be using a multiplication on the same lines of 2 to 1 in the servo, the servo moving through twice the angle given - 4 to 1 - and a total of 5 to 1 compared with the direct braking. This is too much, and too great a proportion on the front wheels. It was noticed when you were here that the levers were in the wrong relative positions, and there was very little travel available on the front brakes. This need not be, and the travel of the wire rope can easily be 2". At the same time since we do not want so much front braking we could have the actuating cam .5 centres instead of .4. We should then get more travel and clearance. It was noticed also that the castellated nut and locking wire intro-duced and adopted by Derby was a very poor and feeble job. By a slight modification, keeping the lever in the same position, but cutting back the boss on the axle, a substantial hexagon nut could be used with an ordinary split pin. We think there is a possibility of making some improvement with the serrations adjustment, it being slightly difficult to twist the brakes on and slide the present ratchet cam along under the loads of the springs. I have shewn DA.{Bernard Day - Chassis Design} where the oversight is. It is rather different to the back axle because in that case we can get to the camshaft to turn the brakes on, whereas we cannot get to the camshaft belonging to the front brakes. I understand DA.{Bernard Day - Chassis Design} has sent all instructions necessary. R.{Sir Henry Royce} | ||