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).
Merits of direct braking systems over servo-assisted brakes for the J. 3. model.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan073 | |
| Date | 21th March 1931 | |
| HS.{Lord Ernest Hives - Chair} FROM E.{Mr Elliott - Chief Engineer} C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} C. to PN.{Mr Northey} BY.{R.W. Bailey - Chief Engineer} HY.{Tom Haldenby - Plant Engineer} SECRET. ORIGINAL E5/M21.3.31. x5360 Japan 3. Brakes. We are suggesting that servo operation for the brakes might be dispensed with on J.{Mr Johnson W.M.} 3. for the sake of simplicity and economy and because since our braking system was first got out there have been considerable advances made in design which now render direct braking more efficient and powerful. The servo moreover is not an unmixed blessing. We have driven more than one car in which the brakes do not come on before the car has rolled forward for a yard, which is very alarming when shunting in a confined space. Again the brakes are not as selective as one would expect. These troubles could no doubt be overcome by reducing the operational friction but while we are doing this we may as well consider direct braking, which reduced operational friction renders possible with a car of the J.{Mr Johnson W.M.} 3. size. The 4.7 litre Invicta relies on direct braking and there is no mention of self wrapping shoes in the specification. We want to arrange to try this car. The author of this memo. has had a car in use for nearly 3 yrs. fitted with direct brakes in which operational friction has been reduced as far as possible to a minimum by simplicity of layout and the use of anti-friction bearings and mountings. This car weighs 33 cwts. unladen and the braking is quite powerful and selective and without excessive pedal pressure. The mileage up to date is about 15,000., a fair part of which is made up of long fast runs and the brakes have just been re-adjusted for the second time. It should be remembered that any frictional resistance in the brake operation results in doubling the effort required on the foot pedal to apply the brake owing to the pull off springs having to be proportionally strong. E.{Mr Elliott - Chief Engineer} | ||