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).
The performance and issues of a servo braking system linkage and its on-road testing.
| Identifier | ExFiles\Box 16\3\ Scan064 | |
| Date | 18th September 1929 guessed | |
| -2- final movement of the scissor levers coming to rest upon the servo stops. He obtains this movement by lifting the centre of the suspension of the 'T' lever up 2.000. The result is the action of the servo leakage is entirely altered as explained on his sketch S.K.362. The swinging arm is made to operate and is part of the servo leakage when the brakes are applied, whereas with the present design its work is to equalize the uneven wear of the front and rear brakes only. By lifting the 'T' arm centre up 2" the rear brakes are always applied first the front coming on after the movement of the swinging arm has taken place. The action is reversed when the brake pedal is released the result being a distinct clank from the stop for the front brakes. This stop is necessary for his arrangement as it is used as a fulcrum to move the swinging arm back to its position. The action of the scissor levers are retarded by the position friction load of the swinging arm in having to bring it back to its normal position. With the car jacked up this arrangement appears to work quite satisfac- torily, but on the road it is far from being satisfactory. The braking at speeds under 15 m.p.h. is very erratic. The front brakes lagging behind the rear causes the front of the car to dip when they come on and in slow moving traffic it is impossible to obtain a smooth braking action. On reverse the clank is no better than at present. The braking at speeds over 20 m.p.h. gives fairly good results. One feature which definately is a disadvantage is the tendency for front brake thumps. The friction load on the swinging arm would have to be constantly checked to prevent it. | ||