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).
Design of a semi-servo braking system, including swivelling friction surfaces and lever proportions.
| Identifier | WestWitteringFiles\L\Jan1924-March1924\ Scan48 | |
| Date | 29th February 1924 | |
| ORIGINAL. S E C R E T. TO SAY-d & ST.{Capt. P. R. Strong} FROM R.{Sir Henry Royce} Copy to CO. RO.{C. C. Rose - Export Manager} F.T. SY. HS.{Lord Ernest Hives - Chair} SEMI-SERVO SYSTEM. N.schs.1756 & 7 &c. SWIVELLING FRICTION SURFACES FOR SERVO. X9910 As before stated I fear alignment of the 2 servo shafts, and think possibly friction surfaces should be spherically mounted as shewn in sketch which does not seem an expensive design. The lever can be forged on the sleeve or brazed, or put in in any other way that is thought best. It will be noticed that the washer must slide. I thought this better than reversing the spherical surfaces. The plates should swivel at the centre of the serrations. SEMI-SERVO. You will see that for patent reasons we shall probably go back to semi-servo system, modified as per my telegram of today. I think that telegram explains exactly, and all. It may require a shaft to allow the foot pressure and servo joining together, and then on to the rear equaliser. The equalisers (bevel) will work O.K. when they set themselves under light load and then have equal elasticity, and so not have to move under load. Please see that this is so as far as possible. The lever proportioner will be free from friction (nearly) and so correct under all conditions. This is one of the beauties of this device. It also seems so very convenient for our conditions. If we use my suggested modified semi-servo, the levers and leverages will be equal both fore and aft. You will remember that I suggested front braking should be 3 to back 5 - total 8 units - that is 3 direct from pedal to rear = 2 units, and leaves servo to give 3 to front and 3 to back. You will also see that the small variations that may occur in the servo will not greatly affect the proportion between front and back, and if the servo goes off we get back braking only, but we should soon notice this, and the regulation of the servo is so simple. There will be powerful stops needed on the servo to prevent it going backwards and a stop somewhere so that if back brakes are so worn that there is risk of the servo not going on the lever to the servo will get to the limit. You will see there are several advantages in this scheme and I am very keen to get it tried out. We are not much like the Americans who by working at a scheme often make a very imperfect one work quite well. In this case there are distinct gains in this scheme, and naturally there will be some slight disadvantages, but I think that the sum total is distinctly in favour of us, outside Hispano and perhaps Renault patents. R.{Sir Henry Royce} | ||