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).
Adjustments and considerations for a 4-wheel brake system, focusing on the equalising lever.
| Identifier | WestWitteringFiles\M\October1924-December1924\ Scan16 | |
| Date | 16th October 1924 | |
| TO HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} Copy to BG. ORIGINAL 4 WHEEL BRAKES. X9940 (X9910 crossed out) Your memo. re. the above to hand. (1) Though we instructed friction in the top joint of the suspension link, we consider this ought not to be more than 35" lbs. (i.e. one third your amount) because it renders imperfect the action of the equalising lever and so upsets the proportion between the front and back braking. (2) We cannot see why much friction is necessary providing the pull off springs are arranged to require an equal rope pull from the equalising lever. (3) The stroke of the rope and clearance of the brakes should be equal each way for equal servo braking at the drum surface. (4) The servo (if the equalising lever is allowed to do its duty) can only give equal rope pull forwards and backwards, and equal stroke (unless the suspension link moves.) Equal stroke should give equal clearance. If this is so in practice I am content. (NO.4. assumes the upper and lower levers to be equal.) (5) The difference in wear (if this is very marked) should be corrected by additional width of the back brake surface as soon as convenient. (6) So that if there is equal leverage back and front the back brakes are more effective by the difference in dia. of the drums and by the addition of the direct foot pressure. If we are adopting still greater difference then the centres of the equalising levers should be altered thus for a difference of say 25%, then the levers should be 25% different for equal clearance, and no movement. [Diagram of an equalising lever with dimensions 3.350 and 4.500] This would require ¼" longer links and ⅛" longer connecting rods. (7) If the 25% difference is used still the pull off springs should be arranged to require equal rope pull at the equalising lever. Mr. Day says we have been awaiting this figure as to the proportion found preferable. The pull off springs can be nearly anywhere - see N. Sch. to follow this memo. R.{Sir Henry Royce} [Stamp: RECEIVED 8H TCO] | ||