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).
Modifications and issues with the Phantom III braking system, including bell crank levers, stops, and clanking noises.
| Identifier | ExFiles\Box 92\4\ scan0227 | |
| Date | 9th October 1936 | |
| To E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to Sft.{Mr Swift} c. to Mx.{John H Maddocks - Chief Proving Officer} c. to Da.{Bernard Day - Chassis Design} c. to Ev.{Ivan Evernden - coachwork} Phantom III Brakes - Memo. E.6/HP.8.10.36. As regards point (2) of this memo., this modified bell crank lever is already on production and is satisfactory in every way. As regards points (1) and (3), we have fitted a pair of stops to a car but have not yet had an opportunity to try it. Although theoretically sound, we do not like the way this stop has been made. The area of contact between stop and lever is very small - theoretically it is line contact - and we are quite sure that after 10,000 miles the lever would have bitten into the stop, allowing the actuating lever to hit the tipping shoe, as these are to be set close. Thus the object of fitting the stop would be defeated. In our opinion all four "off" stops on the car should be rubber faced, the stops so arranged that if the rubber were to fall off a metal stop would come into action. The rubber should be placed to be hit by a point of the brake mechanism having a long travel, thereby reducing the load on the rubber and making a few thousandths compression or wear of no importance. The object of using rubber is, of course, to deaden the clank of the brakes coming off, which is particularly bad on the rear of the Ph.III. While on the subject of clanks, we might mention the action the air dash pot has on Ph.III. Mx.{John H Maddocks - Chief Proving Officer} has repeatedly complained of a clank which occurs when the brakes are applied. The clank is due to clearance between the end of the slotted link on the rear foot brake intermediate shaft and the pin it pulls against. Although the rod may be of correct length to start with, on some cars this clearance keeps reappearing even though the rod is repeatedly shortened. We have traced the trouble to the air dash pot which if unduly full of oil does not allow the front brakes to come "off". We are running 35-EX in London without this dash pot, since its removal entirely cures this trouble and moreover does not give rise to clanks on the front of this car, the complexity of the front brake linkage and its general stickiness not allowing the brakes to come off too quickly. | ||