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).
Experiments conducted to resolve 'brake thumps' by modifying the braking system.
| Identifier | ExFiles\Box 30\6\ Scan225 | |
| Date | 7th November 1933 | |
| x1559 209 To Sg.{Arthur F. Sidgreaves - MD} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}14/KT.7.11.33. x254 BRAKE THUMPS. We have carried out several experiments on 2.B.IV. with the front brake dashpot N.Sch. 3804. connected between the swinging arm and a continuation of the plate lever of the brake differential. The suction side of the dashpot seems very ineffective all the resistance to a quick movement being due to the pressure side. Although the thumps were diminished they were not eliminated. For a trial therefore, we increased the compression ratio of the dashpot by plasticine until the space for the compressed air was about 1/16" long. The thumps were again less but still present. From these experiments we can say that this dashpot will not cure brake thumps. Sometime ago we fitted a scheme to GLN.60 that was very effective. On 2.B.IV. however, the same scheme was not nearly so good as it has to cope with a much greater movement of the balance lever. On 2.B.IV. we have arranged direct braking to all four wheels by eliminating the take up link in the rear differential and fixing the swinging arm so that it cannot move. By altering the length of the front differential levers to the ropes from 1.350 to 1.650 we obtain 50 : 50 direct and servo braking but uncompensated like this there are no thumps but the sponge in the front brake mechanism slightly reduces the amount of front braking. We are running the car arranged in this manner to see how wear affects the brake ratio. If it does not affect it the scheme might be useful as a cure for thumps. We shall therefore try as soon as possible Da{Bernard Day - Chassis Design}'s new scheme of direct compensated braking to all four wheels, as this would appear to be the solution of the trouble. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||