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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).
Technical analysis of issues with the Phantom II braking system, specifically regarding pedal travel loss due to heat.

Identifier  ExFiles\Box 12\5\  05-page144
Date  1st November 1923
  
X 7420

To A.{Mr Adams} from Hs{Lord Ernest Hives - Chair}/an.
c. SG.{Arthur F. Sidgreaves - MD}
c. Wor.{Arthur Wormald - General Works Manager} H.{Arthur M. Hanbury - Head Complaints}
c. Da.{Bernard Day - Chassis Design} EV.{Ivan Evernden - coachwork}

Hs{Lord Ernest Hives - Chair}/Ra2/ADS.11.23.

PHANTOM II. BRAKES.

One or two points have been raised from time to time with regard to the R.S. brakes which we think merit attention.

(1) New brakes, insufficient pedal travel available to allow reasonable wear margin before brakes require re-adjustment.

Analysing this complaint we have.

(a) Total theoretical pedal travel (R.{Sir Henry Royce} Sch. 2645) to boards. 4.300"

(b) Travel left after taking up shoe clearance (.02) at shoe centre) servo clearance, star spring clearance. 2.550"

(c) Travel left after severe brake application due to elasticity in the system. 1.425"

(d) Pedal travel left, condition c. brake drums heated up. .500"

This last loss of pedal travel is due to the brakes heating up the drums and causing them to expand.

This is more serious than we thought. We should say that on a steep hill such as Porlock, a loss of 1.00" pedal movement is a conservative estimate.

We can lose 1.5" of movement if we run with the brakes on until they smell but without damage to the liner.

We are worse off in this respect than with the old V.series drums which had greater heat capacity.
  
  


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