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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).
Brake pedal pressure distribution for the front brakes only.

Identifier  WestWitteringFiles\K\December1923\  Scan68
Date  12th July 1923
  
R.R. 493A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary}

EXPERIMENTAL REPORT. Expl. No. 9940 REF: HS{Lord Ernest Hives - Chair}/AD/L.RHO.12.21

EAC-111 BRAKE PEDAL PRESSURE DISTRIBUTION.
(To front brakes only).

Front brake equaliser (locked)
Pressure distributor (connection to servo locked)

W = Pressure applied to pedal connection on pressure distributor.

ω = Pressure available for distribution to both front brake cam operating levers i.e., pressure at end of each brake cam lever = ω/2 for pressure W at pedal lever.

Leverage on this car measured up and found to be as 1 : 1.45. i.e. W x 1 = ω x 1.45.

| W lbs. | lbs. | Theor: (= W/1.45) | Loss of to friction. | Mech: effic: |
|---|---|---|---|---|
| 50 | 17 | 34.5 | 17.5 | 49.3% |
| 75 | 35 | 51.7 | 16.7 | 67.6% |
| 100 | 50 | 68.9 | 18.9 | 72.5% |
| 125 | 60 | 86.2 | 26.2 | 69.6% |
| 150 | 73 | 103.4 | 30.4 | 70.5% |
| 175 | 87 | 120.7 | 33.7 | 72.1% |
| 200 | 101 | 137.9 | 36.9 | 73.2% |
| 225 | 115 | 155.4 | 40.4 | 74.0% |
| 250 | 127 | 172.4 | 45.4 | 73.66% |
| 275 | 120 | 189.6 | 69.6 | 63.3% |
| 300 | 128 | 206.8 | 78.8 | 61.8% |
| 325 | 143 | 224.1 | 81.1 | 63.8% |
| 350 | 153 | 241.3 | 88.3 | 63.4% |

Mechanical efficiency (average) = 67.3%
  
  


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