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).
Comparison and analysis of brake sponginess in the Peregrine system versus other models.
| Identifier | ExFiles\Box 1\10\ B001_X106 TO X 110-page032 | |
| Date | 16th February 1933 | |
| FILES. X.4027. X106. 16.2.33. BRAKE SPONGINESS - PEREGRINE. (1) Comparison of 1.Per.II. with 19.G.IV. (20/25). On 20/25 a pedal pressure of 150 lbs. causes a deflection of the pedal of .8". Overall brake ratio of direct braking = (handwritten: 270) 377 / 14 = 27. (handwritten: 19 1/2) Load at one rear brake cam = 150 x (handwritten: 19 1/2) 27 / 2 = 2000 lbs. (handwritten: 1970) On Peregrine 150 lbs. pressure causes a deflection of .55" with overall brake ratio of 18.3, giving a load on one brake cam of 18.3 X 150 / 2 = 1370 lbs. To give a cam load of 2000 lbs. the lost movement of the pedal would be .859 (handwritten: 1970) To give a cam load of 2000 lbs. with an overall ratio of (handwritten: 19 1/2) 27 would mean a lost movement of 1.18 (handwritten below: 63) For a given load at the brake shoe the Peregrine system is almost 50% more spongy than the 20/25, and this, inspite of the cam and radius of 20/25 being greater in the ratio of .430 / .325 hence magnifying to a greater extent all the pedal, shoe and drum distortion. (2) Analysis of where losses occur in Peregrine system. (Diagram with labels: .325 cam, H.8, A) Pull at A.{Mr Adams} for 2000 lbs. on cam = 135 lbs. Measured deflection at A.{Mr Adams} for this load = .390" Consequent deflection at brake pedal = .485" Due to the twisting of the actuating shaft G.100300 the lost movement at the pedal = .185" With an overall ratio of 27 these figures would be .715 and .27 respectively. Tests on 3.Per.II. Requires a pull at A.{Mr Adams} of 73 lbs. to put pilot shoe full on resulting in a lost movement measured at A.{Mr Adams} of .57". With an overall ratio of 27 the loss at the pedal = 1.23" cont'd.{John DeLooze - Company Secretary} | ||