Brake system tests, covering pedal effort, braking ratios, and temperature effects.
| Identifier | ExFiles\Box 84\2\ scan0191 | |
| Date | 29th October 1934 | |
| -2- Variations in shoe clearance have not been of any importance. Zinc wire wound Ferodo MZ linings also help to convey heat to the shoe. (2) Pedal Effort to take up Brake Clearance. In spite of the reduction in sponge and temperature effects we have had to reduce the overall ratio to 7.9:1 to front and 9.1 : 1 to rear. We then removed all exterior pull off springs other than the pedal return spring, ran with .010 shoe clearance and had no sign of a decrease of this clearance. The pedal effort for shunting is now normal. The total braking has been increased by using a crinkly plate servo, needle bearing bridge and 30º cams. The brake layout is shown on GL. {G. Linnett} 747. We realise that the levers in the front equalisers look long but have intentionally done this to prevent the plate lever moving through such a large angle ending in line with the pull from the servo. (3) Variations in ratio of Front to Rear Braking. It must not be thought that direct braking to front and rear altogether overcomes this trouble. We have on several occasions experienced increase in the amount of rear braking. Thermo couples were inserted in a rivet of the wrapping shoe on the rear side both front and back. By driving in a manner similar to someone in a hurry between Derby and the Red Gate on the Holyhead Road but ending in a fast descent of a long hill, we obtained very high temperature readings, as much as 295ºC. at the rear and about 50º less in front. When the brakes were again cool it was obvious that the coefficient of friction of the rear linings was higher than that of the front. We consulted Ferodo's who agreed that this phenomenon does occur. It is also borne out by our recent tests on servos (see separate report). To reduce therefore the maximum temperature of the rear brakes we are making tests increasing the thickness of metal in the rim and the depth of the ribs. | ||
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).