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 system issues, including liner bedding, overheating, material compatibility, and performance on Bentley models.
| Identifier | ExFiles\Box 130\2\ scan0356 | |
| Date | 15th December 1936 | |
| -2- Rm{William Robotham - Chief Engineer}/GWH{George W. Hancock - Head Chateauroux}6/R.15.12.36. (3) The bad bedding of liners, of which in service there has been ample evidence, causes squeaks through inadequate damping effect at the critical time. Also, the general effect of bad bedding is to cause vibrations to start. In service, the squeak from rust is not met with. The action of the tipping shoes is to apply the necessary damping load to prevent the start of the drum vibrating; its action is limited. Where the shoes are bedding badly, the vibrations set up are such that the damping effect of the tipping shoes is unequal to the periodicity. Again, the load of the tipping shoe in service has not been consistent; on the 30 H.P., it is 40 lbs; the Bentley 60 lbs. The setting of the shoe to a minimum clearance found in service of .006" does not allow the damping effect to take place at the right moment. The minimum setting should be .010" and a load of 60 lbs. With the change of liners the load should be changed to suit. (4) Over-heated liners are a definite cause, as the co-efficiency increases. (5) The brake drum material and the linings should be mated up. It is a well-known fact that what is a good liner from most points in service, with a certain material used for the brake drum, will not give the same results using another material. Ferodo's have ample charts to show the varying results. ------------ The recent Bentley 6.B.IV which ran in France with Aluminium drums was not more efficient than the present standard. They were more consistent. The liners were worn out, and the drums so badly scored that they were useless for further work. The statement in AFM{Anthony F. Martindale}'s memo that the position of Bentley brakes is really not very satisfactory. They are not up to their job is not what is found in service. Frazer Nash and others have stated that our braking system is very good. Kingsbury have no troubles with regard to brakes wearing out. Squeaks are the chief troubles and binding. | ||