Summary of tests carried out on front wheel brakes fitted on model 12-EX to overcome squeaks.
| Identifier | ExFiles\Box 12\5\ 05-page017 | |
| Date | 20th October 1926 | |
| To R. {Sir Henry Royce} from Hs {Lord Ernest Hives - Chair} /GWH. {George W. Hancock - Head Chateauroux} C.c. to RH. {R. Hollingworth} EV. {Ivan Evernden - coachwork} C. to GY. X7420 not sent out Hs {Lord Ernest Hives - Chair} /GWH {George W. Hancock - Head Chateauroux} 1/LG20.10.26. SUMMARY OF TESTS CARRIED OUT ON FRONT WHEEL BRAKES FITTED ON 12-EX TO OVERCOME SQUEAKS. We carefully checked over the bedding of the brakes and found that on the N.S. the wrapping shoe was bedding most on the heel of the shoe, the toe just showing signs of touching. The non-wrapping shoe was just bedding and fairly even. We filed away the portion of the heel of the wrapping shoe, making the bedding come on to the toe with more load than other portions of the shoe, both wrapping and non-wrapping. This entirely cured this brake from squeaking, our theory being that when the toe of the wrapping shoe is not fully bedding on the heel, a condition is obtained whereby a vibration is set up between the shoe and the drum at this point, the lessened contact of the shoe bedding hard at heel portion only not being sufficient to damp the vibrations out. This was also proved to be the case on the O.S. brake. In this case the wrapping shoe was just bedding fairly evenly, up to the last portion at the heel where it showed up more. The non-wrapping was bedding hard on the heel and in this case this was the chief cause, as this portion was receiving the load on the shoes leaving the other portions of the shoes in a condition to cause vibrations. In this case, by clearing away the heavy bedding of the heel of the trailing shoe, we effectively stopped the squeak. We are carefully obtaining data between contd :- | ||
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).