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).
Letter from New-Hudson Ltd regarding the test results and analysis of a Girling brake sample.
| Identifier | ExFiles\Box 120\3\ scan0130 | |
| Date | 3rd January 1935 | |
| TELEGRAMS: WONDER, BIRMINGHAM TELEPHONE: CENTRAL 0321 (6 LINES) CODES: A.B.C. 5TH EDN. BENTLEYS CONTRACTORS TO H.M. GOVERNMENT WAR OFFICE, G.P.O., COLONIAL AND FOREIGN GOVERNMENTS NEW-HUDSON LTD PROPRIETORS OF ST GEORGE'S ENGINEERING WORKS. Icknield Street BIRMINGHAM-18 OUR REF AF/AL. Your Ref: Hs{Lord Ernest Hives - Chair}/AFM{Anthony F. Martindale}/1/KW. 3rd January 1935. Handwritten note: GRY{Shadwell Grylls}? We should write these 3 people further on the subject of efficiency. Rm{William Robotham - Chief Engineer} Handwritten note: Martindale? Messrs. Rolls Royce Ltd., DERBY. Dear Sirs, For Attention of Mr. Robotham. With reference to yours of the 29th ult., re GIRLING BRAKE sample submitted for test, we were very interested to have the figures you obtained during efficiency tests, and offer the following comments :- The amount of sponge you obtained was not excessive, considering the pull of 300 lbs (= 947 lbs on each shoe tip) and the condition of the test i.e. unbedded linings. With linings completely bedded by wear, the sponge would be considerably reduced. We think also that a stiffer drum is required, which would reduce the sponge to a minimum. The drum design we have found most satisfactory has the rib nearest in line with the centre line of the shoes, at least .875" deep. If the stiffness varies with the cube of the depth, the gain in stiffness over the shallow ribs is enormous. We do not think that the sponge occurs in the GIRLING mechanism, as with the exception of the short pull rod, all the parts are hardened steel in compression. As the brake linings extend to points in line with the Expander Plungers the bending movement on the shoes is reduced to a minimum. The sponge, therefore, arises partly from compression of lining, but much more from drum deflection. With reference to your standard clearance continued - | ||