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).
Performance and issues of a modified Bentley car, focusing on suspension, engine, steering, brakes, and crankshaft damper.
| Identifier | ExFiles\Box 82\3\ scan0208 | |
| Date | 17th April 1935 | |
| H.{Arthur M. Hanbury - Head Complaints} GRT. MARTINDALE x200a To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} From G.W.H. Hotel de France. Chateauroux. France. 17/4/35. 5 B IV. We have received your memo Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} 12/Kw 15/4/35. We have the car running as reported yesterday. It is nearer a Bentley than it has been since we brought it out. It is running at present with the following alterations. 4 B IV 4 3/4 transverse Front Axle. Pivot lean 1 3/4º Toe in of wheels 1/16. Standard Brakes. Original front springs. Buffer clearances OS 1 1/2" NS{Norman Scott} 1 7/16" Engine. Crankshaft damper 15 Lbs true friction load at 17 1/2" rad. K.L.G. 805 type plugs 020" gap. These plugs are giving good results and have got rid of the hesitation at slow speeds when getting away. The steering under these conditions is selective and stable, joggles of steering wheel no worse than standard. Braking good at any speed. The Car is now safe to drive. Engine. No half crankshaft period, maximum period has not been affected - - - - With reference to your memo. Water Excluders. The Water excluders would not have given trouble had not the brake shuddered. The water excluders would not have given trouble with a brake shudder had the brake anchorage plate been designed throughout with sufficient strength. The anchorage plate for the brake shoes is rigid but the dust cover plate is not, and when the whole brake mechanism gets into a violent vibration the thin steel dust cover evidently whips. The cast brake drum recessed for the flange of the water excluder does not allow for excessive vibrations of the dust cover and consequently the rotating action of the brake drum collard hold of the water excluder flange and pulled it further into the recess of the drum bending it inwards. The action of bending a round flanged piece (like a tin lid{A. J. Lidsey}) tends to straighten out the flange at 90º to the bend. This causes a further seizing effect of the drum and dust cover. The dust cover should have been made with approx. three indents to make it rigid (see 14" brake design). Engine periods? We are very much surprised at your statement re poundage of the crankshaft damper. 17 Lbs friction load (true slipping not initial load) is all that be obtained using cotton duck friction discs on the Bently or 25 H.P. dampers. The loadings springs come choc-a-bloc if more load is attempted. I have tried to obtain stronger springs to get a greater friction load but the space is too limited. Very high rated springs would be of much use as they cause initial sticking and loose too much poundage for a slight wear of the fabrics. The recess for the springs require enlarging in dia. so that a larger area [Handwritten note on left margin]: GRY{Shadwell Grylls}4S. Is there anything in this? [Handwritten note on right margin]: Martindale | ||