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).
Layout and objections to a gearbox silence test rig using a slipping belt drive.
| Identifier | ExFiles\Box 155\3\ scan0029 | |
| Date | 2nd October 1935 | |
| To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} X1373/ Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}12/KW.2.10.35. Gearbox Silence Test Rig. The attached sketch shows a possible layout of a gearbox test rig using the principle of slipping belt drives to obtain a large torque on the box with small input of power. The second gearbox shown on the countershaft is necessary to avoid having a set of pulleys at one end to suit every ratio in every box tested. The torque measurement could be obtained by arranging the second gearbox in a swinging frame. The objections to this type of drive are as follows :- (1) The life of the slipping belt drive would probably be very short. (2) It is almost certain that the belts would squeal badly due to their slipping. The belts driving the drums of the bumper squeal if the clutch is let in suddenly. (3) The necessity for having the same gear ratio in the second gearbox would, in practice, mean having two gearboxes of every type that is tested. (4) It is very doubtful whether the torque at which a belt drive slips is reasonably constant. Slight eccentricity of a pulley or slight variation in the thickness of the belts would cause considerable fluctuation of torque. The slipping torque also depends upon the coefficient of friction between the belt and the pulley. Our experience with brakes and servos suggests that this is very unreliable with the result that constant attention would be required to maintain any desired torque. | ||