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).
Efficiency and friction test results for a nut and screw, cheeses, and a rocker shaft.
| Identifier | ExFiles\Box 67\3\ scan0177 | |
| Date | 21th July 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/ACL/LG21.7.25. The results were corrected for the friction of the ball bear-ings, which was very small. For the overall efficiency the same units as used for the above experiments were built up in the box and tested as shewn in the appended print. RESULTS. Nut and screw. Torque required to produce an axial thrust of 1200 lbs. = 324 lbs.ins. Mechanical effcy. of thread = 66.3% Co-efficient of friction of thread considering the angle of the thread (not sq. thread) = 0.111. Cheeses. Torque to rotate cheeses in the nut when axial thrust is 1212 lbs. = 239.19 lbs.ins. Efficiency of cheeses in transmitting torque to the rocker shaft = 91.4% Average efficiency taken for axial loads varying from 1200 lbs. to 400 lbs. = 90.7% Co-efficient of friction at face of cheeses = .218. Note. The high efficiency with the large co-efficient of friction is due to the small movement of the cheeses relative to the movement of the nut. Overall efficiency. Torque required at steering wheel to produce 251.25 lbs. pull at the end of the pendulum lever = 319.5 lbs.ins. therefore overall efficiency = 58.2%. Rocker shaft. From consideration of the above, the efficiency of the rocker shaft in transmitting torque must be 96% to give an overall efficiency of 58.2%. Hs{Lord Ernest Hives - Chair}/ACL. | ||