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).
Tests conducted on Bentley II steering gear shear pins to determine maximum load capacity.
| Identifier | ExFiles\Box 83\2\ scan0355 | |
| Date | 1st June 1939 | |
| 200a + 250 To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} c. HS.{Lord Ernest Hives - Chair} c. Da.{Bernard Day - Chassis Design} c. Da{Bernard Day - Chassis Design}/Ev.{Ivan Evernden - coachwork} Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer}1/MH.{M. Huckerby}1.6.39. BENTLEY II STEERING. We have been carrying out tests to find the maximum load to which the steering gear of O.B.IV, an 'M' series Bentley, can be subjected by driving over kerbs etc. without damaging any part of the car. The loads were measured by shear pins fitted to the rear side steering tube joint which allowed about 1/4 turn of backlash when fractured. The following tests were carried out. Normal maximum load is assumed to be the maximum load under parking conditions which is 35 lbs. ft. torque on the steering wheel, or, allowing 80% mechanical efficiency of the gear, 650 lbs. load in the side steering tube in the central position. Test 1. Shear pins of 1250 lbs. capacity fitted. It was found to be impossible to break these under any conditions. Test 2. Shear pins of 675 lbs. capacity. One of these fractured at the first attempt by driving at 30 m.p.h. over the 6 1/2" high kerb round the island at the junction of the By-pass and Derby Lane. Test 3. 2nd. test of 675 lbs. capacity pins. These were driven for 70 miles at high speeds over all the rough roads that could be found, including the road across Osmaston Park, also over comparatively low kerbs at high speeds, and various angles, but remained intact. They were then driven over the 6 1/2 high kerb mentioned above at 25 m.p.h., 28.m.p.h. and finally one fractured at 30 m.p.h. | ||