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).
Ball race thrust tests for the Wraith Gear Box 1st Motion Shaft Bearings.
| Identifier | ExFiles\Box 8\11\ 11-page167 | |
| Date | 24th May 1939 | |
| 628 To Rm.{William Robotham - Chief Engineer} from HPS{Horace Percy Smith - Experimental Factory Mgr}/Bl. c. to Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} c. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} c. to Ey. HPS{Horace Percy Smith - Experimental Factory Mgr}/Bl.1/CB.24.5.39. BALL RACE THRUST TESTS. With particular reference to Wraith Gear Box 1st Motion Shaft Bearings. In connection with the "knocking" attributed to the float in these bearings, measurements were taken of the movement of the inner race relative to the outer race due to thrust load, whilst supporting a journal load of 500 lb. The desired No. 340 (000) ball and roller bearings not being immediately available, the tests were carried out with a combination of No. 325 (000) ball and roller bearings. The apparatus is roughly illustrated in the key diagram on BL.2340. The outer races of the bearings were held in blocks with a shaft fitted through the inner races, (the roller bearing was merely a support) sleeves fitting over the shaft on each side of the ball bearing supported the journal load and the thrust load was applied through the sleeves to the inner race of the ball bearing. The movements of the shaft were recorded relative to the bearing blocks. Both push and pull thrust loads were applied. In BL.2340 the full hysteresis curve up to ±500 lb. thrust load whilst supporting 500 lb. journal load is shown, whilst in BL.2341 the deflections with no journal load are given. In BL.2342, the deflections about the central position with the 500 lb. journal load are shown on an enlarged scale - this test was taken up to ±300 lb. thrust load with small load increments up to ±100 lb. - from which it will be observed that the thrust load required to overcome the journal load was approximately ±30 lb. A pair of the larger 40 x 90 x 23 m/m No. 340 bearings is now available and the tests will be repeated with them as soon as possible. HPS{Horace Percy Smith - Experimental Factory Mgr}/W.Bell. | ||