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).
End thrust tests of a Skefko ball bearing compared to Hoffman and D.W.F. bearings.
| Identifier | ExFiles\Box 20\7\ Scan083 | |
| Date | 12th May 1914 | |
| 12A (150 H) (W.W. 276. 12-5-14) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 0547. From Exp. Dept. Copies to: J.{Mr Johnson W.M.} J.{Mr Johnson W.M.} H.{Arthur M. Hanbury - Head Complaints} Na.{Mr Nadin} By.{R.W. Bailey - Chief Engineer} Wor{Arthur Wormald - General Works Manager}/Hy{Tom Haldenby - Plant Engineer}11/B3714. Report on end thrust tests of ball bearing. X.548. Further to my reports Wor{Arthur Wormald - General Works Manager}/Hy{Tom Haldenby - Plant Engineer}12/L26614 and Wor{Arthur Wormald - General Works Manager}/Hy{Tom Haldenby - Plant Engineer}9/L29614, the Skefko bearing size 35 x 80 x 21 m/m has now been put through the same tests as the Hoffman and D.W.F. bearings. It has run 20 hours with 1500 lbs. end pressure and 10 hours with 2000 lbs. end pressure at 152 revs. per min. There is a double row of balls .406" dia. and 14 balls in each row. They are held by a sheet metal retainer. After the test the outer race was found to be scored all round and the skin was broken through in two places. This bearing seems to have fared worse than the other makes although the Hoffman was in about the same condition, but this was due to the grooves which are cut to insert the balls. The Skefko has simply broken down due to overload. In order of merit the different makes are, D.W.F. deep groove, very good condition after test; Hoffman broke down due to groove in sides of races being too big and allowing balls to foul when big load applied endways; Skefko broke down simply due to inability to carry the load imposed. I think this is due to the greater wedging action of the balls as a result of the large radius of the outer race. I am carrying out a further series of tests at 567 revs. per min. instead of 152 revs. per min. | ||