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).
Analysis of bearing loads under various balance weight schemes, with calculations and conclusions.
| Identifier | ExFiles\Box 115\2\ scan0396 | |
| Date | 29th December 1938 | |
| - 2 - BY/B.S/G.29.12.38. | Scheme of Balance Weights Used. | Load on each of bearings below due to rotating masses only. (lbs). | Max'm.{Mr Moon / Mr Moore} load on each of bearings below due to rotating and reciprocating masses combined.(lbs). | |---|---|---| | | A.or G.{Mr Griffiths - Chief Accountant / Mr Gnapp} | B.or F.{Mr Friese} | C.or E.{Mr Elliott - Chief Engineer} | D.{John DeLooze - Company Secretary} | A.or G.{Mr Griffiths - Chief Accountant / Mr Gnapp} | B.or F.{Mr Friese} | C.or E.{Mr Elliott - Chief Engineer} | D.{John DeLooze - Company Secretary} | | No bal. weights. | 1140 | 1963 | 1960 | 3475 | | 3430 | | 6050 | | R.R. | 324 | 1445 | 1354 | 1355 | | 2872 | | 3892 | | Sch.(a). | 918 | 975 | 1138 | 2037 | | | | | | Sch.(b). | 928 | 1228 | 1185 | 1308 | 1790 | 2687 | 2630 | 3865 | | Sch.(c). | 923 | 1093 | 1116 | 1670 | | 2568 | | 4237 | After deducting end radii and oil grooves :- Area of intermediate bearing B (or F) = 2.5 (1.325 - .2 - .125) = 2.5 sq.ins. Area of centre bearing D = 2.5 (1.825 - .2 - .175) = 3.625 sq. ins. With Scheme (b) of balance weights, the maximum bearing pressure intensity at 3500 R.P.M. due to rotating and reciprocating masses combined :- On bearing B or F = 2687 / 2.5 = 1075 lbs. sq.inch. " " D = 3865 / 3.625 = 1066 lbs. sq.inch. Again with Scheme (b) of balance weights it is of interest to note that the maximum loads (due to rotating and reciprocating masses combined) at the various bearings occur for the crank positions given below :- Maximum load at centre bearing D occurs when cranks 1 and 6 are at 120° to T.D.C. i.e. when cranks 3 and 4 on each side of D are at T.D.C. Maximum load at inner intermediate bearing E occurs when cranks 1 and 6 are vertical, i.e. when cranks 4 and 5 on each side of E are at 240° and 120° to T.D.C. respectively. Maximum load at outer intermediate bearing F occurs when cranks 1 and 6 are at 120° to T.D.C. i.e. when cranks 2 and 5 on each side of F are at 240° and 120° to T.D.C. respectively. Conclusions. Scheme (b) is the best of those considered. | ||