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).
Notes on a proposed scheme for 'Packard' type balance weights on a Phantom III crankshaft.
| Identifier | ExFiles\Box 115\2\ scan0393 | |
| Date | 2nd February 1939 | |
| DI. Dg. Rm.{William Robotham - Chief Engineer} 1020 BY/B.20/G.2.2.39. Bearing File General SPOONER. PHANTOM III CRANKSHAFT. NOTES REGARDING PROPOSED SCHEME (E.CD.284) FOR "PACKARD" TYPE BALANCE WEIGHTS, WITH WIDER INTERMEDIATE BEARINGS. The maximum bearing loads at 3500 R.P.M. due to reciprocating and rotating masses combined; the effective bearing areas after deduction of radii and oil grooves; the consequent bearing pressure intensities; and the crank angles of cranks 1 and 6 after the top central position at which such maximum loads occur, are given in the table below :- | Bearing. | Max'm.{Mr Moon / Mr Moore} bearing load. (lbs.) | Effective bearing area. (sq.ins) | Max'm pressure intensity (lbs.□") | Crank angle of 1 & 6 at which maximum pressure occurs.(degs) Exact | Approx. | | :--- | :--- | :--- | :--- | :--- | :--- | | Centre bearing D.{John DeLooze - Company Secretary} | 9200 | 4.44 | 2072 | 105 | 120 | | Inner inter.brg. C or E.{Mr Elliott - Chief Engineer} | 5230 | 3.48 | 1518 | 15 | 0 | | Outer inter. brg. B or F.{Mr Friese} | 5150 | 3.48 | 1480 | 135 | 120 | Comparing these results with those given for Wraith III in BY/B.8/G.29.12.38, it will be seen that the bearing pressures in Phantom III with the proposed scheme are larger even than those in Wraith would be with no balance weights, viz. 1668 lbs/□" on centre bearing. and 1372 lbs/□" on outer inter. bearings. With my Scheme (b) system of balance weights, the pressure on both centre and intermediate bearings is about 1075 lbs/□", in the case of Wraith III. The 'Packard' scheme is bad from the point of view of bearing loads for the following reasons :- (1). Centre bearing. The inner balance weights, instead of being directly opposite cranks 3 and 4, are at an angle of 45° to this position. Thus the centre bearing is not sufficiently relieved of the heavy load due to the combined action of cranks 3 and 4 on each side of the centre bearing. | ||