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).
The main bearing loading for a flat 12-cylinder engine.
| Identifier | ExFiles\Box 115\2\ scan0506 | |
| Date | 16th November 1939 | |
| 10204 111b Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}8/JH.16.11.39. Main bearing loading on a flat 12 cylinder Engine. The attached polar loading diagrams have been drawn for a flat 12 cylinder engine using Phantom III size and type crankshaft and connecting rods and Bentley V pistons. The following figures for load, pressure and P.V. factor assuming bearings of P.III size may be deduced from diagrams on Sheets 3, 4, and 5. | | Projected area of bearings on P.III crankshaft. | Max. press. lb/in.sq. | P.V. factor at 3500 rpm. | Max. load lbs. | |---|---|---|---|---| | End bearings | 4.81 sq.in. | 775 | 32500 | 3730. | | Intermediate bearings. | 2.75 | 1400 | 59000 | 3870. | | Centre bearings. | 4.81 | 1250 | 52400 | 6000. | These figures are for 3500 r.p.m. which with 2.75" dia. journals gives a rubbing speed of 42 ft/sec. A system of balance weights recommended by Bower in By/B.8/G.29.12.38 was adopted. This consists of six equal weights each attached to an inner flange. Each was assumed to couterbalance 75% of the rotating forces referred to it. | ||