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).
Investigation into oil pressure loss in the 'SS' lower half crankchamber during heavy braking and the proposed solution.
| Identifier | ExFiles\Box 14\1\ Scan007 | |
| Date | 24th January 1929 | |
| R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. to BJ. Hs.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} X7000 E2/M24.1.29. 'SS{S. Smith}' LOWER HALF CRANKCHAMBER. X.7000 X.7010 It is complained, and has been demonstrated to us, that after heavy braking the oil pressure falls away to almost nothing and takes some time to build up to normal. This appears to us to be due to the oil in the base chamber uncovering the suction port of the oil filter. With the normal quantity of oil a downward gradient of 1 in 5 uncovers the port. The braking effort which would pile the oil up to 1 in 5 is not excessive. It corresponds to bringing the car to rest from 60 m.p.h. in a distance of 600 ft. occupying 14 secs. With very heavy braking on say dry concrete the oil might assume a 1 in 2 gradient. This represents a braking force equivalent to half the weight of the car and brings the vehicle to rest from 60 m.p.h. in 240 ft. occupying 5 secs. approx. This latter condition is extreme and would spill some of the oil over the divisions in the base. There are three cross webs in the base chamber each of these at the present time having a substantial port way in it of about 4 sq.ins. area. We propose to reduce the area of these portways to the minimum so that they will temporarily hold up the oil particularly in the compartment containing the filter during periods of braking. [strikethrough]Exex[/strikethrough] These periods should not persist for more than a few seconds at a time, and any subsequent acceleration tends to restore the oil at about a 1 in 10 gradient rearwards. Lec.2643 of which a blueprint is attached gives particulars. The connecting holes must be large enough to avoid starving the filter compartment should the car be suddenly put up a steep gradient on a low gear even before the oil is fully wramed up. We have shewn .5" cored holes. These we think could be satisfactorily moulded with a small inserted core. Experiments could be made on existing SS.{S. Smith} chassis with baffle plates fixed over the existing portways. The original drg. is attached to BY's copy. E.{Mr Elliott - Chief Engineer} | ||