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 leakage from the rear hub, caused by excessive brake usage on long descents, and a proposed solution.
| Identifier | ExFiles\Box 49\2\ Scan192 | |
| Date | 14th July 1924 | |
| X3457 Hs.{Lord Ernest Hives - Chair} BY8/H.{Arthur M. Hanbury - Head Complaints} 14. 7. 24. REAR AXLE. LEAKAGE OF OIL FROM REAR HUB THROUGH THE BRAKES OR OIL DRAINS WHEN THE REAR BRAKES ARE EXCESSIVELY USED. We have had a complaint from Mr. Skinner which to our minds is unique. It is, however, quite a reasonable complaint which we should have anticipated, namely, that when the brakes are used excessively on long down grades like the Alpine Passes, where miles and miles of down hill are encountered, and the foot brake and hand brake are relied upon solely to keep the speed correct, the resulting effect of the heated up drums is to cause oil leakage from the hub. Possibly you may have heard of this complaint before, but I do not remember leakage from this particular source having been drawn to our attention before. I think the reason that it leaks is obvious, namely, we pack the ball bearings with grease and put a fair amount of oil in the hubs, and the result of the heated up brake drum is to warm the hub and the inner ball bearing, thereby melting the grease and making it liquid. In the meantime, the air trapped in the hub is heated up and pushes out the oil against the oil lock which would not be very effective under such conditions. It seems to me that the air is trapped between the ball bearing at the inner end and the ball bearing at the outer end. The grease in the bearings acting as a lock, the air in between expands and has no means of escape. If, however, we were to drill through the Distance Piece G.4826 about half way along its length and drill two small holes somewhere in the same position in the axle tube on a horizontal line, this would permit the air from the outside of the hub to escape into the axle box itself and from there escape again through the torque tube to atmosphere. Would you kindly have some tests made, by which the cars are run against their rear brakes until leakage sets up, to prove that leakage would occur on a normal car, and then have the axle treated in the manner described, to see whether this would prevent such leakage. BY.{R.W. Bailey - Chief Engineer} | ||