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).
Confidential letter from Ogilvie & Partners regarding the use of Sumet metal in Wright Aeronautical engine bearings.
| Identifier | ExFiles\Box 46\1\ Scan105 | |
| Date | 17th October 1924 | |
| COPY OF LETTER FROM OGILVIE & PARTNERS LTD. 104, High Holborn, London, W.C.1. 811/C/B2. 17th October, 1924. PRIVATE AND CONFIDENTIAL. Dear Basil Johnson, You may be interested to know that the Wright Aeronautical Corporation are extending the use of Sumet to the main bearings on their engines and they have just placed an order for 3,000 pounds of metal for this purpose. The query has recently been raised as to whether there is any likelihood of Sumet seizing up on the shaft, but we are informed by the Sumet people that there is no possibility of this. If the bearings fit too closely, so that the expansion due to frictional heat of running takes up oil space, a higher frictional load will be produced due to the shaft rubbing directly on the bearing with no oil film between. This of course will produce a braking effect, which in time may disappear if there is plenty of oil to cool the bearing whilst it is wearing on to its seat. In order to avoid any possibility of such overheating the Americal aeronautical engine makers have adopted rather larger clearances than are practised in this country. The present American standards have been arrived at after considerable experiment and they may be of interest. The general practice is to allow .0015 inches per inch of shaft diameter. On their T.3 engine having a 3" shaft, the clearance allowed between the bearing and shaft is .005". This bearing also has an outer rod which works on the outside of the bearing, the outside diameter being about 3-5/8". The clearance between the outer rod and the outer service of the bearing is .007". Side or end clearance for a bearing 2 1/2" to 3" long is from .008" to .010". Any further information on this matter is at your service. Yours faithfully, (Sgd.) W.A. Bristow. PS. A T.3 engine is now up for test fitted throughout with Sumet metal, both in the main bearings and the connecting rods. | ||