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).
Draft document discussing the design, production, and cost comparison of Bentley Lead Bronze Bearings.
| Identifier | ExFiles\Box 114\2\ scan0113 | |
| Date | 23th February 1935 | |
| DRAFT 4633 23.2.35. BENTLEY LEAD BRONZE BEARINGS. We note that Lead Bronze Bearings of the flanged type with metalled liners have been instructed for "E" series chassis engines. Lead Bronze lined Conn. Rod Liners are expensive to produce, because they must first be cast in the form of a ring which after lining with Lead Bronze has to be formed to shape and then sectioned to make the liners. Similar pieces have been produced for Experimental purposes but they are not recommended for production on account of cost, as actually the deletion of the liner is the biggest saving that can be obtained in connection with the thin type bearing shell. The bearing can be produced as a complete shell and collapsed after separating to form two perfect halves and for existing Conn. Rods a steel liner could be inserted between Rod and Cap as a spacing piece which would not only be suitable for completing the final machining operations but would also be used for the assembly, the only difficulty which arises being the means of keying the bearing to prevent same from rotating and losing its position relative to the oil hole for the gudgeon pin feed. In order to prevent this happening, it could perhaps be arranged to fit hollow dowel in the bottom of the drilled oil passage. Alternatively, the forging could be made sufficiently large to permit of the big end housing being split along the centre line, in which case liners would, of course, be unnecessary. This scheme would permit of a more definite scheme for keying the bearing to prevent rotation. Regarding the thin type of bearing shells, Messrs. Vandervell Products Ltd. have submitted a quotation of £20.0.0d. for six sets of Strip type Lead Bronze Connecting Rod Bearings, this being equivalent to £3. 6. 8d. per set. We estimate that this type of bearing could be produced in our own Factory for £2. 0. 0d. per set, which would shew 40% reduction - £1. 6. 8d. per set, providing liners were not used. In comparing the cost of the plain thin shell bearings with that of the existing flanged type the biggest economy is effected by the deletion of liners which, as stated, would in Lead Bronze increase production costs enormously. For the reasons stated above, liners metalled with Lead Bronze are expensive to produce and it is chiefly due to the fact of strip type bearings removing the necessity for liners, which makes it possible to produce this type of bearing for the figure stated. continued. | ||