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).
Technical analysis of a Mercedes-Benz C.I. engine's balance weights and a comparison with a Daimler petrol engine's valve gear and cam design.
| Identifier | ExFiles\Box 179\1\ img097 | |
| Date | 19th November 1931 guessed | |
| (2) On the Mercedes-Benz 6 cyl. C.I. engine balance weights are fitted apparently solely for relieving the inertia loading on the central bearing, since they are arranged as shown in the sketch. The bearings are all of equal length. The method of attaching these weights is reminiscent of a recent RR. sch. but is not as simple and reliable. The main bearing caps maintain their section concentrically around the shaft centre thereby providing extended mating faces with the crankcase. In a bearing of this type this appears to be a commendable feature since the cap derives support from the case in resisting the effect of heavy vertical loading. PETROL ENGINES. It is interesting to note that the Daimler are offering a poppet valve power unit, this being a 6 cyl. engine of orthodox push rod overhead valve design, 103.5 x 130 mm., which goes into the same space as the sleeve valve 97 x 130 mm. There are no balance weights but the crankcase is heavily boxed on the sides. The crankshaft pinion for the rear timing gear chain drive is apparently produced solid with the shaft and there is but a single rear bearing. It is claimed that cam profiles have been evolved for use on this engine which allow much greater tolerance in tappet adjustment than the total clearance now in common use without any sacrifice of mechanical silence. The particular point about these profiles must necessarily be the use of extended cam feet having low values of acceleration. This is an old RR. sch. originally evolved for aero engine work where a large variation of permissible clearance was called for, on all of our present profiles in a modified form. The cam feet used on the Daimler are sufficiently extended to allow of clearances of the order of .06 to .075 it is understood. We see no reason why such cams should not solve the clearance problem on an engine such as J.5., where both cyl. block and head are of aluminium, without having recourse to the use of automatically adjusting tappets. (TO BE CONTINUED.) E.{Mr Elliott - Chief Engineer} | ||