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 an unexpected increase in production chassis costs due to a modification of the tappet doors.
| Identifier | ExFiles\Box 88\4\ scan0172 | |
| Date | 12th September 1936 | |
| SECRET. X254 Swett G/Rb.{R. Bowen} from E.{Mr Elliott - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Sft.{Mr Swift} E.1/HP.12.9.36. Re Production Chassis Costs. An investigation into the difference in chassis cost due to the modified tappet adjustment on the 25/30 HP. and 4 1/4 litre Bentley has revealed an instance where the cost of production is considerably higher than it need be due to an obvious lack of co-ordinated effort throughout our organisation. It is obviously useless for one department to concentrate on reducing chassis costs unless the importance of this point is realised and studied by all the various departments through which modifications must pass before they appear in the flesh on our products. The case in point is the tappet doors. On the 25/30 HP. and 3 1/2 litre Bentley there consisted of aluminium die castings held in position by two thumb nuts per tappet door. The doors were not interchangeable and necessitated 4 dies to produce the four tappet doors used on the two cars. The total cost of this item per chassis was 13/- assuming 175% charges. Of this amount the material cost was 6/7d and labour 2/4d. The tappet doors themselves cost 2/6d in material and 1/6d in labour. On the redesigned tappet adjustment the parts were made common to both chassis, and further than this the two tappet doors on each engine were made interchangeable; this was done to reduce cost and so that one die need only be made for both tappet doors on both chassis. In spite of all this we find that the new tappet doors are more expensive than the old, the doors themselves cost 2/6d in material and 4/- in labour, so that with charges the total cost of the doors and their retaining studs etc. amounts to 15/- (instead of 13/-). On investigating the cause for the 4/- labour cost on the new tappet doors (compared with 1/6d labour cost on the old) we find that it is based on these being produced from a | ||