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).
Repeated piston failures on a Benaport car in France, attributing the cause to faulty castings and dispatching improved replacements.
| Identifier | ExFiles\Box 179b\3\ img367 | |
| Date | 26th March 1933 | |
| To H.{Arthur M. Hanbury - Head Complaints} From Hs.{Lord Ernest Hives - Chair} C. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} C. to R.{Sir Henry Royce} Le. C. to Hy.{Tom Haldenby - Plant Engineer} Hay. RE: BENAPORT CAR IN FRANCE. We have heard from G.W.Hancock that another piston has failed on this car in a similar manner to the first one, that is, the head has broken away where the saw cut is made for a flexible skirt. The history of the piston failures in France is that on the original pistons after 5000 miles the circlips worked loose and damaged the pistons. A fresh set of pistons were sent out made to the same drawing and one of these failed after 500 miles. Another one failed after 1500 miles. It was first thought that owing to a thin gasket being used under full load conditions the piston may have touched the top of the cylinder head. We have since been assured by G.W.H. that this could not happen. The only reason, therefore, for the failure of these pistons is that the castings must have been faulty. E.{Mr Elliott - Chief Engineer} has gone into the stress and finds that the stress due to inertia is quite low. It had already been decided that on the 200 sets of material for Benaport we should use the standard 25 HP. die-cast piston. The difference between this piston and the one that has been run on Benaport is that the top of the crown is .030 lower but the combustion chamber has been modified to obtain the same compression ratio. We are sending out today to France a set of die-cast 25 HP. pistons fitted with improved circlips. We also expect to receive from Chateauroux the two damaged pistons so that they can be examined. Hs.{Lord Ernest Hives - Chair} | ||