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).
Mechanical failures identified during high-speed running of the Phantom II engine.
| Identifier | ExFiles\Box 182\M19\ img274 | |
| Date | 1st November 1931 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. Sg.{Arthur F. Sidgreaves - MD} c. Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} EV.{Ivan Evernden - coachwork} ORIGINAL x7770 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/ADS.11.31. HIGH SPEED RUNNING OF THE P.II ENGINE. Recently we have done quite a fair amount of test bed running between 3000 and 3500 R.P.M. on the P.2. engine. The unit appears to be quite smooth at these speeds but we have had a number of mechanical failures which are as follows :- (1) Centre main bearing cap broken. (2) Bottom half cracked, bolt head sheared off securing the bottom half to the top half of the crankcase in the centre. (3) Erosion of piston stops. These piston stops disappear in a peculiar manner - no trace of them being discovered in the bottom half. A piston which has one or more piston stops missing usually produces a distinct knock. We have caught some piston stops in the process of disappearing and they are worn away at the side. We will bring a sample to W.S. in the immediate future. (4) The bosses carrying the pedestals which hold the rocker shaft have cracked where they run into the head. The conditions under which cracking occurred were not standard as it took place with the high lift rockers which have these pedestals slightly off-set and which were operating with valve springs which produced a load of 165 lbs when the valve is fully open. With the 114 W.W. shaft we find that the valve spring+necessary to keep the valves on their seats at 3500 R.P.M. is 160 lbs. + load at full lift Naturally these failures have taken a number of hours to produce and it is hardly conceivable that they are likely to occur on the road even with the latest power output. We have had, however, a case of a main bearing cap break on the road on one of our experimental cars and for this reason are pressing forward with the balance weights to scheme 1549 of which you have approved. These should remove the troubles mentioned in paragraphs 1 and 2. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||