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 specifications and proposed alterations for the 25HP Japan 1 model.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan191 | |
| Date | 12th May 1931 | |
| BY.{R.W. Bailey - Chief Engineer} HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} (HS{Lord Ernest Hives - Chair} is struck through) C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} (struck through) C. to HY.{Tom Haldenby - Plant Engineer} RHO. (struck through) ORIGINAL. 25HP. - JAPAN 1. X5??0 (handwritten) X5010 (handwritten) x634 (handwritten) BODIES (BONNET.) This has always been for existing stock bodies. The extra length of bonnet is obtained by the radiator being pushed forward. It is to be made with shorter tubes and the bonnet goes a small distance over the dash: perhaps it is not quite 3" - say 2.750". FRAME. The side channels can be ordered; the front dumb irons are new ones because they carry the first cross tube. I had the impression that we bought side channels only and made up the frame with our own cross members. The 2nd. cross member is also tubular, carrying the front of the engine and the radiator. The 3rd. cross member may need to be somewhat further back as the gearbox is about 2" longer. CRANKSHAFT. This is unaltered in dimensions but has the larger pins - 2" - and all crankshafts should be ordered suitable for the 8 balance weight scheme, (as is also being tried on the 'R' aero engine.) I sent a special telegram cancelling all other schemes when TSN. found this to be the lightest for a given improvement when we could not go to full balance. I pointed out how easily the 12 weight scheme you had could be converted to this four of .5, and four of .25 scheme, even without taking the crankshaft out of the engine. Apparently this has never been done in spite of my efforts, time, money, and energy wasted. CON. RODS. There is no alteration in length but they must be suitable for the larger 2" pins, (the extra .5" being cancelled.) CYL. BLOCK. In view of the above item, there is no alteration to the cylinder block. PISTONS. These are new, with greater distance between pin centres and top. HS.{Lord Ernest Hives - Chair} may like longer skirt. CRANKCHAMBER. There is no alteration except that lower half has already been scalloped for larger pins - (last 10,000 miles test.) BRAKES. Will have swivelling tips (anti-squeak.) REAR AXLE. If the hypoid failed it should have been improved until it was right as the faults were curable, in not being the gears proper, and I understood that this had been done. If however Sales do not object to higher floor - .750" - or pots in the floor, I agree to go on with spiral bevels, but it would be regrettable. PETROL PUMP. We must have this with twin carburetters as they are usually much higher. R.{Sir Henry Royce} | ||