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).
Issues including cracking of cylinder castings and heads, and seized pistons due to liner distortion.
| Identifier | ExFiles\Box 179\3\ img104 | |
| Date | 30th March 1932 | |
| -3- Hs.{Lord Ernest Hives - Chair}3/MJ.30.3.32. Cont'd.{John DeLooze - Company Secretary} Cracking of the Cylinder Casting at the Bottom Between the Bores. We are now producing engines with raised floor blocks. This should definitely reduce the risk of cracks between the bores and we believe this, in conjunction with the increased liner clearance, should clear this trouble completely. We are running some engines with the forged aluminium plate at the bottom of the cylinders but we are of the opinion that this will not be found necessary. It will be a good thing if this is the case, because the forged aluminium plate necessitates another joint, and it is also an expensive and difficult piece. Seized Pistons Owing to Liner Distortion. We attach herewith a copy of a report which shows the investigations which have been carried out showing the liner distortion. Briefly, the position is that with our present construction we have got to accept a certain amount of liner distortion when blocks are tightened down but in this particular fault several moves have been made which should alleviate this trouble. We have developed a special ground piston which is an oval piston slightly barrelled, which is a very positive improvement over the one we are at present using. Until we developed this piston we could not run the evaporatively cooled Type Test. Another feature is that we are now making engines with a stiffer top flange to the crankcase. This, again, definitely reduces the liner distortion. We have also in hand tests with slightly modified liners to go into the present cylinders which again helps to a certain extent. The position therefore is that we see no hope with the present construction and dimensions to get rid entirely of cylinder distortion, but we shall be very much better than the engines which have as far been supplied and therefore the troubles as regards seized pistons should be considerably reduced. The other scheme which will help us in this direction is when we get the extra oil for starting up. Cracking of Cylinder Heads Between the Valve Seats. We think this can always be attributed to take place when an engine boils excessively. Tests with thermo couples show that is we take a standard engine with the small water pump and boil it vigorously, i.e. under full power conditions, it is possible to register very high temperatures on some parts of the cylinder head owing to steam pockets being formed. It should be noted that this only occurs under full power conditions when a lot of steam is being formed. We do not think this should occur under conditions where the water just boils. The alterations, | ||