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).
Causes of and solutions for backlash and noise in Goshawk engine half time gears.
| Identifier | WestWitteringFiles\K\June1923\ Scan22 | |
| Date | 25th June 1923 | |
| TO HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} c. to GJ. GOSHAWK - HALF TIME GEARS. Please find attached questions we desire answering as regards the effect of backlash in half time gears (R4/M25623.) (Handwritten note: bring the same memo. as that referred to in R3/M25623.) (1) One fears that the matter is not so simple as to come from a single source but no doubt the chief source of the noise is the effect of the valve springs on the camshaft. (2) There are also knocks however arising from unavoidable variation in firing of the engine with very light throttle opening and very slow speed. (3) There is also a possible third reason for knocks in these gears, and that is due to the speed variation of the crankshaft caused by the variation of torque due to the alternate compressions and explosions when the engine is turned lightly. If these two latter causes are of little or no importance we should anticipate an engine with a friction damped drive and the gears between the camshaft and crankshaft quite free from backlash to run satisfactorily if the other three pairs of teeth contacts are slack. If however there is a speed variation in the crankshaft due to any cause such as Nos. (2) and (3) above the engine will probably demand that the dynamo and possibly the other gears must also be closely meshed. In this case no amount of care in the first pair of gears or double wheels or fetch and carry can cure the trouble, and neither would spring plungers on the camshaft. It is this we want to ascertain but it may be that a fully satisfactory scheme can be made if the backlash is taken out of the camshaft crankshaft gears, and the camshaft dynamo gears. You will see that the reply to these questions will tell us whether a fetch and carry gear between the crankshaft would cure most of the troubles, and also whether your suggested triangular drive is needed, and also whether the triangular drive could hope to cure the whole trouble. Naturally I think you would agree that the triangular fan belt drive is very undesirable, if we can achieve our object by the more mechanical fetch and carry system of split gearing which has been many times suggested. R.{Sir Henry Royce} | ||