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).
Design, advantages, and disadvantages of a constant mesh helical gearbox.
| Identifier | ExFiles\Box 173\3\ img004 | |
| Date | 22th March 1934 | |
| -2- Internally the box is of conventional design except for :- 1. Centrifugally-operated multiplate clutch. 2. Two free wheel clutches. 3. Two small cam rings. The gears, of course, are constant mesh helical. The advantages of the gear as I see it are:- 1. Does away with side levers giving entrance on the driving side of the car. 2. Requires no pre-selection or hand control for normal driving. 3. Throws little strain on the clutch or transmission as changes are made without shock. 4. Utilises 90% normal gearbox parts. 5. Prevents the engine being over-revved on the lower gears. Disadvantages :- 1. Free-wheeling in the lower gears. 2. Appreciable increase in bulk and weight of the gearbox, probably 10% more than our present standard synchro-mesh but little more than an all synchro-mesh. SUMMARY. Actually from a customer's point of view this has nothing on the Wilson box and fluid flywheel. I think it lies between our synchro-mesh and the epicyclic gear. We have given our transmission such a lot of attention lately that I hardly think we are justified in playing with this job. Am trying to arrange, however, for us to try a car with the box on as there are two in Paris, and also for diagrammatic sketches of the operation to be sent on to us. NOTE. Noticed one very ingenious novelty on this box. A screw thread cut on the shaft is used as an oil pump to force oil into the shaft centre. They claim they can pump up to 80 lbs/sq.in. by this method. Ha/Rm.{William Robotham - Chief Engineer} | ||