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).
Improvements to the steering worm, nut, and spring return mechanisms.
| Identifier | WestWitteringFiles\Q\April1927-June1927\ 26 | |
| Date | 20th April 1927 | |
| TO HS.{Lord Ernest Hives - Chair}) FROM R.{Sir Henry Royce} SY.) (At Le CanadelHenry Royce's French residence.) ORIGINAL R2/M16.4.27. REC'D DURING EASTER, AND DESPATCHED 20.4.27. C. to BJ. WOR.{Arthur Wormald - General Works Manager} PN.{Mr Northey} B. CWB. re. STEERING WORM AND NUT, X8430 X235 AND SPRING RETURN. X8470 4457 My impression is that we fairly well know what we want for good steering, but that it is difficult to get all the unit correctly proportioned and constant. I can however clear the ground I believe. (1) We want reversibility after wear to be about the same as at present newly fitted. I suggest we go definitely 25% decrease in angle of thread. We do not want to decrease the speed of the steering except that this is the only way we know to get less road shocks (more irreversibility) with the present parts. Therefore .940 should be made .875, about 7 1/2% slower, and .720 should be .685 i.e. about 5% slower. We cannot do more without altering the levers and increasing the stress, and perhaps spoiling the geometry, until we make a worm of larger dia. which I want you to draw. Add about one fifth to the dia. and see if we can get this in. I think it would be wise to limit ourselves to this rather than instruct so many. Some of this I understand has been done some time ago: only waiting for Derby. (2) I think that the steering nuts and worms should be as perfect as we know how to make them, for bedding, finish, and freedom without slack, or only so much slack that the oil will fill the space, and I believe that casting the nut lining on the worm, or on an exactly similar worm a little larger in dia., is the best and quickest way of obtaining this object. (3) For safe and straight steering we must have a fairly good lean back on the axle pivots. My memory says about 30', but this involves us into low speed wobbles even on our best axle, (i.e. 2nd. Phantom), but it ought to be possible to damp these from building up by - (A) Mechanical friction depending on pressure of a spring (but at present is ball pressing on cross tube.) (B) Hydraulic damper on axle. (C) Damping friction in pendulum lever. All these are being tried in various proportions, (A) with much success, though I fear hardly thorough and obvious enough to last 15/20 years on a car. (4) Finally we come to the self centre-ing so necessary for slow steering, and quick and safe handling. Here we have schemed the independent spring return, which we want to try with the greater irreversibility. I do not think this is required (1) | ||