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).
Comparison of loads on the working faces of a proprietary steering gear and its equivalent Weller gear.
| Identifier | ExFiles\Box 15\6\ Scan113 | |
| Date | 27th May 1930 guessed | |
| COMPARATIVE LOADS ON THE WORKING FACES ON A TYPICAL HEAVY DUTY PROPRIETARY STEERING GEAR AND ITS EQUIVALENT WELLER GEAR. Proprietary Gear. Turn of wheel - 4¼". Length of internal lever from centre of rocker shaft to point of contact - 3¼". Reduction ratio:- 23.5/1. Load ratio (20" wheel) - 10" divided by 3.25" x 23.5 = 72.5. Load on working faces at 100 lbs. pull on rim of wheel:- 72.5 x 100 = 7250 lbs. This particular gear employs a thrust bearing to support the roller element which forms the follower, and this works at a mean radius of 2". The load, therefore on this thrust at this radius is 11,800 lbs. This is neglecting the rather unfair tipping action to which this thrust bearing is subjected. Weller Gear. Turn of wheel:- 4¼". Length of internal lever from centre of rocker shaft to point of contact:- 4¼". Reduction ratio:- 23.5/1. Load ratio (20" wheel) :- 10" divided by 4.25" x 23.5 = 55/1. Load on working faces at 100 lbs. pull on rim of wheel:- 55 x 100 = 5500 lbs. It must be understood of course that the figure of 100 lbs. pull on the rim of wheel is taken mainly as a comparative one, and to form a datum line. Any shocks transmitted from the road wheels may be considerably greater than this, but they will stress the gear in the same ratio, as indicated by these comparative figures. It will be seen therefore that normal and shock loads on the working faces of the Weller gear are under any circumstances in the neighbourhood of 40% less than the proprietary gear referred to. In addition, this is not taking into account the fact that all other cam and lever gears at best only obtain a theoretical line contact between follower and cam. In the Weller gear of course a considerable degree of surface contact is obtained. | ||