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).
Mechanical analysis of the forces and irreversibility within a steering worm and nut assembly.
| Identifier | ExFiles\Box 67\4\ scan0331 | |
| Date | 13th July 1927 | |
| Hs{Lord Ernest Hives - Chair}/Tsn/LG13.7.27. IRREVERSIBILITY OF STEERING WORM AND NUT. The nut and worm can be represented respectively by a weight and an inclined plane. In case (1) to be considered, the worm will be considered as driving the nut i.e., the plane will be lifting the weight. This is 'Parking'. Imagine a force P. between the two, ⊥ to the surface of the plane, and of un- known magnitude. The only two external forces are :- Fn = force on nut and is the force resisting motion. Fw = force on plane. This is force on worm, considered as acting at Pitch Radius. Direction of motion of worm (plane). Equating forces in vertical plane : Fn + μP sin θ = P cos θ Fn = P cos θ - μP sin θ Similarly in horizontal plane : Fw = P sin θ + μP cos θ Fw sin θ + μ cos θ ---- = ----------------- FN cos θ - μ sin θ Calling Y "∠ of friction" μ = tan Y = sin Y / cos Y contd :- | ||