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).
Explaining the mechanics and forces involved in the irreversibility of a steering worm and nut system.
| Identifier | ExFiles\Box 67\4\ scan0327 | |
| Date | 13th July 1927 | |
| 48430 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. [DIAGRAM] Labels on diagram: - P - NUT - WORM - μP - θ - P - Fw - Fn - Direction of motion of worm (plane). [/DIAGRAM] Equating forces in vertical plane : Fn + μPsinθ = P cosθ Fn = P cosθ - μPsinθ Similarly in horizontal plane : Fw = P sinθ + μPcosθ Fw/FN = (sinθ + μcosθ) / (cosθ - μsinθ) Calling Y "∠ of friction" μ = tan Y = sinY/cosY contd :- | ||