Article from 'Automotive Industries' on an improved 'Nut and Lever' steering gear by Lavine.
| Identifier | ExFiles\Box 154\3\ scan0080 | |
| Date | 9th June 1934 | |
| x 3682 721 Lavine Develops Improved "Nut and Lever" Steering Gear for Passenger Cars AN improved Lavine steering gear featuring multiple rolling contacts has been developed for passenger car installation by the Lavine Gear Co., Milwaukee, Wis. It is a small, unusually compact unit, designed to meet the close chassis clearances of present day cars; it will supplement the present line of Lavine heavy-duty equipment which is widely used on trucks, tractors, and industrial units. According to the manufacturer, the improved steering gear offers the following unique features: Ease of steering plus control No wheel fight under any conditions High factor of safety Shock absorption within the steering mechanism Ease of adjustment Positive lubrication As will be noted in the illustration, the Lavine gear provides in a small compact mechanism the necessary steering leverage to meet present day demands. This is accomplished through a nut-and-lever system (patented) which converts a moderate effort at the steering wheel into the needed force at the pitman arm. The mechanism comprises a worm of rather small diameter and small pitch, from which the steering effort is transmitted to a ball nut carrying two steel balls which engage in the worm track. The ball nut has a wide slot in its outer face at right angles to the worm axis, in which there is a slideable trunnion connected to the trunnion lever by a pin permanently fixed in the lever. With this arrangement the pressure between the driving and driven elements is distributed over surfaces of considerable area, which reduces the rate of wear. One of the outstanding features of the construction is the mounting of the trunnion lever on "roll-free" bearings, providing a bearing surface which extends practically the entire length of the trunnion-lever shaft. The rollers are retained in position by shoulders on the shaft which is undercut to accommodate them. All parts of the gear mechanism are of a special analysis, high-manganese steel, with about 0.40 per cent carbon, heat treated. Ease of adjustment is attained in two ways—first by locating the point of adjustment accessibly, and second by concentrating all adjustments at one point. Adjustment is made by turning a single screw, which is located on the gear-box cover. Wheel fight is said to be entirely eliminated through the action of multiple rolling contacts and working parts moving at 90 deg. to each other, simultaneously. Over-steering is prevented by the change in direction of the trunnion, which assures a complete pause when arriving at the center position. A certain amount of reversibility is desirable in a steering gear, as it permits the wheels to straighten out automatically when coming out of a turn. Too much reversibility, on the other hand, is quite undesirable because it throws the wheel back too sharply and leaves the gearing subject to road shock. In the Lavine gear, the degree of reversibility decreases with the distance from the central position. Multiple rolling contacts are said to result in such positive control of road shock that kick shackles or snubbing devices of any kind are not needed in the steering-gear linkage. The damping characteristics and relative irreversibility of this gear also are said to eliminate the effects of shimmy or wander due to uneven tire wear or misalignment. Another important feature of the new steering gear is the system of lubrication. Investigation has shown that the ball nut acts as a sort of oil pump, which constantly moves lubricant and distributes it to the moving elements. A representative of Automotive Industries drove a well-known, high-priced car that had been equipped with the Lavine gear. This car with its regular steering gear is said to be rather hard-steering. It gave an unusual feeling of security and positive control, despite the fact that the wheel required comparatively little effort. Right and left turns with only one hand on the wheel were made with exceptional ease. Stretches of dirt road with rail crossings and holes were taken with the hands off the wheel; yet there was no evidence of wheel kick or change in direction. It might be interesting to mention that this test car is being run with the kick shackle locked and the springs removed from the tie-rod ball ends. Automotive Industries June 9, 1934 | ||
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).