Proceedings of the Institution of Mechanical Engineers: Automobile Division

The demand for still greater reductions in weight together with the general stepping-up of vehicle performance with larger power units has placed upon the transmission engineer the onus of producing a small, lightweight and compact design yet capable of giving a satisfactory life. Economy in both weight and cost has become a primary requirement, and if this is to be met, a close study must be made of all the detailed components in order that the utmost can be obtained from each pound of material used.

The maximum possible life of spur and helical gears is seldom achieved, as premature tooth failure occurs through poor face comformity of the mating teeth. The causes and effects of such nonconformities, whether dimensional or resulting after heat treatment, are dealt with, and the measures that can be adopted for their correction discussed. The elimination of any tendency to corner loading and, to a finer degree, the crown shaving of the teeth enable higher basic stresses to be adopted with corresponding smaller and more economical gear trains.

Investigations into syncromesh mechanisms have indicated that synchronizing efficiency depends largely on attention to certain small details. An appreciation of these points will permit of quite small diameter synchronizers functioning satisfactorily without their useful life being in any way impaired by the higher loadings involved. Syncromesh problems are treated generally with particular detailed reference to design for high performance.

It is unfortunate but nevertheless axiomatic that the tendency to self-disengagement of the gears increases as the loadings and stresses of the components are increased, and no paper on the design of an efficient economical transmission could be complete without its mention. The general causes of self-disengagement are discussed together with design features which can be embodied for its avoidance. The problems generally associated with the gear train which present definite requirements, of the casing, shafts, selector mechanism, etc., are dealt with.

In conclusion, descriptions of the test equipment and tests used in the development of high-duty transmissions are given.

The MS. of this paper was received at the Institution on 5th February 1953. For the Report of the meeting in London, at which this paper was presented, see p. 27.

In this paper, the numerous factors affecting the operation of plain bearings, principally crankshaft, main, and pin bearings, are considered, and the problems of bearing design, from the aspect of selection of the various materials which are combined in the construction of a bearing assembly, are discussed. An attempt is made to bring together conclusions reached by studying the factors referred to, and the performance of bearings in practice. The latter is based on a study in summary of the three kinds of bearing failure, namely, seizure, excessive wear, and mechanical breakdown. Comment on recent work by Lunn and by Roach is made, and a working hypothesis on the effective fatigue strength of a bearing lining is proposed.

The MS. of this paper was received at the Institution on 6th October 1953. For the report of the meeting, on 8th December 1953, at which this paper was presented, see p. 145.

The MS. of this paper was received at the Institution on 23rd November 1953. For the report of the meeting in London, at which this paper was presented, see p. 44.

The object of this paper is to survey the rapidly broadening range of vehicle types to which power assisted steering is being fitted, to give descriptions of some of the various approaches to the problem of making such provision and to comment on particular features of systems using alternative installation layouts and/or different sources of power.

Emphasis has been given to the problems of applying power assistance to the steering of the General Service or Public Service classes of vehicle, since it is felt that in these spheres the higher road performance attainable with the aid of such assistance may give rise to operating troubles with designs that previously have proved satisfactory over a long period of development and usage.

Special purpose vehicles would normally be expected to go through a proving period, while the steering of private cars up to the limit of road adhesion is possible without power assistance.

It is considered that it is in recent months rather than in recent years, a marked practical interest in steering assistance has developed in Great Britain, and although this ground has been largely covered previously in published articles and particularly in American literature, some recapitulation should prove of interest and, it is hoped, of value, to those who, until a comparatively short time ago, had not given very serious thought to the likelihood of a more general demand arising, but who are now attempting to judge the strength of the present trend.

Brief remarks are made regarding the history and development of powered steering installations, but such observations that are made are not intended to present a full story.

The MS. of this paper was received at the Institution on 23rd December 1953, and in its revised form, as accepted for publication on 5th January 1954. For the Report of the meeting at which this paper was presented, see p. 94.

The MS. of this paper was received at the Institution on 1st January 1954. For the report of the meeting in London, at which this paper was presented, see p. 112.

The authors define the characteristics of a pneumatic tyre which affect the handling, or stability, of a car, and briefly describe a machine which was developed to measure these characteristics.

The results are given of various experiments showing the effect of several factors on the characteristics; the applicability of these results to the behaviour of a tyre on the road is also discussed.

Briefly defining oversteer and understeer, the authors outline a proposed method for directly determining the handling performance of a car while it is still in the drawing board stage. It is pointed out that this will only apply to steady conditions and some of the factors affecting transient behaviour are discussed. In particular, the importance of the self-aligning torque is stressed.

The problem of breakaway is mentioned and doubts are cast on the applicability of the machine results to high-speed cornering, or racing; the technique of drifting a car round a corner is discussed.

The MS. of this paper was received at the Institution on 17th November 1953, and in its revised form on 11th January 1954. For the report of the meeting in London, at which this paper was presented, see p. 134.

The MS. of this paper was received at the Institution on 14th May 1954. For the report of the meeting in Delft, at which this paper was presented, see p. 146.