Co-operating organizations

The Mechanical Engineering Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations:—

The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this standard:—

This British Standard, having been approved by the Mechanical Engineering Industry Standards Committee and endorsed by the Chairman of the Engineering Divisional Council, was published under the authority of the General Council on 31 December 1953

Foreword

This standard makes reference to the following British Standards:—

BS 969, Plain limit gauges. Limits and tolerances.

BS 1044, Recommended designs for gauges.

This British Standard has been prepared under the authority of the Mechanical Engineering Industry Standards Committee in order to combine in a single publication a revision of the four British Standards which have hitherto related to the various types of splines and serrations and which have now been superseded by this comprehensive standard covering the needs of the general engineering, aircraft and automobile industries.

The first British Standard relating to splines was No. 5015, “British Standard dimensions for splines (bottom fitting) for automobiles”, which was published in 1927 by the British Engineering Standards Association (the earlier name of the British Standards Institution). It included dimensional details and tolerances for 4, 6, 10 and 16 straight sided splines based on the existing S.A.E. standards.

In 1929, Part 2 of No. 46 was published with the title “Splines and serrations’ (Part 1 of No. 46 having been concerned with keys and keyways) and was in effect an extension of No. 5015 relating to a larger range of shaft diameters than those covered by the automobile standard. A fundamental distinction between the two standards was that while the fits in No. 5015 were based on those of the S.A.E., those in No. 46, Part 2, were based on the provisions of report No. 164, 1924, which later developed into BS 164, “Limits and fits”.

By 1935 it was apparent that revision of both the specifications was necessary and it was decided to embody the revised provisions for the automobile industry in the revision of BS 46‑2. The draft proposals were completed and circulated to industry for comment in May, 1939, but the war intervened before the matter could be completed.

Early in 1941, resulting from the problems of production, an investigation into the question of gauges for both spline and serration production disclosed that neither BS 46‑2, nor the proposed revision, included tolerances which were suitable for war production, and this led to the decision to prepare a war emergency specification relating to serrations and appropriate gauges, suitable for the aircraft industry. This specification, BS A.19, was issued in two parts, Part 1 in 1941 and Part 2 in 1942, which were subsequently brought together in one publication. The specification covered a range of fine and a range of coarse serrations, together with dimensional details for a complete set of Full Form and feature gauges. The issue of A.19 for serrations was followed by the publication, later in the same year, of A.20 for spline shafts and holes prepared for the same reason and under the same terms as A.19. In both cases it was found desirable and possible to relax the tolerances given in BS 46‑2, to reduce the number of classes of fit, and to reduce the actual number of serrations and splines respectively.

In view of the urgency with which the provisions of A.20 were awaited, it was not felt possible to delay publication while the gauging provisions were finalized. Accordingly this specification, unlike A.19, was issued without a section on spline gauges, but a note under Clause 4 stated that a recommended gauging system would be issued later as a supplement.

Due to wartime conditions and a subsequent decision to proceed with the preparation of a comprehensive standard, the supplement was never completed.

The present standard supersedes BS 46‑2; BS 5015 and BS A19 and BS A20, and embodies the results of a considerable amount of research in the aircraft, automobile and general engineering industries. The subject matter allows for convenient division into two parts, of which the first relates to straight-sided splines, together with the appropriate gauges and the second to straight-sided serrations, together with the appropriate gauges.

The widespread development and use of involute splines has made necessary the preparation of a separate British Standard for this type. Consequently, instead of being divided into aircraft, general or automobile types, splines will be differentiated as being of straight-sided or involute form.

This specification has been prepared on the hole basis; that is to say, the hole is the constant member and different fits are obtained by varying the size of the splined or serrated shaft.

NOTE This practice accords with the recommendation in BS 1916, “Limits and fits for engineering”. BS 1916 superseded BS 164, in which a similar recommendation appeared.

In all the tables in the standard actual maximum and minimum figures have been given while the maximum metal condition has been shown first in all cases.

A number of appendices give appropriate information on various aspects of gauging, calculations, effects of errors, tolerances, etc.

A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application.

Compliance with a British Standard does not of itself confer immunity from legal obligations.

Part 1: Straight-sided splines (parallel rectangular section) and gauges for splines

1 Introduction

2 Scope

Part 1 of this British Standard relates to straight parallel-sided splines, produced in holes or on shafts having a nominal size from ½ in. to 6 in. inclusive.

Provision is made for 6 equi-spaced splines in all cases irrespective of diameter and for two depth designated “shallow” and “deep”. The type is that known as “bottom fitting” (top clearance).

The nomenclature and terms used are defined.

The dimensions given in Table 1 and Table 2 allow for three grades of fit and apply whether the components are in the heat-treated condition or not. (Details of these fits are given in the introduction.)

Details are given of dimensions and design of the gauges required for all sizes.

Details are also included of the maximum errors of twist permissible when a spline is considerably longer than the gauges, thus making direct measurement necessary.

Notes on a method of producing various fits and a graphical representation of such fits are given in Appendices.

3 Nomenclature and definitions

4 Dimensions and fits

5 Gauges

6 Alignment errors in long splines

BS 2059:1953

Specification for straight-sided splines and serrations

Current

Published:

31 Dec 1953