BS-AU-177A-1980.pdf

BRITISH STANDARD AUTOMOBILE SERIES BS AU 177a:1980 Incorporating Amendment No. 1 Specification for Electrical connections between towing vehicles and trailers with 6 V or 12 V electrical equipment: type 12 S (supplementary) UDC 629.114.3:728.76:621.316.541*12S Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 177a:1980 This British Standard, having been prepared under the direction of the Automobile Standards Committee, was published under the authority of the Executive Board and comes into effect on 31 March 1980 © BSI 02-2000 The following BSI references relate to the work on this standard: Committee reference AUE/- Draft for comment 74/77642 DC ISBN 0 580 11297 7 Foreword This British Standard, which has been prepared under the direction of the Automobile Standards Committee, specifies requirements for 6 V or 12 V type S (supplementary) electrical connectors between towing vehicles and trailers and is based on ISO 3732:1976 “Road vehicles Electrical connections between towing vehicles and trailers with 6 or 12 V electrical equipment Type 12 S (supplementary)” published by the International Organization for Standardization (ISO). Connectors manufactured in accordance with the requirements of this standard are interchangeable with those made in accordance with ISO 3732, but the standards are not identical. It is expected that, in due course, ISO 3732 will be revised and aligned with this British Standard, except for the horizontal free space, which will probably remain at 55 mm. United Kingdom legislation requires that rear fog lights are fitted to new vehicles and trailers manufactured on or after 1 October 1979 and first used on or after 1 April 1980. The No. 2 pin of the type N connector, as specified in BS AU 149:1969, which was not previously allocated, was frequently used for power supplies. This pin has now been allocated to rear fog lights (see BS AU 149a:1980) and the No. 4 pin of the type S connector (not previously allocated) has been allocated to power supplies in addition to the No. 6 pin. The horizontal free space has been reduced from 55 mm (ISO 3732), which is considered excessive, to 40 mm to align with current UK practice (see Figure 3). Terminology and conventions. It has been found convenient to reproduce most of ISO 3732 for this British Standard. Some terminology and certain conventions are not identical with those used in British Standards; attention is especially drawn to the following. The comma has been used throughout as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. 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. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 5 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.Date of issueComments 3687October 1981Indicated by a sideline in the margin Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 177a:1980 © BSI 02-2000i Contents Page ForewordInside front cover 1Scope and field of application1 2Reference1 3General requirements1 Figure 1 Socket3 Figure 2 Plug4 Figure 3 Socket and plug assembly (free space)5 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 177a:1980 © BSI 02-20001 1 Scope and field of application This British Standard specifies requirements which will permit, by means of a socket and a plug, type 12 S, interchangeability of supplementary electrical connections between towing vehicles and towed vehicles (see Figure 3). These requirements apply to vehicles fitted with electrical equipment operating at a nominal voltage of 6 V or 12 V. These sockets and plugs are not interchangeable with type 12 N (normal) sockets and plugs. (See BS AU 149a.) 2 Reference The following standards publication is referred to in this standard. BS AU 149a, Electrical connections between towing vehicles and trailers with 6 V or 12 V electrical equipment Type 12 N (normal). 3 General requirements 3.1 Number of necessary contacts The functions of the seven contacts are as follows: 1) Reversing light and/or reversing catch for inertia brakes. 2) No allocation. 3) Common return. 4) Power supply. 5) Sensing device with common return. 6) Power supply. 7) No allocation. 3.2 Arrangement of the contacts The arrangement of the contacts is shown in Figure 1 (socket) and Figure 2 (plug). The numbers designating the contacts correspond to those indicated in 3.1. 3.3 Socket The socket shall be mounted on the rear of the towing vehicle. The socket is provided with: 4 tubes (Nos. 1, 3, 4, 6); 1 tube 3 mm longer (No. 7); 2 spring pins (No. 2, 5). Tube and pin design details are given in Figure 1. Pins Nos. 2 and 5 shall be able to spring back over a minimum length of 9,5 mm. The diameter of the pins shall be such that the corresponding tubes of the plug can be connected with a moderate push, but they shall ensure a good electrical contact. Contact No. 3 shall be insulated, as are the other contacts. After fitting, contact No. 3 may be connected to the common return of the vehicle. The rear terminals shall each be capable of receiving two conductors of at least 1,5 mm2 cross-section. The contact designations shall be permanently marked on the inside of the socket cover and on the terminal face (except where the cable is moulded into the socket) in symbols not less than 2 mm high. These symbols, which are not necessarily numbers, may be different from those indicated in Figure 1, provided that the specified pin locations of the different functions are complied with. The socket shall be provided with a splashproof cover which shall close automatically when the plug is disengaged. The hinged cover on the socket shall be provided with a lip to retain the plug when it is engaged. All metallic parts of the socket shall be made of corrosion-resistant material or be adequately protected against corrosion. 3.4 Plug The plug shall be mounted on the trailer. The plug is provided with: 4 spring pins (Nos. 1, 3, 4, 6); 1 spring pin 3 mm longer (No. 7); 2 tubes (Nos. 2, 5). The pins Nos. 1, 3, 4 and 6 and tubes Nos. 2 and 5 of the plug correspond respectively to the tubes Nos. 1, 3, 4 and 6 and to the pins Nos. 2 and 5 of the socket. Pins Nos 1, 3, 4 and 6 shall be able to spring back over a minimum length of 9,5 mm. Pin No. 7 shall be able to spring back over a minimum length of 15,5 mm. The diameter of the pins shall be such that the corresponding tubes can be connected with a moderate push, but they shall ensure a good electrical contact. The rear terminals shall each be capable of receiving one conductor of at least 2,5 mm2 cross-section. The contact designations shall be permanently marked on the terminal face (except where the cable is moulded into the plug) in symbols not less than 2 mm high. These symbols, which are not necessarily numbers, may be different from those indicated in Figure 2, provided that the specified pin locations of the different functions are complied with. All metallic parts of the plug shall be made of corrosion-resistant material or be adequately protected against corrosion. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 177a:1980 2 © BSI 02-2000 The manufacturer shall provide means for fixing and sealing the cable. 3.5 Allocation of cable colours The cable colours of the seven-core connecting cable shall be allocated to the different circuits as follows: 3.6 Distinguishing marking The 12 S connector shall be distinguished from the 12 N connector (see BS AU 149a) by means of a different colouring at least of the insulating parts, and/or cover. A light and permanent colour shall be used for the 12 S connector. 3.7 Text deleted Contact No. Circuit Cable colour 1 2 3 4 5 6 7 Reversing light and/or reversing catch for inertia brakes No allocation Common return Power supply Sensing device with common return Power supply No allocation yellow blue white green brown red black Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 177a:1980 © BSI 02-20003 Figure 1 Socket Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 177a:1980 4 © BSI 02-2000 Figure 2 Plug Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 177a:1980 © BSI 02-20005 Figure 3 Socket and plug assembly (free space) Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:52:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 177a:1980 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. 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