1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-22626-8 SANS 765:2009Edition 1SOUTH AFRICAN NATIONAL STANDARD Off-the-road (OTR) tyres Earth-moving tyres for earth-moving machinery Repai
4、rs and retreading Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 765:2009 Edition 1 Table of changes Change No. Date Scope Foreword This South African standard was approved by National
5、 Committee SABS SC 31A, Tyres, rim dimensions and repairs Retreaded tyres and repairs, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in November 2009. Introduction The use of earth-moving tyres that have
6、 been badly repaired, retreaded, maintained or that have no service record (i.e. where the correct procedures have not been followed) poses safety risks to persons and might damage machinery and even the environment. The control of inspections, repairs, retreading and maintenance is necessary not on
7、ly to ensure a high standard but also to establish a safe and sound environment. Site management is essential to ensure that all hazards are identified and risk controls are put in place. This standard was designed to assist the users in the correct procedures in order to minimize safety risks. SANS
8、 765:2009 Edition 1 1 Contents Page Foreword Introduction 1 Scope 3 2 Normative references 3 3 Terms and definitions 3 4 Maintenance of in-service tyres (practical maintenance for operators on site). 8 5 Inspections to determine repairability 9 6 Repair limits. 10 7 Repair of tyres . 12 8 Retreading
9、 of tyres 17 9 Marking 19 SANS 765:2009 Edition 1 2 This page is intentionally left blank SANS 765:2009 Edition 1 3 Off-the-road (OTR) tyres Earth-moving tyres for earth-moving machinery Repairs and retreading 1 Scope This standard specifies requirements for the identification, inspection, repair, r
10、etreading and maintenance of off-the-road (OTR) pneumatic tyres for OTR machinery. 2 Normative references The following referenced document is indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the r
11、eferenced document (including any amendments) applies. Information on currently valid national and international standards can be obtained from the SABS Standards Division. SANS 20108/ECE R108, Uniform provisions concerning the approval for the production of retreaded pneumatic tyres for motor vehic
12、les and their trailers. 3 Terms and definitions For the purposes of this document, the terms and definitions given in SANS 20108 and the following apply. 3.1 bead part of a tyre that is manufactured to secure and seat the tyre against the rim NOTE A number of high-tensile steel wires fashioned in a
13、hoop shape are encased in the tyre casing or structure. This may involve one bead core (radial-ply) or multiple bead cores on each side (bias-ply) (see figure 1). 3.2 bead area area of the tyre below the rim line NOTE See figure 1. 3.3 bias-ply tyre pneumatic tyre in which the ply cords in the tyre
14、casings are laid at alternate angles that are substantially less than 90 to the centre line of the tread area NOTE See figure 1. SANS 765:2009 Edition 1 4 Figure 1 Cross reference of a bias-ply and a radial-ply tyre and tyre areas 3.4 buffing preparation of the surface of the tyre before the applica
15、tion of cement or rubber (or both) 3.5 building application of uncured rubber to the buffed and prepared surface area of the casing 3.6 casing structure and components of a bias-ply or radial-ply tyre 3.7 casing ply major fixed dimension structural component of a tyre that is wrapped around the bead
16、s, and that plays a major role in determining the load-carrying capacity of the tyre NOTE See figures 1 and 2. 3.8 casing separation detachment of casing plies from each other or the internal detachment of a number of plies resulting in a loss of structural strength SANS 765:2009 Edition 1 5 Figure
17、2 Section of a radial ply tyre showing the different belts 3.9 cement solution of rubber or other chemical compounds capable of being cured, compatible with the process in use, and used as a bonding agent to repair or retread tyres (or both) 3.10 cementing application of cement to the buffed surface
18、 of the tyre 3.11 competent person person with enough skill or knowledge to do something well or to the necessary standard 3.12 cords individual strands that when arranged parallel and encased in rubber form the structure of the tyre 3.13 crown portion of the tread area between the shoulders of the
19、tyre NOTE See figure 1. 3.14 curing vulcanization application of controlled temperature and pressure for the necessary duration to transform the rubber from its solid state to its elastic state SANS 765:2009 Edition 1 6 3.15 cushion gum uncured rubber compound used to assist adhesion between the buf
20、fed casing and the new tread or patch (repair unit) 3.16 inflation pressure measurement of force that is exerted on the inner surface of a tyre so as to tension the structure and to provide a vital element in the safe operation of the tyre 3.17 inner liner layer that forms the inside surface of a ty
21、re, and that, in a tubeless tyre, retains the inflating medium within the tyre NOTE See figure 1. 3.18 load and speed index numerical code associated with the maximum load and speed rating assigned to the tyre 3.19 major repair repair to a tyre that requires the installation of a structured internal
22、 tyre patch (repair unit) 3.20 minor repair repair to a tyre that does not require the installation of a structured internal patch (repair unit) 3.21 non-repairable deemed unsafe for repairing or retreading (or both) 3.22 patch/repair unit sections of rubber that may be reinforced by fabric or steel
23、 cords in a variety of sizes dedicated to either bias-ply or radial-ply tyres in order to stabilize a damaged area, to prevent the loss of inflation pressure, and also to ensure no loss of load capacity in repaired areas 3.23 ply layer of substantially parallel rubber coated cords forming a structur
24、e which is part of the tyre casing 3.24 protection belt layer of steel cord material that protects the working belts below NOTE See figure 2. 3.25 radial-ply tyre pneumatic tyre in which the ply cords that extend from bead to bead are laid at substantially 90 to the centre line of the tread, with th
25、e casing being stabilized by circumferential belts comprising two or more layers of substantially inextensible cord material NOTE See figure 1. SANS 765:2009 Edition 1 7 3.26 repairable able to be repaired and then be deemed safe for continued service 3.27 retreading process of refurbishing or repla
26、cing the tread of a worn tyre 3.28 shoulder transitional area of a tyre between the sidewall and the crown area NOTE See figure 1. 3.29 sidewall portion of a tyre between the shoulder and the bead area NOTE See figure 1. 3.30 skiving removal of a bevelled cut of damaged material when doing a repair
27、on a tyre 3.31 stitched repaired by removing air between two surfaces by applying pressure 3.32 stitching method used to remove air between two surfaces by applying pressure 3.33 TKPH tonne-kilometres per hour calculation used to determine the suitability of a specific off-the-road tyre for a given
28、equipment application NOTE The TKPH is the mean tyre load times the work day average speed. 3.34 tread portion of the tyre that comes into contact with the road NOTE See figure 1. 3.35 tread-depth pattern distance from the bottom of the tread grooves to the top of the tread, excluding the tread-wear
29、 indicators 3.36 tread rubber rubber compound specifically formulated to have the properties of heat, cut and wear resistance SANS 765:2009 Edition 1 8 3.37 tread-wear indicator feature incorporated into the tread of a tyre to indicate when the tread has worn down to a predetermined minimum tread-de
30、pth pattern 3.38 tubeless tyre pneumatic tyre designed for use without an inner tube 3.39 turn-up ply part of the casing ply that is the free end of the casing ply located in the sidewall area of the tyre NOTE See figure 1. 3.40 tyre size 3.40.1 large tyre tyre with diameter of a minimum of 483,6 mm
31、 (39 inches) up to 1 600,2 mm (63 inches) 3.40.2 small tyre tyre with diameter of up to 483,6 mm (39 inches) 3.41 undertread thickness of rubber between the bottom of the tread void and the top of the breaker, belt or casing 3.42 working belt two or more layers of inextensible cord material embodied
32、 circumferentially within a tyre immediately outside the casing ply and under the tread NOTE The cord angle relative to the tyre circumference is lower than that of the casing ply. Working belts are used in radial ply tyres and form an integral component of the tyre construction (see figure 2). 4 Ma
33、intenance of in-service tyres (practical maintenance for operators on site) 4.1 Selection of tyres Tyres shall be selected in accordance with the manufacturers specifications and include, but not be limited to, the following: a) the tyre load and speed; b) the TKPH rating; c) site conditions; and d)
34、 the age and condition of the tyres. All tyres submitted for repair or retreading shall be inspected before any work starts. SANS 765:2009 Edition 1 9 4.2 Pre-fitment inspections Before the fitment of a tyre, an inspection (internal and external) undertaken by a competent person should include, but
35、not be limited to, the following: a) that the tyre is in a sound state and suitable for fitment for the required application and position; b) that the tyre is clean and free of foreign objects and contaminants; c) that previous repairs and other markings are noted; and d) site-specific requirements.
36、 4.3 Periodic inspections Periodic inspections of fitted tyres shall be undertaken in accordance with the manufacturers recommendations and site requirements, and shall include, but not be limited to, the following: a) inflation pressures; b) wear; c) damage; d) separation; e) fatigue; and f) valve
37、stems, spuds, cores and caps. 5 Inspections to determine repairability 5.1 General 5.1.1 Following an inspection undertaken in accordance with 4.2, a tyre shall be removed for repair and for further inspections to determine the appropriate actions. 5.1.2 Figure 3 shows a flowchart to assist in the d
38、ecision-making of the appropriate actions. 5.1.3 Tyres shall be removed from the wheel or rim assemblies before inspection. 5.1.4 Tyres shall be thoroughly inspected internally and externally. Tyres that have been treated inside with any liquid additive or other substances that might impair the insp
39、ection process shall be cleaned out for visual inspection. Any existing repair(s) shall be closely inspected, and if its condition does not comply with the requirements of this standard it shall be removed and replaced. 5.2 Internal inspection The inner liner of the tyre shall be inspected to verify
40、 that it is in sound condition and free from any foreign objects and contaminants. There should be no exposed casing plies and no significant cracking, cuts or deformation of the inner liner. In the case of any uncertainty the manufacturers specifications shall be consulted or a visual review shall
41、be requested. SANS 765:2009 Edition 1 10 Figure 3 Inspection and repair flow chart for OTR tyres 5.3 External inspection The tread sidewall and bead areas shall be inspected to verify that the structure of the tyre is in sound condition. Cut damage and areas of deformation shall be carefully inspect
42、ed to verify the extent of the damage to the structure of the tyre. Tyres beyond repair should be clearly marked and disposed of. Tyres that do not contain a serial number or unique identification number shall not be repaired until the history of the tyre can be verified. 6 Repair limits 6.1 General
43、 Whilst it is acceptable to repair tyres, any repair might reduce the operating performance of the tyre and consideration should always be given to the failure mode if the repair is unsuccessful and likely to place users at risk. It is not acceptable to repair areas of the bead that are integral to
44、the structure of the bead area. 6.2 Repair limits for bias-ply tyres 6.2.1 Minor repairs Minor repairs to bias-ply tyres are conducted on tyres with rubber damage or local damage of a cosmetic nature. SANS 765:2009 Edition 1 11 6.2.2 Major repairs Major repairs in bias-ply tyres are conducted on tyr
45、es with damage exceeding that as specified in 6.2.1. Included are cut-through penetrations and structural damage of 50% or greater than 50% to the actual casing plies, and damage that does not exceed the repair limits specified in 6.3. 6.3 Non-repairable damage to bias-ply tyres The following types
46、of damage shall be deemed non-repairable: a) major damage in the bead area as shown in figure 1; b) damage exceeding the recommended repair limits as set by the manufacturer of repair materials; c) damage to the casing involving casing break-down (break-up) or casing separations; and d) deterioratio
47、n of inner liners, i.e. loose or detached rubber, splits or cracks. 6.4 Number of repairs to bias-ply tyres Only one major repair is permitted in any quarter segment (more than 90 apart) of the tyre circumference, with no limit on the number of minor repairs. 6.5 Repair limits for radial-ply tyres 6
48、.5.1 Minor repairs Minor repairs to radial-ply tyres are conducted on tyres with damage within the following limits: a) Rubber damage or local steel belt damage to the crown area protector belt(s), including the top working belt and not exceeding 25 mm in diameter with no damage whatsoever to the se
49、cond belt from the crown and without any cut-through damage. b) Damage to the turn-up ply shall not extend into the non-repairable area. The distance that the turn-up ply extends into the sidewall will vary from manufacturer to manufacturer. The tyre manufacturers shall be consulted for exact limitations for turn-up ply damage. 6.5.2 Major repairs Major repairs in radial-ply tyres are conducted on tyres with damage exceeding that specified in 6.5.1. Included are cut-through penetration and structural damage to the radial casing ply that shall not exceed 7
