GB/T 20786-2025Rubber track (English PDF)

1 Scope

GB/T 20786-2025 is the Chinese national standard covering the rubber track of an excavator or a tracked carrier - the steel cord and the embedded links, the tensile strength and the resistance to tearing off the drive lugs, the wear of the tread, and the dimensions that must match the sprocket. Issued on 5 October 2025, it has been in force since 1 May 2026, replacing GB/T 20786-2015.

This document defines the terminology and definitions of rubber tracks; provides information on product classification, structure, marking; specifies technical requirements such as dimensions, appearance quality, performance; describes the corresponding test methods; specifies inspection rules, marking, packaging, transportation, storage, use. This document applies to the manufacture and inspection of rubber tracks, which are made of rubber and metal or fiber materials through vulcanization, mainly used in the running gear of agricultural machinery, construction machinery, transport vehicles.

2 Normative references

The following documents, through normative references herein, constitute essential provisions of this document. For dated references, only the edition cited applies; for undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 528 Rubber, vulcanized or thermoplastic - Determination of tensile stress- strain properties

GB/T 529 Rubber, vulcanized or thermoplastic - Determination of tear strength (Trouser, angle and crescent test pieces)

GB/T 1682 Rubber, vulcanized - Determination of low-temperature brittleness - Single test piece method

GB/T 1689 Rubber vulcanized - Determination of abrasion resistance (Akron machine)

GB/T 2941 Rubber physical test methods - General procedures for specimen preparation and conditioning

GB/T 3512 Rubber, vulcanized or thermoplastic - Accelerated ageing and heat resistance tests-Air-oven method

GB/T 7760 Rubber, vulcanized or thermoplastic - Determination of adhesion to a rigid substrate - 90 degrees peel method

GB/T 8358 Steel wire ropes - Determination of measured breaking force

GB/T 16586-2014 Rubber, vulcanized - Determination of adhesion to wire cord

GB/T 31333 Dipped cords - Test methods adhesion strength

GB/T 32108 Test methods of tensile properties for dipped yarns and cords

GB/T 39693.4 Determination of hardness of vulcanized rubber or thermoplastic rubber - Part

4.Determination of indentation hardness by the Shore hardness meter method (Shore hardness)

3 Terms and definitions

The following terms and definitions apply to this document.

3.1 Rubber track An annular rubber belt fitted onto the running gear of agricultural machinery, construction machinery, transport vehicles to assist movement, which is made of rubber vulcanized with metal or fiber materials.

3.2 Tread rubber The outer rubber layer of a rubber track that faces the ground when moving.

3.3 Roller rubber The inner rubber layer of a rubber track that faces the wheel in the wheel system of the running gear when moving.

3.4 Metal core The metal or other material skeleton in a toothed rubber track that transmits power, provides guidance, offers lateral support.

3.5 Strength layer The skeleton layer in a rubber track that bears tension and transmits power, typically made of materials such as steel wire cord (fiber rope).

3.6 Guide lug The raised portion of a friction-type rubber track that guides movement.

3.7 Drive lug The raised portion of a wheel-hole type rubber track that transmits power and provides guidance.

3.8 Pitch The center-to-center distance between two adjacent repeating units (two metal cores, two guide lugs, or two drive lugs) of a rubber track.

4 Classification, structure, marking

4.1 Classification and structure Rubber tracks are classified into the following three categories according to their drive method, as shown in Table 1. - Toothed rubber tracks, denoted by CRT; - Wheel-hole type rubber tracks, denoted by KRT; - Friction-type rubber tracks, denoted by MRT.

4.2 Marking Rubber tracks are marked in the following order. Rubber track type code - This document number - Specification [Width (mm) × Pitch (mm) × Number of sections - Applicable maximum machine mass (t)] Example. A toothed rubber track with a track width of 400 mm, a pitch of

72.5 mm, a number of sections of 80, an applicable maximum machine mass of 5 t is marked as. CRT-GB/T 20786-400×72.5×80-5.

5 Technical requirements

5.1 Specifications and dimensions Specifications and dimensions and permissible deviations shall conform to the provisions of Table 2. Table 2 -- Specifications and dimensions and permissible deviation

5.2 Appearance quality Rubber tracks are not allowed to have exposed steel wires (or fiber ropes), surface impurities, spongy texture, delamination, cracks, or splits. There are no visible scars or blisters with a diameter greater than 10 mm and a depth greater than 2 mm are allowed. For visible scars or blisters with a diameter greater than 10 mm and a depth greater than 2 mm, the quantity shall be not more than 3 places for rubber track which has a center circumference of not more than 5 m; or it shall be not more than 5 places for rubber track which has a center circumference of more than 5 m.