GB/T 20786-2015 English PDF (GBT20786-2015)

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GB/T 20786-2015: Rubber track
GB/T 20786-2015
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.140.99
G 47
Replacing GB/T 20786-2006
Rubber track
橡胶履带
ISSUED ON: OCTOBER 09, 2015
IMPLEMENTED ON: MAY 01, 2016
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Product structure ... 7
5 Classification and marking ... 8
6 Requirements ... 9
7 Test methods ... 11
8 Inspection rules ... 13
9 Marking, packaging, transportation, storage and use ... 15
Appendix A (Normative) Measurement methods of rubber track overall dimensions 16
Rubber track
1 Scope
This Standard specifies the terms and definitions, product structure, classification and
identification, requirements, test methods, inspection rules, marking, packaging,
transportation, storage and use of rubber tracks.
This Standard applies to rubber tracks which are made of a composite of rubber and
metal or fiber materials and are mainly used for the walking parts of agricultural
machinery, engineering machinery and transport vehicles.
2 Normative references
The following referenced documents are indispensable for the application 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 531.1, Rubber vulcanized or thermoplastic - Determination of indentation
hardness - Part 1: Duromerer method (Shore hardness)
GB/T 1689, Rubber vulcanized. Determination of abrasion resistance (Akron
machine)
GB/T 3512, Rubber, vulcanized or thermoplastic - Accelerated ageing and heat
resistance tests
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, Rubber, vulcanized - Determination of adhesion to wire cord
HG/T 2821.1, Dipped polyester cords for V-belts and V-ribbed belts - Part 1: Stiff
cords
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
rubber track
An annular rubber belt composed of rubber and metal or fiber material, which is mainly
applied to the walking parts of agricultural machinery, engineering machinery and
transport vehicles.
3.2
lug
The geometry of the ground contact side of a rubber track.
3.3
outer rubber
The outer side of the rubber track, the part that contacts the ground when traveling.
3.4
inner rubber
The inner side of the rubber track, the part opposite to the running wheel when traveling.
3.5
core metal
The part of the rubber track that transmits power, guides and provides lateral support.
3.6
strength layer
The skeleton layer in the rubber track that bears tension and transmits power, which is
usually made of materials such as wire cord (fiber rope).
3.7
pitch
The center distance of two adjacent core metals of the straight part of the rubber track.
7.2.2 Tensile strength, elongation at break, and permanent deformation at break
The determination of tensile strength, elongation at break and permanent deformation
at break shall be carried out in accordance with the provisions of GB/T 528, using type
1 samples.
7.2.3 Tearing strength
The tearing strength shall be determined in accordance with the provisions of GB/T 529
using a crescent-shaped samples.
7.2.4 Akron wear
The Akron abrasion test shall be carried out in accordance with the provisions of GB/T
1689.
7.2.5 Hot air aging
The determination of hot air aging performance shall be carried out in accordance with
the provisions of GB/T 3512.
7.3 Core metal
7.3.1 Bonding strength between core metal and rubber
The determination of the bonding strength between core metal and rubber shall be
carried out in accordance with the provisions of GB/T 7760, and the test samples shall
be prepared from semi-finished products.
7.3.2 Bending resistance of core metal
7.3.2.1 Test method: Use the length of the core metal minus 20 mm as the span, the two
ends minus 10 mm as the fulcrums; use a hardened steel rod with a diameter not greater
than 50 mm as the support, the center point of the meshing part as the pressure point,
and a steel rod with a diameter not greater than 20 mm as the pressure head.
7.3.2.2 Equipment: Universal testing machine, pressure head speed 5 mm/min ~ 10
mm/min.
7.3.2.3 Stress value: The maximum stress at which the core metal maintains elastic
deformation when subjected to bending force.
7.4 Bonding strength between wire cord (fiber cord) and rubber
The bonding strength between wire cord (fiber cord) and rubber shall be determined in
accordance with the provisions of GB/T 16586, using method B, and the test samples
shall be prepared from semi-finished products.
7.5 Longitudinal tension
All technical requirements listed in Chapter 6 are type inspection items. Type inspection
shall usually be carried out in any of the following situations:
a) During trial type identification of new products or old products transferred to the
factory;
b) After formal production, if there are major changes in structure, materials and
processes, which may affect product performance;
c) During normal production, inspections shall be carried out at least twice a year
at regular intervals or after a certain amount of production has been accumulated;
d) When production which is suspended in long term (for more than half a year) is
resumed;
e) When the delivery inspection result is significantly different from the previous
type inspection;
f) When the national quality supervision institutions propose a requirement to carry
out type inspection.
8.3 Determination rules
8.3.1 If any one of the appearance quality is unqualified, the track is unqualified; if the
external dimensions are unqualified, then the batch of tracks is unqualified.
8.3.2 If any item of the physical and mechanical properties listed in Table 1 fails to meet
the requirements, double the number of samples shall be taken from the same batch of
tracks for retesting of the item. If the retest results are still unqualified, the batch of
products shall be unqualified.
8.3.3 If the bonding strength between core metal and rubber listed in 6.2.1 does not
meet the requirements, double the number of samples shall be prepared from the same
batch of rubber and standard metal parts for retesting. If the retest results are still
unqualified, the batch of products shall be unqualified.
8.3.4 If the bending resistance of the core metal listed in 6.2.2 does not meet the
requirements, double the number of samples shall be taken from the same batch of
tracks for retesting of this item. If the retest results are still unqualified, the batch of
products shall be unqualified.
8.3.5 If the longitudinal design tension of the rubber track listed in 6.4 does not meet
the requirements, double the number of samples shall be taken from the same batch of
tracks for retesting of this item. If the rete...