GB/T 31883-2015Road vehicles -- Drawbar couplings, drawbar eyes, fifth wheel kingpins, hook couplings and toroidal eyes -- Wear limits for in-use mechanical couplings (English PDF)

3.1.1 Under the normal operating conditions, the mechanical contact between the

traction connecting pin and the drawbar eye bushing shall cause wear on the surface of the connecting pin; and form an elliptical section on the horizontal symmetry plane of the connecting pin; its minimum dimension is in the longitudinal axis direction of the vehicle (detection size is shown in Figure 1).

3.1.2 Directly measure or use a special gauge to check the size of the connecting pin after wearing.

3.2 40mm and 50mm drawbar eyes

3.2.1 Under the normal operating conditions, the mechanical contact between the

drawbar eye bushing and the traction connecting pin shall cause wear on the surface of the connecting pin; and form an elliptical section on the horizontal symmetry plane of the bushing; its maximum dimension is in the longitudinal axis direction of the vehicle (detection sizes are shown in Figures 2 and 3).

3.2.2 Under the normal operating conditions, the mechanical contact between the

drawbar eyes and the drawbar couplings shall cause the wear on the upper and lower planes of the drawbar eyes, resulting in thinning of the thickness between the upper and lower planes of the drawbar eye center; the bushing deviates from the normal working position (detection sizes are shown in Figures 2 and 3).

3.2.3 Directly measure or use a special gauge to check the size of the traction ring hole after wearing.

3.2.4 Check the thickness of each side of the longitudinal center plane of the drawbar eyes.

couplings and drawbar eyes can see Tables 2 and A.2.

Table 2 -- Wear Limit Size of 50mm Drawbar Couplings and Drawbar Eyes

Mechanical couplings Use limit size

50mm drawbar couplings a >=46.5

50mm drawbar eye bushing b <=51.5

50mm drawbar eye thickness c >=41.5 a Size of connecting pin: see standard design size shown in the side view of the Figure 7 in ISO

3584:2001.

b Internal size of bushing: see standard design size shown in Figures 2 and 3 of GB/T 4781-2006.

c Thickness of drawbar eye: see standard design size shown in side view of Figure 1 of GB/T 4781-

2006.

4.3 50# fifth wheel kingpins

Check as per the provisions of 3.3; the wear limit use of 50# fifth wheel kingpin shall refer to Tables 3 and A.3.

Table 3 -- Wear Limit Size of 50mm Fifth Wheel Kingpins

Mechanical couplings Use limit size

Upper cylinder of 50# fifth wheel kingpin a >=71

Middle cylinder of 50# fifth wheel kingpin b >=49 a External size of upper cylinder of kingpin: see standard design size shown in Figure 1 of GB/T 4606-

2006.

b External size of middle cylinder of kingpin: see standard design size shown in Figure 1 of GB/T 4606-

2006.

4.4 90# fifth wheel kingpins

Check as per the provisions of 3.3; the wear limit size of 90# fifth wheel kingpin shall refer to Tables 4 and A.4.

Table 4 -- Wear Limit Size of 90# Fifth Wheel Kingpins

Mechanical couplings Use limit size

Upper cylinder of 90# fifth wheel kingpin a >=112

Middle cylinder of 90# fifth wheel kingpin b >=86 a External size of upper cylinder of kingpin: see standard design size shown in Figure 1 of GB/T 4607-

2006.

b External size of middle cylinder of kingpin: see standard design size shown in Figure 1 in GB/T 4607-

2006.

4.5 Hook couplings and toroidal eyes

Check as per the provisions of 3.4 and 3.5; the wear limit size of 68mm and 76mm toroidal eyes and corresponding hook couplings shall refer to Tables 5 and A.5.

Unit: mm

Unit: mm

Unit: mm

Appendix A (Normative)

Specified Size, Use Limit Size and Allowable Wear Extent of

Mechanical Couplings

A.1 40mm drawbar couplings and drawbar eyes

The specified size, use limit size and allowable wear extent of 40mm drawbar couplings and drawbar eyes can refer to Table A.1.

Table A.1 -- Specified Size, Use Limit Size and Allowable Wear Extent of 40mm

Drawbar Couplings and Drawbar Eyes

Mechanical couplings Basic size

Use limit size

Allowable wear extent Detection position

40mm drawbar couplings 38 (ISO 3584) >=36.5 <=1.5

Check the connecting pin wear from the longitudinal axial direction of the vehicle, see

Figure 1

40mm drawbar eye bushing 40 (ISO 8755) <=41.5 <=1.5

Check the busing wear form the longitudinal axial direction of the vehicle, see Figure 2

40mm drawbar eye thickness 30.5 (ISO 8755) >=28 <=2.5

Check the thickness of each side of the longitudinal center surface of the drawbar eyes, see Figure 2

A.2 50mm drawbar couplings and drawbar eyes

The specified size, use limit size and allowable wear extent of 50mm drawbar couplings and drawbar eyes can refer to Table A.2.

Table A.2 -- Specified Size, Use Limit Size and Allowable Wear Extent of 50mm

Drawbar Couplings and Drawbar Eyes

Mechanical couplings Basic size

Use limit size

Allowable wear extent Detection position

50mm drawbar couplings 48.6 (ISO 3584) >=46.5 <=2.1

Check the connecting pin wear from the longitudinal axial direction of the vehicle, see

Figure 1

50mm drawbar eye bushing 50 (GB/T 4781) <=51.5 <=1.5

Check the busing wear form the longitudinal axial direction

Unit: mm

Unit: mm

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