GB/T 39015.2-2020Road vehicles--Interchangeability of mechanical couplings between tractors and semi-trailers - Part 2: Low-coupling tractors and high-volume semi-trailers (English PDF)

2.1 Ground clearance of coupling of tractor under maximum load

Under the maximum load condition, the height h of the joint surface of the

coupling of tractor (see Figure 1) shall be 900mm~975mm.

Figure 1 -- Ground clearance of coupling of tractor

2.2 Ground clearance of coupling of tractor when disengaged from semi-

trailer

part of the gooseneck of the semi-trailer [see 2.4.1d)];

w1 - Forward angle;

w2 - Backward angle;

phi - Articulation angle.

Figure 2 -- Free space between tractor and semi-trailer

2.4 Gooseneck shape

2.4.1 The gooseneck shape shall be located on the outer area of the surface

composed of multiple different planes and a rotating surface connecting the two

planes. There shall be a smooth transition between the surfaces, as shown in

Figure 3. The planes and rotating surfaces are determined as follows:

a) The first plane AB is perpendicular to the horizontal plane of the traction

pin axis. The length is L1. The width is the same as the width of semi-trailer,

and ends at the intersection with the second plane as described in b);

b) For the second plane BC, the width is same with the width of semi-trailer.

The angle with the first plane is gamma1. It ends with the line of intersection with

the third plane as described in c);

c) For the third plane CD, the width is same with the width of semi-trailer. The

angle with the first plane is gamma2. It ends to the line of intersection with the

rotating surface as described in d);

d) A vertical line segment EF and a segment of arc DE with a radius of r2

between the third plane and the vertical line segment, form a rotation

curve. The rotation curve takes r3 as radius to rotate around the traction

pin axis to form a rotating surface. Each surface shall be continuous;

e) The fourth plane AU is a horizontal plane at the front end of the semi-trailer

and perpendicular to the traction pin of the semi-trailer. The length is L3.

The width is same with the width of semi-trailer. It ends to the intersection

of the inclined plane UV with an angle alpha of the horizontal plane. The

foremost point V shall not exceed the vertical plane rotated with a radius

of 2040mm as the center of the traction pin axis.

2.4.2 The shape of the gooseneck is determined by the following parameters:

- The horizontal length of the first plane, L1=500mm;

- The sum of the horizontal length of the first plane and the second plane,

L2=1350mm;

- The horizontal length of the fourth plane, L3<=1800mm;

- The arc radius between the third plane and the vertical line of the

keys:

L1 - The horizontal length of the first plane (AB);

L2 - The sum of the horizontal lengths of the first plane and the second plane (AB and BC);

L3 - The horizontal length of the fourth plane (AU);

r1 - Front turning radius of semi-trailer;

r2 - Arc radius (DE);

r3 - The radius of rotation (EF) formed by the distance between the axis of the traction pin

and the vertical line of the gooseneck;

alpha - The angle between the horizontal plane and the inclined plane;

gamma1 - The angle between the second plane (BC) and the first plane (AB);

gamma2 - The angle between the third plane (CD) and the first plane (AB).

Figure 3 (continued)

3.1 Longitudinal inclination angle of semi-trailer relative to tractor

When a semi-trailer train is running straight, when the front and rear inclination

angles of semi-trailer relative to tractor (see Figure 2) meet the following

requirements, it shall not contact with the tractor (except hinged parts):

- Forward angle w1<=3.5°;

- Backward angle w2<=4.5°.

3.2 Lateral inclination angle

When the lateral inclination angle delta of semi-trailer relative to tractor (see Figure

4) changes within +/-2°, there shall be no interference between tractor and semi-

trailer.

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