This standard specifies the requirements for the interchangeability of mechanical connections between tractors and trailers. This standard applies to articulated vehicles with a towed vehicle mass greater than 3.5 t. GB/T 4781-1984 Interchangeability of mechanical connections between tractors and trailers GB/T4781-1984 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Interchangeability of mechanical connection devices between tractors and full trailers
UDC629.114
.2/.3.013
GB/T4781-84
Mechanical connection between towing vehicle and full trailers forinterchangeability
This standard specifies the requirements for interchangeability of mechanical connection devices between tractors and full trailers. This standard is equivalent to IS01102-1975 "Road vehicles-Mechanical connections between tractors and full trailers-Interchangeability", and adds the part on dimensional interchangeability of hook and eye mechanical connection devices. 1 Scope of application
This standard applies to fully articulated vehicles with a total towing mass greater than 3.5t 2 Interchangeable dimensions
In order to ensure the interchangeability requirements, the following provisions are made: a: Type and main dimensions of mechanical connection device (see 3): b. Drawbar swing angle (see 4);
C. Drawbar front distance* (see 5):
d. Distance of the front rotation surface of the trailer (see 6); e: Horizontal rotation angle allowed by the drawbar (see 7): f: Drawbar height* and height of the articulated axis of the full trailer drawbar (see 8) 3 Type and main dimensions of mechanical connection device 3.1 Pin-type mechanical connection device
3.1.1 Pin-type mechanical connection device (see Figure 1). Pin
Drawbar
Diagram 1)
3.1.2 Type and size of towing ring (see Figure 2). a. Without bushing:
b. With bushing.
3.2 Hook-and-loop mechanical connection device
3.2.1 The types of hook-and-loop mechanical connection devices are shown in Figures 3 and 4. Note: This type of structure shall not be used for new models or replacement vehicles. Figure 3 (schematic diagram)
Figure 4 (schematic diagram)
3.2.2 The dimensions of the hook-and-loop mechanical connection device are shown in Table 1a without bushing b with bushing
Drawbar swing angle
After the drawbar is combined with the towing device of the tractor, the drawbar should be able to rotate freely, and the angle formed by it and the horizontal line located in the longitudinal symmetry plane of the tractor and passing through the connection point has the following minimum value: 4:1 Rotation angle (refers to the angle formed by the drawbar rotating around a vertical axis passing through the connection point): the minimum value is 75. (See Figure 5).
4:2 Longitudinal swing angle (refers to the angle formed by the drawbar rotating around a horizontal axis passing through the connection point and perpendicular to the longitudinal symmetry plane of the vehicle) Angle formed): minimum value is 20° (see Figure 6). Positive use of spherical pin
b use of revolving pin
4.3 Side swing angle (refers to the angle formed by the rotation of the towing bar around a horizontal axis passing through the connection point and located in the symmetry plane of the vehicle (see Figure 7)
): minimum value 25.
5 Lead distance of traction device (α)
Lead distance of traction device (see Figure 8), for the tractor, its maximum distance is 300mm. Distance of the rotating surface at the front end of the trailer (c)
Dimension c is the distance from the articulation center of the towing device of the tractor to the rotating cylindrical surface at the front end of the trailer. Its minimum value is 950mm (see Figure 8).
7 Towing rod Permissible horizontal clearance angle
Under normal driving and turning conditions, the axis of the drawbar is on either side of the longitudinal plane of symmetry of the tractor, the horizontal swing angle is within the limit of 60°, and the tractor and the front end of the trailer shall not conflict. Determine the length of the drawbar*, which should comply with this condition 8 The height of the towing device and the height of the articulation axis of the trailer's drawbar. The size range shown in Table 2 applies to loaded or unloaded vehicles Table 2
Maximum total mass of tractor or trailer
Height of the towing device on the tractor
>10~12
>12~14
>14 and above bzxz.net
600~900
650~950| |tt||7001000
750~1050
800~1100
The height of the traction rod connecting the axle center on the full trailer
625~825
675~875
700~900
725~925
775~975
Additional instructions:
This standard was proposed by the People's Republic of China and the Ministry of Machinery Industry, and is under the jurisdiction of the Changchun Automobile Research Institute of China National Automotive Industry Corporation.
This standard was drafted by the Changchun Automobile Research Institute of China National Automotive Industry Corporation and the Highway Research Institute of the Ministry of Communications. The main drafters of this standard are Kang Huiming and Yang Deyou.
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