GB/T 44044-2024Road vehicles - Trailers up to 3.5 t - Requirements for jockey wheels and drawbar supports (English PDF)

4.1 Bench test requirements

After testing according to 5.3, the jockey wheels or the drawbar support device shall not move (slide).

After the test load is stopped being applied, the jockey wheels shall have no visible damage or deformation, function normally, and their load lifting capacity shall not be lower than the test load.

4.2 Static vehicle test requirements

During the test according to 5.4, there shall be no movement (slippage) of the jockey wheels or the drawbar support device.

After the test load is stopped being applied, there shall be no visible damage or deformation of the strut and components.

4.3 The operating force requirements for the jockey wheel operating handle and

T-bolt in the working state (the trailer is disconnected from the towing vehicle)

The operating force of the jockey wheel operating handle and T-bolt shall not be greater than 250 N, and the strut shall be securely locked under the nose weight condition.

4.4 Installation protection requirements in a non-working state (trailer connected

to towing vehicle)

4.4.1 When the jockey wheels and support devices are in the retracted state, protective devices shall be installed to prevent them from being accidentally released and parts from loosening or falling.

4.4.2 The movable handles and other parts used when the jockey wheels and support device are in a working state shall be securely fastened when they are retracted to prevent them from falling off and being lost.

4.4.3 When the jockey wheels and support device are extended, the parts shall not separate abnormally; the design of the safety protection device shall ensure that the handle operating force can still function at 250 N.

4.4.4 When the trailer is in the horizontal connection state, the minimum ground clearance of the jockey wheels and/or clamping system shall not be less than 150 mm.

4.4.5 When the trailer is in motion, the adjustment mechanism with functions such as the lifting and lowering or up and down swinging of the screw shall not move due to vibration.

4.5 Design requirements

4.5.1 The drawbar support device shall be designed and installed with a protective device to prevent the strut locking tool from being lost or falling off due to the vibration of the trailer during driving, thereby causing scratches on the ground.

4.5.2 The drawbar support device with a lifting system shall have relevant mechanisms to prevent the inner and outer casings from accidentally separating.

4.5.3 After the drawbar support device is installed, the ground clearance of the trailer in the horizontal non-connected state shall be no less than 150 mm.

4.5.4 The operating handle and other moving parts shall be securely fixed and shall not become loose or fall off when not in operation.

5.1 Test load

The jockey wheels and support device shall be able to withstand twice the static vertical allowable load lifting capacity in the vertical direction. The test load calculation formula is shown in formula (1).

Where.

PT -- the test load, in kilograms (kg);

PS -- the static vertical allowable load lifting capacity, in kilograms (kg).

5.2 Lifting force

5.3 Bench test procedure

The bench test is carried out in the following steps.

a) Fix it stably to the test bench with a threaded plate or clamping locator;

b) Use the clamping accessory to ensure that the jockey wheel is firmly clamped and the main casing is in a vertical state;

c) With the main casing in a vertical position, turn the handle to adjust the height of the jockey wheel to the highest position specified by the manufacturer;

d) Determine the test position of the jockey wheel, which is located at the front end of the clamping accessory or the fastening plate;

e) Apply the test load determined in 5.1 and maintain it for 5 min.

5.4 Static vehicle test procedure

Static vehicle testing is carried out in the following steps.

a) Place the trailer on a flat, level ground;

b) Check the drawbar support device to ensure that the trailer coupling head has an adjustable height of 550 mm from the ground (the drawbar support device uses the lifting function);

c) Check the drawbar support device to ensure the ability to adjust the height of the trailer coupling head from the ground (the drawbar support device does not use the lifting function);

d) Make the jockey wheel installation position bear a vertical static load of twice the lifting force;

e) Apply a maximum force of 250 N on the operating handle to operate the clamping system or locking system and lock the strut of the drawbar support device. The test shall use new products without damage;

f) After the test load is applied for 1 min, the jockey wheel or the drawbar support device shall not move (slide) at all [the height of the traction connection point of the towing vehicle is adjusted according to b) or c)];

g) Adjust the strut height to the middle position and repeat the above test steps d)~f);

h) When the drawbar support device is retracted in the combination state, the height of the lower end of the drawbar support device from the ground shall not be less than 150 mm.

6.1 Marking

Permanent markings shall be placed on the visible parts of the non-movable outer surfaces of the jockey wheels and support devices, and the following contents shall be marked.

-- the name of the manufacturer;

-- the load lifting capacity.

6.2 Installation

6.2.1 The jockey wheels shall be securely installed and maintain an operating space of not less than 25 mm with the surrounding fixtures.

6.2.2 The selection and installation of the jockey wheels shall ensure that the lifting height from the center of the drawbar spherical connection device to the ground is not less than 550 mm.

6.2.3 After the jockey wheels are installed and fixed, the ground clearance when driving shall be no less than 150 mm.

6.2.4 The exact installation position of the jockey wheels shall be designed and determined by the trailer manufacturer and shall meet the following requirements.

a) The distance between the operating handle, strut and other parts of the drawbar support device and the surrounding fixing devices shall not be less than 25 mm;

b) The jockey wheel lifting mechanism can ensure that the height from the center of the trailer coupling head to the ground is adjusted to 550 mm;

c) When the trailer is not connected and only the jockey wheels and support device are used, the jockey wheels and the struts of the support device can ensure the stability of the trailer within the working height range.

6.2.5 When not in operation, the jockey wheels should be raised to the highest position and securely fixed.

6.3 Operation and maintenance instructions

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