II. Disc Axle Installation Requirements

2.1 Installation Direction of Axle Brake

During installation, ensure that the direction of the brake caliper's long pin toward the short pin is consistent with the wheel rolling direction or the direction indicated by the sticker (painted arrow) on the axle. The left and right positions of the brake caliper must be correctly assembled.

For axles equipped with air suspension, the brake chamber shall be positioned in the front lower area of the axle centerline;for axles equipped with leaf spring suspension, the rotation direction must remain consistent front and rear, and the brake chamber shall be positioned in the rear lower area of the axle centerline.

2.2 Welding of Axle Connection Upper and Lower Plates

During operation, the support plate is located at the maximum bending moment area of the axle and is a region of concentrated stress. Therefore, the welding quality between all support plates and the axle is extremely important. Incorrect welding methods or excessive welding seams may lead to axle fracture.

Before welding, check whether the support plate fits tightly against the axle beam. If not, correct it before welding.

During any welding operation (including vehicle body welding), grounding through the axle or wheel rotation is strictly prohibited to prevent electrical damage to bearings or axle components.

2.3 Wheel Installation

2.3.1 Wheel Installation Procedure

(1) Clean the mating surfaces between the wheel and hub. No dirt, burrs, or foreign matter is allowed between the surfaces; otherwise, it may cause uneven preload on hub bolts, reduce friction on the mating surface, and eventually lead to loosening of individual or multiple hub nuts, wheel movement, or bolt failure.

(2) Use a proper socket and torque wrench that match the nut size. Incorrect socket size may damage the nut hex surface or cause slipping, making tightening impossible.

(3) Tighten the nuts in sequence as shown in Figure, applying torque evenly one by one.

(4) Tightening torque for the nuts: 570–630 N·m.

2.3.2 Applicable Wheel Rims for the Axle

Wheel Rim: 7.50V-20 – suitable for 10.00-20.00 tires;

Wheel Rim: 8.00V-20 – suitable for 11.00-20.00 tires.

2.3.3 Precautions

(1) Wheel components must be selected according to the type and specifications of the hub, brake disc, and wheel bolts. Unqualified wheels will seriously affect the safety of the axle and tires. Please ensure the wheels are sourced from certified manufacturers. Pay special attention that the inflation valve angle relative to the tire axis must be less than 12° during installation.

(2) When tightening wheel nuts, the tire must be lifted off the ground and tightened according to the specified torque sequence to ensure uniform force on each nut, preventing loosening and improving bolt service life.

(3) Brake chamber installation requirement: After vehicle installation and commissioning, the plug closest to the ground (i.e. the one facing downward) must be removed. Failure to remove the plug closest to the ground will prevent water accumulation inside the chamber from being discharged, which may cause damage to the brake chamber.

(4) Brake pad wear warning device must be installed. The brake pad wear sensor shall accurately indicate the wear condition of the brake pads and remind the user to replace them in a timely manner.

(5) For vehicles equipped with disc brakes: the tractor must be fitted with a hydraulic retarder, and the trailer must be equipped with an ABS anti-lock braking system or an EBS electronic braking system. Water spraying devices or similar equipment are strictly prohibited on disc brake axles.

(6) When using disc brake axles, a soft brake valve (1:1) must be used, and brake boosters are strictly prohibited. Any brake system or air suspension control circuit failures, or damage to the axle brakes, suspension, or air lines caused by customers’ unauthorized modifications to the trailer braking air circuit or air suspension control circuit, or by replacing parts with non-compliant aftermarket components, shall not be covered by our company's warranty.

2.4 ABS System Installation on the Axle

According to the mandatory national standard GB1276-1999, effective from October 1, 2003, all trailers of Category O4 with a maximum gross mass exceeding 16 tons must be equipped with a Category 1 anti-lock braking system (ABS) that meets the requirements of GB13594.

According to customer requirements, the company will install the ABS tone ring and sensor on the axle. The user shall independently install other ABS components such as the ECU and the electromagnetic relay valve.

During installation:

Apply lubricant inside the elastic bushing and press it into the mounting bracket hole until both small flanges of the bushing are fully seated against the bracket.

Manually insert the sensor into the elastic bushing until the sensor head makes contact with the tone ring.

Secure the cable to the axle or chassis using clamps or zip ties.

Routine maintenance shall include cleaning sediment accumulated between the tone ring teeth, checking and tightening loose cables, and replacing damaged cables in a timely manner.

For tandem-axle trailers, a 4S/2M ABS system layout is recommended, and for tri-axle trailers, a 4S/3M layout is recommended. Vehicles equipped with 20"–22.5" tires generally use a standard 100-tooth tone ring. The brake control system is required to ensure synchronized braking times between the first three axles of the tractor and the three axles of the trailer, without the need for the rear axles to brake sequentially after the front axles.