(1) Fault phenomenon
During braking, the braking efficiency of the left and right wheels is different, causing the vehicle’s driving direction to deviate.
(2) Fault cause
① The tire pressure on both sides is different and the degree of wear is inconsistent.
② The exposed length of the brake chamber push rods on both sides is different, and the extension speed is different.
③ The brake clearance and friction pad wear degree of the wheel brakes on both sides are inconsistent.
④ The preload adjustment of the wheel hub bearings on both sides is inconsistent.
⑤ The front wheel alignment adjustment on both sides is inconsistent, and the elastic force of the leaf springs on both sides is different.
⑥ The brake hose on one side is not ventilated or leaking.
⑦ The friction pad of the brake shoe on one side is stained with oil.
⑧ The brake shoe and brake drum on one side are deformed, resulting in poor fit of the shoe and drum.
⑨ The fastening bolts of the brake bottom plate on one side are loose.
⑩ The front wheel alignment is inaccurate.
(3) Fault diagnosis and troubleshooting
① First, conduct a road test. On a good road surface, perform an emergency braking test on the vehicle. If the drag marks of the wheels on both sides are basically the same, and the vehicle also deviates when the brakes are not applied, the reason is similar to the deviation during driving. Then check whether the tire pressure, pattern and wear degree of the left and right wheels are consistent; check whether the front suspension spring is broken or has unequal elasticity; check whether the wheelbase of the front and rear axles is consistent; check whether the frame is deformed.
Diagnosis and troubleshooting of brake deviation of dump trucks
② If the vehicle deviates to the left or to the right when braking, measure the toe of the front wheels. If the toe does not meet the requirements, adjust it; check whether the ball pin of the steering horizontal and vertical tie rod is loose. If it is loose, it means that the ball pin is adjusted too loose or worn seriously, and it should be adjusted or replaced.
③ If the wheels do not have drag marks when braking, and the vehicle deviates to one side, it means that the braking force of the wheel on the opposite side is insufficient or the braking is too late. One person can step on the brake pedal while the other person checks the working condition of the wheel brake chamber. Listen for air leakage. If there is air leakage, it means that the brake chamber diaphragm is broken, the air pipe or joint is leaking, and it should be replaced or repaired.
④ Check the extension and retraction of the brake chamber push rod. If the push rod is bent or stuck, it should be repaired. If the brake chamber is in good working condition, the wheel should be supported and the technical condition of the wheel brake should be checked.
⑤ Remove the brake inspection hole cover and observe. If the brake clearance is too large, it should be adjusted: If there is oil on the brake shoe friction plate, the wheel brake should be removed and the brake shoe friction plate should be cleaned.
⑥ If the above inspection is normal, but the brake is still biased, the wheel brake should be removed for maintenance. Check the condition of the friction plate. If the friction plate is severely worn, hardened or the rivets are exposed, it should be replaced; check the condition of the brake shoe return spring. If it is broken or the elastic force is weakened, it should be replaced: measure the roundness and cylindricality of the brake drum. If it is out of tolerance, it should be bored: check whether the rotation of the brake arm and the brake shoe is flexible. If there is a carding phenomenon, it should be lubricated.
Dump truck
Solution to deviation: The tire patterns on both sides are different or the patterns are one deep and one shallow. The whole vehicle uses the same type of tires. At least the two tires on the front and rear axles need to be the same, and the pattern depth needs to be the same. If it exceeds the wear limit, it needs to be replaced. The tire pressure on both sides is not the same. Unequal tire pressure will make the tires different in size, and they will inevitably deviate when rolling. The front shock absorber spring is deformed and the buffering on both sides is inconsistent. The quality of the shock absorber spring can be judged by pressing or disassembling it. The front shock absorber fails. After the front shock absorber fails, the two suspensions are one high and one low during vehicle driving, and the force is uneven, resulting in deviation. The absorption degree of the shock absorber can be tested by a special shock absorber tester to judge the quality of the shock absorber; if it cannot be disassembled under certain conditions, it can be judged by stretching. The vehicle chassis parts are worn too much and there is abnormal gap. The steering rod ball head, support arm rubber sleeve, stabilizer bar rubber sleeve, etc. are common parts with excessive gaps. The vehicle should be lifted and carefully checked. The brake of a certain wheel is not returning properly and is not completely separated. This is equivalent to always applying partial braking on one side of the wheel, and the vehicle will inevitably deviate when driving. When checking, you can feel the temperature of the wheel hub. If one wheel exceeds the other wheels by a lot, it means that the brake of the wheel is not returning properly. The overall frame is deformed. The wheelbase on both sides is too different and exceeds the allowable range. It can be measured with a tape measure; if it exceeds the range, it needs to be corrected with a correction table.
