Semi-trailers have become the mainstay of transportation in the world today. Many semi-trailer drivers lack understanding of the structure, design, and maintenance of semi-trailers. They are often helpless when the brake system fails during driving, and even cause serious accidents.
So how should semi-trailers be operated correctly? What are the common faults of semi-trailers and how to eliminate them?
- Air brake system
① Fault: poor braking, slow braking
Causes and troubleshooting methods: too large clearance between brake shoe friction pad and brake drum (adjust clearance), excessive wear of brake shoe friction pad (replace brake shoe friction pad), air leakage in air brake system causes pressure drop (check leaking parts, repair or replace parts), emergency relay valve malfunction (replace emergency relay valve)
② Fault: unable to release brake, slow release of brake
Causes and troubleshooting methods: emergency relay valve has emergency braking effect (increase air brake system pressure to specified value), brake return spring is broken (replace spring), pipe is blocked (check and clear), brake air chamber push rod is bent (repair or replace parts), brake air chamber push rod stroke is incorrect (readjust) - Suspension
Fault: noise
Causes and troubleshooting methods: leaf spring is broken (replace leaf spring), U-shaped nut bolt is loose (tighten as required) - Axle
Fault: tire swing, wheel hub overheating, tire Severe wear and eccentric wear of tires
Causes and troubleshooting methods: loose wheel nuts (tighten), sintered axle bearings (replace bearings), bent axles (replace), poor return of brake shoes (adjustment and repair), sintered axle bearings (correctly tighten bearing locking nuts, replace bearing grease on time, replace axle bearings), tire pressure is too high or too low (adjust tire pressure as required), overload or eccentric load (carry cargo as required) - Support device
Fault: Too much resistance to shaking the crank handle
Causes and troubleshooting methods: poor lubrication (replenish lubrication), sintered bearings (replace), eccentric or worn gears (check and replace), screw thread damage (replace screw) - Electrical system
Fault: Bad headlights
Causes and troubleshooting methods: Bad bulbs (worse bulbs), loose or damaged plugs or sockets (repair or replace) - Fault: Air pressure is lower than 0.7MPa for a long time or obvious drag brake phenomenon occurs during trailer driving
Solutions: ① Replace the front of the vehicle and eliminate the tractor fault; ② Check the source of air leakage by applying soapy water to eliminate possible faults such as “leakage at the handshake connection”, “leakage at the pipe joint”, “cross-breathing of the brake air chamber”, “leakage of the emergency relay valve”, and “leakage of the trailer ABS valve”.
If the leakage phenomenon still exists, it is necessary to check whether the valve body has water ingress or obvious rust can be seen. This phenomenon indicates that the filtration and drying effect of the trailer air pipeline is not good, and the valve body may need to be replaced. - Fault: The trailer cannot be started after parking and is always locked
Solution: ① First unplug the ABS spiral wire to see if it can start normally to eliminate circuit problems; ② Put the tractor in the state of inflating, unplug the air pipe of the manual valve, and check whether the air pressure of the “air outlet” is normal (the air pressure should be very high in the state of inflating); ③ Check whether the parking brake is in the released state; ④ If there is no problem with the air circuit inspection, the mechanical fault of the axle content should be checked in the end.
In all braking states of the trailer brake system, the air supply pipeline is completely kept unobstructed in safety design. The foot brake and parking brake measures of the tractor are both effective by supplying air to the control pipeline.
Now more and more customers are modifying the trailer air circuit by themselves. Due to improper modification, the original braking system is damaged, and improper use causes many safety and quality accidents. Here, it is necessary to remind the majority of car owners that vehicle modification must be completed in a regular modification unit or the original factory.
