Semi-trailer Full Maintenance Manual

Safety is always the first priority for truck drivers in transportation. If the purpose of renting trailers is to save worry, then the maintenance of trailers is to renew life. Check everything before driving and you can go on the road.
Based on the feedback from the former Trailer drivers and the rich practical experience of the market service professionals after Dongfang Post Station, we summarize the knowledge of semi-trailer usage, semi-trailer maintenance and maintenance, which can provide reference for the majority of drivers of Kayou:
1. Introduction of Main Assembly of Semi-trailer
Suspension system (steel): transfer load and absorb vibration.
Axle and hub system: single, two and three axle assemblies with the same structure are installed under the suspension system. Tires and rim assemblies are fastened to the hub with tire bolts to support the weight of the vehicle.
The outrigger lifting mechanism: In order to make the semi-trailer parked reliably after leaving the tractor, two outriggers with linkage or single action are installed at the front end of the frame. It is composed of screw transmission mechanism, bevel gear transmission mechanism, double speed reducer, transmission rod, operation handle, etc.
When the handle is pushed in, the rotation can rise and fall at a high speed. When the handle is pulled out, the rotation can rise and fall at a low speed. When the outriggers touch the ground, they can only be lifted in low gear.
Traction pin and guide plate/frame: There are traction pins and traction pin connecting plates connected with the saddle of tractor at the lower part of the front end of the frame. Traction pin is mainly used to transfer traction force and braking force of tractor.
2. Semi-trailer Circuit
The semi-trailer connects the spiral cable plug of the tractor with the circuit socket of the front end of the trailer, and plays the role of transmitting the light signal of the main vehicle to the trailer.
Therefore, the vehicle is equipped with an international general electric system matching the tractor. The electrical system generally consists of seven-core socket, multi-core cable, junction box, waterproof connector and various lamps and lanterns.
Seven-core circuit connection diagram:
3. Semi-trailer air way
Three major components: emergency relay valve, ABS valve and brake chamber. Most of the faults come from these three components.
Emergency Relay Valve: The pneumatic components of the vehicle brake system can realize emergency braking when the inflatable pipeline of the semi-trailer is damaged or the intake is cut off, shorten the braking lag time and quickly relieve the braking function, replacing the brake valves, distribution valves, acceleration valves and quick release valves in the original semi-trailer brake system.
ABS (Anti-lock brake system): Electronic control system for monitoring and controlling vehicle speed during braking, including ABS solenoid valve, ABS wire harness, ABS probe, gear ring and other components. With the relay valve to perform the braking function; to prevent braking lock, through the probe to detect the wheel speed, when the speed drops to zero, the signal will be fed back to the solenoid valve, the solenoid valve regulates the air pressure, reduces the braking force, prevents braking lock, and increases the driving safety factor.
Brake chamber
Braking system of_4 and semi-trailer
It is composed of trachea joint, inflatable pipeline, operation pipeline, air storage cylinder, brake chamber, relay valve, ABS valve, ABS sensor and wheel brake.
The inflatable pipeline is connected with the air storage cylinder of the tractor through the quick joint, and the control pipeline is connected with the brake valve of the tractor through the fast joint. When the semi-trailer brakes, each brake chamber acts simultaneously.
Driving brake: In the process of driving, the driving brake (foot brake) is generally used to facilitate the deceleration and parking in the forward process.
Parking brake: Parking brake is a kind of brake that is used when the car is at rest. It is also called "hand brake". Its main function is to prevent the car from sliding forward and backward.
Air-break brake (emergency brake): air-break or serious air leakage of inflatable pipe, emergency brake action of trailer brake system automatically, control pipe breaking will not be carried out, but "foot brake" will fail.
Importance: When the head air pump is damaged or the inflatable pipe is disconnected, and the air storage cylinder leaks seriously, the "foot brake" of the vehicle fails or the effect is not good. The air-breaking brake is an important guarantee for the safety of the vehicle or personnel.
_Working braking state in normal braking:
When stepping on the brake pedal, the control pipeline can supply air to the emergency relay valve_and the emergency relay valve_controls the air storage cylinder to supply air to the brake pump_to generate braking force; when the brake pedal is loosened, the emergency relay valve can release the compressed air of each pump quickly and release the braking state quickly.
▎ feedback braking state during inflation:
Trailer parking time is long, when there is no air pressure in the brake system, the parking brake system (air-break brake) plays a role. When the tractor inflates to the trailer_cylinder through the gas supply pipeline, the emergency relay valve is in a safe braking state.
In the safe state Emergency relay valve first sends compressed air into each 4 brake sub-pump. When the air pressure of the trailer_storage tank rises to 4.5 bar, the safety state is relieved. This function is abbreviated as feedback braking function. Braking sub-pump generates braking force under inflatable condition, which is a safety protection function.
_Automatic braking state in case of emergency gas breakdown:
When the air supply pipeline is accidentally damaged during driving, compressed air in the trailer_storage cylinder enters the brake pump through_emergency relay valve, and automatically executes braking measures to ensure the safety of the vehicle in emergency situations. It can travel to the maintenance office in a short time, but it will not last too long. When the tractor stops, it is necessary to disconnect the gas supply pipeline of the trailer. It can also be seen that the brake pump of the trailer works on the same principle.
Inspection and Maintenance of_5 and Semi-trailers
Vehicles need to do a good job of basic inspection and maintenance, inspection and maintenance can avoid unnecessary safety risks and reduce the cost of use.
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