Fault analysis and of the braking system of the mo

2022-08-13
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Fault analysis and troubleshooting of the braking system of the regular zlm50e loader

1 structural characteristics of the braking system

the braking system of the regular zlm50e loader adopts the air driven oil, caliper disc, double pipe service braking system, and is equipped with a parking brake directly operated by the handle with a flexible shaft (see Figure). This kind of braking system has higher reliability and safety than the ordinary single pipe braking system without emergency braking

1. Air compressor 2 Oil water separator 3 Pressure controller 4 Double circuit air brake valve 5 Wiper valve connector 6 Barometer 7 Air horn

8 Air reservoir 9 Check valve 10 Tee joint 11 Booster 12 Stop light switch 13 Brake

figure: the brake system structure of the regular zlm50e loader

the high-pressure gas generated by the engine driven air compressor enters the air reservoir after passing through the oil-water separator and the air pressure regulator. When the brake pedal is pressed, the high-pressure gas enters the air brake valve from the air reservoir, and then enters the air booster pump group. After the booster cylinder generates large pressure, it pushes the booster cylinder. The brake fluid at the other end then enters the caliper disc brake of each wheel through the oil pipe, pushing the piston to clamp the brake disc, so as to brake the wheels. When lifting the brake pedal, the piston in the air brake valve cuts off the high-pressure gas channel and connects the gas in the valve with the atmosphere. The booster pump set returns under the action of spring force to reduce the brake oil pressure in the brake pipeline, so as to release the braking of the wheels

2 analysis of common faults of the braking system

common faults of the braking system of the regular zlm50e loader include: brake failure, brake failure, brake deviation, brake drag, etc

2.1 insufficient braking air pressure

fault phenomenon:

the braking fault caused by insufficient air pressure shows that the air pressure cannot express the specified air pressure value (0..70mpa), and there is no braking reaction when pressing the brake pedal

fault cause:

1) the pipeline leaks, and the gas in the air reservoir has no pressure or the pressure is too low, which is not enough to drive the booster pump set to generate braking force

2) the air compressor does not work properly and cannot produce enough compressed air

3) the one-way valve is rusted and stuck, resulting in the inability or slow air inlet to the air reservoir

4) the oil drain plug of the oil-water separator is not tightened, and the air leakage is serious

5) the pressure regulating valve leaks seriously

Troubleshooting:

first check the air leakage of the pipeline, and then check the working state of the air compressor. Remove the air outlet pipe of the air compressor and press the air outlet with your thumb. If the exhaust pressure is low, the air compressor is faulty. If the air compressor is in good working condition, check the oil drain plug or pressure regulating valve of the oil-water separator to avoid bypass. Finally, check the two check valves in the three-way joint. If the check valve is stuck, it will cause failure to air into the air reservoir or slow air intake

2.2 brake failure

fault phenomenon:

when the loader is driving, it cannot slow down and stop when braking

fault reason:

1) insufficient brake air pressure, unable to push the brake piston action

2) the brake valve fails, the piston is stuck or the compensation hole and vent hole are blocked, which cannot generate sufficient air pressure

3) there is air in the brake oil pipe, causing oil pressure fluctuation or insufficient flow, which cannot push the brake piston to act

4) there is no brake fluid or the brake fluid is insufficient, resulting in insufficient brake fluid oil entering the brake cylinder, and the output power of the brake cylinder is low, which cannot push the brake piston

5) the brake oil pipe is broken or the oil pipe joint leaks oil, which reduces the amount and pressure of brake fluid entering the brake cylinder

6) the piston of the afterburner cylinder is stuck or the sealing ring is damaged, and the output brake fluid volume and pressure are reduced

7) the caliper disc brake oil cylinder leaks seriously, and a large amount of pressure oil leaks, which cannot push the brake piston to act

8) the piston in the caliper brake cylinder is stuck, and the piston cannot act

9) the brake friction plate has oil stains or is seriously worn, the friction coefficient decreases or the brake clearance increases, and the braking force decreases

fault diagnosis and Troubleshooting:

1) check the brake air pressure, eliminate the fault of low brake air pressure, and ensure that the brake air pressure value is 0 70Mpa。

2) when pressing the brake pedal, the air pressure is normal and the brake pedal does not move, indicating that the piston of the brake control valve is stuck. Disassemble, repair or replace the brake valve

3) step on the brake pedal, the pedal position is very low, and then continue to step on the pedal, the pedal gradually rises, but I feel that the brake pedal is very weak, and the braking effect is not good, indicating that there is air in the braking system, which should be eliminated

4) if you step on the brake pedal continuously, you will feel heavy, but the pedal position gradually decreases, indicating that the brake system is leaking oil, so you should check and repair it. If necessary, remove the brake for maintenance, and replace the rectangular seal ring or brake piston

5) after the air in the oil pipe is removed, the brake pedal is still weak. Open the filler cap and find that the brake fluid has violent overturning, indicating that the seal in the caliper disc brake is deformed or damaged. Check and replace the damaged parts to promote the development of the new material industry

6) the piston in the caliper brake cylinder is stuck, and the piston and seal should be repaired

7) when the brake friction plate is worn to 1/3 of the original thickness, the friction plate should be replaced to prevent damage to the brake disc

8) when the brake disc has deep grooves or serious deformation, repair or replace the brake disc. Please tell each other that

2.3 braking is ineffective

fault phenomenon:

when the loader is driving, the brake pedal is pressed to the bottom, and it still cannot stop, decelerate quickly, and continue to slide

fault cause:

1) there is air in the brake oil pipe or brake cylinder, causing oil pressure fluctuation or insufficient flow

2) the free stroke of the brake pedal is too large

3) the seals of brake valve, booster cylinder and brake cylinder are seriously worn, or the cylinder barrel and piston are seriously worn, resulting in air leakage and oil leakage

4) the compensation hole or vent hole of the brake valve is blocked

5) the brake oil pipe is broken or the oil pipe joint leaks oil

6) the clearance between brake disc and friction plate is too large

7) the surface of the friction plate is hardened, the rivet is exposed or there is oil stain

8) the quality of brake fluid is poor, and it is easy to evaporate by heating

9) the brake pipeline is sunken or blocked

fault diagnosis and Troubleshooting:

1) check the brake air pressure, eliminate the fault of low brake air pressure, and ensure that the brake air pressure value is 0 70M。

2) when pressing the brake pedal, the position is very low, and then when continuously pressing the pedal, the pedal can gradually rise, but the reaction force is small and the braking effect is not good, indicating that there is air in the brake oil pipe or brake cylinder, which should be eliminated

3) one foot braking is ineffective, and the pedal position gradually rises when continuously pressing the brake pedal, feeling a large reaction force, and the braking effect is good. It means that the free travel of the brake pedal is too large or the clearance between the friction plate and the brake disc is too large. First check and adjust the free travel of the brake pedal, and then adjust the clearance between the friction plate and the friction disc

4) step on the brake pedal continuously and feel heavy, but the position of the brake pedal gradually decreases, indicating that the brake system leaks oil, so it should be checked and repaired. If necessary, remove the brake for maintenance, and replace the rectangular seal ring or brake piston

5) after the air in the oil pipe is removed, the brake pedal is still weak. Open the filler cap and find that the brake fluid is violently overturned, indicating that the seal in the caliper disc brake is deformed or damaged, and the damaged parts should be replaced

6) when pressing the brake pedal, the pedal position is very low, and then when continuously pressing the brake pedal, the pedal position cannot be raised. Generally, the vent hole or compensation hole of the brake valve is blocked, which should be dredged

7) when stepping on the brake pedal, the free stroke and height of the pedal meet the requirements, and it is not weak and sinking, but the braking effect is not good, it is the fault of the caliper disc brake, which may be caused by the hardening of the friction plate, the exposure of rivets, serious oil contamination, the deformation of the brake disc, etc. At this time, service the brake and polish the brake disc if necessary

2.4 braking deviation

fault phenomenon:

the wheels on both sides cannot be braked at the same time during the driving process of the loader, or one wheel brakes and the other wheel rotates, causing the vehicle to deflect to one side, causing the vehicle to not travel in a straight direction

fault cause:

1) the contact area and clearance between the left and right wheels and the brake pad are inconsistent

2) some wheel friction plates are greasy, hardened or rivets are exposed

3) the friction plate materials of the left and right wheels are inconsistent

4) there is air in some brake cylinders, the piston movement is blocked, or the oil pipe is blocked

5) left and right tire pressures are different

6) individual brake discs are deformed

the root cause of braking deviation is the unequal braking force of the wheels on both sides

fault diagnosis and Troubleshooting:

when the loader is driving and the foot brake is used, the vehicle deflects to one side, which indicates that the wheel brake on the other side fails. After parking, check the drag marks of the wheels on both sides on the road. The wheels on the side with short or no drag marks do not work well. When it is determined that the braking of a wheel is ineffective, check the deformation of the brake disc and eliminate the air in the brake cylinder. If it still doesn't work, disassemble the wheel brake, check the piston and seal of the brake cylinder, find out the location of the fault and make necessary repairs

2.5 braking drag

fault phenomenon:

loader braking this equipment is used to display the pressure of the oil pump and lift the brake pedal. All or individual wheels still have braking effect, causing the brake disc to heat up and drive weakly, commonly known as "braking does not return"

fault cause:

1) the free stroke of the brake pedal is too small or the brake pedal is not returned properly

2) the return spring of the control valve piston is too soft or broken, and the piston is stuck

3) the seal of the brake valve cup expands, making the return spring weak

4) brake piston does not return, etc

fault diagnosis and Troubleshooting:

1) touch the brake discs of each wheel by hand after the loader has driven a certain distance. If all the brake discs are heated, it indicates that the fault is in the brake valve; If individual brake discs are heated, it indicates that the fault is the brake of the wheel

2) for the heating of all brake discs, disassemble the brake valve, check the working conditions of seals, pistons, breather holes, compensation holes and return springs, and replace them if necessary

3) for the heating phenomenon of individual brake discs, loosen the bleeder screw of the brake first during the inspection. If the brake fluid ejects rapidly and the piston returns, it can be recognized that the oil pipe is blocked, and the brake pipeline should be dredged; If the brake piston still cannot return, remove the brake for maintenance

3 maintenance of brake system

in order to ensure that the power system of the regular zlm50e loader is always in good working condition, the following inspection and maintenance items should be paid attention to in use:

1) regularly check the connection and fastening of all parts of the brake

2) regularly check whether there is leakage in the brake valve, brake cylinder, afterburner cylinder and pipeline. If there is any oil leakage, it should be eliminated in time. If there is oil on the friction plate, it should be cleaned in time

3) the dirt on the caliper disc brake should be cleaned after the daily work task is completed because the brake disc is exposed

4) check the working condition of the brake pedal, whether it is stuck when pressing the brake pedal, and whether it can return quickly when loosening

5) check whether there is air in the hydraulic system. If there is air, press the pedal to feel soft and weak, and the braking effect is reduced

6) check the amount of brake fluid if necessary,

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