How to repair the master cylinder and cylinder in the hydraulic brake system of the forklift?
1. Maintenance of hydraulic brake master cylinder
1. Remove the hydraulic brake master cylinder from the forklift. Remove the brake pedal, clutch pedal return spring, two push rods on the master cylinder and the oil outlet pipe; remove the fixing bolts on the master cylinder and remove the brake master cylinder assembly.
2. Disassembly of the master cylinder. The hydraulic brake master cylinder and clutch hydraulic master cylinder produced in the early stage are made into one body. When disassembling, the parts in the two chambers should be placed with S separately to prevent wrong installation.
① Remove the dust cover clip, remove the piston push rod and dust cover, clean the outside, unscrew the oil plug, and release the internal brake fluid.
②Remove the lock ring, take out the thrust collar, piston and cup, return spring and oil outlet valve; remove the outlet and return valve from the return spring, and remove the seal ring from the piston
③Remove the pump cover and the oil pipe joint, clean the internal parts with alcohol, and at the same time dredge the oil return hole, compensation hole, small hole in the piston head and the vent hole on the fuel plug of the master pump.
3. Maintenance of parts of master cylinder
① If the star valve on the piston is loose, it should be riveted.
② The free length of the return spring in the master cylinder is 107mm. Under a pressure of 53.9 ~ 68.6N, the compression length should not be shorter than 67mm, otherwise it should be replaced.
③ The oil outlet valve, oil return valve, leather cup, sealing ring, dust cover, etc. should be replaced with new ones.
4. Assembly and test of the brake master cylinder
① Before assembling, all parts should be cleaned, and then assembled in the reverse order of decomposition. After the installation, the piston should be pushed with the push rod several times to check whether the movement of the piston in the cylinder is flexible and free, and whether there is any card issuance. After loosening the push rod, use a very thin steel wire to check whether the oil return hole and compensation hole are smooth in the liquid storage chamber. If the oil return hole is closed by the leather cup, the back washer should be thinned and removed; otherwise, the brake will bite, and the return spring with greater spring force can be replaced.
② Test of master pump: After installation, pressure test is performed. Check whether each part is sealed, whether there is oil leakage, and whether it is working properly, otherwise, these faults should be ruled out before loading the vehicle. During the pressure test, the master cylinder must be filled with brake fluid, and then turn the handle to make the oil pressure reach
8820kPa, keep for 3min, the master and centrifugal pumps must not leak oil, the oil pressure drop should not exceed 294kPa, otherwise it should be reassembled.
Second, the maintenance of the pump
The hydraulic brake cylinder is installed on the wheel brake, and the maintenance method is the same as the master cylinder. The inner diameters of the two cylinders on the same wheel should be the same. After disassembly, the leather cup and apron should be replaced. The free length of the spring in the cylinder is 42mm. Under a pressure of 24.5 ~ 34.3N, the compression length should not be shorter than l7mm, otherwise it should be replaced. Carry out pressure test together with the master pump after installation, and there shall be no oil leakage.
