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 pushrods 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 brake master cylinder.
The hydraulic brake master cylinder produced in the early stage is integrated with the clutch hydraulic master cylinder. All parts in the two chambers should be placed in s separately to prevent incorrect installation during disassembly.
① Remove the dust cover clamp, remove the piston push rod and dust cover, clean the outside, unscrew the oil filler plug and drain the internal brake fluid.
② Remove the lock ring, take out the thrust ring, piston and cup, return spring and oil outlet valve; Remove the oil outlet and return valves from the return spring and remove the sealing ring from the piston.
③ Remove the pump cover and oil pipe joint, clean the internal parts with alcohol, and dredge the oil return hole, compensation hole, small hole at the piston head, and vent hole on the refueling plug.
3. Maintenance of master cylinder parts
① If the star valve plate on the piston is loose, it shall be riveted tightly.
② The free length of the return spring in the master cylinder is 107mm. Under the pressure of 53.9 ~ 68.6N, the compression length shall not be less than 67mm. Otherwise, it shall be replaced.
③ The oil outlet valve, oil return valve, leather cup, sealing ring, dust cover, etc., shall be replaced with new parts.
4. Assembly and Test of brake master cylinder
① All parts shall be cleaned before assembly and then assembled in the reverse order of disassembly. After reassembly, push the piston several times with the push rod to check whether the piston moves flexibly and freely in the cylinder barrel and whether there is card clamping. After loosening the pushrod, use a skinny steel wire to check whether the oil return hole and compensation hole are unblocked in the liquid storage chamber. If the oil return hole is closed by the leather cup, the gasket at the back shall be thinned and eliminated; Otherwise, a braking seizure will occur, and the return spring with large elastic force can also be replaced.
② Test of master cylinder: conduct pressure test after reassembly. Check whether each part is sealed, whether there is oil leakage and whether it usually works. Otherwise, remove these faults before loading. During the pressure test, the master cylinder shall be filled with brake fluid, and then turn the handle to make the oil pressure reach 8820kpa for 3min. The master cylinder and slave cylinder shall not leak oil, and the oil pressure drop shall not exceed 294kpa; otherwise, it shall be reassembled.
2、 Maintenance of wheel cylinder
The hydraulic brake cylinder is installed on the wheel brake, and the maintenance method is the same as that of the master cylinder. The inner diameter of two-wheel cylinders on the same wheel shall be the same. Replace the cup and leather ring after disassembly. The free length of the spring in the slave cylinder is 42mm. Under the pressure of 24.5 ~ 34.3n, the compression length shall not be less than l7mm, otherwise it shall be replaced. After reassembly, the pressure test shall be carried out with the master cylinder, and there shall be no oil leakage.
I hope this blog is helpful. Please click here for more about our forklift parts.