Failure Analysis of Clutch Booster

(1) The clutch booster does not work

The main symptom of the clutch booster not working is that you feel weak when you step on the clutch pedal, the clutch cannot be disengaged, and the booster does not work. The main reasons for it are:

①The oil passage leading to the control valve is blocked, and the oil pressure cannot push the relay valve.

②The gasket of the relay valve swells.

③The stroke of the diaphragm mandrel is not enough.

④ The piston seal of the power cylinder is swollen or rusted, and the compressed air cannot be pushed.

⑤ The oil seal at the front of the power cylinder piston leaks oil, which fills the front cavity with hydraulic oil and generates reverse thrust, so that the power cylinder piston cannot move.

⑥The sealing ring of the hydraulic cylinder is swelled.

The above ①, ②, and ③ are all caused by the gas path, and the consequence is that the gas path cannot be opened. ④, ⑤, ⑥ belong to the reasons of the oil circuit, which may cause insufficient increase in the oil circuit, or cannot transmit hydraulic pressure and gas pressure. At this time, the oil circuit and the gas circuit should be checked separately. When the intake and exhaust are unobstructed, the oil circuit should be checked mainly.

(2) The clutch booster is seriously deflated

The sign of serious deflation is to step on the clutch pedal, and the compressed air is discharged from the exhaust hole, which does not have an afterburner effect. The main reasons for it are:

①The seal between the poppet valve and the diaphragm mandrel is not good, and the compressed air enters the left side of the diaphragm from the hole in the middle of the mandrel, and is discharged from the exhaust hole.

②The diaphragm is broken or damaged.

③The poppet valve is damaged.

When eliminating this kind of failure, generally only need to dismantle the upper control valve.

(3) The clutch booster does not return

The sign of the booster not returning is that the clutch pedal feels forceful, but there is no exhaust after releasing it, and the clutch slips. The main reasons for it are:

①The sealing ring of the power cylinder, the gasket of the relay valve, and the sealing ring of the hydraulic piston expand. When you step on the plate, it can move to a certain position, and when you release it, due to swelling, it always generates resistance and cannot return to its original position, making the clutch in a semi-disengaged or slipping state.

②The stroke of the diaphragm is too long, so that the gas path cannot be opened.

Since the gas circuit and the oil circuit affect each other, if the fault is excluded, it should be checked and eliminated in sections according to the cause of the fault.