The gearbox is one of the important transmission components of the wheel loader. It is responsible for transmitting the speed and torque from the engine to the final drive system, changing the transmission ratio between the engine and the wheels, and realizing the forward and reverse gear manipulation of the loader. The following are common faults and causes of wheel loader gearboxes

1. When in gear, the gear cannot be smoothly entered.

The reasons are:

(1) The pressure of the pressure valve is too low;

(2) The hydraulic pump is not working well and the seal is not good;

(3) The hydraulic pipeline is blocked;

(4) The clutch sealing ring is damaged or leaked;

(4) The gear stem is not in place.

2. When the gearbox changes speed, the gear cannot be disengaged.

The reasons are:

(1) The piston ring is swelled;

(2) The friction plate of the clutch is burned;

(3) The return spring of the clutch is invalid or damaged;

(4) The oil return line is blocked.

3. The gear has been put on, but the loader is weak and cannot even walk.

The reasons are:

(1) The friction plate is severely worn and the gap is too large;

(2) The automatic emptying valve of the clutch is not tightly sealed, causing the pressure to drop;

(3) The pipeline of the shift control valve is blocked;

(4) The cut-off valve cannot return;

(5) The positioning spring of the variable speed valve is fatigued or broken, and the steel ball jumps;

(5) Clutch piston rings and sealing rings are severely worn, causing serious leakage.

4. The operating pressure is too low.

The reasons are:

(1) Insufficient oil in the gearbox oil pan;

(2) Oil leakage in the main oil passage;

(3) The gearbox filter is clogged;

(4) The steering pump (or hydraulic pump) is damaged, causing serious internal leakage;

(5) Improper pressure adjustment of the gearbox pressure regulating valve;

(6) The spring of the gear pressure valve is invalid or broken.

5. The gearbox is automatically out of gear or out of gear.

The reasons are:

(1) The positioning device of the shift control valve fails. The main reason for the failure is that the positioning steel ball is severely worn, or the spring is invalid;

(2) Due to the long-term use of the shift lever, the position and length of the lever change, and the proportion of the lever is not accurate, which makes the operating position deviate, resulting in misalignment.

How to carry out preventive maintenance of gearbox?

1. According to JB/Z194-83, combined with the actual maintenance, the following regulations should be followed:

(1) Routine maintenance: check the oil level in the lower shell of the oil;

(2) 50 hours (or weekly): check whether the shifting joystick is flexible and effective;

(3) 250 hours (only after the first 250 hours of work): Clean the transmission oil pan and the filter element of the transmission oil filter;

(4) 500 hours: Clean the oil pan filter and replace the gearbox oil;

(5) 2000 hours: Disassemble the gearbox and torque converter for inspection and maintenance.