Is the tractor out of gear, automatic off gear, shaking lever and abnormal noise very annoying? This article tells you how to deal with it

Transmission is a device that transmits the power output by the engine and changes the speed of the engine. Because the load of the tractor changes greatly during operation, the speed also changes frequently. The relative movement of parts in the transmission is very frequent, and the wear and deformation of parts is inevitable. Therefore, the transmission often has faults, such as disordered gear, automatic off gear, abnormal noise, etc., which affect the normal use of the tractor.

1. The transmission is out of order
Phenomenon:
When engaged, the required gear cannot be engaged, but other gears; Or the tractor cannot run when it is engaged in two gears at the same time.
Causes:
(1) The front bearing of the second shaft of the transmission is sintered due to serious heating.
(2) The gear selector head is seriously worn or the groove of the shift fork guide block and the ball head at the lower end of the shift lever are seriously worn.
(3) Transmission interlock failure.
Judgment and elimination:
(1) The front bearing of the second shaft of the transmission is sintered to connect the first shaft with the second shaft and rotate together. Inspection method: put the transmission in neutral, slowly release the clutch, and move the tractor forward, indicating that the bearing is sintered. In case of such fault, the vehicle cannot be driven. Disassemble the transmission immediately, replace the bearing and repair it.
(2) When the ball head of the gear selector, the groove of the shift fork guide block and the ball head at the lower end of the shift lever are seriously worn, the ball head at the lower end of the shift lever will come out of the groove of the shift fork guide block, and the gear position cannot be judged when shifting, resulting in disordered gear.
(3) Failure of transmission interlock device may cause the phenomenon that two gears are engaged at the same time. In this case, the engine sound and speed change significantly, or the engine stops, and the vehicle cannot move. In case of such failure, be careful not to add oil and loosen the clutch pedal, otherwise it will cause damage to gears, shafts and other parts, but shut down the engine, and then disassemble the transmission to check the interlock device.
2 automatic gear disengagement
Phenomenon:
The shift lever automatically moves into the neutral position, which is called automatic gear disengagement.
Causes:
(1) The steel ball in the positioning groove of the shift fork shaft is seriously worn, and the elastic force of the locking spring is too weak or broken, which makes the locking function of the locking mechanism unreliable, and the automatic gear disengagement is caused by vibration.
(2) The shift fork groove of the shift fork and sliding gear is excessively worn, the clearance is too large, and the shift fork and shift lever are bent or deformed, reducing the stroke of the sliding gear. In this case, the gear cannot be fully meshed, the positioning steel ball cannot enter the positioning groove, and the gear will automatically disengage due to vibration.
(3) The gear end face is seriously worn, and the wear along the tooth length direction is too large, or even partially worn into a cone.
Judgment and elimination:
(1) When a gear is found to be out of gear, still shift the control lever into the gear and turn off the engine. First check whether the adjustment of the operating mechanism is correct, and then disassemble the rear housing of the gearbox to check the gear meshing and synchronizer meshing. If the engagement is not good, check whether the bearing is worn and loose, whether the shift fork is deformed, and whether the clearance between the shift fork and the shift fork groove on the joint sleeve and gear is too large. If the engagement is good, check the locking of the operating mechanism.
(2) Push the shift fork out of gear by hand to check the positioning device. If the positioning is poor, remove the shift fork shaft and check the positioning ball and spring. If the spring is too soft or broken, replace it. If the groove of the shift fork shaft is excessively worn, repair or replace it. Fasten the loose parts, repair the worn or deformed parts, and replace the new parts without repair value.
3 transmission shake lever
Phenomenon:
After the transmission is engaged in a certain gear, the control lever keeps shaking. Holding the control handle with your hand, there is an obvious shaking movement.
Causes:
(1) The transmission self-locking device fails. The self-locking groove of the shift fork shaft is excessively worn, and the steel ball and shift fork shaft are excessively worn.
(2) The shift fork is bent, deformed or severely worn.
(3) The spline shaft matched between the spline hole of the sliding gear and the second shaft is excessively worn and loose, the radial and axial clearance increases, and vibration occurs during gear transmission.
Judgment and elimination:
(1) Shift into a certain gear, slowly release the clutch pedal, hold the transmission control handle, feel vibration and change with the engine speed, it is the fault of the transmission shaking lever.
(2) Disassemble the transmission and check the self-locking device on the transmission cover. If the clearance between the self-locking steel ball and the hole on the transmission cover is too large and the spring is weak, the shift fork shaft will move axially, causing the transmission to shake.
(3) Check whether the shift fork is bent or twisted.
(4) Check whether the spline hole of the sliding gear and the spline shaft on the second shaft are seriously worn, resulting in looseness, resulting in unstable gear transmission and rod shaking.
4 abnormal transmission noise
Phenomenon:
When the tractor is working, the transmission makes an abnormal sound.
Causes:
(1) The first shaft bearing of the transmission makes a noise because the bearing is seriously worn, the radial clearance is too large or the outer ring of the bearing is loose.
(2) The causes of noise caused by gear meshing are: the gear meshing clearance becomes larger after the gear tooth surface is worn; The gear tooth surface peels off, resulting in poor gear meshing; During repair, the meshing gears are not replaced in pairs.
(3) Individual gear teeth are broken or dirt is embedded.
(4) The spline part of the spline shaft and the spline groove of the gear are worn and the clearance is too large.
(5) The shift fork is deformed and scrapes the gear, or the shift fork collides with the shift fork groove of the joint sleeve.
(6) There is a lack of gear oil in the transmission.
(7) The rolling key or keyway at the connection between gear and shaft is loose.
Diagnosis and inspection methods:
(1) When the gear is not engaged, the sound disappears when the clutch is disengaged. Generally, the outer ring of the bearing is loose; Noise can be heard when driving or shifting gears. Generally, the radial clearance of the bearing is too large. The general axial clearance of roller bearing shall not exceed 0.3 ~ 0.5 mm, and the radial clearance shall not exceed 0.25 mm. If the bearing is seriously worn, replace it with a new one.
(2) When a gear is engaged, the noise increases and the tone increases. Generally, the backlash of the meshing gear of the gear is too large; The sound is uneven, but the periodicity is strong. Most of them are poor gear meshing or not replaced in pairs. If the meshing clearance of gear teeth becomes larger, it shall be replaced in pairs.
(3) The transmission sends out periodic impact sound, and the volume is strong, mostly individual gear teeth are broken. If dirt is embedded in the gear, thoroughly clean the transmission and completely replace the gear oil.
(4) When the tractor just starts, the transmission produces impact noise, mostly due to the excessive clearance between the spline shaft and the spline groove of the gear. If the spline part and gear on the shaft are worn and the clearance exceeds the limit, replace the spline shaft and gear.
(5) When the transmission is short of oil, noise and overheating usually occur at the same time. Frequently check the oil level of transmission gear oil and add it in time if it is insufficient.