As the driving conditions change, the car needs to change its traction and driving speed frequently while driving. The function of the transmission is to adapt to various driving conditions by changing the torque of the engine to the driving wheel and expanding the range of its speed change. need. Therefore, the transmission works under changing load and speed. After long-term use, the wear of each machine is gradually increased, even with misalignment, deformation or breakage, making the transmission difficult to shift and jump in the work. Faults such as disorder, abnormal noise, etc., thus affecting the safety of the driving and the personal safety of the driver. Therefore, it is especially important to properly and reasonably use and repair the transmission.
1. Structure of the Transmission The transmission includes two parts: a transmission transmission mechanism and an operating mechanism. The transmission mechanism is mainly composed of a gear, a shaft, a casing and a support member, and the function thereof is to change the speed ratio and the rotation direction; the operating mechanism is composed of a shift lever, a dial block, a shift fork, a fork shaft and a locking device, and the like It is to achieve shifting.
Second, the common faults of the transmission diagnosis and maintenance of common faults are: jump gear, chaos, gear difficult and abnormal noise.
1 Jumping fault phenomenon: When the car is driving in a certain gear, the shift lever automatically jumps back to neutral.
The cause of the fault: the toothed end of the gear, the ring gear or the toothed sleeve is tapered along the tooth length direction, or the meshing depth is insufficient; the second shaft spline tooth and the sliding gear spline groove are worn loosely; the transmission shaft bearing is worn, The front or rear bearing wear of the transmission is not parallel with the axis of the first and second shafts and the axis of the intermediate shaft, and the transmission fixing bolt is loose to cause the transmission axis to be different; the self-locking steel ball or the lock ball groove of the fork shaft is worn or its position is out of alignment. The self-locking spring is too soft.
Fault diagnosis: If the car finds a gear skip during driving, it will still hang the shift lever into the gear. When the car is slightly retracted, the shift lever will automatically jump back, extinguish the engine, remove the transmission cover, and check whether the gear is engaged. Conical shape is formed. If the sliding gear is not tapered, check whether the second shaft spline tooth and the sliding gear spline groove are loose. If the gear is intact, check if the input shaft bearing is loose. When the input shaft bearing is loose, not only abnormal noise but also jump gear can be caused. When checking, step on the clutch pedal and use a crowbar to pull a shaft gear to see if the bearing is defective. If it is, it should be repaired or replaced. When the car is running, if the shift lever is vibrating and there is abnormal noise, and the accelerator pedal is disengaged, check whether the second shaft gear cast iron bushing and the thrust piece are worn or broken. If the shifting lever has little or no resistance when the transmission is in gear, and the gear is blocked, check whether the groove on the self-locking steel ball and the fork shaft is too worn, and whether the self-locking spring is too soft or broken.
2 disordered phenomenon: When the clutch technology is in normal condition, the car starts to shift gear or shifts during driving. The shift lever cannot be engaged in the required gear position, that is, it can not be returned to the neutral gear or the two gears can be retracted once. Bit.
The cause of the malfunction: the shifting rod ball head positioning screw is short or dislodged, or the shifting rod ball head is worn too much, and the control lever is lost. The shift lever cannot move in the correct direction; the lower end of the shift lever has a curved working surface and the fork tip groove or The contact surface of the dial block is excessively worn; the interlocking pin or the steel ball is worn out and the interlock device is disabled.
Fault diagnosis: If the shift lever can be rotated in a circle, it indicates that the ball positioning screw is short or loose and loses control. If the swing is large, it indicates that the positioning screw is seriously worn and causes a disorder; the transmission can only be engaged and cannot be returned to neutral. If the shift lever can be rotated to cause a misalignment, the arc working face or the dial groove of the lower end of the shift lever is worn too much. If the shifting lever swings a large amount and the gear cannot be returned to the neutral gear, the lower working end of the shift lever is curved. The dial groove has been removed. To completely eliminate this fault, it is necessary to restore the technical standard of the curved working face and the fork groove at the lower end of the shift lever; if two gears can be engaged at the same time, the interlocking pin or the steel ball wears. Even the interlock device is disabled.
3 Gears are difficult. Cause: If the transmission mechanism itself is standard, the difficulty of gearing is mostly due to the synchronizer.
Fault diagnosis: the spiral groove of the cone in the synchronizer ring wears, so that the inner cone surface of the synchronizer ring and the outer cone surface of the gear become smaller, the friction between the tapered surfaces is reduced, and the braking effect is weakened. When it becomes zero, it loses its braking effect. Therefore, when checking the synchronizer fault, first check the gap. The width of the taper surface of the domestic automobile synchronizer lock ring should not be less than 015mm, and the gap between the lock ring and the gear cone is usually 115mm.
The synchronizer slider slides in the slot of the spline hub. This sliding action is caused by the sliding of the sleeve when the protrusion in the middle of the slider and the sleeve are engaged, so if the slider and the slots are severely worn The slider cannot be properly engaged with the corresponding slot on the synchronizing ring, which makes the shifting difficult. Check that the gap between the toothed end of the joint sleeve and the lock ring should be larger than the gap between the slider and the groove end of the lock ring. If the slider wears, it is not suitable and must be replaced.
The spring ring of the synchronizer has an important function of supporting the slider to the correct position. If the spring force of the spring ring is weakened, the slider can also be prevented from sliding, which makes the shifting difficult, so it is necessary to check the working state of the spring ring support slider. Check if the slider is tilted in the slot. If the spring is too weak, it must be replaced.
4 Transmission abnormal sound failure phenomenon: transmission neutral noise; direct noise operation without abnormal noise, other gears have abnormal noise; low speed gear has abnormal noise, high-speed gear when the sound is weakened or disappeared; transmission gears have abnormal noise; transmission gears There are abnormal noises.
The cause of the malfunction: the reason for the abnormal noise of the transmission is nothing more than two aspects. First, the bearing is loud, mainly because the bearing is worn and damaged. Second, the gear is engaged with abnormal noise, the lubricating oil may be too small, and the dry friction is formed; the gear wears too much, so that the tooth side clearance is too large, so that the transmission has abnormal noise during operation; the gears are not matched; the first and second shafts are coaxial with the crankshaft. Degree over tolerance; shaft bending deformation; wear and looseness of each shaft bearing can cause abnormal noise in the transmission.
Fault diagnosis: In the neutral position of the transmission, the transmission has uniform noise when the engine is idling, the sound is louder when the handbrake is tightened, and the abnormal noise of the clutch pedal is extinguished, which is caused by poor gear meshing. The neutral running sound is not obvious. When the car starts and shifts, the metal friction sound occurs in the clutch half-engaged state, and when the clutch is completely engaged, the first shaft leading bearing is damaged. There is no abnormal sound in the direct transmission of the transmission, and the other gears have abnormal noise. The main reason is that the needle shaft bearings at the front end of the intermediate shaft and the second shaft are not subjected to the load during the direct gear operation, while the other gears are working. The load causes a sound, so the fault must be on the intermediate shaft or the second shaft needle roller bearing. The low speed gear has abnormal noise, the high speed block sound is weakened, the rear axle can be lifted, the engine can be started, the transmission can be operated in the low or reverse gear, and the two-shaft rear bearing and the reverse gear can be heard. When the car is stationary, the transmission is placed in neutral, the hand brake is released, and the second shaft flange is swayed radially. If the radial clearance is too large, the second shaft rear bearing is worn loose or damaged. There is abnormal noise in a certain gear, generally the gear is not properly meshed or damaged. If there is noise in each block, it is caused by the wear and deformation of the base parts or the low repair quality of the car during long-term use.
Third, the maintenance of the main parts of the transmission 1 gear maintenance gears often work under constant speed and load, the gear tooth surface will be affected to varying degrees, will inevitably lead to tooth surface damage, so that the transmission can not work properly.
Gear wear: Wear along the length of the tooth should not exceed 30 of the tooth length. The tooth wear of the normal meshing gear should not exceed 025mm. The tooth wear of the joint gear should not exceed 040mm. The tooth thickness of the spline should not exceed 020mm. The gear meshing area is not. It should be lower than the tooth surface 23, the meshing gap of the permanent meshing gear is 015050mm, and the meshing clearance of the engaging gear is 010015mm. The tooth thickness can be measured by the gear vernier caliper. The meshing gap can be measured by the dial gauge or the lead wire method. If it exceeds the limit, it should be paired. replace.
Gear teeth broken: If the pieces fall off no more than 2mm, they can be polished and smoothed with oil stone. If the crushing is serious, it should be replaced.
2 Synchronizer overhaul lock pin type synchronizer mainly damages cone and ring disc wear. When the groove of the tapered cone of 04 mm deep has worn to 010 mm, the synchronizer assembly should be replaced. If the cone ring and the bottom of the cone are in contact with the wear scar, the taper ring face turning is allowed to be repaired, but the cumulative turning amount should not exceed 1mm. If the original cone is still used after updating the synchronizer cone, check the cone end face and cone The distance between the end faces of the discs shall be not less than 03 mm. When the lock pin type synchronizer is in a loose frame, the riveted pins shall be re-riveted after being riveted.
The main damage of the lock ring synchronizer is the wear of the inner cone surface of the lock ring, the ring gear key and the three notches that cooperate with the slider. When pressing the lock ring against the tapered surface of the corresponding shifting gear, the rotation of the lock ring by hand should have a slight sense of resistance. The thickness gauge should be measured at multiple points along the circumference. The gap between the lock ring and the end face of the gear should be not less than 050mm. If it does not meet the requirements, the synchronizer lock ring should be replaced. Synchronizer ring gear locking surface is seriously worn, the slider is seriously worn, the spring force of the slider spring is weakened or broken, and the key teeth are worn so that the matching gap between the joint sleeve and the spline hub key teeth exceeds 050 mm, etc., and new parts should be replaced.
3 bearing repair bearings, especially needle bearings, should be replaced during overhaul of the transmission. If the transmission is found to be abnormal, the bearing should be inspected. Check the bearing ball and the ball track for pitting, peeling, and rupture. When the hand is gripped by the inner and outer rings of the bearing and the shaft is pushed back and forth, there should be a slight axial clearance. If the radial clearance is too large, the normal bearing should be replaced. When the inner ring of the bearing is rotated, the outer ring should be even and there is no impact noise. When disassembling the bearing, the pressing method should be used as much as possible. When using the knock-in method, apply a soft metal pad and evenly apply force around the circumference without skewing, and gradually tap to avoid deformation of the bearing.
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