Views: 1 Author: PEAK Publish Time: 2024-01-30 Origin: Original
Tractors need to complete various operations such as plowing, rotary tillage, raking, trenching, sowing, harvesting, and transportation. These assignments have different loads and require different driving speeds. But the engine speed remains basically unchanged at full throttle. Strictly speaking, the change in speed and torque from no-load to full load is about 200 r · min-1, which is far from meeting the operational requirements. Therefore, a gearbox must be installed to increase the torque transmitted to the drive wheels and reduce the speed. By changing gears and gear ratios, the tractor's traction and driving speed can be changed without changing the engine torque and speed. With the engine crankshaft rotation direction unchanged, shifting the gearbox to forward or reverse gear can move the tractor forward or backward. In addition, the tractor can be stopped for a long time without the engine stalling, or fixed operations such as threshing and pumping can be carried out. In summary, the functions of a gearbox can be summarized into four aspects: increasing torque and reducing speed, changing torque and changing speed, parking in neutral, and driving in reverse.
1. Key technical points for use
In order to extend the service life of the gearbox, it is advisable to avoid large impact loads on gears, shafts, and bearings during use. Therefore, it should be noted that:
(1) When shifting gears, gear should be engaged, disengaged, or shifted with the clutch completely disengaged. To avoid gear impact in the gearbox and prevent damage to parts, the clutch should be disengaged quickly and engaged smoothly, and no sudden impact should be used to cross obstacles; Slow down when encountering uneven road surfaces; Do not control the vehicle speed with the clutch half engaged; Do not work excessively for a long time; When shifting gears, the gear lever should be pulled in place to fully engage the gear teeth. Note that only the gear lever can be pulled at normal speed, shifting one gear at a time, and the neutral position can be changed to any forward or reverse gear. The time for adjusting the gear position should not be less than 2 seconds, and it should not be changed too fast or too aggressively. This interval can achieve the same effect as releasing the clutch.
(2) Pay attention to whether there are any abnormal noises or other phenomena in the gearbox during use. When abnormal situations are found, they should be diagnosed and eliminated in a timely manner. They should not be operated with defects to prevent the fault from expanding and damaging components. Regular attention should be paid to the temperature of the gearbox during use. If it exceeds 80 ℃ (feels hot when touched), it indicates insufficient oil or abnormal operation of certain parts. It should be checked and eliminated.
(3) Regularly inspect and tighten the bolts at the fixed connections of the gearbox; Before each shift, the oil level in the gearbox should be checked, and the oil dipstick on the gearbox cover should be unscrewed. The oil level should be checked between the upper and lower markings on the dipstick. When measuring, the tractor is on a level ground, parked for more than half an hour, and the oil dipstick nut is not screwed into the thread. When the oil level is insufficient, it should be added in a timely manner. If oil leakage is found, the cause should be promptly identified and eliminated; According to the instructions, regularly clean the gearbox cavity and replace it with new oil.
Common troubleshooting of transmission
Tractor gearbox failures occur frequently and should be promptly resolved upon discovery. The common faults and troubleshooting methods are as follows.
2.1 Difficulty in shifting gears
The common reasons for difficulty in shifting gears are: (1) Incomplete clutch separation. (2) The speed lever or shift lever is bent or deformed, the fastening bolts of the speed lever are loose, or the shift lever is not in place. (3) The transmission case is severely deformed, and the position of the gear lever on the limit frame cannot match the required position of the shift fork. (4) The positioning steel ball or positioning spring is stuck. (5) There are burrs on the end face of the gearbox gear, shift fork or shift fork shaft. (6) Spline wear causes shoulder wear, making it difficult for the variable speed gear to slide.
The troubleshooting depends on the above reasons, and if it is a clutch fault, the clutch fault troubleshooting method can be used; Belonging to deformation, looseness, or wear of components, they can be corrected, tightened, or repaired and replaced separately; Burrs and shoulders on components can be resolved by grinding or replacing them with oil stones.
2.2 Automatic gear disengagement
The reasons and troubleshooting methods for automatic disengagement are as follows: (1) The locking spring force is too weak, too short, or broken. Qualified new springs should be replaced or the adjustment bolts on the transmission cover should be adjusted. (2) The bearings are severely worn, causing the axis lines of two pairs of gears to deviate or not be parallel, resulting in jumping during operation. The bearings should be replaced. (3) After the gear meshing parts wear out, they become conical and generate significant axial force during meshing operation, causing gear disengagement. At this time, the gears should be replaced in pairs. (4) If the positioning groove of the shift fork shaft is severely worn, the shift fork end face is severely worn, or the axial clearance of the shift fork shaft is too large, the shift fork shaft, shift fork should be replaced or the axial clearance should be adjusted. Axial clearance adjustment is usually completed by adding or removing flat pads at one or both ends of the shift fork shaft based on the deviation of the gear meshing center. (5) Due to wear and tear, the clearance between the spline and the spline shaft inside the gear is too large, causing the gear to sway and generating axial force during meshing operation, resulting in gear disengagement. In this case, the spline shaft and gear should be replaced. (6) The positioning steel ball of the shift fork is stuck in the positioning spring hole or the shift fork shaft is installed incorrectly, causing the position of the shift fork positioning groove to be completely incorrect. At this time, the jamming fault should be eliminated or the shift fork shaft should be reinstalled.
2.3 Random gear shifting
The causes and troubleshooting methods for gear shifting are as follows: (1) The ball joint or shift fork groove at the lower end of the gear lever is severely worn and can be repaired or replaced by welding. (2) The spline shaft is excessively worn, and the positioning retaining ring (stop spring) that fixes the gear or shaft falls off. The positioning steel ball is stuck in the positioning spring hole of the shift fork. (3) The interlock mechanism has failed due to excessive wear and tear, and parts should be replaced to eliminate it. (4) A tractor that has been used for a long time has an I-shaped groove on the gear plate, which collides with the gear lever and creates a gap at a certain gear position, resulting in gear shifting disorder. In this case, it can be solved by welding or replacing parts.
2.4 Transmission has abnormal noise
The reasons and troubleshooting methods for abnormal noise in the gearbox are as follows: (1) If the gearbox is out of oil, the oil quality is deteriorated or not clean, sufficient lubricating oil should be added or replaced with new lubricating oil. (2) If there are burrs, peeling off or broken teeth on the tooth surface or end face of the gear, the tooth surface should be ground or replaced in a timely manner. (3) If the gears are severely worn or the bearings are severely worn or even damaged, they should be replaced. (4) The internal splines of the spline shaft and gear are severely worn, and parts with severe wear should be replaced.
2.5 Transmission heating
Common causes and troubleshooting methods for gearbox overheating: (1) The lubricating oil level is too low, the lubricating oil is too dirty or deteriorated, and the viscosity of the lubricating oil is severely reduced. At this time, it is necessary to inject sufficient qualified lubricating oil or replace it with new lubricating oil in a timely manner. (2) Rolling bearings may peel off or the bearings, gaskets, and washers are assembled too tightly. In this case, the bearings should be replaced or reassembled.
