Common Faults Of Excavators

1. Reasons for "jumping gears"
(1) The W4-60 excavator adopts a mechanical shifting and variable speed transmission mechanism, which relies on the sliding gear sleeve to move axially on the fixed gear sleeve and mesh with the driven gears of each gear to achieve shifting. During frequent gear shifting, the tooth end faces of the meshing gears mentioned above are prone to grinding into cones, resulting in a decrease in their meshing performance and causing gear shifting.
(2) The performance of the self-locking mechanism decreases. In order to prevent the transmission from shifting, this type of excavator is equipped with steel balls and springs that play a self-locking role in the box cover holes above the shift forks for gears II, III, IV, and V of the transmission, as well as in the shift forks for gears I and reverse. When the elasticity of the spring that plays a positioning self-locking role weakens or breaks, the self-locking performance of the self-locking mechanism will decrease until it disappears, causing the transmission to "jump gears". At the same time, if the groove on the positioning steel ball or shift fork shaft is worn, it can also cause the transmission to shift.
(3) Improper adjustment of the shifting device. The gearbox of this excavator adopts a mechanical manual shifting method. If the gear lever, vertical axis, horizontal axis, and vertical fixing screws are loose, it can also cause the gearbox to "jump".
(4) Sudden changes in external loads can also cause the gearbox to shift due to the working nature of the excavator and the design of the machine itself. When the road surface is uneven, the machine is driving downhill, or the driving route is improper, causing a sudden change in external load, this sudden change in load will act on the gear meshing gear of the transmission through the wheels and transmission shaft, causing the gear meshing gear to detach due to axial thrust, causing the transmission to "jump gears".
(5) Improper operation of excavators on slopes (especially downhill driving) can also cause the transmission to "shift" if operated improperly.
2. Preventive measures
(1) Strictly follow the operating procedures and driving essentials to avoid gear shifting and minimize gear wear.
(2) Strictly implement the maintenance system and strengthen the maintenance of the gear shifting device. When the gear shifting device linkage is not properly connected, it should be adjusted in a timely manner to ensure good performance of the gear shifting device.
(3) Pay attention to the maintenance and upkeep of the self-locking mechanism. For positioning steel balls, springs, and shift forks that have reduced or lost positioning effectiveness, they should be repaired or replaced in a timely manner to ensure that the self-locking performance of the self-locking mechanism is in good condition.
(4) When assembling the transmission, it is necessary to strictly follow the operating procedures to ensure that all components of the transmission are adjusted correctly and tightened appropriately. When driving on steep downhill roads, drivers should strictly follow the instructions for downhill movements and must not violate any rules.
3. Emergency response methods
During the operation of the excavator, if the gearbox trips, the machine should be stopped (or continued to drive) in a timely manner, and the cause should be identified and the fault eliminated. The specific method is:
(1) When there is a "gear shift" when driving on flat roads, you can stop the machine according to the normal shutdown instructions, carefully investigate the cause, and troubleshoot the problem.
(2) When there is a "gear jump" when driving uphill, you can set the gear to the low speed position or the first gear position, and stop the machine when it reaches the top of the slope to troubleshoot; If the downshifting is unsuccessful or if there is another "gear jump", the machine should be stopped according to the action instructions and requirements of the ramp shutdown, and then the fault should be eliminated.
(3) When there is a "gear jump" when driving on a downhill slope, the gear should be shifted to a high speed position according to the instructions for upshifting or "emergency downshifting" measures should be taken. After the machine reaches the bottom of the slope, it should be stopped for inspection and troubleshooting; If "upshifting" or "downshifting" is unsuccessful, or if "skipping" occurs again (in neutral gear), the driver can control the engine speed at medium speed (to prevent the engine from stalling), use the "braking" method to slide the machine to the bottom of the slope, and then troubleshoot. If "upshifting" or "grabbing gear" is unsuccessful, or if "skipping gear" occurs again (in neutral gear), and the machine is in a downhill slope (at this time, the machine will quickly "dive" towards the bottom of the slope), it should be quickly stopped according to the action essentials and requirements of the downhill shutdown, and then the fault should be deducted.
1： Rotary operation pilot_ Is the secondary pressure within the normal range (normal pilot pressure above 35KG);
2： Is the rotary overflow valve damaged and whether the rotary overflow pressure is within the normal range (overflow pressure: 280KG);
3： Whether the main rotary valve core is switched in place and whether the return spring of the rotary valve core is broken;
4： Wear and damage of the distribution valve, causing internal leakage of the rotary motor;
5： The pump body and plunger of the rotary motor are worn and damaged, causing internal leakage in the motor;
6： Only if the rotary action is slow and other actions are normal, can faults in the hydraulic main pump and main relief valve be ruled out.