Common faults of excavators

1. Reasons for "jumping gears"
(1) Wear of the variable speed transmission mechanism. The W4-60 excavator adopts a mechanical shifting transmission mechanism. This transmission mechanism relies on the sliding gear sleeve to move axially on the fixed gear sleeve and communicates with the driven gears of each gear. Engage to achieve shifting. During frequent shifting, the tooth end surfaces of the above-mentioned meshing gears are easily ground into a tapered shape, resulting in reduced meshing performance and "jumping gears".
(2) The performance of the self-locking mechanism is degraded. In order to prevent the transmission from "jumping gears", this type of excavator places the gears in the box cover holes above the transmission fork shafts of II, III, IV, and V gears and in the I and reverse gear forks. Both are equipped with steel balls and springs that have a self-locking effect. When the elasticity of the spring that plays a positioning and self-locking role is weakened or broken, 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 positioning steel ball or the groove on the shift fork shaft is worn, it can also cause the transmission to "jump gears".
(3) Improper adjustment of the shifting device. The transmission of this type of excavator adopts a mechanical manual shifting method. If the transmission lever, longitudinal axis, horizontal axis and vertical fixing screws are loose, it may also cause the transmission to "jump gears".
(4) Sudden changes in external loads. Due to the working nature of the excavator and the design of the machine itself, sudden changes in external loads will also cause the transmission to "jump". When the road surface is uneven, the machine is driving downhill, or the driving route is improper and the external load suddenly changes, 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 change. It disengages due to the generation of axial thrust, causing the transmission to "jump gears".
(5) Improper operation method When the excavator is driving on a slope (especially downhill), improper operation will also cause the transmission to "jump".
2. Precaution
(1) Operate strictly in accordance with the operating procedures and driving essentials, and try to avoid "beating the gears" when shifting gears to reduce wear of the gear pair.
(2) Strictly implement the maintenance system and strengthen the maintenance of the gear shifting device. When the shift device lever is improperly connected, it should be adjusted in time to ensure that the shift device performs well.
(3) Pay attention to the repair and maintenance of the self-locking mechanism. The positioning steel balls, springs and fork shafts whose positioning effect is reduced or lose their positioning performance should be repaired or replaced in time to keep the self-locking performance of the self-locking mechanism in good condition. .
(4) When assembling the transmission, the operating procedures should be strictly followed to ensure that all parts of the transmission are adjusted correctly and tightened appropriately. When driving on a large downhill road, the driver should strictly follow the downhill movement essentials and must not violate the rules.
3. emergency response methods
During the driving process of the excavator, if the transmission "jumps" occurs, the machine should be stopped (or continue driving) in time, and then the cause should be found and the fault should be eliminated. The specific method is:
(1) If "jumping gear" occurs when driving on a flat road, you can stop the vehicle according to normal shutdown procedures, carefully find the cause, and eliminate the fault.
(2) If "jumping gear" occurs when driving uphill, you can set the gear to the low-speed position or the I gear position, and then stop the machine when it reaches the top of the slope to troubleshoot; if the downshift fails or "jumps" occurs again When "jumping gear", the engine should be stopped according to the instructions and requirements for stopping on a slope, and then the fault should be eliminated.
(3) When "jumping gear" occurs when driving on a downhill slope, the gear should be set to a high-speed position according to the up-shifting action or take "rushing gear" (emergency downshifting) measures until the machine reaches the bottom of the slope. Stop the machine again to check and eliminate the fault; if the "upshift" or "upshift" is unsuccessful or "jumping gear" occurs again (it is neutral at this time), the driver can control the engine speed to a medium speed (to prevent the engine from stalling) , use the "point braking" method to slide the machine to the bottom of the slope, and then troubleshoot. If "add gear", "block grab" is unsuccessful or "jump gear" occurs again (it is neutral at this time), and the machine is going down a large slope (at this time, the machine will move toward the bottom of the slope at a very fast speed) "Dive"), you should quickly stop according to the action essentials and requirements of downhill stop, and then eliminate the fault.
1: Whether the pilot pressure of the rotary operation is within the normal range (normal pilot pressure is above 35KG);
2: The rotary relief valve is damaged and whether the rotary relief pressure is within the normal range (overflow pressure: 280KG);
Three: Whether the main rotary valve core is switched in place and whether the return spring of the rotary valve core is broken;
Four: The distribution valve is worn and damaged, causing internal leakage of the rotary motor;
Five: The pump body and plunger of the rotary motor are worn and damaged, causing internal leakage of the motor;
6: Only the rotation movement is slow and other movements are normal, the fault of the hydraulic main pump and main relief valve can be ruled out.