This chapter introduces the common faults of the excavator, 1. reasons for "gear jump", 2. preventive measures, and 3. emergency disposal methods. During the driving of the excavator, if the transmission "jumps", stop the machine (or continue driving) in time, find out the cause and eliminate the fault in time.

1.Reasons for "skip gear"

(1) Worn transmission mechanism W4-60 excavator uses a mechanical transmission mechanism to shift gears. This transmission mechanism relies on the sliding gear sleeve to move axially on the fixed gear sleeve and mesh with the driven gear of each gear to achieve gear shifting. In the process of frequent shifting, the tooth end faces of the above meshing gears are easy to be tapered, resulting in the reduction of their meshing performance and "gear skipping".

(2) The performance of the self-locking mechanism is reduced to prevent the transmission from "gear skipping". This excavator is equipped with steel balls and springs for self-locking in the case cover holes above the shift fork shafts of gears II, III, IV and V of the transmission and in the shift forks of gears I and reverse. When the elasticity of the spring that plays the role of positioning self-locking is weakened or broken, the self-locking performance of the self-locking mechanism will decline until it disappears, causing the transmission to "skip gears". At the same time, if the groove on the locating steel ball or shift fork shaft is worn, the transmission may also "skip".

(3) Improper adjustment of gear shifting device The transmission of this excavator adopts a mechanical manual gear shifting mode. If the gear lever, vertical axis, horizontal axis and vertical fixing screws are loose, the transmission can also "skip".

(4) Sudden change of external load Due to the working nature of the excavator and the design of the machine, the sudden change of external load will also cause the transmission to "skip". When the external load changes suddenly due to uneven road surface, downhill driving of the machine or improper driving route, the sudden change of load will act on the gear engagement gear of the transmission through the wheel and transmission shaft, causing the gear engagement gear to disengage due to the axial thrust, causing the transmission to "skip".

(5) Improper operation method When the excavator is driving on a slope (especially downhill), improper operation will also cause the transmission to "skip".

2.preventive measure

(1) The operation shall be carried out in strict accordance with the operating procedures and driving essentials, and the "tooth beating" during gear shifting shall be avoided as far as possible to reduce the wear of the gear pair.

(2) Strictly implement the maintenance system and strengthen the maintenance of gear shifting device. When the linkage of the gear shifting device is not connected properly, it shall be adjusted in time to ensure good performance of the gear shifting device.

(3) Pay attention to the repair and maintenance of the self-locking mechanism. For the positioning steel ball, spring and fork shaft whose positioning function is reduced or has lost the positioning efficiency, they should be repaired or replaced in time to make the self-locking performance of the self-locking mechanism in a good state.

(4) When assembling the transmission, the operation shall be carried out in strict accordance with the operating procedures to ensure that all parts of the transmission are correctly adjusted and properly tightened. When going downhill on a large road surface, the driver should strictly follow the main points of the downhill action and must not violate the rules.

3.Emergency disposal method

During the driving of the excavator, if the transmission "jumps", stop the machine (or continue driving) in time, and then find out the cause and eliminate the fault. The specific methods are:

(1) In case of "gear jump" when driving on the flat road, stop the vehicle according to the normal stopping principle, carefully find out the cause and remove the fault.

(2) If "skip gear" occurs when driving uphill, the gear can be set to the low speed position or gear I position, and the machine can be stopped when it reaches the top of the slope to remove the fault; If the downshift is unsuccessful or "gear jump" occurs again, stop the machine according to the action essentials and requirements of the shutdown on the ramp, and then remove the fault.

(3) In case of "gear jump" when driving on the downhill slope, shift the gear to the high speed position according to the action essentials of gear up or take "gear rush" (emergency gear down) measures, and stop the machine for inspection and troubleshooting after the machine reaches the bottom of the slope; If the "upshift" and "upshift" are not successful, or the "skip" occurs again (at this time, the gear is neutral), the driver can control the engine speed at medium speed (to prevent the engine from stalling), use the "snub" method to slide the machine to the bottom of the slope, and then remove the fault. If "gear up", "gear rush" is unsuccessful or "gear jump" occurs again (at this time, it is neutral), and the machine is on the downhill slope (at this time, the machine will "dive" to the bottom of the slope at a very fast speed), the machine should be stopped quickly according to the action essentials and requirements of downhill shutdown, and then the fault should be deducted.

1： Swing operation pilot_ Whether the secondary pressure is within the normal range (the normal pilot pressure is above 35KG);

2： The rotary overflow valve is 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： The valve block is worn and damaged, causing internal leakage of the swing motor;

5： The pump body and plunger of the swing motor are worn and damaged, causing internal leakage of the motor;

6： Only when the slewing action is slow and other actions are normal, faults of the main hydraulic pump and the main relief valve can be eliminated