Six common faults in the hydraulic circuit of ZL50 loader (2)

This series of articles will talk about common faults in the hydraulic circuit of the ZL50 loader working device through actual cases. We will first look at the fault symptoms and then discuss the solutions. The first two faults have been analyzed in the previous article. In this article, we will continue to analyze other faults.

Fault phenomenon 3: Bucket retraction is weak

Reason analysis:
1) The main pump fails and the filter is clogged, resulting in insufficient oil delivery and insufficient pressure in the hydraulic pump.
2) The main safety valve fails. The main valve core is stuck or the seal is not tight or the pressure regulation is too low.
3) The flow control valve fails. The gap is too large and the one-way valve in the valve is not tightly sealed.
4) The bucket reversing valve valve core and the valve body hole are too large, stuck in the oil drain position, and the return spring fails.
5) The double-acting safety valve fails. The main valve core is stuck or the seal is not tight.
6) The sealing ring of the bucket hydraulic cylinder is damaged, severely worn, and the cylinder barrel is strained.
Troubleshooting:
1) Check whether the boom lift is strong. If the boom lift is normal, it means the hydraulic pump, filter, flow control valve, main safety valve and oil temperature are normal. Otherwise, troubleshoot as described in Symptom 2.
2) Check the gap between the bucket reversing valve valve core and the valve body hole. The limit gap is within 0.04mm. Clean the slide valve and repair or replace parts.
3) Disassemble and inspect the sealing and flexibility between the valve core and valve seat of the double-acting safety valve and the valve core and valve seat of the one-way valve, and clean the valve body and valve core.
4) Disassemble and inspect the bucket hydraulic cylinder. It can be carried out according to the inspection method of the boom hydraulic cylinder described in fault phenomenon 2.

Fault phenomenon 4: The settlement of the boom hydraulic cylinder is too large (the boom is dropped)

Reason analysis:
Lift the fully loaded bucket and the multi-way valve is in the neutral position. At this time, the sinking distance of the boom hydraulic cylinder piston rod is the settlement amount. This machine requires that when the bucket is fully loaded and raised to the highest position for 30 minutes, the sinkage should not exceed 10mm. Excessive settlement not only affects productivity, but also affects the accuracy of work equipment operations, and sometimes even causes accidents.
Causes of boom hydraulic cylinder settlement:
1) The spool of the multi-channel reversing valve is not in the neutral position, and the oil circuit cannot be closed, causing the arm to drop.
2) The gap between the valve core and the valve body hole of the multi-way reversing valve is too large, and the seal is damaged, causing large internal leakage.
3) The piston seal of the boom hydraulic cylinder fails, the piston becomes loose, and the cylinder barrel is strained.
Troubleshooting method: Check the reason why the multi-way reversing valve cannot reach the neutral position and eliminate it; check the gap between the multi-way reversing valve valve core and the valve body hole, ensure that the gap is within the repair limit of 0.04mm, replace the seal; replace the boom hydraulic pressure Cylinder piston sealing ring, tighten the piston, and inspect the cylinder barrel; check the pipelines and pipe joints, and deal with any leaks in time.

Due to the limited number of words, this article still only introduces two fault analyses. We will see you in the next article.  In addition, if your loader needs to purchase relevant loader accessories during maintenance and repair, you can contact us. If you need to buy a new loader or a second-hand loader, you can also contact us. CCMIE provides comprehensive loader sales services.