1. Small excavator with weak lifting force on the upper arm

fault diagnosis

If there is a malfunction in the use of a small excavator during construction operations where there is no force for the boom lifting, but other parts are not affected, and the hydraulic system of the small excavator has sufficient pressure to provide it, the possibility of malfunction caused by problems with the working pump and safety valve of the hydraulic system can be ruled out. At the same time, the possibility of malfunction caused by problems with the oil and filter used in the hydraulic system can also be ruled out, After excluding all the above influencing factors, it can be determined that the main problem is in the small excavator arm. Therefore, we need to inspect and troubleshoot the oil valve, sealing components, and oil pipe positions of the small excavator arm to find the specific cause of the malfunction.

After identifying the specific fault point, first remove and clean the valve body and oil pipe components of the small excavator arm, and carefully inspect the oil circuit to determine if there are any blockages. Secondly, carefully inspect the sealing components for loose joints, damage, and failure, as well as check for oil leakage in their oil circuits. If there are no problems with the above-mentioned areas after inspection, then dismantle the oil pipe in the boom without rod chamber, continuously fill it with oil, and carefully check for oil leakage at the outlet to determine if there is a problem with the oil cylinder. Finally, it is also necessary to check for any damage to the sealing components inside the boom slide valve of a small excavator.

Fault repair

After completing the above fault diagnosis work, if the inability to lift the boom is caused by oil leakage in the hydraulic system cylinder, the cylinder body should be disassembled and its internal condition should be carefully inspected using scientific methods. However, if the inability to lift the boom is caused by damage or scratches to the sealing components, it is necessary to replace the damaged parts as soon as possible. In the process of checking whether the oil cylinder is leaking, it is best to use the method of position inspection to improve the efficiency of identifying the fault points of different system equipment, and determine the fault location in a short time. For the piston rod, it is necessary to check whether there is any damage, whether the dimensional accuracy and concentricity are good; Check for aging and wear issues in the sealing parts of the equipment, as well as the accuracy of the sealing groove and the compatibility of the hydraulic oil; Check whether the oil quality and category of hydraulic oil are qualified, whether the pressure level and viscosity meet the standards; Check whether the cycle cycle and sliding speed of the feed device are normal; Check whether there are cracks or welds inside the oil cylinder and whether the surface roughness meets the standard.

Fault diagnosis and maintenance methods for hydraulic systems of small excavators

2 small excavators with normal arms but weak buckets

fault diagnosis

If such a malfunction occurs, the first step is to carefully study and analyze the mechanical schematic of the small excavator, because the large arm of the small excavator is not a problem and the bucket is not strong, so it can be basically concluded that the problem is not caused by factors such as the hydraulic system's oil filter, working pump, main safety valve, and oil quality, And as long as we focus on testing and troubleshooting whether there are any faults in the sealing parts of the bucket's slide valve and safety valve.

Fault repair

The method used to repair this type of bucket weakness fault is the same as the method used to repair the boom lifting weakness fault, both of which require checking and troubleshooting the equipment for oil leakage before replacing the damaged sealing parts. However, if a single action of a small excavator malfunctions, it is generally due to problems with the components that control or execute this action, thereby ruling out the possibility of malfunctions in the control and transmission parts of the small excavator.

Fault diagnosis and maintenance methods for hydraulic systems of small excavators

3 small excavators have abnormalities in both the large and small arms

fault diagnosis

When both the large and small arms of a small excavator experience abnormal phenomena, it is not just a problem of damage to individual parts of the equipment, but the area where the relief valve in the hydraulic system is slightly forward, which is the common part of the small excavator's large and small arms, is the most likely place to have problems. In response to such problems and malfunctions, the main focus is to detect and troubleshoot whether there is sufficient oil in the hydraulic system, whether the transmission devices of the hydraulic pump and engine components are still working properly, and whether the oil guide pipe can pass through normally.

Fault repair

In the process of repairing both the upper and lower arms with abnormalities, as this fault is holistic, the first step is to eliminate the problems with the parts that control and execute individual actions one by one, and then use effective inspection and maintenance work to ensure that the transmission connection between the upper and lower arms can work normally.

Fault diagnosis and maintenance methods for hydraulic systems of small excavators

All four sets of operation valves have control actions that are problematic

fault diagnosis

If only a group of control valves have a malfunction, and the performance of the entire small excavator is good, it can be accurately determined that the malfunction is not caused by the common connection part, but rather by the malfunction in the control valves that control this group of actions, mainly caused by problems with the main relief valve of the control valve or the hydraulic pump of the subsystem.

Fault repair

When repairing such faults, the displacement comparison method is usually used to solve them. The specific method is to connect a high-performance relief valve into the faulty relief valve and carefully observe the effect to determine whether the fault is caused by the main relief valve. At the same time, the displacement comparison method can also be used in the maintenance process of hydraulic pump faults in the subsystem, which is beneficial for workers to promptly remove and repair after identifying the fault point.