Exclusion of common faults of overload valve

2 When the valve is in the position of the oil inlet, the oil can freely enter the hydraulic cylinder through the check valve 4. When the control valve is in the neutral position, the check valve can keep the hydraulic cylinder in the correct working position. At the same time, the overload valve at the position of the return port needs pilot oil pressure to open. The oil from the oil pressure line is used as the pilot oil, and the pilot oil can enter from the pilot line 3, and at least the opening pressure of 1.53 can make the main valve core. 2 Move left to the open position and return the oil to the hydraulic cylinder. The pilot valve of the overload valve is very small, diameter is 0.8, 1., 1 overload valve installation position A overload valve 1. spring 2. main spool 3. pilot oil passage 4. one-way valve 5.0 ring table, 1660 open air In the work of the rig, when the boom is lifted and locked, the lift cylinder automatically drops. According to experience, this should be caused by the failure of the lift cylinder piston seal, but why can't the fault be eliminated after replacing the piston seal? Actually, before we open the lift cylinder, we ignore the inspection and install it in the lift cylinder inlet and outlet ports. The two overload valves were carefully inspected and found that there were large particles of impurities in the overload valve of the lift cylinder stuck in the joint surface of the check valve plug and the valve sleeve, which caused the valve plug to close and lift. The oil in the lower chamber of the cylinder automatically flows back to the tank through the gap in the spool and the neutral position of the control valve, and thus cannot support the weight of the boom. After cleaning the overload valve and the hydraulic system to replace the hydraulic oil, and reinstalling the lift cylinder, the test engine has been fault-checked. 2 When the cylinder chamber is filled with oil, the other chamber is unable to return to the oil station and the 1 rig 00 is suddenly used. There is a problem with the unbiased motion of the boom. Check all the valve seals and the connecting tubing. The results are all in good condition and the pressure at the inlet is normal, but the hydraulic cylinder cannot operate. The overhaul valve with the oil outlet removed and carefully inspected and found that there is dirt blocking in the pilot oil passage on the valve. Because the pilot oil passage is very small, it is easily blocked by the waste. After cleaning with kerosene, the high pressure air is swept away and reinstalled, the fault is eliminated.

To prevent the cylinder from overloading If the pressure of the hydraulic cylinder is too high due to the external force, the valve plug 2 will open against the force of the spring 1 when the pressure exceeds the set pressure of the valve, so that the hydraulic cylinder will return to the oil and be automatically unloaded. Protect the hydraulic cylinder. Generally, the overload lift valve pressure in the working arm system and the rotary cylinder in the workmanship system of 1 person and 00 are all 35. The overload valve pressure of the other hydraulic cylinders is 27.

Keeping the work arm working smoothly When the hydraulic pressure at the inlet of the hydraulic cylinder is not high enough to reach the pilot pressure value of the outlet overload valve, the valve can keep the oil return pressure from decreasing, so as to prevent the impact of the moving inertia due to the weight of each working arm from being maintained. The working status is stable.

When the arm in the working arm is in a working position and the control valve is in the neutral position, the overload valve can prevent the oil in the hydraulic cylinder from automatically returning to the tank and maintain the accuracy of the working position of the arm.

The overload valve can be used as a safety valve when the connection tubing ruptures due to external causes during operation.

1The boom lifting cylinders are automatically lowered during operation. Failure to eliminate the failure after replacing the lifting cylinder seals. 3 The equipment is in the normal horizontal position when the hydraulic cylinder is in the normal stop position. Obviously, this means that the rotary cylinder automatically produces creep during placement. Initially, it was considered that the equipment had just been overhauled and that all seals including the overload valve had been replaced, and the possibility of failure due to defective seals could be eliminated. After that, it may be that the overload valve has been working for a long time, and the sealing surface has been lax and caused internal leakage. Remove the valve to the connection between the control valve tubing, wipe the valve port and place the observation, it was found that there is oil dripping valve. This confirmed that it was due to the failure of the internal seal of the overload valve. Replace the new overload valve and place it for observation. The fault has been eliminated.

The overload valve is not easily damaged during long-term use. In most cases, the leakage is caused by the damage of the seal ring 5. Therefore, when replacing the seal ring, be careful to install it. In addition, the pressure of the valve has been adjusted when the equipment is shipped from the factory and cannot be readjusted or repaired during use. If the valve body has actually leaked out and becomes inoperative, the new valve assembly needs to be replaced. Author Address Xinzhuang Tom Lock Luoyang Machinery Co., Ltd. 4901, Mengjin County, Luoyang City, Henan Province, China

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