When the driver is working, he often finds that the forklift fork can't always rise to the highest position, causing the work to progress. Later, the investigation was caused by oil leakage, which prevented it from rising to the highest point.
Oil leakage is the most common problem with multi-way reversing valves. In case of such doubts, don't worry, analyze the factors:
1. Internal leakage
When the multi-way reversing valve has an internal leakage, the working oil passage communicates with the oil return passage or the oil spill passage, and the hydraulic oil directly flows back to the fuel tank, which cannot be completed, and the lifting hydraulic cylinder is lifted or unable to lift, and the fork is self-propelled. The downswing and the gantry are leaning forward. The factors and exclusions of internal leakage are:
(1) The wear gap between the valve stem and the valve body is too large
The multi-way reversing valve has three grooves on each of the hoisting and tilting valve stems. The groove and the oil passage cooperate to close or block the oil circuit and change the operation mode. The gap between the valve stem of the good distribution valve and the valve body is small, and the oil leakage is extremely small, so the hydraulic cylinder is lowered or the amount of inclination is small, and the operation is not affected. However, when the wear gap is too large, the hydraulic oil will form the oil in the working oil passage to communicate with the oil return passage or the oil spill passage under the pressure generated by the working pump, and actively return to the oil tank. The main reason is that the valve stem and the valve body are worn out due to the long-term use of the distribution valve or the oil is not cleaned, which destroys the cooperative sealing surface and causes oil leakage. If the stem is worn lightly during the correction, the stem can be chrome-polished; if the stem is severely worn, it needs to be replaced.
(2) Oil leakage between valve bodies
Since the working oil passage, the oil return passage and the oil spill passage are penetrated between the three single-piece valve bodies, the sealing request between the valve bodies is very good, and after the O-ring is arranged between the valve body and the valve body oil passage, The valve body is bolted to the intent to reach the seal.
If the bolt's consolidation torque is different, it may cause the valve body to warp. If the sealing ring fails, the internal leakage occurs; if the valve body is damaged or the O-ring is aged or damaged, the valve body is also prone to internal leakage under the effect of oil pressure. When repairing, if the valve body is damaged, it is necessary to grind, replace the O-ring, and tighten the bolts in order and torque request.
(3) Safety valve spring failure
The safety valve is used to adjust the operating pressure of the system to keep the pressure within a certain range, and to avoid damage to various parts of the hydraulic system caused by overload, hydraulic cylinder piston to extreme orientation or other factors. The safety valve is mainly intended to press the steel ball against the valve position to reach the opening and closing. When the hydraulic pressure output by the hydraulic pump exceeds the regular value, the pressure of the high pressure oil overcomes some of the high pressure oil returning to the tank through the safety valve spillway. When the oil pressure reaches the regular value, the spring spring presses the steel ball against the valve position under the effect of its own preloading force, and the safety valve is closed.
If the safety valve spring fails, the hydraulic oil can force the steel ball out of the valve position to flow into the oil spillway under the system pressure, forming an internal leak and invalidating the system. It is necessary to replace the spring when repairing, and then use the adjusting screw to adjust the spring pressure to the regular 14 Mpa. When adjusting, load 7.5t of goods according to the need of 600mm from the load base. When the goods are locked up with lock nuts, the pressure at this moment is the pressure to be adjusted.
(4) Multi-way reversing valve stem cannot be reset
The valve stem return spring device is at the lower end of the valve stem, and the spring can be tightened regardless of the valve stem in the upper position. When there is no external force, the spring force of the spring spring can quickly recover the valve stem to the original Orientation. If the valve stem cannot be reset and the groove is in communication with the oil passage, an internal leak will occur. First, because the valve stem reset spring is deformed or damaged, the spring force of the spring is lowered without returning the valve stem to the original position, and the spring must be replaced when repairing; second, the valve body and the valve stem are not clean, and a large resistance occurs. It is difficult to reset the valve stem, and the inside of the multi-way reversing valve must be cleaned during repair to eliminate the resistance.
(5) cone valve wear
The cone valve is used to avoid oil backflow. If the cone valve wears out and the oil passage is not tight, the hydraulic oil will flow back and the system will be ineffective. When repairing, it should be ground or replaced. Eliminate backflow.
2, valve body leakage oil
The sealing of the valve stem and the valve body is completed by the O-ring. If the sealing ring is aged or damaged, the hydraulic oil will flow along the valve stem under the pressure effect of the system, causing the valve body to leak oil. To eliminate this problem, just replace the O-ring.
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