Elimination of oil leakage of CPCD60 forklift multi-directional valve
CPCD60 forklift uses ZS series, split-type multi-way directional valve. It is composed of four single-piece valve bodies with oil inlet valve body, lifting directional valve body, tilting directional valve body and oil return valve body connected by bolts. to make. The oil channel, working oil channel, oil return channel, oil overflow channel and total oil return channel are formed inside, so that the hydraulic oil can flow in the respective oil channels under different working conditions of the forklift to achieve different working purposes. The system working pressure is 16MPa and the flow rate is 160L/min.
1. Multi-way valve leakage
When an internal leak occurs, the working oil passage is connected to the oil return passage or the oil spill passage, and the hydraulic oil directly flows back to the oil tank, unable to complete the required action, causing the lifting to be weak or unable to lift, the fork sliding down on its own, and the mast moving forward pour. The causes of internal leakage may have the following aspects, which must be eliminated one by one.
(1) The wear gap between the valve stem and the valve body is too large, causing internal leakage
Multi-directional reversing valve has three grooves on the stem of the lift and tilt. The cooperation of the groove and the oil passage can open or cut the oil passage and change the working mode of the forklift. The gap between the valve stem and the valve body of a good distribution valve is very small, and there is very little oil leakage, which causes a small drop or tilt of the hydraulic cylinder, so it will not affect the work. If the wear gap is too large, it will cause the oil in the working oil channel to communicate with the oil in the oil return channel or the overflow oil channel, and automatically return to the oil tank. The main reason is that the distribution valve is used for a long time or the oil is not clean, which accelerates the wear of the valve stem and the valve body, destroys the matching sealing surface and causes oil leakage. During repair, if the valve stem is lightly worn, the valve stem can be chrome plated and polished; if the valve stem is seriously worn, it needs to be replaced.
⑵ Oil leakage between valve bodies
Since the working oil passage, the return oil passage, and the oil overflow passage penetrate between the four single-piece valve bodies, the sealing performance between the valve bodies is very high, and each valve body must be firmly connected with bolts. An O-ring seal must be installed between the oil passages of the valve body. If the tightening torque of each bolt is different, it may cause valve body warpage, seal ring failure and internal leakage; if the accuracy of the valve body surface is damaged during installation, or the O-ring seal ages or is damaged, there is also a gap between the valve bodies Easy to produce internal leakage. During repair, if the valve body is damaged, it is necessary to grind, replace the O-ring, and tighten the bolts in accordance with the order and torque requirements.
⑶The safety valve spring fails to cause internal leakage.
Safety valve is used to adjust the working pressure of the system to keep the pressure within a certain range, to prevent damage to various parts of the hydraulic system due to overload, hydraulic cylinder piston to the limit position, or other reasons. The switch of the safety valve is mainly determined by the spring force.
If the safety valve spring fails, the hydraulic oil can force the steel ball to leave the valve seat and flow into the overflow passage under the pressure specified by the system, causing an internal leakage and invalidating the system. During the repair, the spring must be replaced, and then use the adjusting screw to adjust the spring pressure to the specified value (14MPa). When adjusting, load 7.5t according to the requirement of the load center distance of 600mm (adjust according to the requirement of 25% overload of the forklift), and lock the adjustment screw with the lock nut when the cargo seems to start or not, the pressure at this time is the required adjustment 14MPa pressure.
⑷Multi-directional reversing valve stem cannot be reset to cause internal leakage
The stem return spring is installed at the lower end of the stem. No matter the stem is working in the upper or lower position, the stem can compress the spring. In the absence of external force, the spring force can quickly restore the valve stem to its original position. If the valve stem cannot be reset, the stem groove communicates with the oil passage and internal leakage will occur.
Reasons: First, due to the deformation or damage of the stem return spring, the stem cannot be returned to its original position due to the reduced spring force, and the spring can be replaced during repair; second, the uncleanness between the valve body and the stem results in greater resistance, causing It is difficult to reset the valve stem. When repairing, just clean the multi-way valve.
⑸ Conical valve is worn to cause internal leakage
Cone valve is used to prevent oil from flowing backwards. If the cone valve is worn, the oil passage is not closed tightly, which causes the hydraulic oil to return and the system function fails. When repairing, it should be ground or replaced to eliminate backflow.
2. Leakage of valve body of multi-way valve
The leakage of the valve body will affect the operation of the system and cause the forklift to lift and tilt. If the O-ring seal between the valve stem and the valve body ages or is damaged, oil will flow out of the valve stem under the effect of the system oil pressure, causing the valve body to leak oil. In this case, you only need to replace the O-ring seal.
