(1) The outlet pressure is almost equal to the inlet pressure, no decompression

This failure is manifested as: the inlet and outlet pressures of the pressure reducing valve are nearly equal, and the outlet pressure does not change with the rotation adjustment of the pressure regulating handle. The causes and troubleshooting methods are as follows.

1Because there is burr on the edge of the main valve core or the hole of the valve body, or there is dirt in the gap between the main valve core and the valve body hole, or the tolerance of the main valve core or valve hole is too poor. The hydraulic clamp is generated, and the main spool is stuck at the position of the maximum opening. Since the opening is large, the oil is not decompressed. At this time, according to the above situation, the method of deburring, cleaning and repairing the valve hole and the accuracy of the valve core can be respectively excluded.

2 Because the main valve core and the valve hole are too tightly fitted, or the valve hole or the valve core is assembled during assembly, the valve core is stuck at the maximum opening position, and a reasonable gap can be selected at this time. J-type pressure reducing valve with clearance is generally 0.007 ~ 0.015mm, can be properly polished before the valve hole, and then with the valve core.

3 The main spool has short damper hole or valve seat hole blockage, and the automatic adjustment function is lost. The main valve spring force pushes the main valve to the maximum opening degree, which becomes straight through and the inlet pressure is equal to the outlet pressure. The orifice can be blown through the φ1.Omm wire or compressed air, and cleaned and assembled.

4 pairs of J-type pressure reducing valve, the damping member with damping hole is pressed into the main valve core, and may be flushed out due to insufficient interference during use. After flushing out, the pressure between the oil inlet chamber and the oil outlet chamber is equal (no damping), and the upper and lower force areas of the valve core are equal, but the oil outlet chamber has a spring, so the main spool is always at the maximum opening position, so that the outlet The pressure is equal to the inlet pressure. At this point, the damper with a slightly larger outer diameter needs to be reworked and re-pressed into the main spool.

5JF type pressure reducing valve, the oil drain 孑L is blocked by the oil plug at the factory. When the oil plug is not unscrewed and used, the main valve core upper chamber (spring chamber) is trapped of oil, causing the main spool to be at the maximum opening without decompression. The J-tube valve is the same. J-type plate valves can also occur if the L-port is not connected to the oil sump when the mounting plate is designed.

6 pairs of J-tube valves, it is easy to install the wrong direction of the valve cover (wrong 90 ° or 180 °) during the disassembly, so that the outer drain port is blocked, the oil can not be drained, resulting in the same trapped oil phenomenon, so that the main valve The top is at the maximum opening without decompression. Install the bonnet assembly direction when repairing.

7 pairs of JF type pressure reducing valve, when the direction of the top cover is wrong, the output oil hole will be connected with the oil drain hole, so that no decompression is required.

(2) The outlet pressure is very low, even if the pressure regulating hand wheel is tightened, the pressure will not rise.