Trouble Shooting Of Pneumatic Reversing Valve In Feeding Part Of Hydraulic Cutting Machine

- Sep 14, 2020-

The faults of the reversing valve of the cutting machine include: the valve cannot be reversed or the reversing action is slow, the gas leaks, and the solenoid pilot valve is faulty.

(1) The reversing valve cannot be reversed or the reversing action is slow, which is generally caused by poor lubrication, stuck or damaged springs, oil stains or impurities stuck in sliding parts, etc. In this regard, first check whether the lubricator is working properly; whether the viscosity of the lubricating oil is appropriate. If necessary, replace the lubricating oil, clean the sliding part of the reversing valve, or replace the spring and reversing valve.

(2) After a long period of use, the directional valve of the cutting machine is prone to abrasion of the valve core sealing ring, damage to the valve stem and valve seat, resulting in gas leakage in the valve, slow valve action or failure of normal reversing. At this time, the sealing ring, valve stem and valve seat should be replaced, or the reversing valve should be replaced with a new one.

(3) If the inlet and exhaust holes of the solenoid pilot valve are blocked by sludge and other debris, the sealing is not tight, the movable iron core is stuck, the circuit is faulty, etc., all of which can cause the reversing valve to fail to reverse normally. For the first three cases, the sludge and impurities on the pilot valve and movable iron core should be cleaned. Circuit failures are generally divided into control circuit failures and electromagnetic coil failures. Before checking the circuit failure, turn the manual knob of the reversing valve a few times to see if the reversing valve can normally reverse under the rated air pressure. If it can reverse normally, the circuit is faulty. During the inspection, the instrument can be used to measure the voltage of the solenoid coil to see if it has reached the rated voltage. If the voltage is too low, further check the power supply in the control circuit and the associated travel switch circuit. If the reversing valve fails to change direction normally under the rated voltage, check whether the connector (plug) of the solenoid coil is loose or not properly connected. The method is to unplug the plug and measure the resistance of the coil. If the resistance is too large or too small, the solenoid coil is damaged and should be replaced.