Inspection of Valves Related to Hydraulic Cylinders

Inspection of Positioning Valve Seal of Hydraulic Cylinder

Check the farm equipment on the fashion, remove the positioning clamps, start the engine, when the hydraulic oil temperature reaches 40～60℃, lift the farm equipment to the highest position, press the positioning valve and close the lower chamber of the cylinder. In the removal of the pipe joint to the lower chamber of the cylinder, observe whether oil leaks at the hole of the pipe joint, such as oil leakage, it means that the positioning valve and the seat seal is not tight, should be removed for repair. If there is no oil leakage, use the sink method to measure the sink of the piston rod in 30 minutes, if the average sink exceeds 30mm, it means that the seal of the piston and cylinder barrel becomes poor, the seal of the piston should be replaced, or wrap kraft paper pad in the ring groove to make up.

Because of troubleshooting more in the case of not hanging farm equipment, can be in the oil pump, distributor performance is good in the case of "maximum pressure observation leakage method" to determine the state of the positioning valve and cylinder sealing performance. The method is as follows.

Inspection of Sealing Performance of Positioning Valves

The inspector makes the piston leave the two limit positions of the cylinder, press the positioning valve, remove the oil pipe leading to the lower chamber of the cylinder, wipe the oil in the street of the cylinder, pull the distributor handle to the "down" position, and keep the engine speed stable above medium speed for 15 seconds. As the positioning valve blocks the lower circuit, the safety valve is forced to open, so that the 12.7MPa pressure oil acts on the upper chamber of the positioning valve, when the valve and valve seat sealing performance is good, the joint should not leak oil: if the slight leakage of oil indicates that the seal has decreased, but can continue to use. If oil leakage has formed a continuous oil flow, it means that the positioning valve seal is damaged and should be removed for repair.

Inspection of Cylinder Sealability

Turn the distributor handle to the "up" position so that the piston is at the uppermost end of the cylinder, remove the pipe joint to the upper chamber of the cylinder, wipe the oil inside the joint, and keep the engine speed stable above medium speed for 15 seconds. As the piston is in the limit position, the safety valve is forced to open and the 12.7MPa pressure oil acts under the piston, if the piston is well sealed with the cylinder, the joint should not leak oil; if the oil leakage has formed oil flow, it means the piston seal is damaged and the piston rod head fixing nut is loose. The same method to remove the oil pipe to the lower chamber of the cylinder, the handle to the "pressure drop" position, you can also observe whether there is oil leakage, so as to determine the sealing performance of the cylinder.

Checking the Reliability of the Dispenser Slide Valve Positioning

Start the starter, make the oil temperature reach 40～60℃, then toggle the handle to each position should be flexible without stalling phenomenon. Move the handle to the "lifting" or "pressure drop" position, and the handle should be able to jump back to the "neutral" position automatically after the implements are lifted or dropped to a certain position; when the handle is pulled to the When the handle is moved to the "floating" position, the handle should be able to position reliably after the tool is lowered.

Inspection of Oil Tank Filter Passing Capacity

The filtering capacity of the oil tank decreases, seriously forcing the filter safety valve to open, so that the hydraulic oil can not be filtered, directly into the system, thus aggravating the wear of hydraulic components or directly affecting the work of the system; if the safety valve pressure is adjusted too high, the rupture of the lower cover of the distributor may also occur.

Check, the filter into the oil pipe connector removed, with special screws connected to 0 ~ 1.0MPa pressure gauge, set the distributor handle in different positions, the filter through the capacity of no more than 0.1MPa, otherwise the filter should be cleaned. The opening pressure of the filter safety valve is 0.25MPa, and the full opening pressure is 0.3~0.35MPa, which should not be adjusted arbitrarily.