Why does Carter CAT306 arm drop automatically?
In the construction of a Carter CAT306 crawler excavator, it was suddenly found that the hydraulic cylinder of the machine arm appeared automatic sinking and leakage phenomenon. Let's solve this problem.
Inspection cause analysis:
Check when the cylinder lifting control valve is in place, the big arm automatically decreases obviously, the cause of the malfunction may be cylinder seals, cylinder, cylinder cover side pull sealing ring damage, cylinder safety valve closed, caused by the oil spill. The cavity channeling or fault in the oil cylinder have leaked, and when the excavator boom cylinder changing internal leakage and leakage shall be carried out when the oil seal. So I decided to disassemble the cylinder and inspect the pseudo replacement of the oil.
Carter CAT306 large arm automatic descent troubleshooting method:
1. traditional methods of elimination
The traditional method of replacing the boom cylinder seal is connected with all the crane boom cylinder assembly hook and dismantle the machine and boom cylinder assembly, and then the boom cylinder assembly hanging down on the ground, the decomposition of the boom cylinder assembly and replace the seal (live, found in this case decomposition the Y shaped groove of the plug both ends of sealing ring wear serious, it also proves that the dynamic wall cylinder automatically sink is the cause of damage caused by oil seal), finally in the opposite order of installation of boom cylinder cylinder automatic sink failure can be ruled out.
2. innovative methods to exclude
The boom cylinder is heavy, such as change in the conditions of the workshop for the oil seal, can be successfully completed, but in the wild, no lifting equipment is single operation, it is very difficult. The method only needs a hand gourd, two adjustable thin steel wire rope, and the other common tools can be completed as follows:
(L) first stop the machine, then stick the bucket to the end, drop the arm, and then put the bucket flat to the ground
(2) the length of wire rope in the arm, short wire rope at the upper end of the boom cylinder (by card key). Hand pulling hoist wire rope hook hook at both ends of the two joints, and then tighten the chains.
(3) remove the pin of the head of the piston rod of the boom cylinder, remove the inlet and outlet tubing, and release the hoist to place the boom cylinder on the platform
(4) the cylinder mouth clasp with circlip pliers remove, with copper rods tapping the guide sleeve to move a distance into the cylinder, until the retaining ring and exposed card key, and then remove the retaining ring and the card key. A special rubber plug in the card slot (mainly for piston rod assembly can ride out the cylinder).
(5) in the boom cylinder is parallel to the height of the excavator arm and boom cylinder rod pin hole sleeve are respectively connected with the steel wire rope, hand chain hoist, and then tighten the hand pulling hoist chains, piston rod assembly can be pulled out.
(6) remove the big nut at the end of the piston, and take out the piston, guide sleeve and sealing parts in turn
(7) change the oil seal
The parts with wash clean, then the inner wall of the cylinder and piston friction surface smear a small amount of hydraulic oil.
The O type sealing ring and ring, Y ring (lips to), dust seal (seal lips outward) in turn into the guide sleeve hole groove, the O type sealing ring is arranged in the guide sleeve of the outer circle of the sealing ring groove. The supporting ring arranged on the piston. And the 2 retaining ring and 2 Y ring back lips are respectively arranged at both ends of the piston groove.
The guide sleeve and the piston assembly are mounted on the piston rod in turn
Fill the rubber bar in the cylinder keyway to make it flush with the inner wall of the cylinder, and assemble the piston rod assembly (together with the guide sleeve) into the cylinder
Remove the rubber strip, install the clamping key, retaining ring and retaining ring of the fixed guide sleeve
(8) hoist the boom cylinder with a hand hoist, connect and enter the oil pipe and insert the pin (such as pin hole can adjust the piston rod of the boom cylinder when the machine can be started by the machine)
The whole process if 3 people work together. Only about 1O min can be completed, such as tension, a maintenance and operation of hand can do homework. Practice has proved that the above method is the biggest advantage of innovation need not use a crane, do not need to disassemble the cylinder assembly, fast and efficient, LIMITED small, fast especially suitable for the repair site.
Hope that the above content for everyone's work to help.
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