(1) Structure of the KATO return filter
The structure of the KATO return filter is as shown in the diagram to the right. The hydraulic oil flows from the inside to the outside of the element to collect the captured dirt into the element, so the dirt does not flow into the oil reservoir structurally when the element is replaced to remove the dirt.
If the element is replaced carelessly, the dirt may get in the hydraulic circuit. Follow the correct procedure and replace the element with care.
88 -(2) Preparation
Prepare the following for element replacement.
1) Genuine KATO elements
2) Clean tray which is already washed: (300mm 450mm or equivalent) 3) Clean paper or cloth: with no nap
4) Hydraulic oil (cleaning fluid): the same new hydraulic oil as the machine is using 5) Ratchet wrench
6) 19mm box wrench 7) O-ring (for the cover) (3) Operation before replacement
Before replacing the elements, run the engine at medium speed (1000 1200min-1) and perform traveling, swing, bucket, arm and boom operation in that order for two minutes respectively to collect the dirt into the return filters from the hydraulic circuit. Then stop the engine.
(5) Disassembly procedure
1) Unscrew the four bolts on the filter cover to remove the cover and O-ring from the filter case.
(4) Reduction of pressure in the oil reservoir
Press the top of the rubber cap to relieve pressurized air in the reservoir.
The size and number of the filter vary with the type of the machine. If you use the breaker, be sure to use the high-performance filter. Always use the genuine KATO filter elements. An imitation element is not guaranteed for performance and durability. If the worst comes to the worst, it could be damaged early and have an adverse effect on the hydraulic equipment. If an imitation filter is used, the hydraulic equipment is not guaranteed.
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2) Pull the element assembly out of the filter case.
3) After pulling out the element assembly, put the removed cover onto the filter case to prevent entry of dirt or dust into the reservoir.
4) Put the element assembly from which the oil is drained onto the tray.
Hold the spring and put the underside of the element on the inside flange of the filter case for about ten minutes to drain the oil from the filter assembly.
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Do not replace the elements in a dusty workplace.
The wind contains dust, so take an appropriate action for protection against the wind in a windy workplace before replacing the elements.
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Use the washed tray. If the tray is dirty, it makes the lower part of the center bolt of the element assembly dirty. If the tray is not washed thoroughly, the hydraulic oil could be contaminated by the dirt, so caution is required.
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-5) Extract the snap pin from the center bolt on the top of the element assembly.
6) Unscrew the castle nut to remove the spring from the center bolt.
7) Extract the safety valve from the center bolt.
8) Remove the center bolt from the elements, and separate the two elements and the retainer.
(6) Cleaning and inspection
1) Thoroughly clean the component parts of the element assembly except the elements using the new hydraulic oil which is prepared in advance.
2) Cover the washed parts with a cloth etc. which is prepared in advance to prevent dirt adhesion.
3) Check the O-ring. If it is damaged or stretched, replace it with new one.
2) Assemble one element to the center bolt.
(7) Assembly of the element assembly
Follow the procedure below to assemble the new elements.
1) Prepare the clean paper or cloth for element assembly.
Do not forget to attach the retainer.
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3) Attach the retainer onto the assembled element.
92 -4) Assemble the other element onto the retainer.
5) Attach the safety valve to the elements.
6) Attach the plate spring onto the safety valve. Tighten the castle nut to the center bolt to the regulation torque (10 15N m).
7) Insert the snap pin into the center bolt.
If the tightening force on the castle nut is insufficient, the filter can not work efficiently.
Tighten it to the regulation torque.
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When storing the element assembly into the filter case, keep the elements not to come into contact with the other parts so that the elements do not get dirty.
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8) Hold the plate spring and store the element assembly into the filter case.
9) Check the O-ring for damage again. Then attach the O-ring in place and put the cover onto the filter case.
10) Attach the washers to the four bolts and tighten the cover to the filter case to the regulation torque (20 34N m).
(8) Element replacement interval
Replacement interval Every 500 hours of operation or six months
After delivery of a new machine or right after the hydraulic oil is changed, the elements should be replaced after 150 hours of operation. Also when you change the hydraulic oil, they should be replaced.
(9) Consumable part number
Refer to the "Consumable parts guide".
You cannot wash the return filter element and reuse it. Always use a new, genuine KATO, filter element.
If you are using the hydraulic breaker, replace the standard filter element with a high-performance type.
When you have replaced the return filter, you should allow a running-in period of approximately 10 minutes at engine low speed with the control levers in their neutral
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