How to Disassembly Cylinder for Kubota U48-4 U55-4 Excavator

It is necessary to remove cylinder when you do replacement or service operation.Here is the instruction show you guide on how to disassemble cylinder for Kubota U48-4 and U55-4 excavator.


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Disassembly Procedures
Cylinder Disassembly

1.Drain the oil from inside the cylinder, and fasten the cylinder bottom in a vice across the bolt width.


2.Place an anti-rotation device in one position of the cylinder head (3).


(3) Cylinder head

3.Use a wrench (hook) or wrench (key) to loosen the cylinder head (3).
While loosening the cylinder head (3) screw, remove the cylinder head.


(3) Cylinder head

4.Pull out the piston rod assembly (2) together with the cylinder head (3), and place on a board.
• Check whether or not the pipe cap has been removed.
• Provide the port on the cylinder head side with an oil receptacle.
• Draw the piston rod assembly (2) out horizontally while keeping it held, to avoid dropping it and causing damage to parts immediately after it is withdrawn.


(2) Piston rod ASSY (3) Cylinder head

5.Fasten the piston rod assembly (2) in a vice across the bolt width and use a cushioning material.
• Place the rod on a block of wood


(2) Piston rod ASSY

6.Remove the set screw (19), and remove the steel ball (20).
• The set screw (19) is caulked in two locations. Use a hand drill or similar device to remove the caulking, then loosen the set screw (19).
• After removing, use a hand tap (M8 x 1.25) to carry off the piston side.
• If the set screw (19) is damaged on removal, replace it with a new one.


(19) Set screw
(20) Steel ball
(a) Drill

7.Use a wrench (socket wrench) on the hexagonal nut section of the piston (16), and loosen it.
If a large amount of torque is required, prepare a dynamic wrench with hydraulic jack – hydraulic cylinder.


(16) Piston

8.Remove the piston (16), cushion bearing (15) and cylinder head
(3) in that order.


(3) Cylinder head
(10) Holder
(15) Cushion bearing
(16) Piston

9.Remove the slide ring (18) by hand, split the seal ring (17) by tapping it with a flat tip screwdriver (a), and remove.
Remove the O-ring (17) with a spatula.
• Do not use seals once removed.


(17) Seal ring, O-ring
(18) Slide ring
(a) Slotted screwdriver

10.Remove the O-rings (7) (9) and backup ring (8) of the cylinder head (3).
• If removal is difficult, use a screwdriver, taking care not to damage the cylinder head.
• Do not use seals once removed.


(3) Cylinder head
(7) O-Ring
(8) Backup ring
(9) O-Ring

11.Remove the wiper ring (6).
The wiper ring (6) is press-fitted.
Use a tool such as a driver, and tap using rubber cushioning.
• Do not use seals once removed.


(6) Wiper ring

12.Lift the U-ring (5) using a screwdriver, and remove it from the cylinder head (3).
• Do not use seals once removed.


(3) Cylinder head (5) U-ring

13.Lift the buffer ring (21) with a screwdriver, and remove it from the cylinder head (3).
• Do not use seals once removed.


(3) Cylinder head (21) Buffer ring

14.Lift the snap ring (11) with a screwdriver, and remove it from the cylinder head (3).
• Do not use seals once removed.


(11) Snap ring

15.Lightly tap out the bushing (4) with a hammer and chisel, taking care not to damage the cylinder head (3).
• Do not use seals once removed.


(3) Cylinder head (4) Bushing


Compression side cushion bearing disassembly (arm cylinder only)
1.Remove the piston (16)
Disassembly is not possible when the piston (16) is fitted.


(16) Piston

2.Remove the snap ring (23).
• Lightly tap out with a plastic hammer to avoid damaging the piston rod (2) and cushion bearing (21).


(2) Piston rod
(21) Cushion bearing
(23) Snap ring

3.Slide the cushion bearing (21) to the thread side of the piston rod (2), and remove the stopper (24) (splits into two)


(2) Piston rod
(21) Cushion bearing
(24) Stopper


4.Remove the cushion bearing (21), and remove the cushion seal (22).
The cushion seal (22) has a split opening in one location, so widen the split to remove.


(2) Piston rod
(21) Cushion bearing
(22) Cushion seal
(23) Snap ring
(24) Stopper

More repair case for Kubota,please refer to:Kubota Trouble Repair

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