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Hyundai Excavator R450LC-7. Service and repair manual - page 23

7-27

7. CYLINDER

Remedy

Piston rod

Cylinder tube

Gland

Replace

Recondition or replace

Replace or replate

Recondition, replate or replace

Replace

Replace if oil leak is seen

Replace

Replace if flaw is deeper

than coating

Part name

Inspection item

Presence of crack

Plating is not worn off to
base metal.

Rust is not present on plating.

Scratches are not present.

Wear of O.D.

Wear of I.D.

Presence of crack

Presence of faults

Wear on inner surface

Flaw on inner surface

Inspecting section

Neck of rod pin

Weld on rod hub

Stepped part to which piston
is attached.

Threads

Plated surface

Rod

Bushing at mounting part

Weld on bottom

Weld on head

Weld on hub

Tube interior

Bushing at mounting part

Bushing

7-33

2. WORK EQUIPMENT

Unit : mm

Mark

Remedy

Remark

Normal

value

Recomm.

service

limit

Limit

of use

Recomm.

service

limit

Limit

of use

Measuring point

(Pin and Bushing)

Bushing

Boom Rear

Boom Cylinder Head

Boom Cylinder Rod

Arm Cylinder Head

Boom Front

Arm Cylinder Rod

Bucket Cylinder Head

Arm Link

Bucket and Arm Link

Bucket Cylinder Rod

Bucket Link

120

100

110

120

110

100

119

109

119

109

118.5

98.5

108.5

118.5

108.5

98.5

120.5

100.5

110.5

120.5

110.5

100.5

121

101

111

121

111

101

Replace

SECTION 8 DISASSEMBLY AND ASSEMBLY

Group 1 Precaution

8-1

Group 2 Tightening Torque

8-4

Group 3 Pump Device

8-7

Group 4 Main Control Valve

8-36

Group 5 Swing Device

8-49

Group 6 Travel Device

8-74

Group 7 RCV Lever

8-114

Group 8 Turning Joint

8-128

Group 9 Boom, Arm and Bucket Cylinder

8-133

Group 10 Undercarriage

8-150

Group 11 Work Equipment

8-162

1. REMOVAL WORK

Lower the work equipment completely to the ground.
If the coolant contains antifreeze, dispose of it correctly.

After disconnecting hoses or tubes, cover them or fit blind plugs to prevent dirt or dust from entering.

When draining oil, prepare a container of adequate size to catch the oil.

Confirm the match marks showing the installation position, and make match marks in the
necessary places before removal to prevent any mistake when assembling.

To prevent any excessive force from being applied to the wiring, always hold the connectors when
disconnecting the connectors.

Fit wires and hoses with tags to show their installation position to prevent any mistake when
installing.

Check the number and thickness of the shims, and keep in a safe place.

When raising components, be sure to use lifting equipment of ample strength.

When using forcing screws to remove any components, tighten the forcing screws alternately.

Before removing any unit, clean the surrounding area and fit a cover to prevent any dust or dirt from
entering after removal.

When removing hydraulic equipment, first release the remaining pressure inside the hydraulic tank
and the hydraulic piping.

If the part is not under hydraulic pressure, the following corks can be used.

SECTION 8 DISASSEMBLY AND ASSEMBLY

6.5

8.5

11.5

13.5

18.5

22.5

GROUP 1 PRECAUTIONS

Nominal

number

Dimensions

10)

11)

12)

8-2

2. INSTALL WORK

Tighten all bolts and nuts(Sleeve nuts) to the specified torque.

Install the hoses without twisting or interference.

Replace all gaskets, O-rings, cotter pins, and lock plates with new parts.

Bend the cotter pin or lock plate securely.

When coating with adhesive, clean the part and remove all oil and grease, then coat the threaded
portion with 2-3 drops of adhesive.

When coating with gasket sealant, clean the surface and remove all oil and grease, check that there
is no dirt or damage, then coat uniformly with gasket sealant.

Clean all parts, and correct any damage, dents, burrs, or rust.

Coat rotating parts and sliding parts with engine oil.

When press fitting parts, coat the surface with antifriction compound(LM-P).

After installing snap rings, check that the snap ring is fitted securely in the ring groove(Check that
the snap ring moves in the direction of rotation).

When connecting wiring connectors, clean the connector to remove all oil, dirt, or water, then
connect securely.

When using eyebolts, check that there is no deformation or deterioration, and screw them in fully.

When tightening split flanges, tighten uniformly in turn to prevent excessive tightening on one side.

When operating the hydraulic cylinders for the first time after repairing and reassembling the
hydraulic cylinders, pumps, or other hydraulic equipment or piping, always bleed the air from the
hydraulic cylinders as follows:

Start the engine and run at low idling.

Operate the control lever and actuate the hydraulic cylinder 4-5 times, stopping 100mm before the
end of the stroke.

Next, operate the piston rod to the end of its stroke to relieve the circuit. (The air bleed valve is
actuated to bleed the air.)

After completing this operation, raise the engine speed to the normal operating condition.
If the hydraulic cylinder has been replaced, carry out this procedure before assembling the rod to
the work equipment.
Carry out the same operation on machines that have been in storage for a long time after
completion of repairs.

10)

11)

12)

13)

14)

(1)

(2)

(3)

(4)

※

8-3

3. COMPLETING WORK

If the coolant has been drained, tighten the drain valve, and add water to the specified level. Run
the engine to circulate the water through the system. Then check the water level again.

If the hydraulic equipment has been removed and installed again, add engine oil to the specified
level. Run the engine to circulate the oil through the system. Then check the oil level again.

If the piping or hydraulic equipment, such as hydraulic cylinders, pumps, or motors, have been
removed for repair, always bleed the air from the system after reassembling the parts.

Add the specified amount of grease(Molybdenum disulphied grease) to the work equipment related
parts.

8-6

PIPE AND HOSE

Thread size

1/4"

3/8"

1/2"

3/4"

Width across flat

(

)

kgf

lbf

21.7

28.9

36.2

86.8

101

ITTING

Thread size

1/4"

3/8"

1/2"

3/4"

Width across flat

(

)

kgf

lbf

28.9

36.2

43.4

94.0

109

)

1. REMOVAL AND INSTALL

REMOVAL

Lower the work equipment to the ground
and stop the engine.

Loosen the breather slowly to release the
pressure inside the hydraulic tank.
Escaping fluid under pressure can
penetrate the skin causing serious
injury.

Loosen the drain plug under the hydraulic
tank and drain the oil from the hydraulic
tank.

Hydraulic tank quantity : 250

ℓ

Remove bolts(16) and disconnect pipe
(1,2).

Disconnect pilot line hoses(4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14).

Remove bolts(15) and disconnect pump
suction tube (3).
When pump suction tube is disconnected,
the oil inside the piping will flow out, so
catch it in oil pan.

Sling the pump assembly and remove the
pump mounting bolts.

Weight : 240kg(530lb)

Pull out the pump assembly from housing.
When removing the pump assembly,
check that all the hoses have been
disconnected.

8-7

GROUP 3 PUMP DEVICE

(1)

(2)

(3)

(4)

(5)

(6)

※

(7)

※

45078MP01

45078MP02

13031GE18

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