Hyundai Excavator R450LC-7. Service and repair manual

8-137

BOOM CYLINDER

Removal
Expand the arm and bucket fully, lower the
work equipment to the ground and stop
the engine.
Operate the control levers and pedals
several times to release the remaining
pressure in the hydraulic piping.
Loosen the breather slowly to release the
pressure inside the hydraulic tank.
Escaping fluid under pressure can
penetrate the skin causing serious injury.
Fit blind plugs in the hoses after
disconnecting them, to prevent dirt or dust
from entering.

Disconnect greasing hoses(1).
Sling boom cylinder assembly.

①
②

(

※

Lower the boom cylinder assembly(6) on
a stand.

④

Remove bolt(4), stop plate(5) and pull out
pin(2).
Tie the rod with wire to prevent it from
coming out.

③

※

13031GE18

29078CY05

29078CY06

29078CY07

8-138

Install

Carry out installation in the reverse order
to removal.
When aligning the mounting position of
the pin, do not insert your fingers in the
pin hole.
Bleed the air from the boom cylinder.
Conformed the hydraulic oil level and
check the hydraulic oil leak or not.

①

※
※

(

Remove bolt(9) and pull out pin(8).
Remove boom cylinder assembly(6).

Weight : 335kg(740lb)

⑥
⑦

Disconnect boom cylinder hoses(7) and
put plugs on cylinder pipe.

⑤

29078CY08

29078CY09

8-139

2. DISASSEMBLY AND ASSEMBLY

STRUCTURE

Bucket cylinder(~#0261)

(1)

Tube assembly

Rod assembly

Gland

DD2 bushing

Snap ring

Rod seal

Back up ring

Buffer ring

Dust wiper

Snap ring

Wear ring

O-ring

Back up ring

Collar

Ring

Cushion ring

Piston

O-ring

Back up ring

Piston seal

Wear ring

Piston ring

Spacer

Hexagon socket head bolt

Band assembly

Pipe assembly

O-ring

Hexagon socket head bolt

Pin bushing

Dust seal

Grease nipple

45078BK01

8-139-1

2. DISASSEMBLY AND ASSEMBLY

STRUCTURE

Bucket cylinder(#0262~)

(1)

15,16

23,24

29 23,24

11,12

9,10 6,7 8 4

29 28 3

Internal detail

Tube assembly

Rod assembly

Gland

DD2 bushing

Snap ring

Rod seal

Back up ring

Buffer ring

Dust wiper

Snap ring

O-ring

Back up ring

Cushion ring

Piston

O-ring

Back up ring

Piston seal

Wear ring

Dust ring

Lock washer

Lock nut

Hexagon socket head bolt

Pin bushing

Dust seal

Band assembly

Pipe assembly

O-ring

Hexagon socket head bolt

Grease nipple

470078BK01

8-140

Arm cylinder(~#0261)

(2)

Tube assembly

Rod assembly

Gland

DD2 bushing

Rod seal

Back up ring

Buffer ring

Dust wiper

Snap ring

Wear ring

O-ring

Back up ring

Collar

Ring

Cushion ring

Piston

O-ring

Back up ring

Piston seal

Wear ring

Piston ring

Spacer

Hexagon socket head bolt

Cushion spear

Check valve

Coil spring

Steel ball

Set screw

Hexagon socket head bolt

Band assembly

Pipe assembly

O-ring

Hexagon socket head bolt

Pin bushing

Dust seal

Snap ring

45078AM12

8-140-1

Arm cylinder(#0262~)

(3)

Tube assembly

Rod assembly

Gland

DD2 bushing

Snap ring

Rod seal

Back up ring

Buffer ring

Dust wiper

Snap ring

Wear ring

O-ring

Back up ring

Cushion ring

Piston

O-ring

Back up ring

Piston seal

Wear ring

Dust ring

Lock washer

Lock nut

Hexagon socket head bolt

Pin bushing

Dust seal

Band assembly

Pipe assembly

O-ring

Hexagon socket head bolt

9,10 11 6,7 8

30 3

4 23 5 31

12,13

1 2

14 15

16,17

24,25

Internal detail

24,25

18 19 20

470078AM01

8-141

Boom cylinder(~#0021)

(3)

Tube assembly

Rod assembly

Gland

DD2 bushing

Rod seal

Back up ring

Buffer ring

Dust wiper

Snap ring

Wear ring

O-ring

Back up ring

Collar

Ring

Cushion ring

Piston

O-ring

Back up ring

Piston seal

Wear ring

Piston ring

Spacer

Hexagon socket head bolt

Band assembly

Pipe assembly

O-ring

Hexagon socket head bolt

Pin bushing

Dust seal

Grease nipple

Snap ring

45078BO01

8-141-1

Boom cylinder(#0022~)

(5)

Tube assembly

Rod assembly

Gland

DD2 bushing

Snap ring

Rod seal

Back up ring

Buffer ring

Dust wiper

Snap ring

Wear ring

O-ring

Back up ring

Cushion ring

Piston

O-ring

Back up ring

Piston seal

Wear ring

Dust ring

Lock washer

Lock nut

Hexagon socket head bolt

Band assembly

Pipe assembly

O-ring

Hexagon socket head bolt

Pin bushing

Dust seal

Grease nipple

9,10

6,7 8

27 3

4,5 23 28

12,13

1 2

14 15

16,17

29,31

30,32

Internal detail

470078BO01

8-143

DISASSEMBLY(~#0261)

Remove cylinder head and piston rod

Procedures are based on the bucket
cylinder.
Hold the clevis section of the tube in a
vise.
Use mouth pieces so as not to damage
the machined surface of the cylinder
tube. Do not make use of the outside
piping as a locking means.

200mm

Full straight

sideways

Lift

Oil pan

(1)

※

①

※

Draw out cylinder head and rod assembly
together from tube assembly(1).
Since the rod assembly is heavy in this
case, lift the tip of the rod assembly(2)
with a crane or some means and draw it
out. However, when rod assembly(2)
has been drawn out to approximately
two thirds of its length, lift it in its center to
draw it completely.

④

※

Loosen and remove socket bolts(25) of
the gland in sequence.
Cover the extracted rod assembly(2) with
rag to prevent it from being accidentally
damaged during operation.

③

※

Pull out rod assembly(2) about 200mm
(7.1in). Because the rod assembly is
rather heavy, finish extending it with air
pressure after the oil draining operation.

②

36078CY21A

45078CY01

36078CY21C

8-144

Rod assembly

Wooden block

Remove the cylinder head assembly
from rod assembly(2).
If it is too heavy to move, move it by
striking the flanged part of cylinder head
with a plastic hammer.
Pull it straight with cylinder head
assembly lifted with a crane.
Exercise care so as not to damage the lip
of rod bushing(4) and packing (6, 7, 8, 9,
10, 11) by the threads of rod assembly(2).

Remove piston and cylinder head

Remove bolt(24) and spacer(23).
Remove piston assembly(17), back up
ring(19), and O-ring(18).

③

※

Place the removed rod assembly on a
wooden V-block that is set level.
Cover a V-block with soft rag.

⑤

※

Note that the plated surface of rod
assembly(2) is to be lifted. For this
reason, do not use a wire sling and
others that may damage it, but use a
strong cloth belt or a rope.

((2)

①
②

36078CY22A

45078CY02

8-145

Disassemble cylinder head assembly

Remove back up ring(13) and O-ring
(12).
Remove snap ring(10), dust wiper(9).
Remove back up ring(7), rod seal(6) and
buffer ring(8).
Exercise care in this operation not to
damage the grooves.
Do not remove seal and ring, if does not
damaged.

(4)

①

②
③

※

Disassemble the piston assembly

Remove wear ring(21).
Remove piston ring(22) and piston seal
(20).
Exercise care in this operation not to
damage the grooves.

(3)

①
②

※

45078CY01

45078CY23

8-146

Press here

(Straight down)

Metal

Rod seal(6) has its own fitting direction.
Therefore, confirm it before fitting them.
Fitting rod seal(6) upside down may
damage its lip. Therefore check the
correct direction that is shown in fig.

※

Fit back up ring(7), rod seal(6) and buffer
ring(8) to corresponding grooves, in that
order.
Coat each packing with hydraulic oil
before fitting it.
Insert the backup ring until one side of it
is inserted into groove.

④

※

Coat dust wiper(9) with grease and fit
dust wiper(9) to the bottom of the hole of
dust seal.
At this time, press a pad metal to the
metal ring of dust seal.
Fit snap ring(10) to the stop face.

②

③

ASSEMBLY

Assemble cylinder head assembly

Check for scratches or rough surfaces if
found smooth with an oil stone.
Coat the inner face of gland(3) with
hydraulic oil.

(1)

※

①

21078DA37

36078CY24A

45078CY24

8-147

Fit wear ring(21) and piston ring(22) to
piston(17).

③

Fit piston seal(20) to piston.
Put the piston seal in the warm water of
60~100

。

C for more than 5 minutes.

After assembling the piston seal, press
its outer diameter to fit in.

②
※

※

Fit back up ring(12) to gland(3).
Put the backup ring in the warm water of
30~50

。

Fit O-ring(11) to gland(3).

⑤
※

⑥

Assemble piston assembly

Check for scratches or rough surfaces.
If found smooth with an oil stone.
Coat the outer face of piston(17) with
hydraulic oil.

(2)

※

①

36078CY25A

8-158(2) 210-7

45078CY04

45078CY05

Gland assembly

Rod assembly

Fit piston assembly to rod assembly.

⑤

Insert cushion ring(16) to rod assembly.
Note that cushion ring(16) has a direction
in which it should be fitted.

④
※

IInstall piston and cylinder head

Fix the rod assembly to the work bench.
Apply hydraulic oil to the outer surface of
rod assembly(2), the inner surface of
piston and cylinder head.
Insert cylinder head assembly to rod
assembly.

(3)

①
②

③

36078CY26A

45078CY06

45078CY07

8-149

Straight

Lift

Appply liquid packing

Fix with a bar

Turn clockwise

Place rag

Apply loctite

Overall assemble

Place a V-block on a rigid work bench.
Mount the tube assembly(1) on it and fix
the assembly by passing a bar through
the clevis pin hole to lock the assembly.
Insert the rod assembly in to the tube
assembly, while lifting and moving the
rod assembly with a crane.
Be careful not to damage piston seal by
thread of tube assembly.
Match the bolt holes in the cylinder head
flange to the tapped holes in the tube
assembly and tighten socket bolts to a
specified torque.
Refer to the table of tightening torque.

(3)

①

②

※

③

※

36078CY27A

36078CY27B

Hyundai Excavator R450LC-7. Service and repair manual - page 35