GROUP 4 DISASSEMBLY AND ASSEMBLY

1. MAIN PUMP
1) STRUCTURE

21

20

13
11 12
22
19
15
8
7 14
6

17
18

9
16
8 15
7 14
6 13
12
11

10

1
2
7407WE12

1 Shaft seal 11 Wearplate 17 Spline coupling

2 Adapter 12 O-ring seal 18 Rear driven gear
6 Back up seal 13 Back up seal 19 Rear drive gear
7 O-ring seal 14 Interface seal 20 Stud
8 Wearplate 15 Dowel 21 Flanged nut
9 Front drive gear 16 Front body 22 Rear body
10 Front driven gear

6 -67
2) DISASSEMBLY

21

20

13
11 12
22
19
15
8
7 14
6

17
18

9
16
8 15
7 14
6 13
12
11

10

1
2
7407WE12

※ Plug all ports prior to cleaning and disassembling pump to prevent ingress of debris or
contamination.
※ Clean the pump thoroughly with a solvent, ensuring no loose debris or contamination remains on
the unit.
※ Mark each interface and then separate into individual pump sections.
(1) Securely clamp pump horizontally on one port face, ensuring that no damage is sustained to the
port face and remove the stud(20) and nut(21).
(2) Remove the front adaptor(2) from the body(16) using a pulling tool centred on the drive shaft(9).
※ Under NO circumstances attempt to prise or chisel cover from body as such action could damage
the machined sealing faces.
(3) Remove and discard the shaft seal(1) from adaptor making sure that no damage is sustained to
the surface of the seal bore.
(4) Unclamp pump and place it vertically with drive shaft up.
(5) Before removing wearplate from the body mark it using a soft pencil or a felt-tip pen to ensure
correct reassembly. Remove wearplate(8) complete with O-ring seal(7) and back up seal(6).

6 -68
 DISASSEMBLY
21

20

13
11 12
22
19
15
8
7 14
6

17
18

9
16
8 15
7 14
6 13
12
11

10

1
2
7407WE12

(6) Mark the gears using a soft pencil or felt-

tip pen to ensure assembly in the same
relative position, see figure on the right,
then withdraw the drive shaft/gear(9) and
driven gear(10) separately to prevent
jamming.
(7) Again, to ensure correct assembly, mark
remaining wearplate(11) using a soft
pencil or a felt-tip pen. Remove wearplate
from body complete with O-ring seal(12) 7607WE34

and back up seal(13).

(8) Discard interface seal(14).
(9) Having separated into individual pumps,
proceed as per paragraph (1)~(7).

6 -69
3) MANDATORY REPLACEMENT PARTS
Discard all seals including interface seals, shaft seals, wear plate seals and back up seals. Fit new
seals on reassembly. Wearplates should also be replaced with new items from seal kit.
4) HANDLING/STORAGE
While disassembling pump, ensure no surfaces are scored or marked in any way. A rubber
surfaced table will be beneficial. All components must be placed in a clean, dry and safe area.
Leakage will be created by scratches on components. If parts are to be left for any period ensure
they are not exposed to dirt, dust and corrosion. Keep gears separate from each other in
protective boxes.
5) INSPECTION OF PARTS
Wash all parts in a solvent and dry.
(1) Adaptor housing and cover
The pump must be replaced if the damage listed is present.

Feature Damage
Corrosion, nicks or burrs(slight burrs can be removed
Surfaces
using and india stone)
Machined sealing lnterfaces Scores, cracks or corrosion
Bearing Loose

(2) Gears
The pump must be replaced if the damage listed is present.

Feature Damage
Corrosion, nicks or burrs(slight burrs can be removed
Surfaces using an lndia stone).
Wear due to seal(s)
Journals Pitting, wear, sufficient wear to change outside diameter
Tooth Cracks or heavy scoring or chipped
Splines/keyways Distortion of wear
End faces Wear, cracks

6 -70
(3) Floating wear plates
The pump must be replaced if the damage listed is present.

Feature Damage

Corrosion, nicks or burrs, amounts of scoring,erosion

Surfaces or any cracks, discoloration caused by overheating

Removing burrs or minor scoring from Scoring of wear plate.

end faces and teeth of the gears.

(4) Bolts/Studs
The pump should be replaced if the damage listed is present.
Feature Damage

Corrosion, nicks or burrs(slight burrs can be removed

Surfaces using an lndia stone), cracks or scoring,
distortion or damage to thread form

(5) Plain bearings

The pump must be replaced if the damage listed is present.
Feature Damage

Surfaces Cracks or socring

PTEF Coating Worn-bronze, sub-layer showing
Bearing Loose in housing/cover

(6) Coupling
This must be replaced if damage listed is present.
Feature Damage

Surfaces Corrosion, nicks or burrs, erosion, cracks or pitting

Splines Distorted or badly worn

6 -71
6) ASSEMBLY

21

20

13
11 12
22
19
15
8
7 14
6

17
18

9
16
8 15
7 14
6 13
12
11

10

1
2
7407WE12

※ It is critical that the wearplates are assembled into the pump with regard to the following:
-The seal side of the wearplate must be adjacent to the adaptor or body.
-The high pressure side of the wearplate must be adjacent to the outlet port.
※ This must take place in a clean dry area, ensuring that all parts are clean and free from
contamination or loose particles. Lightly oil all surfaces.
(1) Place body vertically with gear pockets upper most.
(2) Slide wearplate(11) complete with O-ring seal(12) and back up seal(13) down through the housing
to the bottom of the gear pockets.
※ Be sure to refit the wearplate the same as that marked from this position during disassembly.
(3) Fit the gears(18,19) within the housing taking care to replace as marked, with the teeth
reassembled to their original related position.
(4) Fit the wearplate(8) complete with O-ring seal(7) and back up seal(6).
※ Be sure to refit the wearplate the same as that marked from this position during disassembly.

6 -72
 ASSEMBLY

21

20

13
11 12
22
19
15
8
7 14
6

17
18

9
16
8 15
7 14
6 13
12
11

10

1
2
7407WE12

(5) Fit new interface seal(14) into groove in body.

(6) Proceed as per paragraph(1)~(5).
(7) Fit adaptor(2) over the drive gear(9) and fit stud(22).
(8) Securely clamp unit and tighten nut(21) to half torque and then full torque.
・Tightening torque : 23.2kgf・m(168lbf・ft)
(9) Fit shaft seal(1) using appropriate tooling, in correct position and orientation.
(10) Pour a little clean hydraulic oil into the ports.

6 -73
2. RCV LEVER
1) STRUCTURE

17

29
B
50 28
26
12
4 1
24 2 13
3

5 6
23
27 4 7
2 2
21
1
3

A
4 1

3 2
8
15
47 25
16
10 9

30
14
18
15 19
20
11
49

22

A
B 7403AWE11

1 Spring 12 Prefeel cage assy 23 O-ring

2 Spring 13 Spindle retainer 24 Wiper seal
3 Spring 14 Spindle 25 Plug
4 Plunger assy 15 Nut 26 Collar
5 Plunger assy 16 Lever assy 27 Handle adapter
6 Plunger assy 17 Handle 28 Nut
7 Plunger assy 18 Universal joint assy 29 Nut
8 Body 19 Screw 30 Insulation tube
9 Prefeel kit 20 Connector assy 47 Nut
10 Prefeel kit 21 Rubber boot 49 Spacer
11 Prefeel kit 22 Solenoid 50 Handle assy

6 -74
2) DISASSEMBLY AND ASSEMBLY
(1) Detach the rubber boot(21) from the
retainer collar and lift the boot clear from 21
the selector assembly.
The capscrew(19) can now be easily
accessed.
Selector assy

7406S 6-78(1)

(2) Loosen and remove all four M6

capscrews(19).
・Tightening torque : 1.0kgf・m(7.2lbf・ft) 19

7406S 6-78(2)

(3) The upper portion of the valve, from the

mounting plate upwards, can now be
detached and placed to one side. Upper portion
※ The magnets will still be connected to the of valve
connector.

7406S 6-78(3)

(4) Remove the ball carriers off of the spindle

guide - carefully detach the spindle
guides, being careful to ensure that no
contamination enters the valve. Spindle
※ The spindle guide are retained by guide
interference between the body and the
guide O-ring.

7406S 6-78(4)

6 -75
(5) The spindle guides can now be replaced.
The O-rings on the spindle guide must be
replaced before the valve is reassembled. O-ring

7406S 6-79

Reassembly is the opposite of

disasembly.

6 -76
3. MAIN CONTROL VALVE
1) Lay out valve components on a clean, flat
working surface. The inlet assembly will
include an O-ring, and the spool section(s)
include an O-ring, a load check poppet and
a load check spring. Tools required for
basic valve assembly include 3/4 and 11/16
open or box end wrenches and a torque
wrench with thin wall sockets.

7406S MCV05(1)

2) Assemble tie rod nuts to one end of each

tie rod with one or two threads showing.
Insert tie rods through tie rod holes of
inlet(Large tie rod at top). Lay inlet on end
with tie rods up, place O-ring into position.

7406S MCV05(2)

3) Place first spool section(O-ring side up) on

inlet section, position O-ring and insert load
check poppet(Nose down) and
spring(Behind poppet) into load check
cavity as shown. Repeat this procedure for
each spool section ; The load check springs
are compressed by the following sections
during assembly.

7406S MCV05(3)

4) Position end section on last spool section

as shown and hand tighten tie rod nuts.
The end section on picture is a "turn
around" section without ports. Universal
outlet/power beyond section and power
beyond and closed center sections are also
used as end sections. These end sections
do not have O-ring grooves.

7406S MCV05(4)

6 -77
5) Position valve assembly with the mounting
pads of the end sections on a flat surface.
To obtain proper alignment of end sections
relative to the spool sections apply
downward pressure to the end sections ;
Snug tie rod nuts to about 10lbf・ft.
Final torque the two 11/16 nuts to 48±
5lbf・ft ; Final torque the 3/4 nut to 74±
8lbf・ft. Check for proper spool movement.
7406S MCV06(1)

6) Install auxilliary valves and plugs and

torque to proper specifications.
※ General assembly notes:
A. Lever assemblies can be installed on
section before or after complete valve
assembly.
B. The load check and spring may be
omitter from assembly in certain circuit
conditions(i.e., motor spools).
7406S MCV06(2)

6 -78
4. BOOM AND BUCKET CYLINDER
1) BOOM CYLINDER

19 7 10,11 23 22 3 4 1 2 13,14 17 15 16 12 18

6,5
9,8

20 24 25,26 21 27,28

7407WE10

1 Tube assy 11 Back up ring 21 Pipe assy

2 Rod assy 12 Piston 22 O-ring
3 Gland 13 O-ring 23 Socket bolt
4 Bushing 14 Back up ring 24 Pipe clamp
5 Rod seal 15 Piston seal 25 Hexagon bolt
6 Back up ring 16 Wear ring 26 Spring washer
7 Buffer ring 17 Dust ring 27 Bushing
8 Dust wiper 18 Nylon nut 28 Dust seal
9 Snap ring 19 Socket bolt
10 O-ring 20 Pipe assy

6 -79
2) BUCKET CYLINDER

7 25 24 3 11,10 4 1 2 14,13 17 15 16 12 19

6,5 18
9,8

22

21
26,27

20 23
7407WE11

1 Tube assy 10 O-ring 19 Set screw

2 Rod assy 11 Back up ring 20 Socket bolt
3 Gland 12 Piston 21 Band assy
4 Bushing 13 O-ring 22 Pipe assy
5 Rod seal 14 Back up ring 23 Pipe assy
6 Back up ring 15 Piston seal 24 O-ring
7 Buffer ring 16 Wear ring 25 Socket bolt
8 Dust wiper 17 Dust ring 26 Bushing
9 Snap ring 18 Nylon nut 27 Dust seal

6 -80
3) TOOLS AND TIGHTENING TORQUE
(1) Tools

Tool name Remark

8 B
Allen wrench
12
Spanner 19
(-) Driver Small and large sizes
Torque wrench Capable of tightening with the specified torques

(2) Tightening torque

Torque
Part name Item Size
kgf・m lbf・ft
Bucket cylinder 20
M14×2.0×55 15±2 108±14.5
Boom cylinder 19
Socket head bolt
Bucket cylinder 25
M10×1.5×45 5.4±0.5 39±3.6
Boom cylinder 23
Bucket cylinder M64×3.0 150±15 1085±108
Nylon nut 18
Boom cylinder M48×2.0 250±25 1808±181
Hex head bolt Boom cylinder 25 M12×1.75×40 5.5±0.6 40±4.3

6 -81
4) DISASSEMBLY
(1) Remove gland and piston rod
① 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.

② Pull out piston rod(2) about 200mm

(7.8 in). Because the piston rod is rather
200mm
heavy, finish extending it with air
pressure after the oil draining operation.

(740-3A) 6-76(1)

③ Loosen and remove socket bolts(19) of

Hexagon
the gland(3) in sequence. socket wrench
※ Cover the extracted piston rod(2) with
rag to prevent it from being accidentally
damaged during operation.

3
19
2
Cover here
with rag
(740-3A) 6-76(2)

④ Draw out gland(3) and piston rod (2)

assembly together from cylinder tube(1).
Lift 1
※ Since the piston rod assembly is heavy
in this case, lift the tip of the piston rod(2)
with a crane or some means and draw it
out. However, when piston rod(2) has 3 2
been drawn out to approximately two
Oil pan
thirds of its length, lift it in its center to Pull straight
sideways
draw it completely.
(740-3A) 6-76(3)

6 -82
※ Note that the plated surface of piston
rod(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.

⑤ Place the removed piston rod assembly

on a wooden V-block that is set level.
※ Cover a V-block with soft rag. Piston rod assy

Wooden block
(740-3A) 6-77(1)

(2) Remove piston and gland assembly

① Remove the nylon nut(18). 13,14 17 15 12 16 18
② Remove piston assembly(12) and O-ring
(13), back up ring(14).

(740-3A) 6-77(2)

③ Remove the gland assembly from piston

Lift with a crane
rod(2).
※ If is too heavy to move, move it by Plastic 3 4 2
Hammer
striking the flanged part of gland(3) with a
plastic hammer. Pull straight
※ Pull it straight with gland assembly lifted
with a crane.
Exercise care so as not to damage the lip
of rod bushing(4) and packing(5, 6, 7, 8,
(740-3A) 6-77(3)
9) by the threads of piston rod(2).

6 -83
(3) Disassemble the piston assembly
① Remove wear ring(16), dusting(17), and 17 15 16
piston seal (15).
※ Exercise care in this operation not to
damage the grooves.

(740-3A) 6-78(1)

(4) Disassemble gland assembly

① Remove back up ring(11) and O-ring 8,9 5,6 7 11 10 4
(10).
② Remove snap ring(9) and dust wiper(8).
③ Remove back up ring(6), rod seal(5) and
buffer ring(7).
※ Exercise care in this operation not to
damage the grooves.
※ Do not remove seal and ring, if does not
(740-3A) 6-78(2)
damaged.

6 -84
5) ASSEMBLY
(1) Assemble gland assembly
※ Check for scratches or rough surfaces if
found smooth with an oil stone.
① Coat the inner face of gland(3) with
hydraulic oil.
3

(740-3A) 6-79(1)

② Coat dust wiper(8) with grease and fit

Press here
dust wiper(8) to the bottom of the hole of (Straight down)
dust wiper.
Metal
③ At this time, press a pad metal to the
8
metal ring of dust seal.
Fit snap ring(9) to the stop face.

(740-3A) 6-79(2)

④ Fit back up ring(6), rod seal(5) and buffer

ring(7) to corresponding grooves, in that
order.
※ Coat each packing with hydraulic oil
Wrong Right
before fitting it.
※ Insert the backup ring until onside of it is
inserted into groove.

(740-3A) 6-79(3)

※ Rod seal(5) has its own fitting direction.

Therefore, confirm it before fitting them.
Push bar
※ Fitting rod seal(5) up side down may
damage its lip. Therefore check the
correct direction that is shown in fig.
5

(740-3A) 6-79(4)

6 -85
 ⑤ Fit back up ring(11) to gland(3).
※ Put the backup ring in the warm water of
30~50° C.
11
⑥ Fit O-ring(9) to gland(3).
10

(740-3A) 6-80(1)

(2) Assemble piston assembly

※ Check for scratches or rough surfaces if 12
found smooth with an oil stone.
① Coat the outer face of piston(12) with
hydraulic oil.

(740-3A) 6-80(2)

② Fit piston seal(15) to piston

※ Put the piston seal in the warm water of
15
60~100° C for more than 5 minutes.
※ After assembling the piston seal, press
its outer diameter to fit in.

(740-3A) 6-80(3)

③ Fit wear ring(16), dust ring(17) to

piston(12). 17 15 16 12
④ Fit O-ring(13) and backup ring(14) to
piston(12).

(740-3A) 6-80(4)

6 -86
(3) Install piston and gland assembly
Gland assembly
① Fix the piston rod assembly to the work
bench.
Piston rod
② Apply hydraulic oil to the outer surface of
piston rod(2), the inner surface of piston
and gland.
③ Insert gland assembly to piston rod(2).

(740-3A) 6-81(1)

④ Fit piston assembly to piston rod.

Piston assembly
Piston rod

(740-3A) 6-81(2)

⑤ Tighten nylon nut(18) to piston rod(2)

・Tightening torque:250±25kgf・m 2 18
(1808±181lbf・ft)

(740-3A) 6-81(3)

6 -87
(4) Overall assemble Fix with a bar
① Place a V-block on a rigid work bench.
Mount the cylinder tube assembly(1) on it
Lift
and fix the assembly by passing a bar
through the clevis hole to lock the
assembly.
Straight
② Insert the piston rod assembly in to the
cylinder tube assembly, while lifting and
moving the piston rod assembly with a
Apply liquid packing (740-3A) 6-82(1)
crane.
※ Be careful not to damage piston seal by
thread of cylinder tube.
③ Match the bolts holes in the cylinder Tube
head flange to the tapped holes in the
cylinder tube assembly and tighten
socket bolts to a specified torque. Piston rod
※ Refer to the table of tightening torque. Hexagon
socket bolt

Gland
(740-3A) 6-82(2)

6 -88