Hyundai Excavator R450LC-7. Service and repair manual - page 24

8-8

INSTALL 

Carry out installation in the reverse order
to removal

Remove the suction strainer and clean it.

Replace the return filter with a new one.

Remove breather and clean it.

After adding oil to the hydraulic tank to
the specified level.

Bleed the air from the hydraulic pump.

Remove the air vent plug(2EA)
Tighten plug lightly
Start the engine, run at low idling, and
check oil come out from plug.
Tighten plug.

Start the engine, run at low idling(3~5
minutes) to circulate the oil through the
system.

Confirmed the hydraulic oil level and
check the hydraulic oil leaks or not.

2)

(1)

(2)

(3)

(4)

(5)

(6)

①
②
③

④

(7)

(8)

8-10

04

Gear pump

080 Proportional reducing 

valve assy

111 Drive shaft
113 Driven shaft
123 Roller bearing
124 Needle bearing
126 Spacer
127 Spacer
128 Bearing spacer
129 Bearing spacer
130 Booster
131 Booster cover
141 Cylinder block
151 Piston
152 Shoe
153 Plate
156 Bushing
157 Cylinder spring
171 Front casing
191 Drive gear
192 Driven gear
211 Shoe plate
212 Swash plate
214 Tilting bushing bushing
251 Swash plate support
261 Front cover

262 Cover
271 Pump casing
312 Valve cover
313 Valve plate(R)
314 Valve plate(L)
405 Hexagon socket bolt
406 Hexagon socket bolt
408 Hexagon socket bolt
409 Hexagon socket bolt
410 Hexagon socket bolt
411 Hexagon socket bolt
412 Hexagon socket bolt
413 Hexagon socket bolt
467 Plug
469 Plug
490 Plug
491 Plug
492 Restrictor
493 Plug
531 Tilting pin
532 Servo piston
534 Stopper(L)
535 Stopper(S)
536 Servo cover
541 Seat
543 Stopper
545 Steel ball

548 Feed back pin
702 O-ring
709 O-ring
711 O-ring
712 O-ring
724 O-ring
725 O-ring
726 O-ring
728 O-ring
732 O-ring
752 Seat packing
774 Oil seal
789 Back up ring
792 Back up ring
806 Nut
807 Nut
823 Snap ring
824 Snap ring
825 Snap ring
827 Snap ring
828 Snap ring
885 Valve plate pin
886 Spring pin
888 Pin
901 Eye bolt
953 Set screw
954 Set screw

8-11

MAIN PUMP(2/2)

079 Proportional reducing valve
325 Valve casing 
407 Hexagon screw

408 Hexagon screw
467 Plug
490 Plug

724 O-ring
725 O-ring
732 O-ring

45070MP04

8-14

DISASSEMBLY 

Select place suitable to disassembling.
Select clean place.
Spread rubber sheet, cloth or so on
overhaul workbench top to prevent parts
from being damaged.
Fix pump casing(271) by using thread
2-M10

×

16 in disassembling.

Remove gear pump, booster cover(131),
booster(130), and cover(262).

3)

(1)

※
※

※

(5)

Remove hexagon socket head cap
screws(412, 413) and remove regulators.
In order to avoid mixing up regulator of
drive shaft side with that of driven shaft
side, mark each of them.

(4)

※

Remove dust, rust, etc, from pump
surfaces with cleaning oil or so on.

Remove outlet port plug(469, lower part of
pump casing) and let the oil out of pump
casing.
In order to be let the oil out of pump
casing easily, remove oil filling port
plug(469, upper part of pump casing).

(2)

(3)

※

45078MP28

45078MP29

45078MP23

8-15

Loosen hexagon socket head cap
screws(410, 411, 412) which tighten valve
cover(312).
Remove regulators before starting this
work.

(6)

※

If necessary, remove needle bearings
(124) from valve cover(312).
Do not remove needle bearings as far as
possible, except when it is considered to
be out of its life span.
Do not loosen hexagon nut(807) of the
valve cover.  If loosened, flow setting will
be changed.

Place pump horizontally on workbench
and separate pump casing(271) and valve
cover(312).
Crane valve cover(312) at this work
because it is heavy(about 60kgf).
There are two spring pins for fixing
position between pump casing(271) and
valve cover(312).  Since they have a tight
fit, remove valve cover(312) upright with
respect to drive shaft(111) and driven
shaft(113), while lightly tapping the valve
cover(312) with a plastic hammer.
Take care not to damage fitting surfaces
between pump casing(271) and valve
cover(312).  Take care not to drop valve
plates(313, 314), check valve subassem-
blies(541, 543, 545), O-rings (724, 725,
726) and seat packing(752) in removing
valve cover(312).

(8)

※

※

(7)

※

※

※

45078MP03

8-16

Pull cylinders out of pump casing(271)
straightly over drive shaft(111) and driven
shaft(113).  Pull out also pistons(151), set
plate(153), spherical bush(156) and
cylinder springs(157) simultaneously.
Take care not to damage sliding surfaces
of cylinder, spherical bush, shoes, swash
plate, and so on.

(9)

※

Remove shoe plate(211) and swash
plate(212) from pump casing(271).

(10)

If  necessary,  remove stopper(L, 534),
stopper(S, 535),  servo  piston(532), tilting
pin(531), and servo cover(536), from
pump casing(271).
In removing tilting pin, use a protector to
prevent pin head from being damaged.
Since adhesive(No.1305N of threebond
make) is applied to fitting areas of tilting
pin and servo piston, take care not to
damage servo piston.
Do not loosen hexagon nut(806) on servo
cover(536).  If loosened, flow setting will
be changed.

(11)

※

※

※

45078MP04

45078MP05

8-17

Remove snap ring(827) and front
cover(261) from front casing(171).
A groove is provided on the outer
circumference of front cover straight with
respect to drive shaft(111) by placing a
minus type screwdriver in the groove.
Since oil seal(774) is fitted on front
cover(261), take care not to damage it in
removing.

Loosen hexagon socket head cap
screws(408) which tighten front
casing(271)

(12)

※

※

(13)

Separate front casing(171) and pump
casing(271).
Take care of front casing not to fall
because it is heavy(about 32kgf).
There are two spring pins(886) for fixing
position between front casing(171) and
pump casing(271).  Tapping lightly with a
plastic hammer, remove front casing(171)
perpendicular to drive shaft(111) because
they are fitted firmly.  When removing, take
care not to damage oil seal sliding surface
of drive shaft(111).
Take care not to damage fitting surfaces
between front casing(171) and pump
casing(271).

(14)

※

※

※

Remove snap rings(823, 825), bearing
spacers(126, 127), drive gear(191), and
driven gear(192).

(15)

45078MP06

45078MP07

45078MP24

8-18

Remove snap ring(828) and bearing
spacer(129) and take out drive shaft(111)
and driven shaft(113) tapping lightly ends
of them.

(16)

If necessary, remove snap rings(824,
825), bearing spacer(128), and roller
bearing(123) from drive shaft(111) and
driven shaft(113).
Do not remove roller bearing as far as
possible, except when it is considered to
be out of its life span.  Use a specified jig
in removing because roller bearing is
shrinkage fitted to shaft.

(17)

※

Loosen hexagon socket head cap
screws(405) which tighten swash plate
supports(251) and pump casing(271).
Adhesive(No.1305N of threebond make)
is applied to hexagon socket head cap
screws(405).

(18)

※

Remove swash plate supports(251) from
pump casing(271).

This is the end of disassembling procedur-
es.

(19)

※

45078MP08

45078MP09

8-19

ASSEMBLY 

For reassembling reverse the disassem-
bling procedures, paying attention to the
following items.

Do not fail to repair the parts damaged
during disassembling, and repair
replacement parts in advance.
Clean each part fully with cleaning oil
and dry it with compressed air.
Do not fail to apply clean working oil to
sliding surfaces, bearings, etc. before
assembling them.
In principle, replace seal parts, such as
O-rings, oil seals, etc.
Apply grease to O-rings, seat packing,
and check valves in assembling them
because they tend to come off.
In case of parallel type pump, rotating
directions of drive shaft and driven shaft
are different.  Take care not to mix up
parts of the drive shaft side with those of
the driven shaft side.
For fitting bolts, plug, etc., prepare a
torque wrench or so on, and tighten them
with specified torques in this
maintenance manual.

(1)

4)

①

②

③

④

⑤

⑥

⑦

Select place suitable to assembling.
Select clean place.
Spread rubber sheet, cloth or so on
overhaul workbench top to prevent parts
from being damaged.
Fix pump casing(271) by using thread
2-M10

×

16 in assembling.

(2)

※
※

※

45078MP10

8-20

Fit swash plates(251) to pump casing
(271) and fix them with hexagon socket
head cap screws(405).
There are O-rings(724) on the matching
surface in contact with pump casing(271).
Fix them with grease so they do not come
off.
Positioning pin(888) is placed on the
pump casing(271) side.  Adjust it so it
enters the groove of swash plate
support(251) and fix it.
Fit swash plate support(251) so it enters
straight, while tapping it lightly.
Apply adhesive(No.1305N of three bond
make) to hexagon socket head cap
screws.

Fit drive gear(191), driven gear(192), and
bearing spacers(126, 127) to drive
shaft(111) and driven shaft(113).  Then fix
them with snap rings(823, 825).
Confirm the attaching direction of drive
gear before fitting.
Direct the sharp edge of snap rings(823,
825) to the outside.

(5)

※

※

To pump casing(271), fit drive shaft(111)
set and driven shaft(113) set with roller
bearing(123), bearing spacer(128), and
snap rings(824, 825).  Then fix them with
snap rings(828).
Direct the sharp edge side of snap
rings(824, 825) to the outside.
Do not tap shafts with hammer or so on.
Assemble them into pump casing tapping
outer race of bearing lightly with plastic
hammer.  Fit them fully using steel bar or so
on.
Both side of snap rings(828) are burnished.

(4)

※

※
※

※

(3)

※

※

※

※

※

45078MP11

45078MP12

45078MP13

45078MP14

8-21

Fit front casing(171) to pump casing(271)
and fix them with hexagon socket head
cap screws(408).
Take care of front casing not to fall
because it is heavy(about 32kgf).
There are two spring pins(886) for fixing
position between front casing(171) and
pump casing(271).  Always fit spring pins
(886) to the pump casing(271) side.
Fit front casing(171) to pump casing(271)
perpendicular to drive shaft(111), while
tapping it lightly because spring pin(886)
has a tight fit.  When fitting, take care not
to damage oil seal sliding surface of drive
shaft(111).
Take care not to damage fitting surfaces of
front casing(171) and pump casing(271).
Apply grease to seat packing(752)
because it tends to come off.

(6)

※

※

※

※

※

Fit front cover(261) to front casing(171)
and fix them with snap ring(827).
Apply grease lightly to oil seal in front
cover.
Assembling oil seal, take full care not to
damage it.
Direct the sharp edge of snap ring(827) to
the outside.

(7)

※

※

※

Place pump casing(271) horizontally.  Fit
servo piston(532), tilting pin(531),
stopper(L, 534), and stopper(S, 535) to
pump casing.  Then fit servo cover(536) to
pump casing and fix them with hexagon
socket head cap screws(406).
Fix pump casing(271) by using thread
2-M10

×

16 in assembling.

In tightening servo piston(532) and tilting
pin(531), use a protector to prevent tilting
pin head and feedback pin from being
damaged.  In addition apply adhesive
(No.1305N of threebond make) to their
threaded sections.

(8)

※

※

45078MP15

45078MP16

45078MP06

8-22

Insert check valve subassemblies(541,
543, 545) and needle bearings to valve
cover(312).
Insert check valve subassemblies into
valve cover in correct order.
Since check valve subassembly tends to
come off, apply grease to matching part of
valve cover(312).

(12)

※

※

Fit valve plates(313, 314) to valve cover,
entering valve plate pin(885) into pin hole.
Take care not to mistake suction/delivery
directions of valve plate.
Apply grease to matching surface in
contact with valve cover(312) because
valve plates(313, 314) tend to come off.

(11)

※

※

Assemble piston cylinder subassembly
[cylinder(141), piston subassembly(151,
152), set plate(153), spherical bush(156),
cylinder spring(157)].  Fit spline phases of
spherical bush and cylinder and insert
piston cylinder subassembly into pump
casing with respect to drive shaft(111) and
driven shaft(113).
Take care not to mix up parts of drive shaft
side with those of driven shaft side.
Confirm that swash plate(212) is not off
from swash plate support(251) and from
tilting pin(531), before inserting them.

(10)

※

※

Fit tilting bush(214) of swash plate(212) to
tilting pin(531) and fit swash plate to
swash plate support(251) correctly.
Take care not to mix up parts of drive shaft
side with those of driven shaft side.
Even after fitting, swash plate(212) comes
off from swash plate support(251), in
some cases.  They do not come off easily
if grease is applied to the sliding surfaces.
Confirm with fingers of both hands that
swash plate can be moved smoothly.

(9)

※

※

※

45078MP17

45078MP25

45078MP18

45078MP26

8-23

Fit O-ring(724, 725, 726) and seat
packing(752) to the matching surface of
pump casing(271) in contact with valve
cover(312).
Since O-rings and seat packing tend to
come off, apply grease to matching
surface.

(13)

※

Fit valve cover(312) to pump casing(271)
and tighten them with hexagon socket
head cap screws(410, 411, 412).
Crane valve cover(312) at this work
because it is heavy(about 60kgf).
Confirm that swash plate(212) is not off
from swash plate support(251) and tilting
pin(531) before fitting.
Needle bearings(124) are located on the
valve cover(312) side place the valve
cover with care.  In order to protect needle
bearing, cover drive shaft(111) and driven
shaft(113) with specified cover shown in
attached dwgs 3 and 4.
When fitting, take care as valve
plates(313, 314) check valve subassem-
blies(541, 543, 545), O-rings (724, 725,
726), and seat packing(752) may come off
in some cases.
There are two spring pins(886) for fixing
position between pump casing(271) and
valve cover(312).  Since spring pin(886)
has a tight fit, fit valve cover(312) upright
to drive shaft(111) and driven shaft(113),
while tapping it with a plastic hammer.
Take care not to damage fitting surfaces
between valve cover(312) and pump
casing(271).

(14)

※

※

※

※

※

※

45078MP19

45078MP20

45078MP21