Hyundai Excavator R210LC-7. Service and repair manual - page 3

1-33

SHOE

9)

B

B

UCKET

10)

Use only oils listed below or equivalent.
Do not mix different brand oil.

9. RECOMMENDED OILS

SECTION  2  STRUCTURE AND FUNCTION

Group   1  Pump Device

2-1

Group   2  Main Control Valve

2-21

Group   3  Swing Device

2-46

Group   4  Travel Device

2-58

Group   5  RCV Lever

2-69

Group   6  RCV Pedal

2-76

2-1

1. STRUCTURE

The pump device consists of main pump, regulator and gear pump.

SECTION  2  STRUCTURE AND FUNCTION

GROUP  1  PUMP DEVICE

P

i1

P

m1

D

r

P

i1

P

m1

P

sv

P

sv

P

m2

P

i2

P

m2

P

i2

a

4

a

4

A

3

B

3

D

r

B

3

B

1

a

3

a

1

a

1

A

1

A

2

A

3

B

3

B

1

D

r

P

i1

P

m1

P

sv

a

2

a

4

a

3

Qmin adjusting screw

Regulator

Regulator

Gear pump

Rear pump

Front pump

Port block

Qmax adjusting screw

Qmin adjusting screw

a

2

Port

A1,2

B1

Dr

Pi1,i2

Pm1,m2

Psv

a1,2,4

a3

A3

B3

Port name

Delivery port

Suction port

Drain port

Pilot port

Qmax cut port

Servo assist port

Gauge port

Gauge port

Gear pump delivery port

Gear pump suction port

Port size

SAE6000psi 3/4"

SAE2500psi 2 1/2"

PF 3/4 - 20

PF 1/4 - 15

PF 1/4 - 15

PF 1/4 - 15

PF 1/4 - 15

PF 1/4-14

PF 1/2 - 19

PF 3/4 - 20

P

m2

P

i2

2-2

MAIN PUMP(1/2)

The main pump consists of two piston pumps(front & rear) and valve block.

1)

04

Gear pump

251

Support

710

O-ring

111

Drive shaft(F)

261

Seal cover(F)

717

O-ring

113

Drive shaft(R)

271

Pump casing

724

O-ring

114

Spline coupling

312

Valve block

725

O-ring

123

Roller bearing

313

Valve plate(R)

728

O-ring

124

Needle bearing

314

Valve plate(L)

732

O-ring

127

Bearing spacer

401

Hexagon socket bolt

774

Oil seal

141

Cylinder block

406

Hexagon socket bolt

789

Back up ring

151

Piston

466

VP Plug

792

Back up ring

152

Shoe

468

VP Plug

806

Hexagon head nut

153

Set plate

490

Plug

808

Hexagon head nut

156

Bushing

531

Tilting pin

824

Snap ring

157

Cylinder spring

532

Servo piston

885

Pin

158

Spacer

534

Stopper(L)

886

Spring pin

211

Shoe plate

535

Stopper(S)

901

Eye bolt

212

Swash plate

548

Pin

953

Set screw

214

Bushing

702

O-ring

954

Set screw

789, 732  532    214   548  531  724   792   534  901   808    954  717    151   152    211   113

535

806

953

886
717
406
261
774

111

824
127
710
123
251

212

702

04

490

153

156 158 157 468 313 124 312 114 466

885

314

141

271

401

728

725

2-3

MAIN PUMP(2/2)

79

Proportional reducing valve

541

Seat

543

Stopper 1

544

Stopper 2

545

Steel ball

544

543

545

541

079

VIEW  A

2-4

REGULATOR(1/2)

2)

A

A

A

B

B

B

SECTION B-B

VIEW  C

P2

Pf

Pm

Pi

KR3G-9C32

755

858

614

615

613

611

438

801

924

647

648

723

642

801

656

438

735

722

897

612

875

874

412

641

730

643

708

644

645

646

728

413

438

496

724

725

436

Port

A

B

Pi

Pm

Port name

Delivery port

Suction port

Pilot port

Qmax cut port

port size

3/4"

2 1/2"

PF 1/4-15

PF 1/4-15

2-5

REGULATOR(2/2)

412

Hexagon socket screw

413

Hexagon socket screw

436

Hexagon socket screw

438

Hexagon socket screw

496

Plug

601

Casing

611

Feed back lever

612

Lever(1)

613

Lever(2)

614

Fulcrum plug

615

Adjust plug

621

Compensator piston

622

Piston case

623

Compensator rod

624

Spring seat(C)

625

Outer spring

626

Inner spring

627

Adjust stem(C)

628

Adjust screw(C)

629

Cover(C)

630

Lock nut

631

Sleeve, pf

641

Pilot cover

642

Pilot cover(QMC)

643

Pilot piston

644

Spring seat(Q)

645

Adjust stem(Q)

646

Pilot spring

647

Stopper

648

Piston(QMC)

651

Sleeve

652

Spool

653

Spring seat

654

Return spring

655

Set spring

656

Block cover

708

O-ring

722

O-ring

723

O-ring

724

O-ring

725

O-ring

728

O-ring

730

O-ring

732

O-ring

733

O-ring

734

O-ring

735

O-ring

755

O-ring

756

O-ring

763

O-ring

801

Nut

814

Snap ring

836

Snap ring

858

Snap ring

874

Pin

875

Pin

887

Pin

897

Pin

898

Pin

924

Set screw

925

Adjust screw(QI)

734

653

654

836

651 652

601

624

629

630

628

655

641

814

898

631

732

733

622

C

801

925

627

732

621

623

625

626

887

763

756

SECTION A-A

2-6

GEAR PUMP

3)

307

Poppet

308

Seat

309

Spring seat

310

Spring

311

Screw

312

Nut

351

Gear case

353

Drive gear

354

Driven gear

355

Filter

361

Front case

433

Flange socket

434

Flange socket

435

Flange socket

466

Plug

700

Ring

710

O-ring

725

O-ring

732

O-ring

850

Snap ring

700

354

351

433

434

311

312

850

355

a3

A3

B3

710

435

361

353

732

309

307

310

308

434

466, 725

2-7

Rotary group

The rotary group consists of drive shaft
(F)(111), cylinder block(141), piston
shoes(151,152), set plate(153), spherical
bush(156), spacer(158) and cylinder
spring(157).   The drive shaft is supported
by bearing(123,124) at its both ends.
The shoe is caulked to the piston to from
a spherical coupling.   It has a pocket to
relieve thrust force generated by loading
pressure and the take hydraulic balance
so that it slides lightly over the shoe
plate(211).   The sub group composed by
a piston and a shoe is pressed against
the shoe plate by the action of the
cylinder spring via a retainer and a
spherical bush.
Similarly, the cylinder block is pressed
against valve plate(313) by the action of
the cylinder spring.

Swash plate group

The swash plate group consists of swash
plate(212), shoe plate(211), swash plate
support(251), tilting bush(214), tilting
pin(531) and servo piston(532).
The swash plate is a cylindrical  part
formed on the opposite side of the sliding
surface of the shoe and is supported by
the swash support.
If the servo piston moves to the right and
left as hydraulic force controlled by the
regulator is admitted to hydraulic
chamber located on both sides of the
servo piston, the swash plate slides over
the swash plate support via the spherical
part of the tilting pin to change the tilting
angle(

)

2. FUNCTION

MAIN PUMP

The pumps may classified roughly into the rotary group performing a rotary motion and working as
the major part of the whole pump function: the swash plate group that varies the delivery rates: and
the valve cover group that changes over oil suction and discharge.

1)

(1) 

(2)

157

211

211

123

111

212

251

532

151
152

531
548

214

124

313

141

158

156

153

2-8

Valve block group

The valve block group consists of valve
block(312), valve plate(313) and valve
plate pin(885).
The valve plate having two melon-
shaped ports is fixed to the valve block
and feeds and collects oil to and from the
cylinder block.
The oil changed over by the valve plate is
connected to an external pipeline by way
of the valve block.
Now, if the drive shaft is driven by a prime
mover(electric motor, engine, etc), it
rotates the cylinder block via a spline
linkage at the same time.   If the swash
plate is tilted as in Fig(previous page) the
pistons arranged in the cylinder block
make a reciprocating motion with respect
to the cylinder block, while they revolve
with the cylinder block.
If you pay attention to a single piston, it
performs a motion away from the valve
plate(oil sucking process) within 180
degrees, and makes a motion towards
the valve plate(or oil discharging process)
in the rest of 180 degrees.   When the
swash plate has a tilting angle of zero,
the piston makes no stroke and
discharges no oil.

(3)

313

885

312

2-9

Negative flow control

By changing the pilot pressure Pi, the
pump tilting angle(delivery flow) is
regulated arbitrarily, as shown in the
figure.
This regulator is of the negative flow
control in which the delivery flow Q
decreases as the pilot pressure Pi rises.
With this mechanism, when the pilot
pressure corresponding to the flow
required for the work is commanded, the
pump discharges the required flow only,
and so it does not consume the power
uselessly.

REGULATOR

Regulator consists of the negative flow control, total horse power control and power shift control
function.

2)

(1) 

Pilot pressure, P

i

Delivery flow

, Q

2-10

Flow reducing function

As the pilot pressure Pi rises, the pilot piston(643) moves to the right to a position where the
force of the pilot spring(646) balances with the hydraulic force.
The groove(A) in the pilot piston is fitted with the pin(875) that is fixed to lever 2(613).   Therefore,
when the pilot piston moves, lever 2 rotates around the fulcrum of point B [fixed by the fulcrum
plug(614) and pin(875)].   Since the large hole section(C) of lever 2 contains a protruding
pin(897) fixed to the feedback lever(611), the pin(897) moves to the right as lever 2 rotates.
Since the opposing-flat section(D) of the feedback lever is fitted with the pin(548) fixed by the
tilting pin(531) that swings the swash plate, the feedback lever rotates around the fulcrum of
point D, as the pin(897) moves.
Since the feedback lever is connected with the spool(652) via the pin(874), the spool moves to
the right.
The movement of the spool causes the delivery pressure P1 to connect to port CL through the
spool and to be admitted to the large diameter section of the servo piston.   The delivery
pressure P1 that is constantly admitted to the small diameter section of the servo piston moves
the servo piston to the right due to the area difference, resulting in decrease of the tilting angle.
When the servo piston moves to the right, point D also moves to the right.   The spool is fitted
with the return spring(654) and is tensioned to the left at all times, and so the pin(897) is pressed
against the large hole section(C) of lever 2.
Therefore, as point D moves, the feedback lever rotates around the fulcrum of point C, and the
spool is shifted to the left.   This causes the opening between the sleeve(651) and spool(652) to
close slowly, and the servo piston comes to a complete stop when it closes completely.

643

654

651

652

613

646

B(E)

874
897

875

C

A

611

C

L

P

1

531

548

D

Small diameter
chamber

Servo piston

Large diameter
chamber

2-11

Flow increasing function

As the pilot pressure Pi decreases, the pilot piston(643) moves to the left by the action of the
pilot spring(646) and causes lever 2(613) to rotate around the fulcrum of point B.   Since the
pin(897) is pressed against the large hole section(C) of lever 2 by the action of the return
spring(654) via the spool(652), pin(874), and feedback lever(611), the feedback lever rotates
around the fulcrum of point D as lever 2 rotates, and shifts the spool to the left.   Port CL opens
a way to the tank port as the spool moves.   This deprives the large diameter section of the
servo piston of pressure, and shifts the servo piston to the left by the discharge pressure P1 in
the small diameter section, resulting in an increase in the flow rate.
As the servo piston moves, point D also moves to the left, the feedback lever rotates around the
fulcrum of point C, and the spool moves to the right till the opening between the spool and
sleeve is closed.

643

654

651

652

613

646

B(E)
874
897

875

C

611

C

L

P

1

531

548

D

Small diameter
chamber

Servo piston

Large diameter
chamber

2-12

The flow control characteristic can be
adjusted with the adjusting screw.
Adjust it by loosening the hexagon
nut(801) and by tightening(or loosening)
the hexagonal socket head screw(924).
Tightening the screw shifts the control
chart to the right as shown in the figure.

Adjusting values are shown in table.

Adjustment of flow control characteristic

Pilot pressure, P

i

Delivery flow

, Q

Adjustment of flow control 

characteristic

Speed

Tightening 

Flow control  Flow change 

amount of 

starting 

amount 

adjusting pressure 

screw(924)

change 
amount

(min 

-1

)

(Turn)

(kgf/cm

2

)

( /min)

2100

+1/4

+1.5

+13.6

801
924

2-13

Total horsepower control

The regulator decreases the pump tilting
angle(delivery flow) automatically to limit
the input torque within a certain value
with a rise in the delivery pressure P1 of
the self pump and the delivery pressure
P2 of the companion pump.
(The input horsepower is constant when
the speed is constant.)
Since the regulator is of the simultaneous
total horsepower type that operates by
the sum of load pressures of the two
pumps in the tandem double-pump
system, the prime mover is automatically
prevented from being overloaded,
irrespective of the load condition of the
two pumps, when horsepower control is
under way.
Since this regulator is of the simultaneous
total horsepower type, it controls the
tilting angles(displacement volumes) of
the two pumps to the same value as
represented by the following equation :
Tin = P1 q/2

+ P2 q/2

= (P1+P2) q/2

The horsepower control function is the
same as the flow control function and is
summarized in the following.(For detailed
behaviors of respective parts, refer to the
section of flow control).

(2)

Delivery pressure, (P

1

+P

2

)

Delivery flow

, Q