Hyundai Excavator R210LC-7. Service and repair manual

3 - 8

When carrying out the combined operation of swing and boom or arm, the boom or arm operating
speed is lowered then normal operation.
To increase working efficieny, swing speed reducing system is used.
When heavy duty working mode in work mode is on, pilot oil from pilot pump flow into Pns port in
main control valve through solenoid valve. Pns oil pressure move swing reducing spool to lower
positon and oil flow rate to the swing motor decreased.
Then, the boom or arm speed is increased.
This is called the boom priority system.

3. BOOM PRIORITY SYSTEM

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

(XBp1)

SWING MOTOR

TRAVEL MOTOR

HYDRAULIC TANK

FRONT

PUMP

REAR
PUMP

SW AM

BK BM

XBa1

XBk

XAb1 XBb1

XAk

XAtr

XBtr

dr2

PG(S/Motor)
PG(MCV)

Pm1

Pm2

XBtl

XAtl

XBs

XAa1

Pns

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAs

XAtl

XBs

XAs

Pns

Dr6

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

3 - 9

When the travel speed switch is pushed, the travel speed solenoid valve is actuated and the
discharged oil from the pilot pump flows to the Pk port of pilot valve in the travel motors.
As a result, the control piston is pushed by the main oil flow, thus the displacement is minimized.
When the travel speed switch is pushed once more, the travel speed solenoid valve is return to
original position by the force of spring, the hydraulic oil of Pk port retums to the hydraulic tank.
As a result, the control piston is returned by the main oil flow, thus the displacement is maximized.

4. TRAVEL SPEED CONTROL SYSTEM

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

(XBp1)

SWING MOTOR

HYDRAULIC TANK

FRONT

PUMP

REAR
PUMP

SW AM

BK BM

XBa1

XBk

XAb1 XBb1

XAk

XAtr

XBtr

dr2

PG(S/Motor)
PG(MCV)

Pm1

Pm2

XBtl

XAtl

XBs

XAa1

Pns

dr3

TRAVEL MOTOR

RED

PILOT VALVE

CONTROL PISTON

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAs

XAtl

XBs

XAs

Pns

Dr6

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

3 - 10

When the power boost switch on the left control lever is pushed ON, the power boost solenoid valve
is actuated, the discharged oil from the pilot pump flows into Pz port of the main relief valve of main
control valve; then the setting pressure of the main relief valve is raised from 330kgf/cm

to 360kgf/cm

for increasing the digging power. And even when pressed continuously, it is canceled after 8
seconds.

5. MAIN RELIEF PRESSURE CHANGE SYSTEM

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

XAtl

XBs

XAs

Pns

Dr6

XAb2

XBa2

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Dr1

XAa1

XAa2

XBa1

XBtl

Btr

(XBp1)

SWING MOTOR

TRAVEL MOTOR

HYDRAULIC TANK

FRONT

PUMP

REAR
PUMP

SW AM

BK BM

XBa1

XBk

XAb1 XBb1

XAk

XAtr

XBtr

dr2

PG(S/Motor)
PG(MCV)

Pm1

Pm2

XBtl

XAtl

XBs

XAa1

Pns

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAs

3 - 11

When the breaker operation mode is selected on the cluster, max flow cut off solenoid valve actuates
automatically.
Thus pilot pressure(Pm1,2) is sent to the regulator and pump discharge volume is decreased.

6. MAX FLOW CUT OFF SYSTEM

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

XAtl

XBs

XAs

XAb2

XBa2

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Dr1

XAa1

XAa2

XBa1

XBtl

Btr

(XBp1)

SWING MOTOR

TRAVEL MOTOR

HYDRAULIC TANK

SW AM

BK BM

XBa1

XBk

XAb1 XBb1

XAk

XAtr

XBtr

dr2

PG(S/Motor)

Pm1

Pm2

XBtl

XAtl

XBs

XAs

XAa1

Pns

dr1

Pm2

(Pi2)

PG(S/Motor)

PG(MCV)

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

Pm1

(Pi1)

Pns

Dr6

3 - 12

When the swing control lever is tilted, the pilot oil flow into SH port of shuttle valve, this pressure
move spool so, discharged oil from pilot valve flow into PG port.
This pressure is applied to swing motor disc, thus the brake is released.
When the swing control lever is set in the neutral position, oil in the swing motor disc cylinder is
drained, thus the brake is applied.

7. SWING PARKING BRAKE RELEASE

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

XAtl

XBs

XAs

XAb2

XBa2

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Dr1

XAa1

XAa2

XBa1

XBtl

Btr

(XBp1)

SWING MOTOR

TRAVEL MOTOR

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

XBs

XAs

dr4

HYDRAULIC TANK

FRONT

PUMP

REAR
PUMP

SW AM

BK BM

XBa1

XBk

XAb1 XBb1

XAk

XAtr

XBtr

dr2

PG(S/Motor)

PG(MCV)

Pm1

Pm2

XBtl

XAtl

XBs

XAa1

Pns

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAs

Pns

Dr6

3 - 13

When the right control lever is pulled back, the boom spools in the main control valve are moved to
the up position by the pilot oil pressure from the remote control valve.
The oil from the front and rear pump flows into the main control valve and then goes to the large
chamber of boom cylinders.
At the same time, the oil from the small chamber of boom cylinders returns to the hydraulic oil tank
through the boom spool in the main control valve. When this happens, the boom goes up.
The excessive pressure in the boom cylinder bottom end circuit is prevented by relief valve.
When the boom is up and the control lever is returned to neutral position, the circuit for the holding
pressure at the bottom end of the boom cylinder is closed by the boom holding valve.
This prevents the hydraulic drift of boom cylinder.

1. BOOM UP OPERATION

XAtl

XBs

XAs

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

(XBp1)

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

SWING MOTOR

TRAVEL MOTOR

HYDRAULIC TANK

FRONT

PUMP

REAR
PUMP

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

Pns

Dr6

GROUP 4 SINGLE OPERATION

3 - 13

1. BOOM UP OPERATION

XAtl

XBs

XAs

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

(XBp1)

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

SWING MOTOR

TRAVEL MOTOR

HYDRAULIC TANK

FRONT

PUMP

REAR
PUMP

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

Pns

Dr6

GROUP 4 SINGLE OPERATION

3 - 14

When the right control lever is pushed forward, the boom spools in the main control valve are moved
to the down position by the pilot oil pressure from the remote control valve.
The oil from the rear pump flows into the main control valve and then goes to the small chamber of
boom cylinders. At the same time, the oil from the large chamber of boom cylinders returns to the
hydraulic tank through the boom spool in the main control valve.
When the down speed of boom is faster, the oil returned from the large chamber of boom cylinder
combines with the oil from the rear pump, and flows into the small chamber of the cylinder.
This prevents cylinder cavitation by the negative pressure when the rear pump flow can not match
the boom down speed. And the excessive pressure in the boom cylinder rod end circuit is
prevented by the relief valve.

2. BOOM DOWN OPERATION

XAtl

XBs

XAs

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

(XBp1)

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

SWING MOTOR

TRAVEL MOTOR

FRONT

PUMP

REAR
PUMP

HYDRAULIC TANK

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

Pns

Dr6

3 - 15

When the left control lever is pulled back, the arm spools in the main control valve are moved the to
roll in position by the pilot oil pressure from the remote control valve.
The oil from the front and rear pump flows into the main control valve and then goes to the large
chamber of arm cylinder.
At the same time, the oil from small chamber of arm cylinder returns to the hydraulic oil tank through
the arm spool in the main control valve. When this happens, the arm rolls in.
The cavitation which will happen to the bottom of the arm cylinder is also prevented by the make-up
valve in the main control valve.

3. ARM ROLL IN OPERATION

XAtl

XBs

XAs

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

(XBp1)

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

SWING MOTOR

TRAVEL MOTOR

FRONT

PUMP

REAR
PUMP

HYDRAULIC TANK

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

Pns

Dr6

3 - 16

When the left control lever is pushed forward, the arm spool in the main control valve are moved to
the roll out position by the pilot oil pressure from the remote control valve.
The oil from the front and rear pump flows into the main control valve and then goes to the small
chamber of arm cylinder.
At the same time, the oil from the large chamber of arm cylinder returns to the hydraulic oil tank
through the arm spool in the main control valve. When this happens, the arm rolls out.
The cavitation which will happen to the rod of the arm cylinder is also prevented by the make-up
valve in the main control valve.

4. ARM ROLL OUT OPERATION

XAtl

XBs

XAs

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

(XBp1)

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

SWING MOTOR

TRAVEL MOTOR

FRONT

PUMP

REAR
PUMP

HYDRAULIC TANK

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

Pns

Dr6

3 - 17

When the right control lever is pulled left, the bucket spool in the main control valve is moved to the
roll in position by the pilot oil pressure from the remote control valve.
The oil from the rear pump flows into the main control valve and then goes to the large chamber of
bucket cylinder.
At the same time, the oil from the small chamber of bucket cylinder returns to the hydraulic oil tank
through the boom spool in the main control valve. When this happens, the bucket rolls in.
The cavitation which will happen to the bottom of the bucket cylinder is also prevented by the make-
up valve in the main control valve.

5. BUCKET ROLL IN OPERATION

XAtl

XBs

XAs

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

(XBp1)

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

SWING MOTOR

TRAVEL MOTOR

FRONT

PUMP

REAR
PUMP

HYDRAULIC TANK

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

Pns

Dr6

3 - 18

When the right control lever is pushed right, the bucket spool in the main control valve is moved to
the roll out position by the pilot oil pressure from the remote control valve.
The oil from the front pump flows into the main control valve and then goes to the small chamber of
bucket cylinder.
At the same time, the oil from the large chamber of bucket cylinder retums to the hydraulic oil tank
through the bucket spool in the main control valve. When this happens, the bucket rolls out.
The cavitation which will happen to the rod of the bucket cylinder is also prevented by the make-up
valve in the main control valve.

6. BUCKET ROLL OUT OPERATION

XAtl

XBs

XAs

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

(XBp1)

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

SWING MOTOR

TRAVEL MOTOR

FRONT

PUMP

REAR
PUMP

HYDRAULIC TANK

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

Pns

Dr6

3 - 19

When the left control lever is pushed left or right, the swing spool in the main control valve is moved
to the left or right swing position by the pilot oil pressure from the remote control valve.
The oil from the rear pump flows into the main control valve and then goes to the swing motor.
At the same time, the return oil from the swing motor returns to the hydraulic oil tank through the
swing spool in the main control valve.
When this happens, the superstructure swings to the left or right.
The swing parking brake, make up valve and the overload relief valve are provided in the swing
motors. The cavitation which will happen to the swing motor is also prevented by the make up valve
in the swing motor itself.

7. SWING OPERATION

XAtl

XBs

XAs

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

(XBp1)

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

SWING MOTOR

TRAVEL MOTOR

XBs

XAs

dr4

HYDRAULIC TANK

FRONT

PUMP

REAR
PUMP

SW AM

BK BM

XBa1

XBk

XAb1 XBb1

XAk

XAtr

XBtr

dr2

PG(S/Motor)
PG(MCV)

Pm1

Pm2

XBtl

XAtl

XBs

XAa1

Pns

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

XAs

Pns

Dr6

3 - 20

SWING CIRCUIT OPERATION

dr4

C(MAKE UP PORT)

PARKING BRAKE
BRAKE RELEASE VALVE
BRAKE OFF
BRAKE ON

MAKE UP VALVE

MOTOR BRAKE VALVE

TO/FROM MAIN CONTROL VALVE

MOTOR BRAKE VALVE

Motor brake valve for the swing motor limits to cushion the starting and stopping pressure of swing
operation.

MAKE UP VALVE

The make up valves prevent cavitation by supplying return oil to the vacuum side of the motor.

PARKING BRAKE

In case that the parking, of the machine at slope is required during operation, there is the danger of
involuntary swing caused by the self weight of the machine. The brake is connected to prevent this
involuntary swing.

PARKING BRAKE "OFF" OPERATION

The parking brake is released by the pilot pressure oil from the pilot pump.
When the left control lever placed in the swing position, the pilot pressure at the shuttle valve is
transferred to the brake release valve and the brake release valve is change over. Then the pilot
pressure lift the brake piston and release the parking brake.

PARKING BRAKE "ON" OPERATION

When the control lever placed in the neutral position, the pressure of the pilot oil passage down.
Then the brake release valve returned to the neutral position and the oil is returned from the brake
piston to the tank. And the brake is set to 'ON".

BYPASS VALVE

This bypass valve absorbs shocks produced as swing motion stops and reduced oscillation cause
by swing motion.

3 - 21

When the travel levers are pushed forward or reverse position, the travel spools in the main control
valve are moved to the forward or reverse travel position by the pilot oil pressure from the remote
control valve.
The oil from the both pumps flows into the main control valve and then goes to the both travel motors
through the turning joint.
The return oil from both travel motors returns to the hydraulic oil tank through the turning joint and the
travel spools in the main control valve.
When this happens, the machine moves to the forward or reverse.

8. TRAVEL FORWARD AND REVERSE OPERATION

XAtl

XBs

XAs

XAb2

XBa2

Dr1

XAa1

XAa2

XBa1

XBtl

(XBp1)

PILOT
PUMP

TRAVEL(LH)

SWING

BOOM 2

ARM 1

ARM 2

BUCKET

BOOM 1

OPTION

TRAVEL(RH)

XAtr

XA0

Atr

XB0

XBtr

Ab1

Bb1

XAb

XBb

Dr4

PbL

XAb2

XBa2

XAa2

(XBp2)

PBP

PaL

Dr3

Dr2

XAk

Ak1

Bk1

XBk

Btr

SWING MOTOR

HYDRAULIC TANK

FRONT

PUMP

REAR
PUMP

SW AM

BK BM

XBa1

XBk

XAb1 XBb1

XAk

XAtr

XBtr

dr2

PG(S/Motor)
PG(MCV)

Pm1

Pm2

XBtl

XAtl

XBs

XAa1

Pns

dr3

TRAVEL MOTOR

RED

ARM

CYLINDER

BUCKET

CYLINDER

BOOM

CYLINDER

XAs

Pns

Dr6

3 - 22

TRAVEL CIRCUIT OPERATION

RED

dr3

TURNING JOINT

TO/FROM MAIN CONTROL VALVE

CHECK VALVE

COUNTER

BALANCE VALVE

OVERLOAD

RELIEF VALVE

Valves are provided on travel motors to offer the following functions.

COUNTER BALANCE VALVE

When stopping the motor of slope descending, this valve to prevent the motor over run.

OVERLOAD RELIEF VALVE

Relief valve limit the circuit pressure below 365kgf/cm

to prevent high pressure generated at at time

of stopping the machine. Stopping the motor, this valve sucks the oil from lower pressure passage
for preventing the negative pressure and the cavitation of the motor.

Hyundai Excavator R210LC-7. Service and repair manual - page 10