SANY Crawler Hydraulic Excavator SY195C9, SY205C9, SY215C9, SY225C9. Service Manual - page 13

4-111

Structure and Function

Operation

1. When in neutral

●

Ports (A) and (B) of the control valve and
ports (P1) and (P2) of the pilot valve are
connected to drain chamber (D) via ori

(f) in plunger (1).

2. Fine control (Neutral to fi ne control)

●

When piston (4) is pushed by disc (5),
retainer (9) is pushed, plunger (1) is also
pushed by metering spring (2), and moves
down.

●

When ori

ce (f) is shut off from drain cham-

ber (D), it is almost simultaneously inter-
connected to pump pressure chamber (PP).
Pilot pressurized oil of the control pump is
led to port (A) from port (P1) via ori

ce (f).

When the pressure at port (P1) becomes
higher, plunger (1) is pushed back and
orifice (f) is shut off from pump pressure
chamber (PP). At almost the same time, it
is connected to drain chamber (D) to re-
lease the pressure at port (P1). As a result,
plunger (1) moves up and down until the
force of metering spring (2) is balanced
with the pressure at port (P1).

●

The relationship of the position of plunger
(1) and body (10) [ori

ce (f) is in the middle

between drain chamber (D) and pump
pressure chamber (PP)] does not change
until retainer (9) contacts plunger (1). Me-
tering spring (2) contracts in proportion to
the stroke of the control lever. Pressure
at port (P1) also rises in proportion to the
stroke of the control lever. In this way, the
control valve spool moves to a position
where the pressure of chamber (A) (same
as pressure at port (P1)) and the force of
the return spring of the control valve spool
are balanced.

ZX215-1002115

Control valve

Pilot

pump

ZX215-1002116

Control valve

Pilot

pump

4-112

Structure and Function

3. During fi ne control (When control lever

is returned)

●

When disc (5) starts to return, plunger
(1) is pushed up by the force of centering
spring (3) and the pressure at port (P1).

●

Because of this, ori

ce (f) is connected to

drain chamber (D), and the pressurized oil
at port (P1) is released.

●

If the pressure of port (P1) is lowered ex-
cessively, plunger (1) is pushed down by
metering spring (2).

●

Orifice (f) is shut off from drain chamber
(D), and it is almost simultaneously in-
terconnected to pump pressure chamber
(PP). Pump pressure is supplied until the
pressure at port (P1) recovers to the level
equivalent to the lever position.

●

When the spool of the control valve re-
turns, the oil in drain chamber (D)

ows in

from ori

ce (f) in the valve on the side that

is not working. The oil passes through port
(P2) and enters chamber (B) to replenish
the chamber with pressurized oil.

4. At full stroke

●

Disc (5) pushes down piston (4), and re-
tainer (9) pushes down plunger (1).

●

Ori

ce (f) is shut off from drain chamber (D),

and is interconnected to pump pressure
chamber (PP).

●

Therefore, the pilot pressure oil from
the self pressure reducing valve passes
through orifice (f) and flows to chamber
(A) from port (P1) to push the control valve
spool.

●

The oil returning from chamber (B) passes
from port (P2) through ori

ce (f) and

ows

to drain chamber (D).

ZX215-1002117

Control valve

Pilot

pump

ZX215-1002118

Control valve

Pilot

pump

4-113

Structure and Function

4.6.8.2 Travel PPC valve

ZX215-1002119

P: From pilot pump
P1: L.H. reverse
P2: L.H. forward
P3: R.H. reverse

P4: R.H. forward
P5: Travel signal
P6: Travel signal
T: To

tank

4-114

Structure and Function

Plate

Body

Piston

Collar

Centering

spring

Metering

spring

Valve

ZX215-1002120

37~30Nm

65~45Nm

13~11Nm

C-C

8~6Nm

B-B

4-115

Structure and Function

Operation

1. When in neutral

●

Ports (A) and (B) of the control valve and
ports (P1) and (P2) of the Pilot valve are
connected to drain chamber (D) via ori

(f) in plunger (1).

2. Fine control (Neutral to fi ne control)

●

When piston (4) is pushed by lever (5),
retainer (9) is pushed, plunger (1) is also
pushed by metering spring (2), and moves
down. When ori

ce (f) is shut off from drain

chamber (D), it is almost simultaneously
interconnected to pump pressure chamber
(PP).

●

Pilot pressurized oil of the control pump is
led to port (A) from port (P1) via ori

ce (f).

●

As a result, plunger (1) moves up and
down until the force of metering spring (2)
is balanced with the pressure at port (P1).

●

The relationship of the position of plunger
(1) and body (10) [ori

ce (f) is in the middle

between drain chamber (D) and pump
pressure chamber (PP)] does not change
until retainer (9) contacts plunger (1).

●

Metering spring (2) contracts in proportion
to the stroke of the control lever.

●

Pressure at port (P1) also rises in propor-
tion to the stroke of the control lever.

●

In this way, the control valve spool moves
to a position where the pressure of cham-
ber (A) (same as pressure at port (P1)) and
the force of the return spring of the control
valve spool are balanced.

ZX215-1002121

Pilot pump

Control valve

ZX215-1002122

5
4

Pilot pump

Control valve

4-116

Structure and Function

3. Fine control (When control lever is

returned)

●

When lever (5) starts to return, plunger
(1) is pushed up by the force of centering
spring (3) and pressure at port (P1).

●

Because of this, ori

ce (f) is connected to

drain chamber (D), and the pressurized oil
at port (P1) is released.

●

If the pressure of port (P1) is lowered ex-
cessively, plunger (1) is pushed down by
metering spring (2).

●

Ori

ce (f) is shut off from drain chamber (D),

and it is almost simultaneously intercon-
nected to pump pressure chamber (PP).

●

Pump pressure is supplied until the pres-
sure at port (P1) recovers to the level
equivalent to the lever position.

●

When the spool of the control valve re-
turns, the oil in drain chamber (D)

ows in

from ori

ce (f) in the valve on the side that

is not working. The oil passes through port
(P2) and enters chamber (B) to replenish
the chamber with pressurized oil.

4. At full stroke

●

Lever (5) pushes down piston (4), and re-
tainer (9) pushes down plunger (1).

●

Ori

ce (f) is shut off from drain chamber (D),

and is interconnected to pump pressure
chamber (PP).

●

Therefore, the pilot pressure oil from
the self pressure reducing valve passes
through orifice (f) and flows to chamber
(A) from port (P1) to push the control valve
spool.

●

The oil returning from chamber (B) passes
from port (P2) through ori

ce (f) and

ows

to drain chamber (D).

ZX215-1002123

f’

Pilot pump

Control valve

ZX215-1002124

f’

5
4

Pilot pump

Control valve

4-117

Structure and Function

Travel hi/lo speed solenoid valve

Swing priority solenoid valve

Bucket

con

uence solenoid valve

Boom to arm priority solenoid valve

Pilot lockout solenoid valve

To oil tank

From accumulator and pilot pump

To center swivel joint port

To main valve port PsP

To main valve port Xbp2

To main valve port PnA2

To pilot valve block P

Pilot valve lock, travel speed, bucket con

uence, swing priority

4.6.9 Solenoid valve

NOTE: For the location of the solenoid valve on the machine, see “Hydraulic equipment layout”
on page 4-24.

WX13060401

4-118

Structure and Function

4.6.10 Accumulator

Gas

plug

Shell

Poppet

Holder

Bladder

Oil

port

Specifi cations

Gas capacity: 300 cm³

ZX215-1002126

4-119

Structure and Function

4.6.11 Pilot oil fi lter

ZX215-1002127

Name

plate

Head

cover

O-ring

Seal

Filter

Case

Max. delivery: 40 L/min
Filter

neness: 10

Operating pressure: 20 Mpa
Max. operating pressure: 40 Mpa
Pressure loss: 0.05 Mpa
Max. allowable pressure difference: 1 Mpa
Speci

cation of inlet/outlet port o-ring: 30×3.1

Specifi cations

Structure and Function

4.6.12 Pump oil pressure sensor

Function

●

This sensor measures pump oil pressure
and uses it to control various machine op-
erations. When oil pressure compresses
the diaphragm, it deforms and this is de-
tected in the form of electric signals.

Pressure

connector

Name

plate

Connector

Vent

hole

ZX215-1002128

4-121

Structure and Function

ZX215-1002129

267±35N·m

27.2±3.6kgm

56.9±10.7N·m

5.8±1.1kgm

544.9±5.1kgm

5340±50N·m

ZX215-1002130

37.4±3.6kgm

367±35N·m

56.9±10.7N·m

5.8±1.1kgm

806.1±5.1kgm

7900±50N·m

ZX215-1002131

27.2±3.6kgm

267±35N·m

5.8±1.1kgm

56.9±10.7N·m

559.2±5.1kgm

5480±50N·m

4.6.13 Hydraulic cylinder

Boom cylinder

Arm cylinder

Bucket cylinder

4-122

Structure and Function

100 hours greasing

500 hours greasing

Unit: mm

No.

Check item

Criteria

Remedy

Clearance between pis-
ton rod and bushing

Cylinder

Standard

size

Tolerance

Standard

clearance

Clearance

limit

Replace

bushing

Shaft

Hole

Boom

-0.036 +0.222

0.083 – 0.312

0.412

-0.090 +0.047

Arm

-0.036 +0.222

0.083 – 0.312

0.412

-0.090 +0.047

Bucket

-0.030 +0.258

0.078 – 0.334

0.434

-0.076 +0.048

Clearance between pis-
ton rod support pin and
bushing

Boom

-0.030 +0.246

0.230 – 0.322

1.0

Replace

pin or

bushing

-0.076 +0.200

Arm

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

Bucket

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

Clearance between cyl-
inder bottom support pin
and bushing

Boom

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

Arm

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

Bucket

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

Unit: mm

No.

Check item

Criteria

Remedy

Clearance between pis-
ton rod and bushing

Cylinder

Standard

size

Tolerance

Standard

clearance

Clearance

limit

Replace

bushing

Shaft

Hole

Boom

-0.036 +0.222

0.083 – 0.312

0.412

-0.090 +0.047

Arm

-0.036 +0.222

0.083 – 0.312

0.412

-0.090 +0.047

Bucket

-0.030 +0.258

0.078 – 0.334

0.434

-0.076 +0.048

Clearance between pis-
ton rod support pin and
bushing

Boom

-0.030 +0.246

0.230 – 0.322

1.0

Replace

pin or

bushing

-0.076 +0.200

Arm

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

Bucket

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

Clearance between cyl-
inder bottom support pin
and bushing

Boom

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

Arm

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

Bucket

-0.030 +0.246

0.230 – 0.322

1.0

-0.076 +0.200

4-123

Structure and Function

ZX215-1002133

ZX215-1002134

A-A

F-F

G-G

H-H

C-C

D-D

E-E

K-K

J-J

B-B

4.6.14 Work equipment

4-124

Structure and Function

Unit: mm

No.

Check item

Criteria

Remedy

Clearance between pin connect-
ing boom and revolving frame and
bushing

Standard

size

Tolerance

Standard clear-

ance

Clearance

limit

Replace

Shaft

Hole

–0.036
–0.071

+0.140
+0.105

0.141 ~ 0.211

1.0

Clearance between pin connecting
boom and arm and bushing

–0.036
–0.071

+0.174
+0.104

0.140 ~ 0.345

1.0

Clearance between pin connecting
arm and rocker and bushing

–0.030
–0.060

+0.335
+0.275

0.305 ~ 0.395

1.0

Clearance between pin connecting
arm and bucket and bushing

–0.030
–0.060

+0.324
+0.270

0.300 ~ 0.384

1.0

Clearance between pin connecting
linkage and bucket and bushing

–0.030
–0.060

+0.373
+0.273

0.303 ~ 0.433

1.0

Clearance between pin connecting
linkages and bushing

–0.030
–0.060

+0.335
+0.275

0.305 ~ 0.395

1.0

Unit: mm

No.

Check item

Criteria

Remedy

Clearance between pin connect-
ing boom and revolving frame and
bushing

Standard

size

Tolerance

Standard clear-

ance

Clearance

limit

Replace

Shaft

Hole

–0.036
–0.071

+0.131
+0.074

0.110 ~ 0.202

1.0

Clearance between pin connecting
boom and arm and bushing

–0.036
–0.071

+0.166
+0.074

0.110 ~ 0.237

1.0

Clearance between pin connecting
arm and rocker and bushing

–0.030
–0.060

+0.158
+0.078

0.108 ~ 0.218

1.0

Clearance between pin connecting
arm and bucket and bushing

–0.030
–0.060

+0.137
+0.074

0.104 ~ 0.197

1.0

Clearance between pin connecting
linkage and bucket and bushing

–0.030
–0.060

+0.166
+0.086

0.116 ~ 0.226

1.0

Clearance between pin connecting
linkages and bushing

–0.030
–0.060

+0.154
+0.074

0.104 ~ 0.214

1.0

100 hour greasing

500 hour greasing

4-125

Structure and Function

Arm dimension

WX13060402

B-B

A-A

C-C

D-D

Structure and Function

Unit: mm

No.

SY195/205/215C-9

SY225C-9

Standard size

Tolerance

Standard size

Tolerance

+0.1

107

±0.5

107

±0.5

310

-0.3
-0.8

310

-0.3
-0.8

-0.036
-0.071

549

±1

549

±1

158

±0.8

158

±0.8

835

±1

835

±1

2,911

±2

2,911

±2

2,643

±2

2,643

±2

411

±0.8

411

±0.8

640

-0.5

640

-0.5

600

—

600

—

458

—

458

—

1,483

—

1,495

—

326.5

—

326.5

—

+0.2

Arm itself

311

—

311

—

When press

ting bushing

325

—

325

—

Min.

1,680

—

1,680

—

Max.

2,800

—

2,800

—

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