SANY Crawler Hydraulic Excavator SY365H-9, SY365BH-9. Shop Manual (2014)

4-64

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

●

When pressure in arm cylinder head end (H) rises

XBa2

Dr1

XBa1

LCAT2

(Ba2)

BaR

XAa2

XAa1

Ba1

LCa

Pna1

Dra

(302-317)

(a)
(c)

(257-103)

WJV3651309

Fig. 4-54

4-65

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

4) Boom

Boom-up operation

(Pilot circuit)

●

When switched to the boom 1 spool (307), the side passage is closed and the pressure in port
Px (work equipment signal port) rises.

(Main circuit)

●

When boom-up operation is performed, the pilot oil is fed to port XAb1 and boom 1 spool
(303) moves to the left as shown in Fig. 4-55. The working oil from port P1 is introduced to the
neutral bypass (2) via the main passage (1). The neutral bypass is cut off by switching boom
1 spool (303). In this way, the working oil in the parallel passage pushes open the cone valve
(511) of the check valve, and

ows to the boom 1 spool (303) via the U passage. It then

ows

to the periphery of boom 1 spool (303) and is delivered to the boom cylinder head end (H) via
port Ab.

●

At the same time, the pilot oil is also fed to port XAb2 and boom 2 spool (307) moves to the
left as shown in Fig. 4-55. The working oil from P2

ows the parallel passage. As the switch-

ing boom 2 spool (307) cuts off the neutral bypass, the working in the parallel passage

ows

into boom 2 spool (307) via the U passage. The oil then pushes open the cone valve (511) of
the check valve, comes into con

uence with the oil from port Ab, and is fed to the boom cylin-

der head end (H). (This is called the boom con

uence function.)

●

On the other hand, the oil

ows to the periphery of boom 1 spool (303) via port Bb from oil re-

turn side of the boom cylinder rod end (R) and goes back to the working oil tank via the ports
R1 and R3.

4-66

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

XBb1

XBb2

511

513

BaR

XAb1

XAb2

AbR

LCb

Dr2

511

WJV3651310

Fig. 4-55

4-67

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

Boom-down operation

(Pilot circuit)

●

When switched to the boom 1 spool (303), the side passage is closed and the pressure in port
Px (work equipment signal port) rises. Pressurized oil is fed to the port PbL at the same time.
Relief signal is sent to the lock valve selector GP (252).

(Main circuit)

●

When boom-down operation is performed, the pilot oil is fed to port XBb1 and boom 1 spool
(303) moves to the right as shown in Fig. 4-56. The working oil from port P1 is introduced to
the neutral bypass (2) via the main passage (1). The neutral bypass is cut off by switching
boom 1 spool (303). In this way, the working oil in the parallel passage pushes open the cone
valve (511) of the check valve, and

ows to the boom 1 spool (303) via the U passage. It then

ows to the periphery of boom 1 spool (303) and is delivered to the boom cylinder rod end (R)

via port Bb.

●

On the other hand, the oil returning from the head end (H) of boom cylinder

ows to the hole (a)

and periphery of boom 1 spool (303).

●

The pressure of return oil rises due to the dead weight of boom. To maintain suf

cient pres-

sure, with the help of the oil passage inside the spool, the cone valve (303-317) in spool is
pushed to the right, as shown in Fig. 4-56, and the oil

ows out of the spool. As the working oil

for boom-down operation, the pressurized oil is again delivered to the boom cylinder rod end
(R) (which is called boom regeneration function). The return oil entering the internal passage
of spool via the hole (a) partially goes back to the oil tank via the hole (b).

XBb1

511

513

BbR

XAb1

LCb

(b)

(a)

(303-317)

WJV3651311

Fig. 4-56

4-68

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

5) Bucket

Bucket-dig operation

(Pilot circuit)

●

When switched to the bucket spool (304), the side passage is closed and the pressure in port
Px (work equipment signal port) rises. The pressure oil is fed to port XBp2 at the same time.

(Main circuit)

●

When bucket-dig operation is performed, the pilot oil is fed to the port XBc and the bucket
spool (304) moves to the left as shown in Fig. 4-57. The working oil from port P1 is guided
to the neutral bypass (2) via main passage (1). As the neutral bypass is cut off by switching
bucket spool (304), the working oil in the parallel passage pushes open the cone valve (511)
of the check valve, and

ows to the bucket spool (304) via the U passage. It then

ows to the

periphery of bucket spool (304) and is fed to the bucket cylinder head end (H) via port Bc.

●

On the other hand, return oil from the bucket cylinder rod end (R)

ows in via port Ac. It then

goes back to the oil tank via the ports R1 and R3 from the periphery of spool.

●

When boom-up and bucket-dig operations are performed at the same time, the pilot oil is led
to the port PAcs. Therefore, the travel of bucket spool is not restricted to the end, but can be
held in a position on the way. As a result, bucket cylinder passage is throttled and working oil

ows to boom 1 spool (303) via bucket spool (304). In this way, boom-up operation have the

priority.

BcR

XBc

LCk

511

AcR

XAc

PAcs

Confluence

WJV3651312

Fig. 4-57

4-69

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

Bucket-dump operation

(Pilot circuit)

●

When switched to the bucket spool (304), the side passage is closed and the pressure in port
Px (work equipment signal port) rises. The pilot oil is also fed to the port XBp2 at the same
time.

(Main circuit)

●

When bucket-dump operation is performed, the pilot oil is fed to the port XAc and bucket
spool (304) moves to the right as shown in Fig. 4-58. The working oil from port P1 is led to the
neutral bypass (2) via the main passage (1). The neutral bypass is cut off by switching bucket
spool (304). Therefore, the working oil in the parallel passage pushes open the cone valve (511)
of the check valve and

ows to the bucket spool (304) via the U passage. It then

ows to the

periphery of bucket spool (304) and is fed to the bucket cylinder rod end (R) via the port Ac.

●

On the other hand, return oil from the bucket cylinder head end (H) enters via the port Bc,
passes the spool periphery of spool, and goes back to working oil tank via the ports R1 and
R2.

BcR

XBc

LCk

511

AcR

XAc

PAcs

Confluence

WJV3651313

Bucket con

uence

●

When bucket-dig or -dump operation is performed, the pilot oil is fed to the port XBp2 and the
neutral bypass stop valve spool (310) is switched. Working oil from port P2 is led to the neu-
tral bypass (4) via the main passage (3). The neutral bypass is cut off by switching neutral by-
pass valve spool (310). Therefore, working oil pushes open the check valve (515) and comes
into con

uence with bucket spool (304) via the internal passage and the U passage.

Fig. 4-58

4-70

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

6) Swing

When swing operation performed separately

(Pilot circuit)

●

When switched to the swing spool (305), the side passage is closed and the pressure in the
port Px (work equipment signal port) rises.

(Main circuit)

●

When swing is operated separately, the pilot oil is fed to the port XAs (or XBs) and swing
spool (305) is switched. Working oil from port P2 is led to the neutral bypass (4) via the main
passage (3). Neutral bypass is cut off by switching swing spool (305). Therefore, working oil
in the parallel passage pushes open the logic cone valve (254-101) of the swing logic com-
ponent and

ows to the swing spool (305) via the U passage. It then

ows to the periphery of

swing spool (305) and is delivered to the swing motor via port As (or Bs).

●

On the other hand, return oil from the swing motor

ows in via port Bs (or port As). Then, it

ows into tank ports R1 and R2 from the periphery of spool and goes back to the working oil

tank.

XAs

XBs

LCs

Pns

(254-101)

Swing motor

WJV3651314

Fig. 4-59

4-71

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

7) Priority function

●

This function enables the working oil from port P to be suf

ciently allocated to the work equip-

ment under higher load in order to improve the operability when the arm-in operation is per-
formed along with swinging operation.

●

The following shows the priority of swinging operation relative to the arm-in operation.

(Main circuit)

●

When pressure oil is applied to the port Pna1 of the logic control valve (255), the piston (255-
356) and spool (253-107) move upward. The lifting distance of cone valve (253-101) is lim-
ited.

●

In this way, the passage from the parallel passage to the U passage is throttle. As a result, oil
from the arm 1 spool has the priority to go to the swing spool, giving the priority to the boom-
up operation.

XAa1

XBa1

LCa

Ba1

(253-101)

(253-107)

(255)

(255-356

Pna1

WJV3651315

Fig. 4-60

4-72

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

8) Backup

The backup spool is used to control attachment such as hydraulic shear.

Backup operation

(Pilot circuit)

●

When switched to the backup spool (309), the side passage is closed and the pressure in port
Px (work equipment signal port) rises.

(Main circuit)

●

When the backup is operated, the pilot oil is fed to the port XAo (or XBo) and the backup
spool (309) is switched. Working oil from port P2 is fed to the neutral bypass (4) via the main
passage (3). Neutral bypass is cut off by switching backup spool (309). Therefore, working oil
in the parallel passage pushes open the cone valve (511) of the check valve and

ows to the

backup spool (309) via the U passage. Then, it

ows into the periphery of backup spool (309)

and is supplied into the attachment via port Ao (or Bo).

●

On the other hand, return oil from the attachment

ows in via port Bo (or port Ao). Then, it

ows into tank ports R1 and R2 from the spool periphery and returns to the working oil tank.

XAo

511

BoR

LCo

XBo

Confluence

WJV3651316

Fig. 4-61

Backup con

uence

To achieve backup con

uence, pilot oil is also fed to port XBp1 and the bypass stop valve spool

(310) is switched. Working oil from port P1 is introduced into neutral bypass (2) via main passage
(1). Neutral bypass is cut off by switching bypass valve spool (310). Therefore, working oil push-
es open the cone valve (515) of check valve and comes into con

uence with backup spool (309)

via the internal passage and the U passage.

4-73

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

9) Straight travel

When travel spool (301) is operated along with other spools at the same time.

The following case shows when travel spool (301) and swing spool (305) are operated at the
same time.

(When pilot oil is delivered to the ports XAtL, XAtr and Xas)

(Pilot circuit)

●

Close the side passage of right/left travel spool (301) and the downstream side passage of
swing spool (305). Pilot oil from port PG is fed to port PTa in order to switch the straight travel
spool (308).

(Main circuit)

●

When straight travel spool (308) is switched, the port P2 and the right/left travel spool (301)
are interconnected through for priority. The port 1 and the parallel passage of swing - boom
2 - backup - arm 1 oil circuit / boom 1 - bucket/ - arm 2 circuit are interconnected through for
priority. Therefore, the working oil from port P2 is mainly delivered to the ports Atl and Atr and
distributed evenly to the two travel motors.

●

On the other hand, the working oil from port P1 is delivered to the swing motor via port As.

●

When oil pressure in the port P2 is lower than that in the port P1, the working oil form port P1
will be partially delivered to the port P2. In this way, sudden drop of travel speed can be pre-
vented.

XBtL

(PTb)

(PTa)

XAtL

WJV3651317

Fig. 4-62

4-74

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

10) Function of lockout valve

The lockout valve selector module (252) is mounted between the arm cylinder rod end (R) and
the arm 2 spool (302) and arm 2 spool (306). It is used to reduce the internal leakage of the spool
due to cylinder pressure.

Likewise, lockout valve selector module (252) is also mounted between the boom cylinder head
end (H) and the arm 1 spool (303) and boom 2 spool (307) to reduce the internal leakage of he
spool due to cylinder pressure.

The

gure below shows the case of boom cylinder head end (H). (Similar case applies to the arm

cylinder rod end (R).)

Spool in neutral position

●

When boom 1 spool (303) and boom 2 spool (307) are in a neutral position, the spool (252-511)
inside the lockout valve selector module is pressed against the seat of the body (252-101) of
the lockout valve selector module, as shown in Fig. 4-63, by the preload of spring (252-512).

●

In this position, working oil in the boom cylinder head end (H)

ows in via hole (a) and

ows

out from hole (b) through the periphery of the lockout valve selector module spool (252-511),
pressing the cone valve (513) against the seat of the valve block via hole (b). By this means,
oil leakage is reduced.

(252-512)

(252-101)

Drb

(252-511)

(b)

(a)

513

LCb

(RH)

XBb1

XAb1

BbR

PbL

WJV3651318

Fig. 4-63

4-75

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

Boom-down operation

In boom-down operation the pilot oil is fed to the ports PbL, XBb1 and XBb2. Spool (252-511) in-
side the lockout valve selector module is pushed to the top by the pilot oil as shown in Fig. 4-64.
Due to the movement of spool (252-511) inside the lockout valve selector module, hole (a) is cut
off and working oil from boom cylinder head end (H) does not go to spring chamber (RH). In addi-
tion, oil in the spring chamber (RH) enters the oil leak circuit via the hole (b). In this way, the cone
valve (513) is pushed open by the pressure in boom cylinder head end (H) and the function of the
lockout valve selector module (252) is deactivated.

(252-512)

(252-101)

Drb

(252-511)

(b)

(a)

513

LCb

(RH)

XBb1

XAb1

BbR

511

PbL

WJV3651319

Fig. 4-64

Boom-up operation

In boom-up operation the pilot oil is fed to the ports XAb1 and XAb2. The cone valve (513) is
pushed open by the oil from boom 1 spool (303) and boom 2 spool (307). The working oil goes to
the port Ab as a result.

4-76

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

11) Function of main relief valve

The main relief valve is mounted on the valve block A (101). It has the following functions:

●

Working oil ful

ls the cavity (a) through the hole in valve post housing (601-101) and valve

post (601-511). The valve post (601-511) is therefore pressed against the housing (601-101).
Reliable sealing has formed as a result.

●

When pressure in passage (P) exceeds the preload of spring (601-521), the cone valve (611)
opens. Therefore, the working oil passes through the gap between the housing (601-101) and
valve pocket (601-102) from the periphery of cone valve (601-401) and goes to the low pres-
sure passage (R).

●

Opening of cone valve (601-401) causes pressure drop in cavity (a). So the valve post (601-
511) is opened. In this way, working oil in passage (P)

ows to the low pressure passage (R)

directly.

●

When pressure oil higher than 3MPa is fed to the port Pz, it pushes plunger (601-302) to the
left. The preload of spring (601-512) increases as a result and pressure boosts at the mo-
ment.

(601-101)

(601-401)

(601-511)

(601-302)

(a)

(601-512)

(601-102)

WJV3651320

Fig. 4-65

4-77

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

12) Function of port relief valve

The port relief valve, mounted between the oil tank port and low pressure passage, can prevent
cavitation as an oil compensation check valve except working as a port relief valve. Functions of
the valve are given below:

Functioning as a relief valve

●

Working oil ful

ls into cavity (B) via the hole (A) on plunger (301). Valve post (511) is pressed

against valve seat (541), and valve seat (541) is pressed onto the seat of the valve block,
forming a reliable sealing.

(A)

(B)

541

301

511

WJV3651321

(C)

611

621

WJV3651322

●

When pressure in passage (P) exceeds the preload of spring (621), cone valve (611) is
pushed open. Therefore, working oil

ows through hole (C) via the periphery of cone valve (611)

and enters the low pressure passage (R).

Fig. 4-66

Fig. 4-67

4-78

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

●

Opening of cone valve (611) causes pressure in cavity (B) to drop and valve post (511) is
opened. In this way, working oil in passage (P) goes to the low pressure passage (R) directly.

(B)

511

611

WJV3651323

Fig. 4-68

Functioning as oil complement check valve against cavitation

When negative pressure is formed in passage (P), working oil is fed from passage (R). When
pressure in passage (R) exceeds the pressure in passage (P), valve seat (541) moves to the right
direction. Therefore, working oil is delivered from passage (R) to passage (P) via the periphery of
valve seat (541). Cavitation is prevented as a result.

541

WJV3651324

Fig. 4-69

4-79

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

ZX215-1002081

4.6 Hydraulic System, Part 3

4.6.1 Swing motor

Type: M5X180CHB-10A-3NA/265

Model

M5X180CHB-10A-3NA/265

Theoretical dis-

placement

180.1 cm

/rev

Safety valve

press. setting

26.0 MPa

Max swing speed

1470 rpm

Brake release

pressure

2.7-4.9 MPa

Speci

cations

A: Main oil port
B: Main oil port
M: Makeup port
PA: Pressure detection port
PB: Pressure detection port
DB: Lubricant port
PG: Brake release port
SH: Brake command port
L: Level stick
IP: Gear oil feed port
(1) Safety valve
(2) Anti-swing valve

Fig. 4-70

SANY Crawler Hydraulic Excavator SY365H-9, SY365BH-9. Shop Manual (2014) - page 10