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SANY Crawler Hydraulic Excavator SY365H-9, SY365BH-9. Shop Manual (2014) - page 12

4-96

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

ZX215-1002096

Oil circuit B

Oil circuit C2

Orifice D3

Damper chamber A2

Orifice D4

Spring chamber 2

Oil circuit C1

Orifice D1

Damper chamber A1

Orifice D2

Spring chamber 1

6-2

7-2

5-2

4-2

2-2

2-1

4-1

5-1

7-1

6-1

8-2

8-1

Braking of motor

●

The double-balanced valve and the relief valve forms the braking circuit.

●

When the main valve is in neutral position, hydraulic oil from the main pump is cut off, and
pressure at port P1 and P2 is the same. As a result, plunger (1) moves to the neutral position,
and the opening area of circuit B decreases.

●

At the same time, because of the inertia of external force, the motor does not stop rotating
(pump effect), and pressure at port M2 rises and serves as the braking force of motor rotation.

●

When the pressure at port M2 reaches the set pressure of relief valve (8), cone valve (8-1)
at port M1 overcomes the force of spring (8-2) and moves to the left, and hydraulic oil

ows

to the port M1. In this way, the impacting force due to inertia at port M2 is under control, and
vacuum at port M1 is avoided.

Fig. 4-87

4-97

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

E. Shuttle valve function for high pressure selection

●

The double-balanced valve can function as a shuttle valve to release travel brake.

●

When hydraulic oil is fed to port P1, plunger (1) moves to the right, as shown in

g. 4. At this

time, drain passage F of motor housing is cut off, and passage D leading to cylinder chamber
E for travel braking is opened.

●

Hydraulic oil

ows to passage G via the ori

ce, and enters travel brake cylinder chamber E to

release the travel brake. In addition, plunger (1) moves to neutral position, as shown in

g 5

when motor stops. Passage D is closed and drain passage F of motor housing is opened.

●

Hydraulic oil in travel braking cylinder chamber E is conducted to the drain passage of motor
housing, and travel brake is applied.

ZX215-1002097

Passage F

Passage D

Passage G

Passage F

Cylinder chamber E

Orifice

ZX215-1002098

Passage F

Passage D

Passage G

Passage F

Cylinder chamber E

Orifice

Fig. 4-88

Fig. 4-89

4-98

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

ZX215-1002099

Travel control valve

ZX215-1002100

Travel control valve

4.6.9.2 Operation of parking brake

1) When starting travel

●

As the travel lever is operated, pressurized
oil from the pump activates back pressure
valve spool (10), opens the parking brake
circuit, and flows to chamber A of brake
piston (12). Pressurized oil overcomes the
force of spring (11) and pushes piston (12)
toward the left.

●

Since the pushing force to plate (13) and
disc (14) disappears, plate (13) is sepa-
rated from disc (14) and the brake is re-
leased.

2) When travel is stopped

●

As the travel lever is placed in neutral,
back pressure valve spool (10) returns to
the neutral position and closes the parking
brake circuit. T

●

he pressurized oil in chamber (A) of brake
piston (12) passes through the orifice of
the brake piston and is drained to the mo-
tor casing. Brake piston (12) is pushed to
the right by spring (11).

●

Plate (13) and disc (14) are pushed against
each other, and the brake is applied. As
brake piston (12) returns, a time delay is
formed by making the pressurized oil pass
through a throttle valve in the slow return
valve (22). This time delay ensures an ac-
tive brake after the machine is stopped.

Fig. 4-90

Fig. 4-91

4-99

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

ZX215-1002101

Travel control valve

ZX215-1002102

Travel control valve

4.6.9.3 Operation of braking valve

●

The brake valve consists of a suction safe-
ty valve (8A) and a counterbalance valve
(18). As shown in the illustration on the
right, functions and operations of respec-
tive components are described below.

1. Counterbalance valve and check valve

Function

●

When traveling downhill, the weight of the
machine tends to make the travel speed
faster than the motor speed. If the machine
travels with the engine at low speed, the
motor may rotate at zero load, resulting
in runaway and inviting a very dangerous
situation. These valves are used to avoid
such a situation by controlling the machine
to travel according to the engine speed
(pump

ow).

Operation when pressurized oil is supplied

●

Operating the travel control lever conducts
the pressurized oil from the control valve
to port (PA). The pressurized oil opens
suction safety valve (8A) and then

ows to

motor outlet port (MB) via motor inlet port
(MA). The motor outlet side is closed by
suction safety valve (8B) and spool (19),
so the pressure at the supply side rises, as
shown in the right illustration.

Fig. 4-92

Fig. 4-93

4-100

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

ZX215-1002103

E1 E2

Travel control valve

ZX215-1002104

Travel control valve

Brake operation in downhill travel

●

If the machine goes out of control while
travelling downhill, the motor will be caused
to rotate without load to decrease the inlet
side oil pressure. Pressure in chamber (S1)
drops via orifices (E1) and (E2). As the
pressure in chamber (S1) goes below the
spool shift pressure, spool (19) is returned
to the left by spring (20) and outlet port (MB)
is throttled. The pressure at the outlet port
side rises, generating rotation resistance
on the motor to prevent the machine from
losing control. On the other hand, the spool
moves to a position where the pressure on
outlet port (MB) can be balanced against
the machine's own weight and the inlet port
pressure. Oil

ow from the outlet circuit is

reduced to ensure the travel speed corre-
sponded to the pump delivery, as shown in
the right illustration.

●

The pressurized oil on the supply side

ows to chamber (S1) via ori

ce (E1) and

ori

ce (E2) of the spool (19). As the pres-

sure in chamber (S1) goes above the spool
shift pressure, spool (19) is pushed toward
the right. Port (MB) and port (PB) are con-
nected, the motor outlet port side opens
and the motor starts rotating, as shown in
the right illustration.

Fig. 4-94

Fig. 4-95

4-101

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

ZX215-1002105

Travel control valve

ZX215-1002107

Spool

2. Safety valve

Function

●

When the machine travel is stopped (or it
is travelling downhill), the double-balanced
valve closes the inlet and outlet circuits of
the motor. Since the motor is rotated by
inertial force, pressure in the motor outlet
port side is abnormally increased, poten-
tially resulting in damages on the motor
and piping. The safety valve relieves this
abnormal pressure to the inlet port side of
the motor in order to prevent damages to
the equipment.

Operation

1) When travel is stopped (or when travelling

downhill or swinging to the right)

●

Reduction of the pressure at motor inlet
(PA) decreases the pressure in chamber
(S1). When it drops beyond the spool shift
pressure, the spool is returned to the left
by spring (20), throttling the oil outlet pas-
sage (B1). At this time, the motor continues
rotating due to its inertial force, thus pres-
sure on the outlet port (MB) is increased,
as shown in the right illustration.

●

When the pressure rises above the set
pressure of the suction safety valve (8A),
the spool opens. The pressurized oil pass-
es through notch (A1) of the counterbal-
ance valve spool (19) into chamber (MA) of
the circuit at the opposite side, as shown in
the right illustration.

Fig. 4-96

Fig. 4-97

4-102

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

ZX215-1002106

Travel control valve

2) When starting travel (or traveling normally)

●

As the travel control lever is operated, the
pressurized oil from the pump moves the
counterbalance valve spool (19) toward
right. In this case, the passage to the suc-
tion safety valve functions as a circuit
which passes through notch (B2) of spool
(19), producing large differential pressure.
The pump pressure rises, providing a large
tractional force to the valve, as shown in
the right illustration.

3. Overload relief valve

●

The structure of the relief valve is shown
in the right figure. This valve is an area-
differential and direct-acting relief valve. It
has impact damping function during start-
ing and braking.

A. Operating principle and function

●

When the main control valve makes the
motor to start or brake, front pressure of
cone valve (2-9-2) rises above the set pres-
sure and the force of spring (2-9-5), and
moves cone valve (2-9-2) to the right and
off the valve seat (2-9-3). Pressurized oil in
the front of cone valve (2-9-2) is bypassed
to the low pressure side. The impact due
to inertia energy at the high pressure side
is put under control and vacuum is pre-
vented from occurring at the low pressure
side through bypassing pressurized oil to
the low pressure side.

Fig. 4-98

Fig. 4-99

Fig. 4-100

ZX365-1304108

ZX365-1304109

2-9-3

2-9-2

2-9-5

4-103

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

ZX365-1304110

2-9-3

2-9-9

2-9-2

2-9-5

Area S2

Area S1

Spring chamber D

ZX215-1002111

Pressure (P)

Damping form

time (T)

B. Damping function

●

When the relief valve begins to function,
damping piston (2-9-9) moves to the left.
As a result, low pressure is maintained in
spring chamber D. At this time, the loaded
area of cone valve (2-9-2) is S1, and gen-
erally it is much larger than the set loaded
area S1-S2 of the relief valve. So, when
damping piston (2-9-9) is moving, the func-
tional pressure of relief valve is maintained
at 1/3 of normal set pressure in order to
absorb the impact at the high pressure
circuit side due to inertial energy. When
the movement of damping piston stops,
pressure in spring chamber D rises. Pres-
sure at both side of cone valve (2-9-2) is
the same, and the relief valve is working
at normal set pressure. In this way, the re-
lief valve reduces the impact during motor
starting and braking by a two-stage action
to provide excellent performance.

Fig. 4-101

Fig. 4-102

4-104

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

Table 2 Repair standard of motor components

Components

Check item

Allowable limit

Remedy

1-4-2 Plunger
assembly

1. Boot sliding surface

Roughness 0.8a or surface rough-
ness, scratch 0.02mm+

Grind the boot sliding
surface. Replace the
cylinder block assembly
if the scratch cannot be
corrected.

2. Plunger outer diameter

Roughness 1.2a or surface rough-
ness, scratch 0.02mm+

Replace the cylinder
block assembly.

3. Plunger outer diameter
and cylinder block inner
diameter

Clearance 0.060.

4. Boot head clearance

Clearance 0.4.

1-4-1 Cylinder
block

1. Valve leaf and sliding sur-
face

Roughness 0.8a or surface rough-
ness, scratch 0.02mm+.

Grind the boot sliding
surface. Replace the
cylinder block assembly
if the scratch cannot be
corrected.

2. Shaft hole inner diameter

Roughness 1.6a or surface rough-
ness, scratch 0.02mm+.

Replace the cylinder
block assembly

3. Shaft hole inner diameter
and 4-2 plunger assembly
outer diameter

Clearance 0.060.

4. Spline at shaft joint

Roller distance below 38.749
(measuring pin diameter

3.333(V1=2.80)); or damaged

1-21 Oil distri-
bution plate

1. Sliding surface

Roughness 0.8a, scratch 0.02mm+
on sliding surface or burned sign

Grind the sliding surface.
Replace the valve sheet
if the scratch cannot be
corrected.

1-4-3 Retainer
1-4-4 Retain-
ing assembly

1. Sliding surface

Roughness 0.8a, scratch 0.02mm+
on sliding surface or sign of burning

Replace the retaining
plate or the retainer.

1-5 Swash
plate

1. Sliding surface

Roughness 0.8a, abrasion on sling
surface or scratch 0.02mm+

Grind the sliding surface.
Replace the valve sheet
if the scratch cannot be
corrected.

2. Hole for assembling steel
ball

Roughness 1.6a.

Replace the swash plate.

Scratch on spherical surface
0.02mm+ or surface roughness

3. Hole for assembling steel
ball

Ball depth 14.5

4-105

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

Components

Check item

Allowable limit

Remedy

1-3 Shaft

1. Oil seal sliding portion outer
diameter

Roughness 1.6a, rough surface, or
scratch 0.02mm+

Replace the swash
plate.

2. Cylinder block matching
spline

Stick spans below 47.380 (testing
pin diameter

3.00), or the stick

breakage.

Replace the shaft.

3. Drive gear connection

Stick spans below 30.498 (testing
pin diameter

3.33), or the stick

breakage.

1-15 Brake pis-
ton

1. Dimension

Height 38.2

Replace the brake
piston.

2. Sliding surface

Roughness 2.5a

3. Appearance

Scratch 0.02mm+ or rough surface

1-13 Disc plate

1. Dimension

Thickness 3.2

Replace the disc
plate.

2. Appearance

Deep scratch on sliding surface or
friction material peeling

1-8 Ball bearing
1-9 Ball bearing

1. Rolling surface

Peeling or fracture

Replace the ball
bearing.

2. Action

Abnormal rotation (noise•uneven
rotation)

1-7 Plunger as-
sembly

1. Boot sliding surface

Roughness 1.6a, rough surface, or
scratch 0.02mm+

Grind the sliding
surface. Replace the

ange plate parts if

the scratch cannot
be corrected

2. Plunger outer diameter

Roughness 1.2a, rough surface,
scratch 0.02mm+

Replace the

ange

plate parts.

3. Plunger outer diameter and

ange part inner diameter

Gap 0.040.

4. Boot head clearance

Clearance 1.0

1-2-2 Plunger
assembly

1. Plunger outer diameter

Roughness 0.8 a, scratch 0.02mm+
or rough surface

Replace the valve
sheet.

2. Plunger outer diameter and
valve sheet inner diameter

Clearance 0.060.

1-2-1 Valve
sheet

1. Assemble the plunger as-
sembly hole

Roughness 0.8 a, scratch 0.02mm+
or rough surface

Replace the valve
sheet and the parts.

2. Valve sheet inner diameter
and plunger outer diameter

Clearance 0.060

3. Valve spool assembly instal-
lation hole

Roughness 0.8 a, scratch 0.02mm+
or rough surface

4. Spool valve sheet inner di-
ameter and valve spool outer
diameter

Clearance 0.060.

5. Movable plunger sliding part
and seat of the relief valve

Scratch 0.02mm+ or surface rough-
ness

4-107

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

Components

Check item

Allowable limit

Remedy

1-2-9 Spool as-
sembly

1. Valve spool out diam-
eter

Roughness 0.8 a, scratch 0.02mm+
or surface roughness

Replace valve sheet
and parts

2. Valve spool outer diam-
eter and valve sheet inner
diameter

Clearance 0.060.

1-2-7-9 Movable
plunger

1. Sliding portion of valve
sheet and valve seat

Scratch 0.02mm+ or surface rough-
ness

Replace relief valve
assembly

1-2-7-1 Case

1. Sling portion of the
movable piston (outer
diameter)

Scratch 0.02mm+ or surface rough-
ness

1-4-7 Spring

1. Dimension

Free length 61.0

2. Appearance

Deformation and surface damage

1-18 Spring

1. Dimension

Free length 39.0

2. Appearance

Deformation and surface damage

1-20 Spring

1. Dimension

Free length 41.5

2. Appearance

Deformation and surface damage

1-2-4 Spring

1. Dimension

Free length 48.5

2. Appearance

Deformation and surface damage

1-2-10 Spring

1. Dimension

Free length 28.3

2. Appearance

Deformation and surface damage

O-ring and oil seal

When removed

Replace o-ring and oil
seal

4-108

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

4.6.10 Control system

ZX365-1304112

Fig. 4-103

4-109

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

(1)  Pilot valve (travel)
(2)  Control lever (left travel)
(3)  Control lever (right travel)
(4)  Pilot valve (Right)
(5)  Control lever (right work equipment)
(6) Accumulator
(7) Block
(8) Hydraulic pump
(9)  Main control valve
(10) Solenoid valve
(11)  Control lever (left work equipment)
(12) Relay

Control lever positions

HOLD

Boom UP

Boom DOWN

Bucket DUMP

Bucket DIG

HOLD

Arm IN

Arm OUT

Right swing

Left swing

Neutral

Travel BACKWARD

Travel FORWARD

4-110

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

4.6.11 Manual pilot valve

P: From pilot pump relief valve
P1: Left pilot valve: Arm OUT / Right pilot valve: Boom DOWN
P2: Left pilot valve: Arm IN / Right pilot valve: Boom UP
P3: Left pilot valve: Swing LEFT / Right pilot valve: Bucket DIG
P4: Left pilot valve: Swing RIGHT / Right pilot valve: Bucket DUMP
T: To tank

ZX365-1304113

64~73.5Nm

19~22Nm

Fig. 4-104

4-111

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

ZX215-1002114

A-A

(1) Plunger
(2) Adjusting spring
(3) Center spring
(4) Piston
(5) Disc

(6) Nut (for control lever connection)
(7) Connector
(8) Plate
(9) Retainer
(10) Valve body

Fig. 4-105

4-112

Structure and Functions

SY365(B)H-9 Crawler Hydraulic Excavator

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. During

ne control (Neutral to

ne control)

●

When piston (4) is pushed by disc (5),
retainer (9) is pushed, plunger (1) is also
pushed by adjusting 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 adjusting 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). Ad-
justing 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 plunger 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 plung-
er are balanced.

ZX365-1304115

Control valve

Pilot

pump

Fig. 4-106

ZX365-1304116

Control valve

Pilot

pump

Fig. 4-107

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