Doosan DX225LC User manual

SP001647
Page 1
Travel Control Valve (with Damper)
SP001647
TRAVEL CONTROL VALVE (WITH DAMPER)
SP001647
Travel Control
Valve (with
Damper)
Edition 1

SP001647
Travel Control Valve (with Damper)
Page 2
MEMO

SP001647
Page 3
Travel Control Valve (with Damper)
Table of Contents
Travel Control Valve (with Damper)
Safety Precautions ............................................... 5
Applicable Models ................................................ 5
General Description.............................................. 7
Theory of Operation ........................................................ 7
Pressure Reducing Valve................................................ 8
Operating Theory of Damper Mechanism ....................... 9
Causes of Faults and Measures......................... 11
Parts List ....................................................................... 12
Specification .................................................................. 14
Torques ......................................................................... 14
Removal ............................................................. 15
Disassembly ....................................................... 16
Cleaning and Inspection (Wear Limits and
Tolerances)......................................................... 18
Reassembly........................................................ 19
Installation .......................................................... 24
Start-up Procedures ........................................... 25

SP001647
Travel Control Valve (with Damper)
Page 4
MEMO

SP001647
Page 5
Travel Control Valve (with Damper)
SAFETY PRECAUTIONS
APPLICABLE MODELS
The contents of this section apply to the following models and
serial number ranges.
CAUTION!
Follow all safety recommendations and safe shop practices
outlined in the front of this manual or those contained
within this section.
Always use tools and equipment that are in good working
order.
Use lifting and hoisting equipment capable of safely
handling load.
Remember, that ultimately safety is your own personal
responsibility.
MODEL SERIAL NUMBER RANGE
DX225LC 5433 and Up
DX225LCA 5167 and Up

SP001647Travel Control Valve (with Damper)
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SP001647
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Travel Control Valve (with Damper)
GENERAL DESCRIPTION
Theory of Operation
The damper valve is divided into two areas of operation. There
is the pressure reducing valve (a) and the damper mechanism
(b). The following hydraulic circuit is an example of a remotely
located control valve.
1
2
3
5
4
ARS1810L
6
Figure 1
Reference
Number Description
1 Remote Control Valve
2 Pilot Pump
3 Main Pump
4 Control Valve
5 Hydraulic Motor
6 Hydraulic Cylinder
Reference
Number Description

SP001647Travel Control Valve (with Damper)
Page 8
Pressure Reducing Valve
1. Neutral Condition
If pedal is in neutral, spool is pushed up by return spring
and spring seat. Port (P) is blocked by bottom part of spool
and four operating ports (left forward and backward, right
forward and backward) are connected to port (T) through
inner hole of spool.
2. Half Operation Condition
If pedal is moved, push rod moves down, and they transmit
this force through spring seat and control spring to spool. If
spool is moved, primary pressure is transmitted through an
inner hole of spool to operating port. If lever is stopped in
middle position, compressed control spring force and
secondary pressure transmitted through hole acts at
bottom part of spool, balance is maintained by hydraulic
force acted upward, and then this pressure is transmitted
to traveling spool of control valve. That is, primary pressure
is transmitted to operating port as secondary pressure
equivalent to control spring force compressed by spool.
3. Full Operating Condition
If pedal is moved to a maximum, bottom part of push rod
presses spool seat to a maximum, and compresses control
spring to a maximum. Primary pressure is transmitted
through inner hole of spool to operation port, secondary
pressure transmitted through spool overcomes control
spring force and pushes spool up, but spool is restricted by
push rod and does not move any more. That is, when
pedal lever is moved to a maximum, control spring does
not function, spool is restricted by push rod, and then
primary pressure equalizes to secondary pressure.

SP001647
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Travel Control Valve (with Damper)
Operating Theory of Damper Mechanism
1. Operation When Operating Lever
When pushing pedal, pushing force pushing push rod and
spool presses cylinder, return spring and hydraulic oil in
cylinder is compressed, piston coming down with push rod
compresses vibration prevention chamber of lower part, oil
of vibration prevention chamber of lower part is flowed
through orifice to oil pressure vibration prevention chamber
of upper part of low pressure, at this time, ball check valve
becomes closing condition because high pressure
operates to vibration prevention chamber of lower part.
2. Operation When Operating Lever In Neutral Condition
Climbing restoring force acting on push rod, raises piston
in oil pressure prevention chamber and compresses upper
oil pressure prevention chamber. This compression
operation of upper oil pressure prevention chamber
prevents the push rod from quickly rising by restoring
spring, and the damping force is generated.
Figure 2
Reference
Number Description
1 Push Rod
2Orifice
3Piston
4 Piston Chamber
1 Neutral Position
2 Maximum Operating Angle 12.4"
Reference
Number Description

SP001647Travel Control Valve (with Damper)
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SP001647
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Travel Control Valve (with Damper)
CAUSES OF FAULTS AND
MEASURES
At times it may be difficult to pinpoint the source of the problem.
The following table lists some of the possible problems, possible
causes and remedies. Refer to this table for possible causes
and remedies to assist in correcting the sometimes difficult
problems.
The table only lists some general problems, possible causes
and their remedies. In many cases the problem is not caused by
the failure of a single part but, may be the result of a
combination of problems from related parts and their
components. Possible problems other than the ones list are not
being specified but that is not to say that these are the only
possible problems that can occur. The technician must diagnose
the problem, considering all possible causes and repair the
source of the malfunction.
Problem Possible Cause Remedy
Secondary pressure will not
increase.
Low primary pressure. Adjust primary pressure.
Defective secondary pressure
select spring.
Replace with new spring.
Gap between damper spool and
casing is abnormally large.
Replace damper spool casing assembly.
Defective operating parts and
components.
Disassemble/reassemble and replace
defective parts.
Unstable secondary
pressure.
Jamming of interconnected parts. Repair/replace cause of jamming.
Unstable tank line pressure. Install direct line to hydraulic tank.
Air in hydraulic lines. Vent air from system.
Abnormally high secondary
pressure.
High tank line pressure. Install direct line to hydraulic tank.
Jamming of interconnected parts. Repair/replace cause of jamming.
No dampening. Air in piston chamber. Vent air from system.
Jamming of interconnected parts. Repair/replace cause of jamming.
Worn damper springs. Replace with new parts.
Worn damper spool and housing. Replace damper spool and housing
assembly.
Defective/damaged check valve. Disassemble and examine check valve.
Worn damper spool orifice. Replace damper spool.
Damper spool feels heavy. Defective interconnected
components.
Repair/replace defective parts.
Restricted movement of damper
spool.
Repair/replace damaged piston.

SP001647Travel Control Valve (with Damper)
Page 12
Parts List
Figure 3

SP001647
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Travel Control Valve (with Damper)
Reference
Number Description
1 Body (1)
2 Body (2)
3Plug
4Plug
5 Spring Seat
6Spring
7Shim
8 Spool
9 Stopper
10 Spring
11 Spring Pin
12 O-ring
13 Push Rod
14 Spring Pin
15 Seal
16 Steel Ball
17 Spring
18 Plate
19 Snap Ring
20 Plug
21 O-ring
22 Rod Seal
23 Dust Seal
24 Cover
25 Hex Socket Head Bolt
26 Cam
27 Bushing
28 Camshaft
29 Set Screw
30 Set Screw
31 Hex Nut
32 Bellows
33 Piston
34 O-ring
35 O-ring
36 Expand
37 Spool Kit
38 Plug Kit
39 Cam Kit
Reference
Number Description

SP001647Travel Control Valve (with Damper)
Page 14
Specification
Torques
7.5 1
Secondary Pressure
Operating Torque
Secondary Pressure (kgf/cm
2
)
Rush Rod Strike (mm)
Operating Torque (kgf.cm)
25 1.5
40
01 0.5 4.8 0.5 5.5
46.4
91.8
112.6
160
FG013534
Figure 4
Travel Control Valve Specification
Type Pilot Control (With Damper)
Pressure / Stroke 25 kg/cm2@ 4.8 mm Stroke
(356 psi @ 0.1890 in Stroke)
Weight 7.8 kg (17 lb)
No Bolt Size Tool Tightening Torque
26 M6 PT1/8 88 kg•cm
(6 ft lb)
30 M8 27 mm 100 kg•cm
(7 ft lb)
32 M10 22 mm 440 kg•cm
(32 ft lb)
37 M10 22 mm 440 kg•cm
(32 ft lb)

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Travel Control Valve (with Damper)
REMOVAL
1. Park on firm and level ground.
2. Lower front attachment (bucket) to ground.
3. Shut down engine.
4. Set safety lever on "RELEASED" position.
5. Turn starter switch to "I" (ON) position.
6. Fully stroke work levers (joysticks) in all directions to
relieve any pressure from accumulators.
7. Set safety lever on "LOCK" position.
8. Turn key to "O" (OFF) position and remove from starter
switch.
9. Hang a maintenance warning tag on controls.
10. Disconnect negative (-) battery cable leading to frame from
battery.
11. Remove cabin under cover by loosening bolts.
12. Tag and disconnect hoses from pedal valve (1, Figure 6).
Plug and cap hoses and ports to prevent contamination
from entering hydraulic system or component.
O
I
FG014348
DO NOT OPERATE
when performing inspection
WARNING
190-00695A
or maintenance
Figure 5
WARNING!
If engine must be running while performing
maintenance, always use extreme caution. Always
have one person in the cab at all times. Never leave the
cab with engine running.
1
2
FG003016
Figure 6

SP001647Travel Control Valve (with Damper)
Page 16
DISASSEMBLY
1. Remove bellows (32).
2. Remove set screw (29) from cam (26).
3. Remove cam shaft (28) from cam (26).
4. Remove hex nut (31) and set screw (30) from cam (27).
Figure 7
Figure 8
Figure 9
Figure 10

SP001647
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Travel Control Valve (with Damper)
5. Remove hex socket head bolt (25) and cover (24) from
each body (1 and 2).
6. Remove push rod assembly from body (2).
7. Remove body (2) from body (1).
Figure 11
Figure 12
Figure 13
Figure 14

SP001647Travel Control Valve (with Damper)
Page 18
8. Remove damper spool assembly and spring (10) from
body (1).
9. Remove plug (3 and 4) and O-rings (12 and 34).
CLEANING AND INSPECTION
(WEAR LIMITS AND
TOLERANCES)
For general cleaning and inspection procedures, refer to
"General Maintenance Procedures" section.
Figure 15
Figure 16
Figure 17

SP001647
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Travel Control Valve (with Damper)
REASSEMBLY
1. Insert spring (10) into body (1).
2. Assemble in proper order, damper spool (8), shim (7),
spring (6), spring seat (5) and stopper (9).
3. Install damper spool assembly into body (1).
4. Assemble body (2) onto body (1).
Figure 18
Figure 19
Figure 20
Figure 21

SP001647Travel Control Valve (with Damper)
Page 20
5. Assemble rod seal (22), dust seal (23) and O-ring (21) into
plug (20).
6. Assemble seal (15), piston (33), steel ball (16), plate (18),
spring (17) and snap ring (19) into push rod (13).
7. Assemble push rod and plug.
Figure 22
Figure 23
Figure 24
Figure 25