Daewoo D20S-2 Manuale utente
Aug. 1996
Specifications
Systems Operation
Testing & Adjusting
Disassembly & Assembly
New Hydraulic Systems
D20/25-2
D20/25/30S-2
G20/25/30S-2
G20/25/30S-2
SB2097E00
Important Safety Information
Most accidents involving product operation, maintenance and repair are caused by failure to observe
basic safety rules or precautions. An accident can often be avoided by recognizing potentially
hazardous situations before an accident occurs. A person must be alert to potential hazards. This
person should also have the necessary training, skills and tools to perform these functions properly.
Improper operation, Iubrication, maintenance or repair of this product can be dangerous and
could result in injury or death.
Do not operate or perform any Iubrication, maintenance or repair on this product, until you
have read and understood the operation, Iubrication, maintenance and repair information.
Safety precautions and warnings are provided in this manual and on the product. If these hazard
warnings are not heeded, bodily injury or death could occur to you or other persons.
The hazards are identified by the "Safety Alert Symbol" and followed by a "Signal Word" such as
"WARNING" as shown below.
The meaning of this safety alert symbol is as follows :
Attention! Become Alert! Your Safety is Involved.
The Message that appears under the warning, explaining the hazard, can be either written or
pictorially presented.
Operations that may cause product damage are identified by NOTICE labels on the product and in
this publication.
DAEWOO cannot anticipate every possible circumstance that might involve a potential hazard. The
warnings in this publication and on the product are therefore not all inclusive. If a tool, procedure,
work method or operating technique not specifically recommended by DAEWOO is used, you must
satisfy yourself that it is safe for you and others. You should also ensure that the product will not be
damaged or made unsafe by the operation, Iubrication, maintenance or repair procedures you
choose.
The information, specifications, and illustrations in this publication are on the basis of information
available at the time it was written. The specifications, torques, pressures, measurements,
adjustments, illustrations, and other items can change at any time. These changes can affect the
service given to the product.
Obtain the complete and most current information before starting any job. DAEWOO dealers have
the most current information available.
1 of 29
WARNING
Index
Specifications
Hydraulic Control Valve .......................................... 5
Systems Operation
Hydraulic Control Valve ........................................ 17
Assembly And Construction .......................... 17
Check Valve .................................................. 21
Flow Control Valve And Relief Valve ............ 20
Valve Operation ............................................ 18
Hydraulic System (D20/25/30S-2,
G20/25/30S-2, GC20/25/30S-2 Model)................. 6
Hydraulic System (D20/25-2 Model Only) ............ 11
Anti-Stall And Remote Relief Valve .............. 14
Testing And Adjusting
Hydraulic System .................................................. 23
Flow Control Valve Adjustment ..................... 24
Relief Valve Pressure Check ........................ 23
Troubleshooting .................................................... 22
Disassembly And Assembly
Assembly .............................................................. 28
Cleaning, Inspection And Repair .......................... 26
General ................................................................. 25
Unit Disassembly .................................................. 25
3 of 29New Hydraulic Systems Index
Specifications
Hydraulic Control valve (1) Torque for bolts that hold control valve sections
together ................ 40.5 ±2 N•m (360 ±18 lb•in)
(2) Adjust TILT and sideshift relief valve pressure as
shown above. See Relief Valve Pressure Check
in Testing And Adjusting.
(3) Torque for nipple assembly ........ 36.5 ±0.5 N•m
(320 ±4 lb•in)
See Folw Control Valve Adjstment in Testing And
Adjusting.
(4) Torque for screws............................12 ±1.5 N•m
(105 ±13 lb•in)
5 of 29New Hydraulic Systems Specifications
CONTROL VALVE
TILT, Auxiliary
Relief Valve
Pressure
±350 kPa
(±50 psi)
15,500 (2250)
15,500 (2250)
15,500 (2250)
Main Relief
Valve
Pressure
±500 kPa
(±75 psi)
18,100 (2625)
19,500 (2825)
21,550 (3125)
Mast
Std
FFL
FFTL
Std
FFL
FFTL
Std
FFL
FFTL
Model
D(G)20(S)
GC20(S)
D(G)25(S)
GC25(S)
D(G)30S
GC30S
2
1
3
IDCS001B
Systems Operation
Hydraulic System
(D20/25/30S-2, G20/25/30S-2, GC20/25/30S-2 Model)
6 of 29New Hydraulic Systems Systems Operation
Basic Hydrauic Schematic With Standard Lift
(1) Lift cylinders. (2) Excess flow protectors. (3) Sideshift cylinder(s)(if equipped). (4) Lowering flow control valve. (5) Hydraulic
control valve. (6) Tilt cylinders (7) Relief valve(lift). (8) Relief valve(tilt and sideshift). (9) Hydraulic oil filter. (10) Hydraulic oil
tank. (11) Priority valve. (12) Oil line(trucks with power brakes only). (13) Oil line. (14) Hydraulic strainer. (15) Hydraulic pump.
(16) Oil line to steering gear. (17) Oil line.
12
11
8
5
7
3
2
1
1
2
4
6
9
10
13
14 15 16 17
IDCS002B
The hydraulic system has hydraulic oil tank (10)
which holds the oil for gear type hydraulic pump (15).
Hydraulic pump (15) sends pressure oil to the power
brakes (if equipped), hydraulic and steering systems.
Pump oil flows from pump (15) to priority valve (11)
where the oil folw divides to the power brakes brake
valve (if equipped)(not shown) through line (12) and
to the steering gear through line (16).
The control valve levers move the valve spools in
control valve (5) to let the pump oil in the control
valve go to lift cylinders (1) and/or (19), tilt cylinders
(6) or sideshift cylinder(s) (3).
The return hydraulic oil from the cylinders flows
through hydraulic control valve (4), line (13), into filter
(9) and hydraulic tank (10). Relief valve (7) in the
control valve body will make the flow control valve
release extra pressure to the hydraulic tank when the
pressure in the lift or tilt circuits goes higher than
relief valve pressure shown in the Control Valve
section of Specifications. Relief valve (8) does the
same thing for the sideshift circuit when it goes
higher than the auxiliary relief valve pressure shown
in the Control Valve section of Specifications.
7 of 29New Hydraulic Systems Systems Operation
The maximum speed at which the lift cylinder(s) are
lowered is controlled by lowering flow control valve (4).
Excess flow protectors (2) and (18) will act as flow
control valve if an oil line between them and flow
control valve (4) is broken when the mast is raised or
lowered. This prevents a sudden fall of the mast or
carriage if an oil line is broken.
The tilt forward, tilt back and sideshift speeds are
controlled by flow control valves in hydraulic control
valve (5). There is an anti-cavitation valve inside the tilt
spool to prevent cavitation (development of air pockets)
in tilt cylinders (6).
REFERENCE : For the Hydraulic Systems Schematics.
8 of 29New Hydraulic Systems Systems Operation
Basic Hydraulic Schematic With Standard Lift
(1) Lift cylinders. (2) Excess flow protectors. (3) Sideshift cylinder(s)(if equipped). (4) Lowering folw control valve. (5) Hydraulic
control valve. (6) Tilt cylinders. (7) Relief valve(lift). (8) Relief valve(tilt and sideshift). (9)Hydraulic oil filter. (10) Hydraulic oil
tank. (11) Priority valve. (12) Oil line(trucks with power brakes only). (13) Oil line. (14) Hydraulic strainer. (15) Hydraulic pump.
(16) Oil line to steering gear. (17) Oil line. (18) Excess folw protector. (19) Lift cylinder(primary).
18 19
1
2
4
6
9
10
13
14 15 16 17
12
11
8
5
7
3
2
1
IDCS003B
Hydraulic System (D20/25-2 Model Only)
11 of 29New Hydraulic Systems Systems Operation
Basic Hydraulic Schematic With Standard Lift
(1) Lift cylinders. (2) Excess flow protectors. (3) Sideshift cylinder(s)(if equipped). (4) Lowering folw control valve. (5) Hydraulic
control valve. (6) Tilt cylinders. (7) Relief valve(lift). (8) Relief valve(tilt and sideshift). (9) Hydraulic oil filter. (10) Hydraulic oil
tank. (11) Priority valve. (12) Oil line(trucks with power brakes only). (13) Oil line. (14) Hydraulic strainer. (15) Hydraulic pump.
(16) Oil line to steering gear. (17) Oil line. (18) Remote relief valve. (19) Oil line(trucks with anti-stall valve only). (20) Anti-stall
valve(if equipped).
1
2
4
6
9
10
13
14 15 16 17 18 19 20
12
11
8
5
7
3
2
1
IDCS004B
The hydraulic system has hydraulic oil tank (10) which
holds the oil for gear type hydraulic pump (15).
Hydraulic pump (15) sends pressure oil the power
brakes (if equipped), hydraulic and steering systems.
Pump oil flows from pump (15) to priority valve (11)
where the oil folw divides to the power brakes brake
valve (if equipped)(not shown) through line (12) and to
the steering gear through line (16). Oil also flows
through anti-stall valve (20), to hydraulic control valve
(5) and back to hydraulic tank (10).
When the lift truck is at idle speed the hydraulic pump
delivers a low oil flow. If the lift, tilt or auxiliaries are
used the pressure in line (17) will increase and
remote relief valve (18) will dump oil to hydraulic tank
(10). As engine speed is increased, oil flow
increases, anti-stall valve (20) now closes the
passage to remote relief valve (18). With remote
relief valve (18) blocked, normal hydraulic relief
pressures are available.
The control valve levers move the valve spools in
control valve (5) to let the pump oil in the control
valve go to lift cylinders (1) and/or (22), tilt cylinders
(6) or sideshift cylinder(s) (3).
The return hydraulic oil from the cylinders flows
through hydraulic control valve (4), line (13), into filter
(9) and hydraulic tank (10). Relief valve (7) in the
control valve body will make the flow control valve
release extra pressure to the hydraulic tank when the
pressure in the lift or tilt circuits goes higher than
relief valve pressure shown in the Control Valve
section of Specifications. Relief valve (8) does the
same thing for the sideshift circuit when it goes
higher than the auxiliary relief valve pressure shown
in the Control Valve section of Specifications.
12 of 29New Hydraulic Systems Systems Operation
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