Daewoo D20S-2, G20S-2, GC20S-2, D20-2, G25S-2 Specifications Systems Operation Testing & Adjusting Disassembly & Assembly

...

Aug. 1996

Specifications Systems Operation T esting & 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.

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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

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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

•

(320

±4 lb

•

in)

See Folw Control Valve Adjstment in Testing And Adjusting.

(4) Torque for screws

............................

12 ±1.5 N

•

(105

±13 lb

•

in)

5 of 29New Hydraulic Systems Specifications

CONTROL VALVE

TILT, Auxiliary

Relief Valve

Pressure

±350 kPa

(

±50 psi)

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

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.

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).

14 15

IDCS003B

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