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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 29

New Hydraulic Systems

Systems Operation

Содержание D20S-2

Страница 1: ...Aug 1996 Specifications SystemsOperation Testing Adjusting Disassembly Assembly New Hydraulic Systems D20 25 2 D20 25 30S 2 G20 25 30S 2 G20 25 30S 2 SB2097E00...

Страница 2: ...rt 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 m...

Страница 3: ...lic 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 Ad...

Страница 4: ...embly 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 29 New Hydraulic Systems Specifications CONTROL VALVE TILT Aux...

Страница 5: ...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 oi...

Страница 6: ...lve 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...

Страница 7: ...prevent cavitation development of air pockets in tilt cylinders 6 REFERENCE For the Hydraulic Systems Schematics 8 of 29 New Hydraulic Systems Systems Operation Basic Hydraulic Schematic With Standard...

Страница 8: ......

Страница 9: ...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 li...

Страница 10: ...ses 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 spo...

Страница 11: ...ilt cylinders 6 REFERENCE For the Hydraulic Systems Schematics 13 of 29 New Hydraulic Systems Systems Operation Basic Hydraulic Schematic With Standard Lift 1 Lift cylinders 2 Excess flow protectors 3...

Страница 12: ...stall valve will increase This pressure increase will be limited by the remote relief valve to 8250 kPa 1200 psi 6R7072 Relief Valve This relatively low system pressure allows for a smoother engine i...

Страница 13: ......

Страница 14: ...e bodies connect each section to the common inlet and tank ports Seal rings between the sections seal the connecting passages Sections are held together by studs and nuts 17 of 29 New Hydraulic System...

Страница 15: ...ered or neutral position Under these conditions fluid in the pressure passage is blocked from the cylinder ports by the spool lands Flow through the valve is through the by pass and tank passages to t...

Страница 16: ...he counterbalance feature prevents the forks from tilting forward faster than the pump can supply oil preventing tilt IDCS012B Auxiliary Spool IN Pressure to B A to tank By pass blocked CENTER A and B...

Страница 17: ...ional secondary relief valve allows the use of lower pressure for tilt and accessory function while higher pressure is provided for the lift function NOTE The secondary relief valve must be set at a l...

Страница 18: ...the sensing orifice is great enough to overcome the force of the large spring the valve spool shifts permitting flow to the tank passage Relief valve sub assemblies in the inlet section are pre set an...

Страница 19: ...ue nuts to specified ratings Remedy Replace detent barrel Replace detent spring Trouble Detent type spools will not stay in detent position Trouble No motion slow or jerky action of hydraulic system P...

Страница 20: ...ngs Group 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 F...

Страница 21: ...low Control Valve Adjustment 1 Flow control valve adjuster 1 Remove the nut from the main hydraulic valve tie bolt stud 2 Remove the stud from the valve 3 Use Hex Wrench 6mm turn the flow control adju...

Страница 22: ...r it must be filtered to remove water and other contamination Be sure the unit is not subjected to pressure Disconnect and cap all lines and disconnect linkage to the spool Attaching Parts 1 Remove th...

Страница 23: ...ean and free from obstruction Examine all mating surfaces for nicks and burrs Minor nicks and burrs can be removed with a crocus cloth or an India stone 2 Discard all old seals and O rings Wash all pa...

Страница 24: ...27 of 29 New Hydraulic Systems Disassembly and Assembly IDCS015B...

Страница 25: ...tall the O ring 31 on the relief plug Tighten the plug securely in valve body DO NOT over tighten CAUTION Hex head of relief valve must be face outside of unit Relief Valve 1 Install a new O ring 27 o...

Страница 26: ...rings in proper bores of inlet and mid body sections Attaching Parts CAUTION Make sure all mating surfaces of valve bodies are clean and free of burrs 1 Install seals 4 O ring 5 and the retainer 3 in...

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