Vehicle System
System Operation
22
Hydraulic Control Valve
Control valve has specific section of lift and tilt.
Overflow valve and flow-priority valve could be
mounted on the side port of inlet.
Oil circuit is of parallel with neutral back-flow
function. When the spool is in the neutral position,
pump is in the free load condition.
When controlling two or more than two spools at the
same time, usually actuator with less load acts first
and the one with more load acts later for the sake of
load difference. Work the more-load spool first and
control the stroke of the less one to have
simultaneous action under different load.
Principle of Side Cover of Inlet Port
Side cover of inlet port is composed of main relief
valve to limit max pressure in circuit, flow-priority
valve to supply oil in priority to steering and PF relief
valve to limit pressure in priority. See the description
of principle of relief valve below is only a introduction
of flow-priority valve.
Flow-priority valve may classify the oil as pre-set
priority flow (PF flow) and maintain flow (MF flow).
PF is for steering, MF is for valve sections to control
the loading.
Oil from Port P goes from throttle hole, check valve,
PF throttling part inside of spool FD into PF port. If
oil from port P is increased, pressure difference will
be generated in front and back of throttle hole.
Because of the pressure difference on ends of FD
spool, the spool goes toward the part to shut the PF
throttle part. And then, pressure difference goes
down as well as PF flow is reduced. Therefore, the
flow set by throttle hole and spring is ensured.
1.
When MF flow pressure is higher than PF flow
pressure (in loading)
When in loading, MF flow pressure increases,
overall pressure increase as well. At this time, flow
in priority is increasing since PF flow pressure is
lower than MF flow. Once flow in priority increases,
pressure difference of throttle increases too. And
throttle effect is generated on PF throttle parts and
flow keeps stable.
2.
When MF flow pressure is lower than PF flow
pressure ( in steering)
When in steering, PF flow pressure increases. And
overall pressure increases too. Flow is increasing
too with one side of MF flow pressure goes down.
So, when flow by throttle hole goes down, the
pressure difference decreases as well and FD spool
moves to the part to shut the MF throttle to keep
flow go stable as well as the pressure difference of
throttle back and forward.
Summary of Contents for D20G
Page 2: ......
Page 5: ...Specifications TORQUE SPECIFICATIONS SB2004E00 D e c 1 9 9 8 ...
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Page 138: ...Diesel Engine Engine System 124 NOTE The crankshaft must rotate freely by hand 02900058 ...
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Page 341: ...4TNV98 4TNE98 Diesel Engine Section 3 Engine 87 4TNE98 Engine Figure 6 1 ...
Page 423: ...4TNV98 4TNE98 Diesel Engine Section 4 Fuel System 169 Fuel System Components Figure 7 1 ...
Page 477: ...4TNV98 4TNE98 Diesel Engine Section 7 Starter Motor 223 Starter Motor Troubleshooting ...
Page 494: ...4TNV98 4TNE98 Diesel Engine Section 8 Troubleshooting 240 Troubleshooting Charts ...
Page 495: ...4TNV98 4TNE98 Diesel Engine Section 8 Troubleshooting 241 ...
Page 496: ...4TNV98 4TNE98 Diesel Engine Section 8 Troubleshooting 242 ...
Page 498: ...4TNV98 4TNE98 Diesel Engine Section 8 Troubleshooting 244 4TNE98 Engine ...
Page 499: ...Service Manual G424FE LP Engine G424F LP Gasoline Engine G20G G25G G30G SB4320E00 Jan 2008 ...
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Page 529: ...G424F FE Service Manual Chapter 2 Recommended Maintenance 29 ...
Page 534: ...G424F FE Service Manual Chapter 3 Engine Mechanical System 34 MAIN BEARINGS 0 50 UNDERSIZE ...
Page 584: ...G424F FE Service Manual Chapter 3 Engine Mechanical System 84 ...
Page 729: ...G424F FE Service Manual 229 Chapter 8 Basic Troubleshooting ...
Page 731: ...G424F FE Service Manual 231 Chapter 8 Basic Troubleshooting ...
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Page 820: ...Power Train System Operation 14 Hydraulic System ...
Page 822: ...Power Train System Operation 16 Hydraulic System ...
Page 824: ...Power Train System Operation 18 Hydraulic System ...
Page 826: ...Power Train System Operation 20 Hydraulic System ...
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Page 1023: ...A374081 01 ELECTRIC SCHEMATIC MODEL D20 25 30G EM0K2 EM0K3 Cummins B3 3 ...
Page 1024: ...A654030 00 ELECTRIC SCHEMATIC MODEL D20 25 30G EM0QM EM0QN Yanmar 4TNE98 Tier 3 ...
Page 1025: ...A604500 00 ELECTRIC SCHEMATIC MODEL G20 25 30G EM0QF EM0QG GM G424F Non Certi LP ...
Page 1026: ...A604510 00 ELECTRIC SCHEMATIC MODEL G20 25 30G EM0QH EM0QJ GM G424F Non Certi GAS ...
Page 1027: ...A604516 00 ELECTRIC SCHEMATIC MODEL G20 25 30G EM0QY EM0QZ GM G424FE Tier 3 LP ...
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Page 1059: ...Safety Section 29 Lean away from the direction of fall Lean forward ...
Page 1071: ...General Section 41 Typical Example Side Shifter Serial Number If Equipped ...