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| Illustration 1 | g01082441 |
(1) Bank valve (2) Tilt right solenoid (3) Blade raise solenoid (4) Tilt left solenoid (5) Blade lower solenoid (6) Pilot lockout solenoid | |
Bank valve (1) for the AccuGrade System consists of five solenoids. Four of the five solenoids send pilot oil to the main control valves in order to actuate the control valve spools. The fifth solenoid acts as a pilot lockout solenoid.
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| Illustration 2 | g01091163 |
(1) Bank valve | |
Bank valve (1) for the AccuGrade System is located in the right hand console underneath the main control valve. Bank valve (1) is accessed by removing the cover and the plate in the cab.
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| Illustration 3 | g01105198 |
The bank valve in auto grade mode (2) Tilt right solenoid (3) Blade raise solenoid (4) Tilt left solenoid (5) Blade lower solenoid (6) Pilot lockout solenoid (7) Signal to pump compensator | |
When the auto grade mode is active, pilot lockout solenoid (6) is energized. This allows pilot oil to flow to each of the four solenoids in the bank valve. When blade movement is necessary, the corresponding solenoid is energized. Pilot oil is then sent to the main control valve.
Load sensing signal (7) sends the pilot oil for the AccuGrade bank valve to the pump compensator. The additional pilot pressure from the bank valve combines with the margin pressure which makes the standby pressure higher in the hold position. The higher standby pressure allows the AccuGrade system to make fine corrections easier because the pump is already pre-stroked. For more information regarding low pressure standby, see the System Operation, "Hydraulic Pump - Piston".
Blade Lift
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| Illustration 4 | g01091184 |
The bank valve in blade lift (1) Bank valve (2) Blade raise solenoid (3) Tilt right solenoid (4) Blade lower solenoid (5) Tilt left solenoid (6) Pilot lockout solenoid (8) Resolver (9) Lift control valve (10) Pilot Valve (11) Resolvers (12) Tilt control valve (13) Pressure Sensor | |
When the AccuGrade System commands the blade to be raised, pilot valve (10) remains in the neutral position. The blade raise solenoid (2) in bank valve (1) sends pilot signal to the side for lift on the lift control valve (9). Pump oil is then sent to the lift cylinders in order to raise the blade.
Signal oil from bank valve (1) is directed to resolver (8). Resolver (8) determines the highest pressure between pilot valve (10) and bank valve (1). The highest pressure is then directed to the resolver network in the main control valve. Refer to System Operation, "Signal Resolver Network" for more information on this subject.
Manual Blade Lower In Auto Grade Mode
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| Illustration 5 | g01103753 |
Bank valve in manual lower of the blade (1) Bank valve (2) Blade raise solenoid (3) Tilt right solenoid (4) Blade lower solenoid (5) Tilt left solenoid (6) Pilot lockout solenoid (8) Resolver (9) Lift control valve (10) Pilot Valve (11) Resolvers (12) Tilt control valve (13) Pressure Sensor | |
If pilot valve (10) is activated and the AccuGrade System is in the auto grade mode, resolvers (11) will only allow the highest oil pressure to pass to the main control valve. The higher pressure from the pilot valves can override the AccuGrade System.
If the blade is manually lowered with the pilot valve and the auto grade mode is active, the AccuGrade System will de-energize. This function only happens when the blade is manually lowered, in the auto grade mode.
Pressure sensor (13) senses pilot pressure from pilot valve (10) for the blade lower. Pressure sensor (13) sends a signal to the ECM. The ECM then disables the AccuGrade System on the machine hydraulic system. When pressure is not sensed from pressure sensor (13) in the pilot circuit for the blade lower, the AccuGrade System is then enabled. This function permits the operator to use the float function while the AccuGrade System is in auto grade mode.
Blade Tilt
The function of the blade tilt left and blade tilt right is nearly identical to the function of the blade raise. When the AccuGrade System commands the blade to be tilted right or tilted left, pilot valve (10) remains in the neutral position. Tilt left solenoid (5) and tilt right solenoid (3) for the blade in bank valve (1) sends pilot signal to the tilt control valve (12). Pump oil is then sent to the tilt cylinders in order to tilt the blade to the left or right.