Right Turn (COORDINATED)
 | |
| Illustration 1 | g01232127 |
Oil Distribution
The auxiliary pump supplies oil to port "P" of the left steering control unit and the auxiliary pump supplies oil to the port "P" of the right steering control unit. Supply oil from the auxiliary pump is also sent to port "P1" of the rear manifold. Inside the rear manifold, supply oil is distributed to the rear steering solenoids.
Front Steering Operation
When one of the steering wheels is turned to the right, the metering pump provides flow to the head end of the front steering cylinder through the port "R". Return oil from the rod end of the front steering cylinder flows into the steering control unit through the port "L". This oil returns to the tank through the port "T" of the steering control unit.
When the steering wheel is no longer turning, the springs in the control spool return the spool to the hold position. This action blocks the supply oil from the auxiliary pump and this action blocks the lines to the steering cylinder. The tracks remain in the current position until one of the steering wheels is moved.
Rear Steering Operation
When the steering mode switch is in the COORDINATED position, the machine ECM operates the rear steering solenoids based on input from the front steering sensor. When the machine ECM determines that the front tracks are turning to the right, the machine ECM energizes the left rear steering solenoid. In this case oil is sent into the rod end of the rear steering cylinder and the front of the rear tracks turn to the left. When the rear track position sensor indicates that the rear tracks have moved to the same degree as the front tracks, the machine ECM discontinues the output to the rear steering solenoid.
Makeup and Relief Valves
If one of the front tracks or one of the rear tracks encounters a large obstruction, the pressure in one end of the steering cylinder increases. When the pressure in one of the steering lines reaches the relief setting, the relief valve opens. In this case, oil from the high pressure line is sent to the tank. At the same time, the pressure in the other end of the steering cylinder decreases. If the pressure in the low pressure side of the steering cylinder falls below the pressure in the return line, the makeup valve opens. In this case, oil flows into the low pressure side of the cylinder.
Right Turn (CRAB)
 | |
| Illustration 2 | g01232143 |
Oil Distribution
The auxiliary pump supplies oil to port "P" of the left steering control unit and the auxiliary pump supplies oil to port "P" of the right steering control unit. Supply oil from the auxiliary pump is also sent to port "P1" of the rear manifold. Inside the rear manifold, supply oil is distributed to the rear steering solenoids.
Front Steering Operation
When one of the steering wheels is turned to the right, the metering pump provides flow to the head end of the front steering cylinder through port "R". Return oil from the rod end of the front steering cylinder flows into the steering control unit through port "L". This oil returns to the tank through port "T" of the steering control unit.
When the steering wheel is no longer turning, the springs in the control spool return the spool to the hold position. This action blocks the supply oil from the auxiliary pump and this action blocks the lines to the steering cylinder. The tracks remain in the current position until one of the steering wheels is moved.
Rear Steering Operation
When the steering mode switch is in the CRAB position, the machine ECM turns the rear tracks in the same direction as the front tracks. When the machine ECM determines that the front tracks are turning to the right, the machine ECM energizes the right rear steering solenoid. In this case, oil is sent into the head end of the rear steering cylinder, and the front of the rear tracks turn to the right. When the rear track position sensor indicates that the rear tracks have moved to the same degree as the front tracks, the machine ECM discontinues the output to the rear steering solenoid.