Operation
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| Illustration 1 | g00573423 |
(A) Left side steering angle (Degree) (B) Modulating pressure (nonadjustable pressure) (C) Steering wheel deadband (left side) (D) Pilot pressure (E) Neutral adjustment screw (IN) (F) Steering wheel deadband (right side) (G) Intersecting pressure (H) Pump deadband (nonadjustable deadband) (J) Right side steering angle (Degree) (K) Neutral adjustment screw (OUT) (L) Intersecting pressure | |
The steering control is set at the factory in order to achieve an acceptable deadband. The pressure curves maintain a general shape, as shown. See Illustration 1. However, the curves may not be identical from the left side to the right side.
The pump deadband is the pressure that is necessary to counteract the control springs. This is also the pressure that is necessary to begin to upstroke the pump. The pressure can be "Bias" in one direction or in the other direction by the use of the neutral adjusting screw.
The "total" deadband is not adjustable, but the band can be moved to positions (E) and (K) .
The pilot pressure intersects with the pressure that upstrokes the pump at locations (G) and (L). This position is the steering angle. When this position is reached, the machine begins to turn.
When the steering angle reaches location (L), the machine begins to turn to the left. When the steering angle reaches location (G), the machine begins to turn to the right.
In Illustration 1, the left side steering wheel deadband (C) is significantly greater than the right side steering wheel deadband.
In order to move the pump deadband (E) upward, turn the neutral adjustment screw (IN). This will move intersection (G) farther to the right and increase steering deadband (F) .
As dimension (H) is nonadjustable, the intersection (L) also moves to the right. The movement toward the right decreases dimension (C). The movement to the right also equalizes the right side steering deadband (F) and the left side steering deadband (C) .
Adjustment Procedure
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| Illustration 2 | g00574098 |
Steering Pump (1) Steering pump (2) Neutral adjustment screw | |
- Start the engine and run the engine at high idle.
- Slowly turn the steering wheel to the left. When the machine begins to turn, record the angle of the steering wheel. This is dimension (C) .
- Slowly turn the steering wheel to the right. When the machine begins to turn, record the angle of the steering wheel. This is dimension (F) .
- Stop the engine.
Note: The adjustment is very fine. Turn the screw no more than 30 degrees at a time.
- If the difference in the angles exceeds 5 degrees, neutral adjustment screw (2) can be used to compensate.
Turn the adjustment screw by 10 degrees for every 5 degrees of difference in the steering deadband.
Use an allen wrench that is 112.0 mm (4.4 inch) long. Moving the wrench 20 mm (0.8 inch) is approximately 10 degrees. Measure the movement from the end of the wrench.
Turning the adjustment screw (in) to direction (E) causes following changes:
- The right side steering deadband increases
- The left side steering deadband decreases
- The right side steering deadband increases
- If left side steering deadband (C) is more than right side steering deadband (F), make the following adjustment: Turn the neutral adjustment screw (IN) by approximately 1/12 turn.
If the right side steering deadband (F) is more than the left side steering deadband (C), make the following adjustment: Turn the neutral adjustment screw (out) by approximately 1/12 turn.
- After each adjustment, tighten the locknut on the neutral adjustment screw to 7 N·m (61 lb in).
- Check the operation of the machine. Start the engine and recheck the angles of the steering wheel.
When the adjustment of deadband is acceptable in forward gears, check the machine in REVERSE gear. Determine if the adjustment of deadband in REVERSE gear is acceptable.
It is necessary to check the adjustment in REVERSE because of the flip-flop valve. The flip-flop valve flips the pilot oil modulating curves. Flipping the pilot oil modulating curves creates new points of intersection at locations (G) and (L) .
As a result, the left side and the right side curves for the pilot valve may be significantly different. Fixing a problem with the deadband in FORWARD may tend to make a problem with the deadband in REVERSE more severe.
In these cases, try to equalize the deadbands as best as possible in both FORWARD and REVERSE.