Hitachi ZW180 Technical Manual page 96

Bucket Auto-Leveler Control
Purpose: Automatically to tilt the bucket at a proper
angle (horizontal) to start digging when re-
turning the bucket to the tilting position
Operation:
1. When bucket dump operation is carried out, the
bar is located in front of the bucket proximity
switch.
While the bar passes near the bucket proximity
switch, the bucket proximity switch is turned ON.
This excites the leveler relay and electromagnet at
the bucket tilt side in the pilot valve.
2. When the bucket control lever is moved farther
than the bucket tilting detent position (position to
move farther than the tilting position), the bucket
control lever is retained by the electromagnet on
the bucket tilting side, and pressure oil from the
pilot valve moves the bucket spool in the control
valve.
3. Pressure oil from the main pump flows to the
bottom side of the bucket cylinder through the
bucket spool in the control valve, and extends the
bucket cylinder. When the bucket cylinder is ex-
tended, the bar also passes by the bucket prox-
imity switch at the same time.
4. When the bar moves apart from the bucket prox-
imity switch, the bucket proximity switch is turned
OFF. As the leveler relay and the electromagnet at
the bucket tilt side are unexcited, the bucket con-
trol lever is returned to the neutral position. As the
bucket spool in the control valve also returns to
neutral, the bucket cylinder stops. Consequently,
the bucket is kept at the proper digging angle
(horizontal).
SYSTEM / Control System
T2-1-54