REPAIR & ADJUSTMENTS
6.8
D. Directional valve #20 de-energizes and shifts to the center position (all ports
closed) stopping the cylinder travel.
8. Valve #26 shifts to the center blocked position from the excess flow position
(time delay following the stopping of the cylinder).
9. Cycle starts over
Valve Operation Status
1. Valve #28 (by-pass valve)
A. By-pass valve #28 is energized and open to reservoir anytime the system is in
manual operation and the cylinder directional valves #20 are in the center po-
sition (no cylinder movement).
B. By-pass valve #28 is energized and open to reservoir for two (2) seconds
when the hydraulic unit starts-up.
C. By-pass valve #28 is energized and open to reservoir when the system is in
automatic and both cylinders are retracted on the home limit switch.
D. By-pass valve #28 is energized and open to reservoir when valve #26 is
shifted to the decompression position.
E. By-pass valve #28 is energized and open for 100 mil/sec when "A" or "B" re-
tracting cylinder hits the retracted limit switch.
F. By-pass valve #28 is energized and open to reservoir when "A" or "B" ex-
tending cylinder hits the extend limit switch and turns off 200 mil/sec after
valve #20 (cylinder directional valve) shifts to the retract position.
2. Valve #26 (decompression)
Valve #26 is shifted to the decompression position whenever an extending cylinder
hits the extend limit switch then closes 200 mil/sec after valve #20 (cylinder direc-
tional valve) shifts to retract position.
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