INTRODUCTION 777 SERVICE MANUAL
1-62 Published 10-01-2012, Control # 045-08
Crawler Lock Pin Retract
See Figure 1-44 for following procedures.
When a crawler lock pin cylinder control valve handle is held
in the retract position, moving the lever upward on lower
accessory valve, the valve section shifts to direct oil flow
from the setup pump section of accessory pump into relief
valve (preset to 3,100 psi / 214 bar) section of lower
accessory valve. Note the system pump oil flow is pressure
limited to relief valve system disable valve which is preset to
approximately 2,700 psi (186 bar).
The oil leaves the pin cylinder valve section of lower
accessory valve and enters the rod end of crawler lock pin
cylinder, causing the cylinder rod to retract the pins,
permitting the crawler to be released and separated from the
carbody.
Oil exhausting from the head end of both crawler lock pin
cylinders returns to lower accessory valve and returns to
tank.
FIGURE 1-44
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