F-15. BOOM CYLINDER HYDRAULIC SUBSYSTEM.
a. The hydraulic fluid power for the
d. Moving the handle of the directional
operation of the boom cylinders is supplied
control valve (1) in the LOWER position
by the hydraulic power subsystem.
directs hydraulic fluid to the retract ports of
the boom cylinders (4), which lowers the
b. The boom
cylinder hydraulic sub-
boom. The relief valve (6) protects the sub-
the power to raise and
valve (2) causes the relief valve (5) to open
Moving the handle of the directional
and allow return flow to the reservoir.
control valve (1) in the RAISE position
check valve of the relief valve (5) to the
control valve (1) is in the neutral position,
extend ports of the boom cylinders (4),
hydraulic fluid is blocked, hydraulically lock-
which raises the boom. The relief valve (6)
ing the boom cylinders in a fixed position.
The emergency release valve (7) can be
releases excess hydraulic fluid
opened to lower the boom.