switch, and grab fully advanced limit switch. The cam
positions are adjusted for individual installations.
RETRACTION ENGINE MANIFOLD
The retraction engine manifold (fig. 4-45) is
mounted on the retraction engine frame and provides
internal fluid passages for various control valve
functions. The manifold contains the bridle tensioner
pilot valve and the internal tensioning inlet and outlet
valves for the bridle tensioning system. The manifold
also contains the advance and retract pilot valve, retract
directional valve, advance directional valve, and
maneuvering valve.
ADVANCE AND RETRACT PILOT VALVE
Used to control the advance directional valve and
retract directional valve, through the advance dump
valve and retract dump valve respectively. When the
advance solenoid (SA) is energized, the pilot shifts,
directing hydraulic fluid flow through the pilot valve,
through the advance dump valve to shift the advance
directional valve. When the retract solenoid (SR) is
energized, the pilot shifts, directing hydraulic fluid
flow through the pilot valve, through the retract dump
valve to shift the retract directional valve
RETRACT DIRECTIONAL VALVE
The retract directional valve (see fig. 4-45) controls
the hydraulic motor during retract. When actuated by
fluid flow from the pilot valve, the retract directional
valve piston shifts, directing fluid flow through the
directional valve to the hydraulic motor. The fluid
returns from the motor and flows through the
directional valve to the gravity tank. When the retract
directional valve is not actuated, no fluid flow is
allowed through the valve. As the traverse carriage
nears the end of a retract stroke, a cam mounted on the
carriage actuates the retract dump valve. This drains the
pressure in the retract directional valve actuating
chamber back to the gravity tank through the dump
valve. The retract directional valve piston then closes,
causing a gradual cutoff of hydraulic fluid from the
hydraulic motor, initiating retraction engine braking.
4-37
INTERNAL-TENSIONING
OUTLET VALVE
INTERNAL-TENSIONING
INLET VALVE
TENSIONER
PILOT VALVE
ADVANCE DIRECTIONAL
VALVE
RETRACT DIRECTIONAL
VALVE
MANEUVERING
VALVE
ADVANCE AND
RETRACT
PILOT VALVE
ABEf0446
Figure 4-45.—Retraction engine manifold.
