Manitowoc 2250 Service Maintenance Manual

Reference Only
HYDRAULIC AND AIR SYSTEMS 2250 SERVICE/MAINTENANCE MANUAL
2-40
Published 07-19-16, Control # 249-01
N-1 PRESSURE-REDUCING VALVE
MAINTENANCE
Operation
See Figure 2-44 and Figure 2-45 for the following.
Air pressure from the main supply passes from the IN port to
the OUT port through the unseated inlet valve of the exhaust
valve unit (1). The inlet valve is held off its seat by a control
spring (2) which forces the diaphragm (3) and exhaust valve
seat (4) upward. While the seat is in the upward position, the
exhaust valve is closed and the inlet valve is held open.
Air pressure at the OUT port also passes through a sensing
port to the top of the diaphragm. When the pressure at the
OUT port reaches the setting of the control spring, it is
compressed, and the valve assembly moves down far
enough to close the inlet valve and keep the exhaust valve
closed. As long as air pressure at the OUT port and spring
force are balanced, the inlet and exhaust valve remain
closed.
The valve automatically compensates for downstream
pressure changes, keeping the control circuit at the
predetermined or set pressure. Pressure changes may be
caused by line leakage, temperature changes, or load thrust.
If air pressure at the OUT port increases over that called for
by the spring setting, the diaphragm deflects downward,
moving the exhaust valve seat away from the inlet and
exhaust valve unit and vents the excess pressure. If the
pressure drops below that called for by the spring setting, the
control spring forces the diaphragm upward and the exhaust
valve seat moves the inlet valve from its seat, opening the IN
port to the OUT port to restore the pressure called for.
S119
FIGURE 2-44
In
Out
Exhaust
Decreasing
Pressure
In
Out
Exhaust
Increasing
Pressure

Manitowoc 2250 Specifications

General

Brand	Manitowoc
Model	2250
Category	Construction Equipment
Language	English