TM 5-3895-374-24-2
MAIN GAS VALVE
HYDRAMOTOR
The gas valve on your heater is equipped with a proof of closure switch. This is an externally
mounted micro-switch which is actuated and closes the control circuit when the gas valve has
returned to the closed position. It prevents the burner from recycling if the gas valve did not fully
close following the previous burner cycle.
The hydramotor and valve assembly are "PUSH when energized" type for ON-OFF operation. The
operating mechanism is completely immersed in oil, which eliminates usual maintenance and
service. (See Gas Flow Schematic, Section 5.9)
Operation
When the actuator terminals are powered, the relief valve closes and the electric motor-driven
pump applies hydraulic pressure to the spring-loaded piston, pushing the actuator stem
downward. When the actuator stem reaches full travel, the travel limit switch opens the pump
motor circuit to stop the pump action. The relief valve remains energized and closed, holding the
stem downward. When the control circuit is broken, the relief valve opens and the spring-loaded
piston and valve stem return to the up, de-energized, position, closing the valve. Note that when
actuator is held in energized position, the motor may restart intermittently to maintain proper
pressure against the piston.
CAUTION:
USE MIL SPEC 5606 OIL FOR REFILLING HYDRAULIC UNIT, AVAILABLE
FROM ITT GENERAL CONTROLS, OR USE GEMLINE REFRIGERATION OIL,
AVAILABLE FROM MOST REFRIGERATION SERVICE OUTLETS.
1.
Remove fill plug from top of actuator pump unit.
2.
Fill unit with oil to within 1/4 to 1/2 inch from bottom of fill plug hole.
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