TM 5-3805-254-20-1
NONELECTRIC GAGES - CONTINUED
ENGINE WATER TEMP GAGE
Gage and sending unit are permanently connected by a capillary tube, making this a nonrepairable one-piece assembly.
The capillary tube and bulb are filled with a liquid, such as ether, whose vapor pressure is proportional to its temperature.
As temperature increases, the liquid expands, exerting pressure to bourbon tube causing it to straighten. This movement
changes needle position in direct relationship to bourbon tube movement.
R.P.M./ENGINE HOURS METER
Tachometer is cable driven from engine fuel injection pump. It indicates engine revolutions per minute (rpm). Meter is
graduated in 100 rpm increments from 0 to 2500 rpm. Speedometer and Tachometer operate similary. However,
Tachometer operates independently of speedometer and is engine driven instead of transmission driven. Hour meter
indicates hours of engine running.
ENGINE OIL PRESSURE GAGE
Mechanical gage connected to engine lubrication system by small diameter tubing. Actual pressure applied to bourbon
tube causes it to straighten, moving needle in direct relationship.
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