Oil Pressure Gauge: Description and Operation

CONSTANT VOLTAGE REGULATOR GAUGE SYSTEM (CVR)

This oil pressure indicating system incorporates an instrument voltage regulator, electrical oil pressure gauge and a sending unit which are connected in series. The sending unit consists of a diaphragm, contact and a variable resistor. As oil pressure increases or decreases, the diaphragm actuates the contact on the variable resistor, which in turn controls current flow to the gauge. When oil pressure is low, resistance of the variable resistor is high, which restricts current flow to the gauge, indicating low oil pressure. As oil pressure increases, resistance of the variable resistor is lowered, permitting increased current flow to the gauge, which increases the gauge reading.

MAGNETIC GAUGE SYSTEM

Fig. 8 Magnetic Guage:

The magnetic gauge movement consists of three primary coils, one of which is wound at a 90° angle to the other two. The coils form a magnetic field which varies in direction according to the variable resistance of the sender unit which is connected between two of them. A primary magnet which is attached to a shaft and pointer rotates to align to this primary field resulting in pointer position. The bobbin/coil assembly is pressed into a metal housing which is attached to the instrument cluster Fig. 8. These gauges require no adjustments, calibrations or maintenance. This gauge system does not use an IVR.