Instruments and Controls Identification Dual System Air Pressure Gauge A dual system air pressure gauge ( Fig. 2.27 ) regis- ters the constant pressure in the primary and sec- ondary air systems. Normal pressure, with the engine running, is 100 to 120 psi (689 to 827 kPa) in both systems. A low-air-pressure warning light and buzzer, connected to both the primary and secondary sys- tems, activates when air pressure in either system drops below a minimum pressure of 64 to 76 psi (441 to 524 kPa). When the engine is started, the warning light and buzzer remain on until air pressure in both systems exceeds minimum pressure. 1 2 3 4 5 6 7 8 9 Fuel Gauge 01/18/95 f600512a 1.
Transmission Oil Temperature Gauge 2. Forward Differential Oil Temperature Gauge 3. Rear Differential Oil Temperature Gauge 4. Engine Oil Temperature Gauge 5. Turbocharger Boost Pressure Gauge 6. Fuel Pressure Gauge 7. Automatic Engine Idler/Timer 8. Intake-Air Restriction Gauge 9. Pana-Pacific Digital Clock The fuel gauge ( Fig. 2.27 ) indicates the level of fuel in the fuel tank(s). If equipped with a second (op- tional) fuel gauge, each fuel tank level is indicated on a separate gauge. Intake-Air Restriction Gauge, Optional An intake-air restriction gauge ( Fig. 2.28 ) measures the vacuum on the engine side of the air cleaner at the air cleaner outlet.
Vacuum is measured in inH 2 O (inches of water). Service the air cleaner when the vacuum reading equals the applicable level shown under "Service" in Table 2.5 . Fig. 2.28, Optional Gauges Intake-Air Restriction Indicator An intake-air restriction indicator ( Fig. 2.29 ) mea- sures the vacuum on the engine side of the air cleaner at the air cleaner outlet. If the yellow signal stays locked at or above the values shown in Table 2.5 , after the engine is shut down, service the air cleaner. Then, press the yellow button to reset the indicator. Intake-Air Restriction Engine Type * Initial inH 2 O Service inH 2 O Cummins 12 25 Detroit Diesel 12 20 Caterpillar 15 25 01/18/95 f600148a Fig.
2.29, Intake-Air Restriction Indicator Fuel Pressure Gauge, Optional A fuel pressure gauge ( Fig. 2.28 ) registers output pressure of the fuel pump. Whenever the engine is operating, the fuel pressure reading should be con- stant. If the fuel pressure drops, investigate the cause and make the necessary repairs. * Turbocharged engines must be checked at full load and governed en- gine speed. Table 2.5, Intake-Air Restriction 2.28