TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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Figure 1-16. Late crankcase breather and fire extinguisher system. 1-23. Sending Units and Switches a. Oil Pressure Sending Unit (fig. 1-1). The electrical oil pressure gage sending unit on early engines was located at the right rear of the right side of the crankcase in the main oil gallery line. On late engines, for ease of maintenance, the sending unit is relocated to the front of the crankcase at the opening in the gallery line at No. 1 right cylinder. This sealed sending unit consists of a threaded plate to which a diaphragm, a radially notched spring, and an overload guard plate are crimped. Electrical resistance in the sending unit varies directly as the oil pressure varies. The resulting variation in the current is transmitted to the electrical oil gage on the vehicle instrument panel. b. Low Oil Pressure Warning Light Switch. The low oil pressure warning light switch is furnished with the engine and it is located at the right rear of the right side of the engine crank- case in the main oil gallery line near No. 5 right cylinder. The electrical contact points in this switch close when the oil pressure in the main oil gallery falls to 1132 psi. The completion of the electrical circuit lights the low pressure warning lamp on the vehicle instrument panel. c. Oil Temperature Sending Unit (figs. 1-1). The oil temperature sending unit is located at the 1-21