(Photo courtesy PD-SEPS)
The low oil pressure (LOP) switch on 2kW military tactical generators (MTGs) MEP-531A (120 VAC, 60Hz) and MEP-501A (28 VDC) has changed. The new LOP switch requires a different coupling that must be changed when replacing the old LOP switch. The couplings are not interchangeable.
Figure 1 in WP 0060 of TM 9-6115-673-13&P (Jun 10) shows the coupling and LOP switch. The new LOP switch is NSN 5930-01-416-0372, PN 183250-39450. The new matching coupling is NSN 4730-01-692-5380, PN 101561-001.
Diagram shows new LOP switch and new coupling
For more info, see Maintenance Informational Message (MIM) CECOM-MI-21-04009, available in the Army Enterprise Systems Integration Program (AESIP) Portal in the Maintenance Management Information System (MMIS):
Or download the MIM from the PS milSuite site: