The "7-Way Military Trailer Converter" is for pulling a military trailer with a tow vehicle that has a 7-Way RV style socket, like a pickup truck.
• 24 Volts @ 10 Amps (240 watts lighting power)
• Surge Suppression
• Overload Protection
• Automatic Reset
• Plug & Play (no wire cutting or splicing)
• Running Lights must be turned on to power adapter
• No modifications required for Turn and Stop signals on Semi-Trailers
How It Works
The converters take power from the tail light circuit and converts it to 24 volts. That 24 volt power is fed into relays that are triggered by the left and right stop/turn circuits. The 24 volts from the power converter and relays are fed to a 12-Pin NATO socket. The semi-trailer versions have additional relays that provide turn and stop lighting for military semi-trailers without adding or modifying the trailers lights.
A note about power
The adapter will supply a total of 10 amps (240 watts) for trailer lighting. The standard taillight bulb draws 26 watts for stop/turn and 8 watts for tail. A typical trailer setup of two stop/turn/tail light bulbs (one per side) with running lights on and brakes applied will use 68 watts, leaving 172 watts for marker lights (they tend to be 8 watts or less). A maximum of 20 amps is drawn from the tow vehicles tail light circuit by the adapter.
Most military trailers have a permanently attached NATO lighting cable that plugs into the tow vehicle, but semi-trailer variants often use an "intravehicular cable".
An "intervehicular cable" is a Male to Female 12-Pin NATO extension cable, similar idea to a J560 coiled power cord, stowed with the semi-trailer but often missing, pic here: Intervehicular Cable