MIL-T-62491 Trucks, Wrecker: 4540 To 40 820 Kilograms 5-Ton To 45-Ton Lifting Capacity, Modified CommercialThis specification covers all commercial, non-tactical wreckers procured for military use. Vehicles procured under this specification are commercial items which are warranted by the manufacturer as specified in acquisition documents.

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MIL-T-62491C

*	(c)	An in-line fuel warmer or preheater unit shall be provided on diesel engine driven vehicles
		to prevent clogging of fuel filters due to wax crystallization in the fuel. The unit shall use
		engine coolant to transfer sufficient heat to the diesel fuel to heat it from an inlet
		temperature of -40°C (-40°F) to an outlet temperature of -13°C (+9°F), with a fuel flow
		rate not less than the maximum fuel demand of the engine fuel system. A coolant shutoff
		valve shall be provided for the coolant inlet side of the fuel warmer unit. The unit shall
		not cause heating of the fuel above 27°C (80°F) under any possible condition.
*	(d)	An in-tank fuel warmer or preheater unit shall be provided on diesel engine driven
		vehicles. The unit shall use engine coolant to transfer heat to the fuel in one fuel tank.
		The warmer shall not cause heating of any fuel above 27°C (80°F) under any possible
		condition, shall not disable or cause elimination of the fuel gage sending unit and shall not
		violate 3.2.1 or any Federal Motor Carrier Safety Regulation. A coolant shut off valve
		shall be included. The units required by 3.4.1.9(c) and (d) may be combined.

* 3.4.1.10 Fuel fired engine preheater. When specified (see 6.2), a diesel fuel fired engine water heater shall be furnished to preheat the engine. The heater shall include a timer, a thermostat and a circulating pump and shall be connected directly to the engine coolant system. The heater shall be capable of starting and operating at -51°C (-60°F) and shall heat the engine to

+4°C (+40°F) from -51°C (-60°F) in not more than 1 hour. The system shall be equipped with a light, visible to the driver, to indicate that the preheater is operating. The system shall include fuel warmers or preheaters conforming to 3.4.1.9(c) and (d).

* 3.4.1.11 Vernier throttle control. When specified (see 6.2), a manual vernier controlled throttle with quick release shall be furnished, except on electronically controlled engines.

3.4.2 Electrical system. The electrical system shall be in accordance with Federal Motor

Carrier Safety Regulations 393.27 through 393.31 and 393.33.

* 3.4.2.1 Starting system. For diesel engine driven vehicles, a 12- or 24-volt direct current (dc) starting system, with a 12-volt dc lighting system shall be furnished. Engine starting equipment shall include an ether starting system, glow plug or grid heater. If an ether system is furnished in lieu of a glow plug or grid heater, it shall be of the measured shot type. The measured shot type ether system shall be key operated or manually operated from the driver's compartment, and shall be inoperative with the engine warm. Complete provisions for a replaceable ether reservoir of not less than 12 fluid ounces shall be furnished. A reservoir need not be furnished. When specified (see 6.2), the starting motor shall be equipped with a thermostat controlled, automatic resetting