instrument panel, hose reel cabinet. In the hose reel cabinet you have 1 1/2-inch hose reel and hose, 2 1/2-
inch hose reel and hose, and 300 GPM meter assembly.
M978 Heavy Extended Mobility Tactical Truck (HEMTT) Tanker. The M978 HEMTT tanker
(Figure 4-2) is used for refueling wheeled and track vehicles, and aircraft, which on today's modern
battlefield, are more mobile than ever before. The M978 comes equipped with two hose reels, each
containing 50 feet of 1 1/2 inch hose, with service nozzle of 2 1/2 inch in diameter and a pressure differential
gage which indicates a dirty or clean filter/separator. There are 18 elements and 18 canisters. The vehicle
can operate in temperatures from 25 to 120 degrees Fahrenheit, ford water up to 48 inches deep for 5
minutes without damage or requiring maintenance before operation can continue, maintain a speed of 25
MPH on a 3 percent grade with full trailer (100,000 lbs) and 40 MPH on a 3 percent grade vehicle only
(60,000 lbs), maintain speed up to 55 MPH while operating at full load without a trailer on good, level road,
and start and climb a 30 percent grade fully loaded with a trailer or start and climb a 60 percent grade fully
loaded without a trailer. The normal operating range for the transmission, eight wheel drive vehicle is 300
miles, based on 159 gallons of fuel. The M978 can be utilized for self-loading (filtered or nonfiltered),
recirculation, bulk delivery filtered, dispensing using over wing/CCR nozzle, and defueling. The M978 can
also be used for aircraft refueling operations by utilizing the HEMTT Tanker Aircraft Refueling System
(HTARS). The HTARS kit, it's components, use, and operation are discussed in the following lesson.
Figure 4-2. M978 HEMTT tanker.
Vapor Recovery System. The vapor recovery system can be installed on all models of tank semi-
trailers, and is required in certain ecological areas. The system allows a fuel depot to collect or recover the
vapors and gases that are present during the loading operation. Vapors can also be recycled back to the
semitrailer through the recovery system during the loading operation. This system consists of a vapor-tight
line running from the sealed hood on the emergency valve vent (directly behind the manhole cover) to the
rear of the tank. The rollover rail on the roadside of the semitrailer is used as part of the line. The adapter
on the end of the line is compatible with the 4-inch quick-disconnect, vapor recovery connections at a
majority of fuel depots.
Tank and Pump Unit. The tank and pump unit consists of a 50-GPM pumping assembly, two 500- or
600-gallon aluminum tanks, and related equipment. The unit is designed to be transported on the 5-ton, 6X6
cargo truck due to the fact that when the unit is filled with fuel it exceeds the load limit of the 2 ,,-ton cargo
truck. The unit can be used to fill and empty 500- and 600-gallon collapsible drums, 55-gallon drums, and 5-
gallon cans; temporarily store product; refuel ground vehicles; and replace or supplement special purpose
vehicles. The unit may also be used to fuel aircraft if no other aircraft refueling equipment is available.
There are several standard models of the tank and pump unit. The main differences are in their pumps,
filter/separators, manifolds, and hoses. TM 10-4930-204-15(Operator's Organizational Direct Support