We take a look at THOR, a military 5-Ton 6x6 M923A2 off-roading cargo carrier.

Overview of THOR & some history:
THOR is a member of the M939 Series of 5-ton, 6x6 military trucks
The M939 series started production in 1982 and consisted of the following initial upgrades from the prior series of 5ton trucks (M809) o Allison 5 speed automatic transmission
o Upgraded Power Steering
o Full Airbrake system
o Upgraded Cooling system
o Three Crewmember cab
o Forward Tilting Hood for greater engine bay access
There were 2 distinct enhancements of the M939 series designated as A1 & A2
§ Super Single Tires from A1 series
§ Cummins 8.3L Turbocharged engine (6CTA8.3)
§ Central Tire Inflation System (CTIS)
• Allows for On-The-Fly tire pressure control o HWY Mode: 70psi*
o Cross-Country: 45psi* o Sand: 35psi*
§ Transition to “Super Single” 14:00xR20 on all 3 axles replacing the traditional “Dual Wheel” 11:00xR20 configuration
o Emergency: 25psi*
o Run-Flat: Checks and inflates tires every 15
seconds (“Run Away from the Bullets!”)
o M939 Series Trucks were produced in 5 primary configurations § M923/A1/A2: Cargo/Troop Carrier
§ M929/A1/A2: Dump Truck
§ M931/A1/A2: Tractor (Tractor-Trailer Rig)
§ M934/A1/A2: Extensible Van (E.g. Radio Equipment)
§ M936/A1/A2: Wrecker
• THOR is an M923A2 Tactical Cargo/Troop Carrier
o Built in 1990 by BMY and retired from military service in 2011 o Served in the State of Washington National Guard
§ 81-181 Brigade Support Battalion (BSB)
§ The 81-181 has been deployed multiple times to Iraq and
Kuwait since 2001
o Sold at Government Auction (GovPlanet) in 2012
o Registered as a CA Historical Vehicle in Nov 2017 o Unique aspects of this vehicle
§ Its simply Silly Big, especially on public highways. People Waive, Honk and/or Stare when they see this 5-Ton military truck
§ CTIS: Push Button Tire pressure control is just CoolJ
§ Can forge up to 4’ of water in stock trim, 7’ with forging kit o Fun Facts
§ 9 MPG (Gulp!)
§ Up to 20psi of turbo boost
§ Weights 21,550lbs.... dry....
§ 10,000lb cargo and 15,000lb towing capacity
§ Top Speed: 60mph (67mph w/16.00xR20 tires)
§ PTO on front and rear axles
§ Differentials are Rockwell “Top-Loading” pinion design
• Elevates location of all drive shafts § Fluid Capacities
• 77 gal of diesel fuel (+5gal “Jerry Can”)
• Cooling System: 44 quarts (yes, that's 11 gallons)
• Crankcase: 20 quarts
• Transmission: 19 quarts
Trail Clearances
• 18” Axle – Pumpkin clearance
• 27” Chassis clearance
• 19.5deg break-over angle
• 48deg Approach Angle
• 40deg Departure Angle o Upgrades/Mods
§ Added Boost and EGT gauges
§ Switched Transmission fluid from HDO-10 to TES295

• To optimize support logistics, the military tries to reduce the various types of fluids required by the fleet. Example: Power Steering & Automatic transmissions use 10w engine oil (HDO-10)
§ New Michelin (military) 16xR20 Super Single Tires
• Best Suspension upgrade: Replaced 26 year old tires
• 53” tall (Original 14xR20 are 48” tall)
• Each Tire+Wheel+beadlock weighs 490lbs !
Added 12v external power connector - Allows jump starting civilian vehicles
§ Added 2000lb winch to deploy & retrieve spare tire
§ Installed CB and HAM radio
§ Over 49 Service Operations performed by current owner