Tractor, MK31 MTVR

The MK31 Tractor is part of the US Navy & USMC Medium Tactical Vehicle Replacement (MTVR) 7 ton 6x6 family of vehicles. Procurement from Oshkosh Trucks began in FY2005. In March 2005 Oshkosh announced a contract calling for production of 92 MTVR Tractor variants and in April 2005 Oshkosh received a delivery order for 190 MTVR Tractor vehicles. Initial fielding of the MTVR Tractor for the USMC was in December 2006.

MTVR Mk31 Tractor lining up to link with a semitrailer
MTVR Mk31 Tractor lining up to link with a semitrailer.

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MK31 Medium Tactical Vehicle Replacement (MTVR) Tractor

The MK31 Medium Tactical Vehicle Replacement (MTVR) Tractor utilizes the same chassis, engine, drive train, and running gear as the MTVR MK23 cargo variant. The MK31 has a commercially compatible 2-inch fifth wheel with a capacity of 38,500 lbs and capable of towing loaded semi-trailers to a Gross Combined Vehicle Weight (GCVW) of 107,700 lbs. Additionally it incorporates hydraulically actuated steerable rear wheels with an integrated commercially available height adjustable hydro-pneumatic suspension system. The second and third axles allow 15.5 inches of height adjustment and manipulation for better control and safer operation of the tractor. This is the same rear suspension currently used by the MK36 MTVR Wrecker variant.

The Marine Corps and Navy Seabees operate the MK31 MTVR tractor as a prime mover for the MK970 refueler and construction equipment semitrailers (especially M870 series), among other missions. The MTVR tractor has a 70% on-road, 25% unimproved-road, and 5% off-road mission profile.

MK31 MTVR Tractor Characteristics

Cab Seating 3-person
Axle Configuration 6x6
Curb Weight 28,000 lbs (12701 kg)
Gross Combined Weight Rating (GCWR) 122,000 lbs threshold (55338 kg)
Length 297.4 in. (7554 mm)
Width 98 in. (2489 mm)
Height 140 in. (3556 mm), reducible to 98 in. (2489 mm)
Wheelbase 184 in. (4674 mm)
Ground Clearance 16.2 in. (411 mm)
Maximum Speed 65 mph (105 km/h) on paved road
Tires 16.00R20 XZL Michelin
Wheels 20 in. x 10 in. (508 mm x 254 mm) two-piece bolt together, steel disc
Central Tire Inflation System (CTIS) Dana electronic controlled system with selectable terrain settings
Fifth Wheel Holland Kompensator® fully oscillating with 2 in. SAE kingpin capability (3.5 in. optional)
Fuel Capacity 78 gal. (295 liters)
Cruising Range 300 mi. (483 km)
Fording 60 in. (1524 mm) without kits
Engine Caterpillar®, C-12 electronic control, ADAM™ III, 425 HP @ 1800 RPM, 1550 ft-lb @1200 RPM
Transmission Allison® 4700SP, automatic electronic control
Transfer Case Oshkosh® 30000 Series
Suspension Oshkosh® TAK-4® Independent Suspension, hydro-pneumatic rear independent suspension
Brakes Bendix Anti-Lock Brake System with automatic traction control, Meritor RDA front and rear
Turning Diameter 60 ft. curb-to-curb

The MK31 MTVR Tractor is rated for transport on the C5, C17 and C141 aircraft with preparation, by CH53 Helicopter at curb weight, shipboard crane loading at curb weight, and by C130 with waiver.

MTVR Mk31 Tractor hauls a Riverine Command Boat (RCB) for qualification tests of the attached first-article Hydraulic Boat Trailer, Aberdeen Test Center, MD, 2009
MTVR Mk31 Tractor hauls a Riverine Command Boat (RCB) for qualification tests of the attached first-article Hydraulic Boat Trailer, Aberdeen Test Center, MD, 2009.

eference photo of MTVR Mk31 Tractor with MK970 refueler
Reference photo of MTVR Mk31 Tractor with MK970 refueler.

MTVR Mk31 Tractor with Armor Kit
MTVR Mk31 Tractor with Armor Kit.