M561 - Gamagoat Technical Data

Curb Weight...............................7,300 lbs.

Payload .....................................2,900 lbs.

Gross weight ............................10,200 lbs.

Front axle GVW ........................2.745 lbs.

Center axle GVW...................... 3,900 lbs.

Rear axle GVW .........................3,555 lbs.

  (2) Dimensions

Length ........................................ 226.6 in.

Width ..........................................83.80 in.

Height (GVW)..............................90.80 in.

Reducible height (GVW................65.00 in.

Tread ...........................................72.00 in.

Ground clearance .........................15.00 in.

  (3) Engine

Make ...................................Detroit Diesel

Series.................................................3-53

Type .............Liquid cooled, vertical in-line

....................two cycle, three cylinder diesel

Displacement ......................159.3 cubic in.

Horsepower ............103HP at 2,800 RPM

Torqu.................217 lbs-ft. At 1,500 RPM

Firing order .........................................................1-3-2

  (4) Transmission

Type .............. ........................Manual shift

Speeds .......... ...Four forward, one reverse

Synchromesh shift........second, third, fourth

Ratios:

First gear .........................................7.06:1

Second gear ....................................3.58:1

Third gear .......................................1.71:1

Fourth .............................................1.00:1

Reverse gear ...................................6.78:1

Lubricant capacity ........................5.5 pints

(5) Transfer

Ranges .....................................High - low

Ratios:

High ....................................................1:1

Low ...............................................1.79:1

Torque rating .........................2,500 lbs-ft.

Lubricant capacity .......................4.5 pints

  (6) Differentials

Type ........................Dual pack limited slip

Ratio ...............................................5.57:1

Lubricant capacity ...........................4 pints

 Center:

Type ........................Dual pack limited slip

Ratio ...............................................5.57:1

Lubricant capacity .........................12 pints

Voltage .............................................24 volts DC

Amperage ..........................................60 amperes

Battery:

Type ......................6TN, 12 volt, 100 amp. hours

Quantity .............................Two, series connected

Alternator ........................24 volt AC 60 amperes

  (8) Fuel System

Capacity..............40 gallons (2 tanks, 20 gal/tank)

Recommended fuel:

Diesel .................................................VV-F-800

Jet .....................................................Mil-J-5624

CITE ............................................Mil-F-45121A

(9) Cooling system

Capacity ..........................19 qts (incl. Surge tank)

Normal operating temp. .................... 160-200° F

Normal operating pressure ..............7-14 PSI max

  (10) Steering System

Type .............................Mechanical front and rear

...........................................simultaneous operated

Steering ratio .................................................24:1

Turning ratio ..............................................29 feet

  (11) Suspension

Front and rear....................... Independent coil and ............................................springs at each wheel

Center ..................single leaf spring and swing axle

   (12) Service Brakes

Type .......................Hydraulic, internal expanding,

................sealed drum, Duo-servo master cylinder

Air pressurization ........................................5 PSI

(Sealed drum cavity)

  (13) Bilge Pump

Type .....................................Electrically operated

Rating .................................54 GPM at 27.5 volts

  (14) Articulation

Roll at center axle ........................... ± 15 degrees

Roll at rear axle ...............................± 30 degrees

Pitch at rear axle ..............................± 40 degrees

Wall climb (vertical) .....................................18 in.

Angle of approach ...............................62 degrees

Angle of departure ..............................45 degrees

Hump angle .......................................140 degrees

  (15) Tires

Type ................................Shredded wire, tubules,

................................non directional, cross country

Size ..................................11:00 X 18, 6ply rated

Pressure:

Highway ...................................................22 PSI

Cross-country ...........................................18 PSI

Snow ........................................................12 PSI

The M 561- Gamagoat - manufactured in Charlotte, NC  by CONDEC Consolidated  Diesel Electric Company with headquarters in Old Greenwich, Conn. It was nicknamed the Gama Goat. "Gama" from the name of the inventor of its powered articulated joint Roger Gamount and "Goat" for its mountain goat-like off-road ability.

This unique vehicle - known to the military as the M651, 6X6 Tactical 1½ ton Military Truck - is air drop-able, can swim rivers and propels itself over extremely rough terrain.

The vehicle is unique because it has 6-wheel drive and 4-wheel steering. In case of necessity, the articulated joint between the tractors and carriers can be locked in position enabling the completed vehicle to operate on 5 wheels without loss of mobility.

A 103-horsepower diesel engine permits the vehicle to transport a 2500 pound load at up to 55 miles per hour. With special modifications, the vehicle can serve as a primary mover of artillery or as an ambulance

The Goat is a dual-body truck with a unique articulation joint between the cab and the carrier. This enables the truck to travel over terrain where other cargo vehicles cannot go. The articulated center joint allows the two hulls to act independently, giving incredible off-road flexing and enviable performance. An all aluminum construction keeps the weight down to just over three tons and keeps corrosion at bay. While lesser off-roader make do with waterproofing, the Goat is fully amphibious, with drive coming from the four front wheels and two rear.

The steering is also unique in that when the front wheels are turned to the left the back wheels turn to the right at 50 percent of the front axle movement The steering is not self centering

The Engine manufactured by Detroit Diesel Corporation its a Series 53 - three cylinder two- stroke 103 horsepower diesel with supercharger. The two-stroke design has a advantage... A "two-stroke" or "two-cycle engine performs intake, compression, power and exhaust in two piston strokes and one crankshaft revolution, twice as often as a four-stroke engine, and this big difference gives two-stroke engines remarkable advantages. 

The Gamagoat was a successful off-road vehicle but due to a plaque of mechanical problems, its loud engine noise, and special driver training because of its four wheel steering habits it was not pursued in future contracts and was eventually replaced in function by the M998 series (High Mobility Multipurpose Wheeled Vehicle) HMMWV.

The truck was build during the late 1960 and into the 1970's.about 15,000 units have been build and only few survived