Gama Goat Detail In Action

Reviewed by Cookie Sewell

Summary

FirstRead

There are times when an idea seems great on paper, tests well, but the reality of its execution leaves much to be desired. Such was the tale of the Gama Goat, a high-mobility amphibious truck rated at 1 1/4 short tons capacity in cross country driving.

The Gama Goat came out about the same time as the similar Swiss Metrac vehicle did, and both were designed to provide a high-mobility 6 x 6 vehicle. Each used the same basic design: a short 4 x 4 tractor unit with a permanently attached trailer with a driven axle. The body was designed to move in two directions only: up and down, to follow the terrain, and roll from side to side to accommodate bumps and obstructions. The body did not trail and would not turn to follow the tractor around corners (with the Gama Goat, if it did that it was grounds to immediately “deadline” the vehicle as unsafe).

Robert Gamaunt, an American engineer, had been toying with a similar design since 1947, and in 1959 Vought Aviation took up the project to create a high-mobility 6 x 6 truck. The resulting prototype was all aluminum, powered by a 6-cylinder Chevrolet Corvair air-cooled engine, and weighed 3,000 pounds. But while this eventually proved a successful design, it also had one of the key Achilles’ heels of the ‘Goat - the front and rear axles both steered, and keeping them in synch proved to be a nightmare.

The prototypes entered testing in 1961 and went more than 6,000 miles mostly trouble free. But after testing in Thailand in 1963 and demonstrating great mobility in swamp and jungle terrain, the Army asked for some “changes” to be made.

The Corvair engine was ditched, and after testing two engines the “winner” was a GM 3-53 diesel; a three-cylinder 103 HP wonder which on paper was half of the 6-53 engine then going into the M113A1. But it was a noisy, nasty engine which was mounted at head level behind the crew, and as such the crew always had to wear protective ear muffs when driving it. It remained amphibious, but now weighed around 7,000 pounds. Between 1968 and 1972 15,274 Gama Goats, officially the M561 6 x 6 1 1/4 Ton Truck, were built but CONDEC.

The ‘Goat replaced the M37 3/4 ton trucks and the unhappy Jeep M715 series 1 1/4 tons trucks in many units, especially airborne, airmobile and “leg” infantry ones. In mechanized units the M561 was used either as an ambulance or a shelter carrier, usually with an S-250 class shelter and set of generators towed on a trailer.

On a good day, the ‘Goat could do about 45 mph on highways with a 1,800 pound shelter and 3,000 pound generator trailer towed behind it. It had very good off-road capability and could climb amazing obstacles, even with the trailer attached. But it was a maintenance nightmare.

Its steering gear rarely stayed aligned, and its “easily serviced” outboard brakes (they are on the outside of the wheel and not inside like 99% of other vehicles) were nearly impossible to properly bleed and adjust. Since it was so articulated, it had around 22 universal joints, the failure of any one of which could bring the vehicle to a halt. If the emergency switch inside the body was inoperative, the vehicle was theoretically deadlined (but with a shelter on the back – which went empty nearly all the time when the vehicle was moving - who was going to crawl over and press it?) Also any damage to the tailgate meant it would not float (a moot point with a shelter and generator trailer anyway).

The ‘Goat first began to be replaced by the M1008 CUCV family of Chevrolet 4 x 4 trucks as they were rated as 1 1/4 ton trucks, but suffered a loss of off-road mobility as a result. The ultimate replacement was the M996 High Mobility Military Vehicle series or Humvee.

Mr. Doyle has a superb collection of photographs and this book contains around 150 of the best that illustrate the history of the ‘Goat and its different versions. While it basically came with only two external options - a winch and a cold-weather hardtop, there were other detail differences such as aluminum or steel engine covers. While they came with troop seats for 10 and a canvas top, most units removed them (they also came with 12 life jackets for use in the water, but they disappeared very quickly among units with shelters).

I was a platoon sergeant in 1981-1984 at Fort Hood and had the unfortunate fate of being signed for 12 of these devils. At the bottom of page 39 of the book are what looks like some of my former charges “racked and stacked” on the Santa Fe for a trip to Beaumont, Texas and REFORGER 84. Two of them appear to be AN/TRQ-37 shelters with a towed PU-620 twin 5 kWt generator set behind them, and one looks to be an AN/TRQ-32. These were signal intelligence systems but often were more reliable than the truck that carried them.

Overall this is a good book for basic modeling of the ‘Goat, but as noted if you want to use it for other than the listed units, you will have to find a shelter or scratchbuild one.

Thanks to Squadron / MMD for the sample www.squadron.com