Our Unimog U1300L Firetruck
With smoke (from fire on Laramie Peak) billowing over the ranch in June, we decided 2002 was a fine year to put together our firetruck. Darrin started with a 1979 ex-Bundeswehr U1300L Unimog which he imported from Germany in 2001. He first fabricated a skid to spread out the weight of the 600-gallon water tank. To this skid, he mounted everything required for operation of the unit. It attaches to the Unimog's drop-side bed with four 2-ton turnbuckles, and can be installed and removed in about twenty minutes.
On the skid along with the 600-gallon tank, you'll find a Navy surplus Hale P250 Model 2 Firefighting/Dewatering pump, drafting and pressure manifolds, an Elkhart foam eductor, and a Hannay SBEF aluminum power-rewind hose reel with 100' of booster hose leading to an Elkhart Chief 30 GPM nozzle .
The pump itself is the heart of the system. The US Navy used them years ago for firefighting and dewatering on their surface fleet, and recently a number of them were released as surplus. As shipped, most of the units seem to be configured to run on JP-5 jet fuel and required some 'conversion' to make them civilian-friendly. As delivered from the Navy, they required a special propane canister for starting. Once the engine was running on LPG for 25 seconds, it was then switched over to JP-5. Here's the pump as shipped...
The pump has a substantial 55 SAE horsepower, created by an OMC two-stroke parallel twin outboard engine. Coupled to a large Hale centrifugal pump, the unit is rated to move 250 gallons per minute at 125 PSI. The fuel system as configured for JP-5 was very complex. Each carburetor had seven fuel lines running to it. There were a number of enriching valves (thumb-wheel needle valves) in the fuel system, the propane starting system, and carburetor heat which was plumbed into the water-cooling system. Here is a pair of images, one before and one after Darrin went through the carburetors and stripped off what he didn't want...
Once modified, Darrin found that the multi-fuel OMC engine, now set up for gasoline, would fire on the first pull of the starter rope almost every time! He then mounted the pump to the skid and constructed the pressure and drafting (suction) manifolds...
The upper pressure manifold has a liquid-filled pressure gauge, 2" and 1-1/2" cam-lock outlets on the back, and 1" and 3/4" NPT outlets on the top and right side. Not seen in the image above, there's a 1" return line heading back into the tank. The lower drafting manifold has three fittings: one 3" line to the pump inlet, one 2" line to the tank outlet, and a 2" cam-lock on the front which is used for drafting water from reservoirs and creeks. At two-thirds throttle, the Hale pump will completely fill the 600 gallon tank in just under six minutes. That's 107 GPM through the 1" return line!
In September of 2004, the mountain on our ranch was hit by lightning. The resulting fire burned about 500 acres of grass, rocks, sagebrush, buckbrush, and cedar. It had been over 30 years since the mountain burned, and maybe hundreds of years since fire consumed this portion. Check out the story and photos here...
If you're interested in more about the Hale Pump conversion, feel free to email Darrin for details.