Featured in the photographs here is a 1968 International DF400 which served the VanNatta Log transportation needs from about 1976 until 1992 when a new Navistar 9300 joined the family. The market and the wood available during this time drove much of the wood to be shipped in short logs (those 24 feet and under) which lent themselves to shipment on a mule train which you see here.
This truck spent its entire life hauling logs having belonged to a sawmill in Kings Valley, Oregon before it joined the Van Natta Family. It was of a classic specifications for a logger of its time. The Engine was a traditional 335 hp. Cummins with the transmissions being the traditional logger favorites of a 5 speed main with a 4 speed progressive brownie. The rear end ratio provided a maximum potential highway speed of about 60 mph -- very slow by 'over the road' truck standards. Indeed, in the 1960's trucks quit being just trucks, and specifications for application became increasingly significant. You see, the line haul trucks rarely leave the Interstate, and logging trucks rarely find the Interstate. A truck such as this must function both on and off the highway. A truck like this needs enough low gears to start out in soft ground and navigate steep narrow roads and maximum GVW, and still be highway legal.
This classic was well suited to the task and is shown here with the trailer configured both for long logs and for short logs (notice the bunk arrangements on the various photographs). Each log bunk is equipped with electronic sensing devices under them which permit the driver to weigh the loads to the nearest 100 lbs as the logs are loaded.
This permits the maximizing of the haul load while avoiding overloads. In computing the maximum gross weight of the vehicle, the driver need only estimate the tare (empty) weight of the truck to determine the total weight. The tare will, of course, vary somewhat depending on the amount of fuel and mud on the truck. The single thing that usually forces the retirement of old log trucks are frame and suspension cracks, and there was no exception here. The aluminum frame rails held up well, the the cross members and the trunion ultimately suffered. Truck frames are designed to flex with the road, and they do, but ultimately metal fatigue takes its toll and the cracks accumulate as the crooked twisty roads push these vehicles to their design limits and beyond.
This final frame shows a mule train load with the larger shorter logs on the truck and the tops on the trailer with the overhand forward. This configuration controls the rear overhang and limits the overall length, while spacing the axles out to meet the bridge formula requirements. This particular loading technique is not widely used but it can be very effective when the timber is correct. Often in second growth the larger logs will be heavily tapered so cutting them in shorter lengths makes sense, while the smaller materials just need to be a length that fits on the truck.