Note: This feature is in the Sept. TT&C 2014 issue.
Gene Gregory is shown with his superbly built remote-controlled 1/4 scale scratch-built CAT Model D5N bulldozer.
Gene’s high-detailed CAT Model D5N’s size in relationship to a ball cap.
The rear view of the CAT bulldozer.
Gene’s CAT is shown being loaded on his transport cart. Note the guides on the cart to properly position the CAT. It’s all done with an invisible leash.
Gene Gregory is a craftsman extraordinaire. And while he has crafted numerous replicas, each new enterprise is more intricate than the previous one.
Asked how he settled on building a scale model CAT with an invisible leash, Gene recounted, “I had built two other remote-controlled 1/4 scale units: a John Deere Model 8020 diesel field tractor and a John Deere Model 5010 diesel construction tractor with a John Deere Model 400 scraper pan. I wanted to build a tractor that was more challenging.”
To Gene’s credit, he fulfilled that inspiration by scratch building a CAT Model D5N bulldozer. An exact replica, and to the nth degree!
Following are details that comprise Gene’s masterpiece. “I took countless measurements, along with pictures from a neighbor’s CAT D5N. I returned for follow-up measurements a dozen or more times. Getting precise dimensions was necessary for accuracy. The CAT was built using 3/4-inch aluminum plate for the base. This thickness allowed taps to be drilled into the edges to support 3/4-inch power supports,” Gene commented.
Building the track housing was rather intricate. Gene carved the housing from a block of wood. This created the form for the eventual cast-aluminum housing that was poured into a mold. The housing was round on top with a flat hollow bottom.
The radiator housing was developed in a similar fashion. Gene made a wood carving from which a mold was formed. Molten cast aluminum was poured in the mold to form the housing. Although not operational, the radiator core is made from copper for authenticity. Side housings behind the radiator are made from aluminum sheet metal.
In the bottom of the base are two 12-volt batteries. Two motors are located behind the batteries, one for each drive wheel.
There is also a jackshaft to regulate the speed for each motor. Gene engineered the desired ground speed at 80 feet per minute when traveling at full speed.
Gene gained valuable knowledge with the electronics from his previous two tractors. This aided his electronic engineering for the CAT. Sophisticated electronics for the D5N are located above the batteries and under the hood. A saber-tooth speed controller associated with the electronics is located in the same area. Speed controls for each motor facilitates turning using a joystick. These are also located among the electronics.
There is a 24-volt hydraulic pump and reserve tank to operate the four-way power blade. The power blade movement is activated with four modified BIMBA air cylinders. The blade can be moved up and down. It can also be angled right or left.
The dash is loaded with switches and gauges that resemble the original CAT Model D5N. They include a switch for power, along with light switches. There are 12-volt LED lights both fore and aft.
Want to read the rest of the story? It's available in the September TT&C 2014 magazine!
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