Small DC motors drive model Caterpillar.
maxon DC motors are widely used in model making. Many locomotives are powered by the small efficient maxon DC motors . However there are many zanier applications for motors that are found in the model making genre. Case in point; the dazzling yellow cat track loader built by Marcel Sigrist, from Switzerland. He constructed three Cat 983B loaders at a scale of 1:8 over a two year period. The miniature excavators are driven by maxon PMDC motors.
These famous Caterpillar loaders are huge machines and they ignite the child in every man. This passion made it a logical decision for Marcel Sigrist to build a model of the caterpillar. Not being satisfied with a simple model that looked like Cat, he conducted research and studied the complete spare parts manual containing exploded views. He also researched photos and took measurements from the real Cat loader. It took over 8 months of exhaustive CAD development for the first 1:8 drawing to be finished. The finished Cat was to be 1050 mm long, 380 mm wide, 440 mm high and weigh 70 kg.
DC motors and controllers at the heart of the Cat.
Marcel Sigrist was thinking about the DC motors and gearheads right from the beginning. maxon DC motors were the only motors he considered. The full size machine utilises spur gearing – so it was evident from the beginning that the model would also use this tooth form. For both sides two 150W maxon DC servo motors were interconnected with a tooth belt and mounted vertically using a 20:1 worm gear for the power transmission. This gave the model all the required power. An electronic control unit for track vehicle models was installed. This 12V motor controller and can output 2x50A of current. To facilitate easy maintenance all electronic and hydraulic equipment is mounted in a drawer system. The hydraulic lines can be simply removed and all electronic components can be accessed easily. The drawer system also houses a hydraulic pump and motor, the hydraulic motor control unit, and also the oil reservoir, filler and de-aeration components. The second compartment contains hydraulic valves and servomotor systems for other functions.
A SMX sound unit with speakers was built into the model. 2 x 12V 12A/h NiMH battery packs provide the power. The model loader can operate for up to an hour.
After just over a year of work the first of three model loaders were completed with all trial runs passed. Then three months later the second unit was ready and number three, three months later again. Mr Sigrist comments; “when I started out, nothing on this model could be bought as a prefabricated part. Planning, measuring and drawing it to get reliable construction plans was a special challenge.”
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