When Caterpillar Inc. set out nearly 20 years ago to redesign the track-type tractor, it knew that it was tampering with success. The Cat D9, the biggest Caterpillar tractor on the market at the time, was a worldwide success. “Some people were afraid we’d ruin the good thing Caterpillar had going.” said Eldon Oestmann, the redesign project supervisor. There were concerns that a redesign failure could prove disastrous. But there was a growing need for a larger tractor to do massive ripping, pushloading and dozing. Any new machine, according to Cat’s own engineers, had to be at least 50% more productive than the D9. They also knew that simply scaling up their existing line wasn’t good enough. What was needed was a machine that was bigger, more productive and more efficient than anything ever manufactured before. Enter Bob Purcell, a Caterpillar research engineer and a born tinkerer. In 1965, he bought a used garden tractor, ripped off its drive wheels and replaced them with an elevated sprocket track. His machine, tested at Cat’s Peoria Proving Ground, had enough muscle to pull a Jeep.
The tests convinced Caterpillar management that the elevated sprocket was the way to go. A team of research and engineering people was thrown together to gather opinions about just what kind of changes need be made to a redesigned tractor. An improved undercarriage that would let the track “float” over obstacles and a new final drive topped the list. More refinements surfaced as the concept teams delved deeper.
In 1969, a D10 design group was assembled and, by 1975, four proto- type models, shrouded in secrecy, were shipped to proving grounds. Two years later, 10 pilot machines had been built in a new factory — Building SS — that had been constructed expressly for the manufacture of the new dozers. In the field, the pilot dozers drew curious on-lookers. At a mine site, an aerial circus developed as customers in helicopters scouted the new, earth- moving marvel. Competitors suspected that an ultra-quiet turbine powered the machine.
The first D10 production model was sold in 1978. A towering 15-ft, mammoth, it weighed 82 tons and was driven by a 700-Hp powerplant. Since then, Caterpillar has sold more than 25,000 elevated sprocket machines in a line that ranges from the small D4H to a second-generation D11N, a 770-Hp monster. Besides the elevated sprocket design that keeps the final drive out of the muck, this line of Cat track- type tractors features modular final drive, transmission, steering clutches and brakes for ease of repair and minimal downtime; a suspended undercarriage; Sealed and Lubricated Track; and a tag-link arrangement that allows better blade-to-machine proximity.
The term “revolutionary” is overworked nowadays. The tag is applied to just about any new idea. But the elevated sprocket does belong in that class, because it marks a significant break with past tradition in earth- moving equipment and probably charts the future course. The upper echelons of Caterpillar management deserve credit for sticking with the project at a time when sceptics abounded. The last word, however, belongs to the engineers who saw it move through that rudimentary garden-tractor stage to final product. And no one summed it up better than Jim Duke, an original member of the engineering team.
“It was the proudest moment of my professional life when that first D10, the X-1, started.”
When Caterpillar Inc. set out nearly 20 years ago to redesign the track-type tractor, it knew that it was tampering with success. The Cat D9, the biggest Caterpillar tractor on the market at the time, was a worldwide success. “Some people were afraid we’d ruin the good thing Caterpillar had going.” said Eldon Oestmann, the redesign project supervisor. There were concerns that a redesign failure could prove disastrous. But there was a growing need for a larger tractor to do massive ripping, pushloading and dozing. Any new machine, according to Cat’s own engineers, had to be at least 50% more productive than the D9. They also knew that simply scaling up their existing line wasn’t good enough. What was needed was a machine that was bigger, more productive and more efficient than anything ever manufactured before. Enter Bob Purcell, a Caterpillar research engineer and a born tinkerer. In 1965, he bought a used garden tractor, ripped off its drive wheels and replaced them with an elevated sprocket track. His machine, tested at Cat’s Peoria Proving Ground, had enough muscle to pull a Jeep.
The tests convinced Caterpillar management that the elevated sprocket was the way to go. A team of research and engineering people was thrown together to gather opinions about just what kind of changes need be made to a redesigned tractor. An improved undercarriage that would let the track “float” over obstacles and a new final drive topped the list. More refinements surfaced as the concept teams delved deeper.
In 1969, a D10 design group was assembled and, by 1975, four proto- type models, shrouded in secrecy, were shipped to proving grounds. Two years later, 10 pilot machines had been built in a new factory — Building SS — that had been constructed expressly for the manufacture of the new dozers. In the field, the pilot dozers drew curious on-lookers. At a mine site, an aerial circus developed as customers in helicopters scouted the new, earth- moving marvel. Competitors suspected that an ultra-quiet turbine powered the machine.
The first D10 production model was sold in 1978. A towering 15-ft, mammoth, it weighed 82 tons and was driven by a 700-Hp powerplant. Since then, Caterpillar has sold more than 25,000 elevated sprocket machines in a line that ranges from the small D4H to a second-generation D11N, a 770-Hp monster. Besides the elevated sprocket design that keeps the final drive out of the muck, this line of Cat track- type tractors features modular final drive, transmission, steering clutches and brakes for ease of repair and minimal downtime; a suspended undercarriage; Sealed and Lubricated Track; and a tag-link arrangement that allows better blade-to-machine proximity.
The term “revolutionary” is overworked nowadays. The tag is applied to just about any new idea. But the elevated sprocket does belong in that class, because it marks a significant break with past tradition in earth- moving equipment and probably charts the future course. The upper echelons of Caterpillar management deserve credit for sticking with the project at a time when sceptics abounded. The last word, however, belongs to the engineers who saw it move through that rudimentary garden-tractor stage to final product. And no one summed it up better than Jim Duke, an original member of the engineering team.
“It was the proudest moment of my professional life when that first D10, the X-1, started.”
Be the first to comment on "Innovations (November 01, 1988)"