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Of all the parts used on crawler-type construction equipment, the track bushings in the undercarriage of large bulldozers are subjected to particularly severe load conditions. A new and innovative heat treatment technology has been developed in order to improve the durability of these bushings from the point of their wear and fatigue crack characteristics. A new steel material has also been specified to match this heat treatment technology. The bushings thus developed have been extensively tested on bulldozers in customer service and proved to be successfully applied for production. They also offer a possibility for considerable reduction in manufacturing cost.

Conventional medium to large-sized bulldozers have a powertrain comprised of a manually operated powershift transmission connected in series with a torque converter. There is a growing need, however, for a power train that is more efficient and easy to operate, thereby increasing bulldozer productivity. One answer to this growing demand is the hydromechanical transmission (HMT) developed by Komatsu for medium to large-sized bulldozers. The HMT consists of a powershift transmission combined in parallel with a hydrostatic transmission (HST) featuring a pair of hydraulic units. The HMT has a continuously variable shifting ratio and achieves high efficiency and automatic shifting. Additionally, it has an electronic controller that controls the transmission ratio to maintain engine speed at the maximum power point. As a result, bulldozers with the HMT demonstrate greatly improved productivity over bulldozers with the conventional powertrain.

Komatsu's bulldozer D65 has undergone a full-scale model change for the first time in 22 years into a new model D65-12. This new model bulldozer has been developed to comply with the company's desired design philosophy “Friendly to People, Kind to People”. A “Revolutionary” advancement was achieved in comparison with the conventional ones which were developed and improved by producers' focus on productivity and economical efficiency. This model change not only has allowed production of a new-age bulldozer equipped with “Strength” and “Friendly to People”, but also has created a new turning point in Komatsu's bulldozer development. To realize this new bulldozer development, a number of new technologies and patents have been devised and put to practical use. This paper presents Komatsu's design philosophy and major new bulldozer technologies put to practical use.