KOMATSU
Debut of Komatsu’s Innovative “Rotary Bushing Track (PLUS)”

By Hitoshi Fujisaki, Komatsu Ltd.
The undercarriage is a very important component of crawler construction equipment. With time, however, undercarriage parts begin to wear until they reach the limit of their useful life, culminating in the need for either rebuilding or replacement.

In the case of bulldozers, customers usually replace the parts used in the undercarriage on several occasions between the time of purchase and disposal. Therefore, it is said that costs associated with the undercarriage account for around half of the total costs expended in repairing and maintaining bulldozers. For that reason, extending the life of undercarriage parts has been a key challenge to reduce customers’ operating costs. Komatsu has always provided long-lasting genuine undercarriage parts of high quality and recently deployed its technological capabilities and expertise to produce an innovative solution.

As the link and bushing on the crawler track—the main components of the undercarriage —undergo wear and tear, replacement becomes necessary. Further, the external surface of the bushing touches the sprocket during operation and is subject to a great deal of torque when the two slide against one another. As a result, the bushing is usually the first component to wear, which in turn also decides the useful life of the crawler track. If the bushing rotates freely, however, it will not slide up against the sprocket, thereby reducing wear and enabling longer life. The newly developed rotary bushing track achieves this objective by changing the link from the conventional offset type to a parallel link. This has long been a goal of undercarriage design engineers, while customers have been demanding the early realization of such an apparatus. Komatsu has dubbed this the “Rotary Bushing Track (PLUS) (Parallel Link Undercarriage System).”

Komatsu succeeded in the development of the highly reliable rotary bushing track through extensive bench tests and application tests based on advanced technology amassed over many years of experience. The track became available as an option for the D65EX/PX-15 bulldozer in April 2008.

The rotary bushing track contributes to even lower operating costs for customers, which gives a great deal of pleasure to Komatsu. Going forward, Komatsu aims to develop other new products for the undercarriage to satisfy customer needs.

Comparison of Current Track and Rotary Bushing Track (PLUS)
Structure and Characteristics of the Rotary Bushing Track (PLUS)


Contributes to Longer Undercarriage Life and Lower Costs
• Doubled life of crawler track relative to conventional types in both sand and clay during application tests
• Low wear in segment teeth and major improvement to extend useful life
• With PLUS, it is not necessary to turn the pin and bushing as before when it wears, consequently eliminating the following costs:
— Cost of turning the pin and bushing (parts expenses, labor charges, etc.)
— Loss associated with operation stoppage to turn the pin and bushing
— Expenses related to removal and transportation, etc., of the crawler track to turn the pin and bushing

Future Sales Plans
In addition to the D65 bulldozer, PLUS will become available for D51 and D61 bulldozer models in the near future.
With regard to rotary bushing for larger equipment, Komatsu has also developed a dual bushing track (structure differs from PLUS) for use with the D275AX-5 bulldozer at special operating sites. Details regarding this product will be introduced at another time.