An example for the optimization of Klaus Koster's excavator business is a mini excavator from Yanmar, which incorporates a Hinowa undercarriage. This moves with the aid of a rubber crawler drive, each crawler powered by an oil engine. In order to distribute its weight equally on the entire base, track rollers are provided to simultaneously guide the rubber crawler sideways. Problem: Due to the rough working conditions for excavator undercarriages, the original structure of the track rollers is vulnerable to damages. Plastic bushings of the iglidur® G type series from igus® should provide a remedy here and replace the expensive and vulnerable grooved ball bearings. Merely a modified axis and two placeholders to fill the hollow space are necessary for them to function reliably. The saved purchased parts together with the very minor retrofitting work lower the costs. Moreover the new design promises an enormously enhanced service life due to its reduced susceptibility to dirt and humidity. According to Klaus Koster, this application has been running faultlessly and without maintenance, now for the fourth consecutive year.
Track roller in the excavator undercarriage
iglidur® G is generally recommended whenever an economical allround bearing is required, which withstands extremely high loads and works in low to medium surface speeds.
The coefficient of friction of the iglidur® G type series varies analogical to the wear resistance with the load: It decreases when the load increases. For this bearing, the maximum temperature permitted on the short term amounts to +220°C, and the lower application temperature lies at -40°C. Even though the compressive strength decreases with increasing temperatures, the permitted surface pressure under the maximum temperature permitted on the long-term (130°) anyhow amounts to over 40MPa. A marked bearing wear arises only from a temperature of +120°C.
iglidur® G bearings withstand chemicals very well. Most of the weak organic and inorganic acids cannot harm the material. Moreover they are resistant to many lubricants.
View of the original track rollers (left) and the modified roller (right)