Large Diameter Bearings for Construction Machinery

Large diameter bearings are key components in many types of construction machinery. They must work reliably and safely under constantly changing loads and in some instances under extremely arduous ambient conditions. Fourpoint contact bearings are primarily used in earthmoving, building and civil engineering machinery, while roller bearings are typically utilized in mobile cranes due to their special requirements.

To guarantee reliable operation throughout the service life of a large diameter bearing, Liebherr says they pay particular attention to three important factors regarding the production of components: reliable design of the bearing, control of the production processes, and systematic quality control using the very latest test methods.

Reliable design of large diameter bearings

The major challenges when designing a bearing for economical use in construction machinery include ensuring optimal adaptability to the environment in which it is used, as well as its adaptability to the service life of the machinery. Safety related aspects of the application must also be considered.

Control of the critical hardening process

The greatest influence on the quality of any bearing is the hardening process. Its flawless execution is critical to the service life of a large diameter bearing. When it comes to large diameter bearings for construction machinery, the raceway and gearing are hardened via induction heating. In this process, all influencing parameters, such as the frequency and induction voltage, the feed rate of the induction tool, the coolants’ temperature and flow, as well as the timing of the quenching, must be precisely coordinated. Only then will undesirable tension fractures be systematically and reliably avoided. 

The optimal required hardening depth and degree of hardness are determined on the basis of strength assessment. In addition to the highly sophisticated manufacturing processes utilized by Liebherr, the company also relies on employing skilled personnel with extensive training and experience in the production of large diameter bearings. With state-of-the-art technology and specially developed induction tools, Liebherr says they consistently manufacture high-quality bearings up to 236 inches (6,000 mm) in diameter.

Systematic and comprehensive quality control

Liebherr has the latest testing and measuring tools at its disposal, including magnetic particle inspection testing, developed exclusively for the company. This enables potential hardness cracks in the magnetized bearing rings to be made visible with UV light. The company has also invested in a unique air-conditioned measuring room in which a 3D-portal machine measures bearings of 236 inches (6,000 mm) diameter with the precision of only a few micrometers, and every bearing is subjected to crack tests and a 100 percent dimensional test.