SETTING THINGS STRAIGHT: Why Swing Bearing Selection is CRUCIAL for Long Life

September 2016

It has been mentioned that E-Crane® uses “Single Row Ball Slewing Rings” by our friendly competition. Let us set the record straight and give you some genuine information on “Slewing Rings” used by E-Crane®.

The single row ball configuration with four point contact raceways is a commonly employed slew bearing for cranes and some material handlers. This design does not meet the E-Crane® standards! Therefore E-Crane® only uses ‘Roller Slewing Rings’ with a line contact between roller and raceway.

First of all, the slew bearing is the most fundamental mechanical element of a crane, excavator or material handler. It is also the most expensive.

E-Crane® slewing rings are manufactured by Rothe Erde, a leading global manufacturer of slewing rings and seamless rolled ring forgings for more than  100 years. The largest manufacturer of slewing rings in North America is Rotek, a member of the Rothe Erde Group.  As a crane manufacturer, there are many type of large diameter slewing rings to choose from.

1The single row ball configuration with four point contact raceways is a commonly employed slew bearing for cranes and some material handlers. It is also the least expensive design. This configuration is OK for light to medium duty applications and diameters up to 1500 mm.

This design does not meet the E-Crane® standards. E-Crane® uses a “Three Row Roller Slewing Ring Configuration”. This design is built with three independent rows of rollers. The three row roller design offers more capacity per unit size than any other slewing bearing available. It is also the stiffest style of construction and is more expensive to produce and employ.

All loading is transmitted directly to raceway surfaces perpendicular to the load direction. The capacity of each rolling element is utilized in the most efficient manner possible. This type of bearing is available for diameters up to 4500 mm or larger and is built to handle extremely heavy loads.

2

E-Crane® has used this design successfully for over 25 years. We at E-Crane® understand full well that this high load carrying capability requires a companion mounting surface that is sufficiently uniform in stiffness and very flat to distribute the load around the ring.

The results have proved excellent durability and longevity with many E-Cranes® continuing to work after 40,000, 50,000, even 60,000 working hours using the original swing bearing.

Mark W. Osborne P.E.
E-Crane International USA
mark.osborne@e-crane.com

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