Rod head bearing assembly

Service News Customer Support

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For over 30 years this specially developed bearing con-cept has been successfully operating in Loesche mills.

Fig. 1 demonstrates the operational principle of the spring system and the direction of the forces within it.

As the Loesche mills became bigger, the safety factor for the bearings (Fig. 2) was also increased to improve the reliability of the machines.

Our engineers are constantly working to improve the productivity of Loesche mills and to modernise their technology. In the past, bearing damage occurred in the rod heads of some of the larger mills. These failures were due to wear on the inner and outer races of the spherical roller bearing installed there. Loesche and the bearing manufacturer, SKF, worked together to analyse the cause of such damage.

The investigation report shows that there is no overloading involved but that a combination of dynamic loads and inadequate lubrication lead to micro-pitting within the loadzone.

This micro-pitting is known in other elds of operation and is called False-Brinelling. The investigation showed that a signi cant improvement in mill reliability could be achieved by redesigning the bearing and changing of the location of the loadzone.

These ideas were con rmed in a computer simulation of the spherical roller bearing at the SKF laboratory in the Netherlands.

Rod head bearing assembly

Loadzoneon top

Fig. 2: Original design of the rod head bearing assembly

Fig. 1: Schematic of the hydropneumatic spring system

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The new design (Fig. 3): 2 cylindrical roller bearings are now installed in the

side cheeks of the fork of the rocker arm, where the movement takes place.

The loadzone has moved to the bottom.

The grease fl ows by gravity into the contact area.

This bearing concept will be applied in future to all mills from Module 30 upwards, as well as to the clinker and slag mills.

Advantage:This concept allows for a better distribution of the loads as well as a reduction in the dynamic forces experi-enced by the bearing, thus almost eliminating the risk of a breakage of the rod head!

Recommendations:Our Customer Support offers you a conversion kit comprising of the following components for the modi- cation of your Loesche mill:

Plain spherical bearing Cylindrical roller bearings Pin Rod head Set of installation parts Set of turned components

N.B.:For a modi cation to the original Module 30 it is neces-sary to increase the seating bore diameter in the fork. This rework can be accomplished with the rocker arm in a workshop or in Situ using a special machine which can be supplied by Loesche.

Contact:If you need further information or have a speci c ques-tion, then contact our Customer Support team by E-Mail at

customer-support@loesche.de

Force

Pressure

Movement

Loadzone at the bottom

Fig. 3: New design of the rod head bearing assembly

1 Rocker arm

2 Rod head

3 Spherical roller bearing

4 Cylindrical roller bearing

5 Plain spherical roller bearing

Rocker arm in working positionRoller

Rocker arm with stop buffer Cylinder of the spring system

Loesche GmbHHansaallee 24340549 Dsseldorf, GermanyTel. +49 - 211 - 53 53 - 0Fax +49 - 211 - 53 53 - 500E-Mail: loesche@loesche.dewww.loesche.com