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 fi elds of operation

and is called “False-Brinelling”. The investigation

showed that a signifi cant improvement in mill reliability

could be achieved by redesigning the bearing and

changing of the location of the loadzone.

These ideas were confi 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-

fi 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 modifi 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 specifi 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 GmbH

Hansaallee 243

40549 Düsseldorf, Germany

Tel. +49 - 211 - 53 53 - 0

Fax +49 - 211 - 53 53 - 500

E-Mail: loesche@loesche.de

www.loesche.com