Otto Schemmerer Mastrollen

MAST ROLLERS
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Nice to know
TEST PROCEDURES
The mast rollers are opened to check how the bearing was made:
Check 1:
The bearing was created by means of loose bearings or bearings that are encased in a cage + we check how many ball bearings the
roller contains.
> If the ball bearings are loose inside the bearing, then there are usually 10 to 14 ball bearings
> If the ball bearings are encased in a cage, they are held at the same relative distance in relation to each other.
Of course a bearing that is completely filled with ball bearings can handle higher forces, but this is not always necessary because this
construction is more expensive. The number of ball bearings in the mast roller depends on the diameter of the mast roller.
In case of bearings that are completely filled with ball bearings, the outer ring of the bearing is usually broken. This is done in the factory
to be able to place more ball bearings, or a piece is milled from the inner and outer ring for the same purpose.
Check 2:
The bearing is created with rollers: the hardness is measured with a hardness tester and the material composition
is checked with a spectrometer.
Hardness tester – scleroscope
Previous to the hardness test the type of steel is determined. The unit for ‘hardness of steel’ we use at TVH is Rockwell C.
Regular steel (construction material) measures hardness 0 HRC, while for instance, the inner ring of a ball bearing is 60 HRC.
The test consists in dropping a diamond tipped hammer vertically from a fixed height onto the surface of the part under test with a
predetermined pressure. If the material is soft, indentation will be about 0,3 mm while in a harder part it will only amount to 0,1 mm.
The depth of the indentation is then converted to HRC value.
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