Page 150 - MercMarForc_Catalog_Flipbook

Mercury / Mariner / Force

GLM’S NEEDLE & CAGED BEARINGS

They look the same but are NOT the same!

Our needle rollers are mainly supplied by needle roller specialist or OEM manufacturers.
The rollers are made of Bearing Steel (SAG 52100) and have been subjected to heat
treatment and precision grinding. The hardness is HV700-860 (HRC 60-66). Both
ends of our rollers used in marine engines are shaped with a special profile, known
as “crowning”.
What is Crowning?

Crowning is also known as “controlled contour”, or coded as “ZB2”. The crowning is
to shape both ends, in a .040”-.080” area, to have a parabolic curvature (as the figure
below, however it is difficult to see this curvature with the naked eye). The purpose of
crowning is to avoid high stress consentration at the end areas of rollers and to ensure
even contact stress between rollers and the race. Because the crowning lessens the
rollers’ maximum stress, it can increase bearing life significantly.

Common Needle Roller GLM’s Crowning Needle Roller

Stress Distribution for This causes HIGH Stress Distribution for This allows stress to be
common needlle rollers stress in both ends crowning needle rollers EVENLY distributed

How About the Cages?

Because the cage is constantly subject to friction between rollers and the race,
the hardness of each corresponding contact area must be assigned appropriately
to achieve optimal bearing life. As a general rule, the roller and surface of the inner
and outer races should have higher hardness, HV 700~860 (HRC 60~66), to ensure
wear resistance. The hardness of the cage should be slightly less than the rollers.
Also, the cage material should be tough enough to avoid cage fracture during
high-load, high-speed operation.

To ensure the high-quality heat treatment of the cages, GLM cages use Swiss made,
automatic carbonitriding furnace. The strict quality inspection also applied to every
production lot to make sure the surface hardness, case depth, and toughness are
consistent with the top quality standards.

GLM’s Cages use High Quality
Swiss Made Automatic Carbonitriding
Furnace Heat Treatment

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