Page 228 - Rollingbearings

Seals Sealing, mounting and
It is not recommended to use shields (sufix 2Z) instead of contact
seals (sufix 2RSH) in this application because there is a risk of dismounting
grease leakage with outer ring rotation. The 2RSH seal design has
the advantage of being more resistant to washout (high-pressure
cleaning) that happens in paper machines, and so this will increase
service life.
Sometimes, simple labyrinth seals are added to protect the bearing
Consider hybrid bearings integral seals further.
The normal mounting and dismounting methods are applicable.
Depending on the paper machine and position of the rope sheave,
the sheave may face higher operating temperatures, which will
reduce the grease life. To increase grease life, the use of hybrid bear-
ings (ceramic balls instead of steel ones) of the same size can Overall conclusions
increase the grease life by at least a factor of two.

Consider design change The bearing that fulils the requirements is a sealed and greased
SKF Explorer bearing 6207-2RSH/C3WT.
By changing the rope sheave hub design so that the bearing’s inner For more demanding operating conditions, or to achieve an even
ring rotates instead of the outer ring, grease life is increased. The longer maintenance-free period, SKF can provide other solutions.
speed factor will be n d = 131 000 instead of nD = 176 400.
m
The grease life, L 10h , of the 6207-2RSH/C3WT bearing will
increase from 50 000 h to 61 000 h.
SKF has developed a rope sheave hub to take the above consider-
ation into account. The bearings have ceramic balls, and WT grease,
and their inner rings rotate (ig. 2). An enhanced design has been
created using special bearings. For additional information, see the
handbook Rolling bearings in paper machines.

Fig. 2
SKF rope sheave hub

C.2 Rope sheave

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