Page 36 - Y-bearing-units

Selection of Y-bearing unit size

Dynamic bearing loads Fig. 2

When dete r m i n i n g a d d i t i o n a l , e x t e r n a l d y n a m i c
f o r c e s , e . g . a n u n b a l a n c e d c o n d i t i o n , i t m i g h t b e
n e c e s s a r y t o r e l y o n e s t i m a t e s b a s e d o n e x p e r i -
e n c e g a i n e d w i t h s i m i l a r m a c h i n e s o r b e a r i n g
a r r a n g e m e n t s .
I n b e l t - d r i v e n a p p l i c a t i o n s , t h e e f f e c t i v e b e l t
p u l l ( c i r c u m f e r e n t i a l f o r c e ) , w h i c h i s d e p e n d e n t
o n t h e t r a n s m i t t e d t o r q u e , m u s t b e t a k e n i n t o
a c c o u n t . T o d o t h i s , t h e b e l t p u l l m u s t b e m u l t i -
p l i e d b y a f a c t o r t h a t i s d e p e n d e n t o n t h e t y p e
o f b e l t , i t s p r e l o a d , t e n s i o n a n d a n y a d d i t i o n a l
d y n a m i c f o r c e s . V a l u e s a r e u s u a l l y p u b l i s h e d b y
b e l t m a n u f a c t u r e r s . H o w e v e r , s h o u l d i n f o r m a -
t i o n n o t b e a v a i l a b l e , t h e f o l l o w i n g v a l u e s c a n
b e a p p l i e d :
• Toothed belts 1,1 to 1,3 Axial load carrying ability
• V-belts 1,2 to 2,5
• Flat belts 1,5 to 4,5 The axial load carrying ability of a Y-bearing
or Y-bearing unit depends not so much on its
T h e l a r g e r v a l u e s a p p l y w h e n t h e a r c o f c o n t a c t internal design as on the way it is locked onto
i s s m a l l , f o r h e a v y o r s h o c k - t y p e d u t y , o r w h e r e the shaft.
b e l t t e n s i o n i s h i g h . For Y-bearings and Y-bearing units with
grub screws or an eccentric locking collar, the
maximum axial load that they can support is
Requisite minimum load approximately 20% of the basic dynamic load
rating if an unhardened shaft is used and the
I f Y - b e a r i n g s o r Y - b e a r i n g u n i t s a r e t o o p e r a t e grub screws are properly tightened.
s a t i s f a c t o r i l y , t h e y m u s t a l w a y s b e s u b j e c t e d t o When a Y-bearing is mounted on an adapter
a m i n i m u m r a d i a l l o a d . A r u l e o f t h u m b i n d i c a t e s sleeve, its axial load carrying ability depends on
t h a t t h i s l o a d s h o u l d c o r r e s p o n d t o 0,01 C. the amount of torque used to tighten the lock
The importance of imposing this load in creases nut. If the torque prescribed in table 2 on
where accelerations in the bearing are high, and page 55, is used, the axial load carrying ability
where speeds are in the region of 75% or more will be between 15 and 20% of the basic dynamic
of the limiting speed quoted in the product tables. load rating.
The weight of the components supported by Where the inner rings are supported by an
the Y-bearing unit, together with external forces, abutment on the shaft († fig. 2), the axial load
normally exceed the requisite minimum load. carrying ability depends on the nature of this
abutment. Generally, however, the axial load
on the bearing should not exceed 0,25 C 0 .
Additional information about the axial load
carrying ability of Y-bearing units is provided
in the appropriate chapters of this catalog.

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