CARB® toroidal roller bearings – a revolutionary ... - Acorn Bearings

1 Product information 2 Recommendations 3 Product data
Page ............. 3 Page ............. 12 Bearing data
Axial displacement
CARB toroidal roller bearings can
accomodate changes in shaft length
within certain limits. The guideline values
for axial displacement given in the
product tables are valid provided there is
• a sufficiently large operational radial
clearance in the bearing, and that
• the rings are not misaligned.
This means that the rollers (➔ fig 4 )
will not protrude from the bearing rings
(a) or interfere with the retaining ring
(b) or with the seal, if any.
If the axial movement exceeds 50 %
of the permissible axial displacement
capability s 1 , it should be checked,
whether the residual radial internal
clearance is sufficiently large. The reduction
of radial clearance C red as a
result of an axial displacement can be
calculated using the equation shown in
the section “Influence of radial operating
clearance on the axial displacement
capability”.
If the axial movement exceeds 50 %
of the axial displacement capability s 1
or s 2 , and the misalignment attains
approximately 0,5°, the actual axial
displacement of the rollers should be
checked additionally. The axial displacement
of the rollers s mis caused
by misalignment of the bearing rings
can be calculated using the equation
Axial displacement
limits s 1 and s 2
a
b
s 1
s 2
Fig
4
shown in the following section “Influence
of roller displacement on the
axial displacement capability”. For
additional information please contact
the SKF application engineering service.
The maximum permissible axial displacement
is obtained from the smaller
of the minimum values of the
• permissible axial displacement s lim
depending on roller complement displacement,
and the
• permissible axial displacement s cle
depending on the clearance reduction,
calculated as explained in the following
part.
Influence of roller displacement
on axial displacement capability
The axial displacement, as well as the
misalignment of one ring with respect
to the other, changes the position of
the roller complement in CARB bearing.
The reduction in the permissible
axial displacement caused by the misalignment
can be estimated using
s mis = k 1 B α
where
s mis = reduction in permissible axial
displacement caused by
misalignment, mm
k 1 = misalignment factor
(➔ product tables)
B = bearing width, mm
(➔ product tables)
α = misalignment, degrees
Assuming a sufficiently large operational
clearance, the maximum permissible
axial displacement is
obtained from
s lim = s 1 – s mis
or
s lim = s 2 – s mis
where
s lim = permissible axial displacement
with respect to the roller complement
caused by misalignment,
mm
s 1
s 2
= guideline value for the axial displacement
capability in bearings
with cage, sealed bearings
or full complement bearings
when displacing away from the
snap ring, mm (➔ product
tables)
= guideline value for the axial
displacement capability in full
complement bearings when
displacing towards the snap
ring, mm (➔ product tables)
s mis = reduction in permissible axial
displacement caused by misalignment,
mm
Influence of radial operating clearance
on axial displacement capability
Axial displacement from a centred
position of one bearing ring in relation
to the other reduces the radial clearance.
The radial clearance reduction
corresponding to a certain axial displacement
from a centred position can
be calculated using
2
k 2 s cle
C red =
B
The clearance reduction cannot be
larger than the bearing operating radial
clearance.
If instead a certain permissible radial
clearance reduction is known, the corresponding
permissible axial displacement
from a centred position can be calculated
using
B C red
s cle =
k2
where
s cle = axial displacement from a centred
position giving a certain
radial clearance reduction C red ,
mm
C red = reduction of radial clearance as
a result of an axial displacement
from a centred position, mm
k 2 = operating clearance factor
(➔ product tables)
B = bearing width, mm
The axial displacement capability can
also be obtained using diagram 1 ,
40