REXROTH MKD025A-144, Manual

Page: 131 / 184

Synchronous Motors MKD Application Instructions
13-13
DOK-MOTOR*-MKD*******-PR07-EN-P Version7.0 19.05.2004
Note: Owing to thermal effects, the flange-sided end of the output
shaft may shift by 0.6 mm in relation to the motor housing. If
skew bevel driving pinions or bevel gear pinions directly
attached to the output shaft are used, this change in position
will lead to
•
a shift in the position of the axis, if the driving pinions are not defined
axially on the machine side,
•
to a thermally dependent component of the axial force, if the driving
pinions are defined axially on the machine side. This causes the risk
of exceeding the maximum permissible axial force or of the play
within the gearing increasing to an impermissible degree.
In such cases, you should, therefore, preferrably use drive
elements with their own bearings, which are connected to the
motor shaft via axially compensating couplings.
Bearing service life
If the MKD motors are operated within the limits specified for radial and
axial loads, the nominal service life of the bearings is as follows:
L
10h
= 30.000 operating hours
(calculated according to ISO 281, ed. 12/1990)
In other cases, the bearing service life is reduced as follows:
30000
3
_
10
⋅








=
ist radial
radial
h
F
F
L
L
10h
: (Bearing service life according to ISO 281, ed. 12/1990)
F
radial
: Determined permissible radial force in N (Newton)
F
radial_ist
: Actually acting radial force in N (Newton)
Fig. 13-19: Calculation of the bearing service life L
10h
if the permissible radial
force F
radial
is exceeded
Note: Under no circumstances may the actually acting radial force
F
radial_ist
be higher than the maximum permissible radial force
F
radial_max
.
Attachment of drive elements
When attaching drive elements to the output shaft, be absolutely sure to
avoid any redundant bearing. The tolerances inevitably present in such
cases will lead to additional forces acting on the bearing of the motor
shaft and, should the occasion arise, to a distinctly reduced service life
of the bearing.
Note: If a redundant attachment cannot be avoided, it is absolutely
necessary to consult with Rexroth.
Nominal bearing service life
Redundant bearing