
Installation conditions • Load capacity of the shaft end and bearing
70
8JSA user's manual V1.00
Caution!
Personal injury and damage to property due to failure or overheating of the drive.
If the maximum permissible operating temperature is exceeded, a drive defect with consequential dam-
age is very probable.
The cause of a defect could insufficient lubrication due to overheating, for example.
•
For safety reasons, switch off the machine if the maximum permissible temperature is exceed-
ed.
•
Ensure unobstructed air circulation and cooling so that no heat accumulation can build up in
the drive or machine.
2 Load capacity of the shaft end and bearing
8JSA three-phase synchronous motors are equipped with grooved ball bearings that are sealed on both side and
lubricated. Bearing elements are not permitted to be subjected to shocks or impacts! Incorrect handling will reduce
the service life and result in damage to the bearings.
Installation
The permissible axial forces F
a
during the installation of pinion gears, couplings, etc. depend on the motor size
and are listed in the following table:
Motor size
Permissible axial force F
a
[N]
Permissible radial force F
r
[N]
2
600
150
3
600
340
4
1400
500
5
1740
830
6
2200
1940
7
3000
2300
Operation
Radial force
Radial force Fr on the shaft end is a function of the loads during installation (e.g. belt tension on pulleys) and
operation (e.g. load torque on the pinion). The maximum radial force F
r
depends on the shaft end type, bearing
type, average speed, the position where the radial force is applied and the desired service life of the bearings.
Axial force, shift in shaft position caused by axial force
Axial force F
a
on the shaft end is a function of the loads during installation (e.g. stress caused by mounting) and
operation (e.g. thrust caused by slanted tooth pinions). The maximum axial force F
a
depends on the bearing type
and the desired service life of the bearings. The fixed bearing is secured on the B-side flange with a retaining
ring. The floating bearing on the B-side flange is preloaded with a spring in the direction of the A-side flange. Axial
forces in the direction of the B-side flange can cause the spring bias to be overcome, which shifts the shaft by
the amount of axial backlash in the bearing (approx. 0.1 - 0.2 mm). This shift can lead to problems with motors
with EnDat encoders (E8, E9, EA, EB). As a result,
no
axial force is permitted in the direction of the B-side flange
when using these motors.
Determining permissible values of F
r
and F
a
For information about determining permissible values of
Fr
and
Fa
, see th diagrams in chapter "Technical data" (sec-
tion "Permissible shaft load" for the respective motor).
The permissible values in the diagram are based on a mechanical bearing lifespan of 20,000 h (bearing lifespan
calculation based on DIN ISO 281).