Technical data

Manual – Gear Units and Gearmotors
51
5
Overhung and axial loads (→ GM, → MM, → GK)
Project Planning for Gear Units
5.5 Overhung and axial loads (→ GM, → MM, → GK)
Determining
overhung load
An important factor for determining the resulting overhung load is the type of transmis-
sion element mounted to the shaft end. The following transmission element factors f
Z
have to be considered for various transmission elements.
The overhung load exerted on the motor or gear shaft is calculated as follows:
Permitted over-
hung load
The basis for determining the permitted overhung loads is the computation of the rated
bearing service life L
10h
of the anti-friction bearings (according to ISO 281).
For special operating conditions, the permitted overhung loads can be determined with
regard to the modified service life L
na
on request.
The permitted overhung loads F
Ra
for the output shafts of foot-mounted gear units with
a solid shaft are listed in the selection tables for gearmotors. Contact SEW-
EURODRIVE in case of other versions.
GM
MM
GK
Transmission element Transmission element factor f
Z
Comments
Gears 1.15 < 17 teeth
Chain sprockets 1.40 < 13 teeth
Chain sprockets 1.25 < 20 teeth
Narrow V-belt pulleys 1.75 Influence of the tensile force
Flat-belt pulleys 2.50 Influence of the tensile force
toothed belt pulleys 1.50 Influence of the tensile force
F
R
= Overhung load in lb
T
d
= Torque in lb-in
d
0
= Mean diameter of the installed transmission element in inch
f
Z
= Transmission element factor
F
R
=
T2
d
d
0
•
•
f
Z
The values refer to force applied in the center of the shaft end (in right-angle gear
units as viewed onto the B-end output). The worst-case conditions are assumed
as regards the force application angle α and direction of rotation.
• Only 50% of the F
Ra
value specified in the selection tables is permitted in mounting
position M1 with wall attachment on the front face for K and S gear units.
• Helical-bevel gearmotors K167 and K187 in mounting positions M1 to M4: A
maximum of 50% of the overhung load F
Ra
specified in the selection tables in the
case of gear unit mounting other than as shown in the mounting position sheets.
• Foot and flange-mounted helical gearmotors (R..F): A maximum of 50% of the over-
hung load F
Ra
specified in the selection tables for torque transmission via flange
mounting are permitted.