32 l
Installation, operation and maintenance manual – Squirrel cage motor – W Line - Horizontal and vertical 11239449
4.8.8.1
Direct coupling
Because of issues about cost, space economy, problems
with belt sliding and more safety against accidents, direct
coupling must be used whenever possible. Also, direct
coupling is preferable in case of transmission with
reduction gearing.
ATTENTION
Align the shaft ends carefully, and, whenever
possible, use flexible coupling, leaving a
minimum clearance (E) of 3 mm between the
couplings, as shown in Figure 4.13.
Figure 4.13: Axial clearance of the coupling (E)
4.8.8.2
Gear coupling
Gear couplings badly aligned generate vibration in the
transmission itself and in the motor. Therefore, caution
must be taken so that the shafts be perfectly aligned,
rigorously parallel in case of spur gear transmissions and
in a correct angle in case of transmissions by bevel or
helical gears.
The gear teeth meshing can be controlled with the
insertion of a paper strip, on which the trace of all teeth
shows up after a gear turn.
4.8.8.3
Belt drive
Figure 4.14: Belt drive
When a reduction or increase in speed is required, the
belt transmission is the most indicated.
In order to avoid unnecessary stress on the bearings, the
shafts and the pulleys must be perfectly aligned.
Belts that operate obliquely transmit alternating jolts to
the rotor and will be able to damage the bearings.
Belt slippage can be prevented by applying a resin like
material, such as pitch for instance.
The belt tension must be just enough to prevent slippage
during operation.
NOTE
Belts too tensioned increase the load on the
shaft end, causing vibration and fatigue, or
even the break of the shaft.
Avoid using too small pulleys, since they cause flexion of
the motor shaft because of the belt traction force that,
which increases as the diameter of the pulley decreases.
ATTENTION
Consult WEG for the correct sizing of the
pulley.
NOTE
Always use properly balanced pulleys. Avoid
extra key lengths, because they increase the
unbalancing mass and increase the motor
vibration.
Correct
Incorrect
Incorrect
