Initial Installation
14
EN 4161.758.101m – 2018-09
Semi-key balancing
Full-key balancing
4.2
Balancing
If using motors with parallel keys, note
the balancing type.
The hubs (2) come with a keyway (1) for
transmitting power from the motor shaft (3) as
standard.
There are two balancing types for the motor and
gearbox: semi-key and full-key, which are
described in more detail in DIN ISO 8821.
It must be ensured that the hub is balanced in the
same way as the motor.
This is why it is very important to indicate the
motor data, dimensions and balancing type when
ordering.
Motor output shafts with standard fitted key in
accordance with EN 50347:2001
Shaft diameter
Fitted key Fitted
key
length
28 mm
A7x7
45 mm
32/38 mm
A10x8
70 mm
42 mm
A12x8
90 mm
48 mm
A14x9
90 mm
In the case of motor shafts with open ends
of the keyway, the parallel key is to be
glued into the groove in order to avoid axial
migration of the parallel key and/or the hub.
Clamping hubs are used for motors without
parallel keys. A balancing type is not required.
4.2.1
Semi-key balancing
In semi-key balancing, the keyway is filled with
a balance compensation corresponding to
approximately half a key, shape B by default. This
is based on the original key, shape, length and
position used by the motor manufacturer and is
defined as a counterweight. In semi-key balancing
– in contrast to full-key balancing – the joint
passes through a shared component. This means
imbalance can arise after assembly due to
tolerance factors.
As a result, it is recommended that rebalancing
should be performed after the joined parts have
been assembled.
4.2.2
Full-key balancing
In full-key balancing, the motor shaft is balanced
with a full key whereas the hub is not. The parallel
key, shape, length and position are not important
in this case.
1
2
3