MGM
BM series brake group
38
General description
Air gap adjustment
BM series
Z
load
=Z
0
•
K
•
R
Permissible start frequency with load
The technical data tables provide the ideal no-load start frequency (Z
0
). The permissible start frequency when an external load is
applied (Z
load
) can be calculated as follows:
where “Z
0
” is the table-value for the selected motor and “K” and “R” are factors determined by the curves on the side; the factor “K”
refers to the calculated ratio between the moment of inertia of the applied load (J
app
) and that of the motor (J
mot
) while the factor “R” is
the calculated ratio between the resisting torque (T
r
) and the starting torque (T
s
). This calculation gives an approximative indication and
it has to be operatively tested for confirmation. If the required starting frequency is close to Z
load
, it is advisable to use a motor equipped
with thermal protectors. It is necessary to check the maximum energy dissipation limit of the brake group and the maximum motor
RPM on those application where high moment of inertia is involved. Please contact MGM technical staff for additional information.
1,2
0
0
K
0,2
0,4
0,6
0,8
1
1
2
3
4
5
6
7
8
J
/J
app
mot
The air gap
(60)
, that is the distance between the two magnetic cores,
the brake coil
(60)
and brake moving element
(60)
, must stay within
the value expressed in the chart below. It is advisable to check periodically
the air gap because it increases as a consequence of the brake disc
wear. In order to restore the air gap within the proper value release the
connecting screws
(60)
, move the brake coil
(60)
towards the brake
moving element
(60)
operating on the fixing screws
(60)
. Once this
operation has been settled be sure to tighten clockwise the connecting
screws
(60)
so to fasten again the brake coil.
0
0,2
0,4
0,6
0,8
1
0
0,2
0,4
0,6
0,8
1
,
0
T
/ T
r
s
R
BM series motors are equipped with DC brake coil. DC brake coil is supplied through a rectifier located in the terminal box (standard
voltage supply is 230V 50/60 Hz).
The rectifier is provided with over-voltage and radio frequencies emission protection devices.
The brake torque remains the same in both directions of rotation and the motor brakes without shaft axial sliding. Brake torque
can be set loosening or tightening the adjustable springs
(78)
where available or removing the central springs or replacing the
fixed ones.
Never set the brake torque to a higher value than the one indicated on the motor nameplate.
BM series motors are fitted as standard with a hexagonal hole on the shaft at non drive end to allow manual rotation. On request
BM series motors can be provided with brake release return lever located on the motor side.
78
84
77
73
74
79
75
78
71
78
60
76
74
75
77
79
75
77
74
60
Frame Size
Min Air Gap [mm]
Max Air Gap [mm]
63/71
0.2
0.6
80
0.2
0.7
90
0.3
0.8
100
0.3
0.9
112
0.3
1.0
132
0.4
1.1
160
0.4
1.1