MGM
BA series brake group
22
BA series
Air gap adjustment
Brake torque adjustment
The brake torque is proportional to the springs
(18)
compression, which can be adjusted tightening or
loosening the locknuts
(20)
. The compression of the three springs must be as even as possible. Once
the brake is properly supplied, if the brake coil isn’t able to attract the brake moving element with a quick
stroke and to keep it attracted without any vibrations, check the air gap adjustment and, if this inconvenience
still persists, loosen the locknut
(20)
by two threads and try again until the proper functioning is obtained.
It is important to consider that some motors can be equipped with 3 springs and some others with 6.
(see page 23). Once this operation is completed, check the brake torque to make sure it is set to the
desired value. Never set the brake torque to a higher value than the one indicated on the motor nameplate.
0
0
K
0,2
0,4
0,6
0,8
1
1,2
1
2
3
4
5
6
7
8
J
/J
app
mot
0
0,2
0,4
0,6
0,8
1
0
0,2
0,4
0,6
0,8
1,0
T / T
R
r
s
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 found with the following
formula:
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” is related to the ratio of the moment of inertia of
the applied load (J
app
) to that of the motor (J
mot
) while the factor “R” is related to the ratio
of the resisting torque (T
r
) to the starting torque (T
s
). This calculation gives an approximative
indication only 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 in those applications where high moment of inertia is involved. On
request is available a special brake disc material capable to withstand very high dissipation
energy. Please contact MGM technical staff for additional information.
Z
load
=Z
0
•
K
•
R
Permissible start frequency under load
Brake coil wiring diagram
As standard BA series motors are equipped with AC brakes with single terminal board
for the brake and the motor while on request it is possible to supply the brake
separately. On request DC brakes are available for BA series with the rectifier located
inside the terminal box. The rectifier is provided with over-voltage protection devices
and with a RFI filter. MGM brake motors equipped with DC brakes can be connected
as in diagram A or B according to the needed braking time. MGM motors provided
with DC brake coil are connected as diagram A. The DC brake coil has to be connected
according to diagram B to have a reduced brake reaction time.
Brake coil
Black
Grey or Brown
Red
White
White
Diagram A
Diagram B
Brake coil
Black
Grey or Brown
Red
White
White
21
20
18
25
27
26
22
60
23
17
24
19
The air gap
(24)
, that is the distance between the two magnetic cores, the brake coil
(24)
and
brake moving element
(24)
, must stay within the value expressed in the chart below. It is not
advisable to exceed the expressed value, in order to avoid vibrations of the brake moving
element, very loud noise, the brake coil burning or even the whole brake assembly failure. It
is advisable to check periodically the air gap because it increases as a consequence of the
brake disc wear. In order to set the air gap to the indicated value, you have to loosen the nuts
(24) (24)
so to move the brake coil
(24)
towards the brake moving element
(24)
. Once this
operation has been settled be sure to tighten the locknuts. The above mentioned procedure
isn’t valid for BA 250-280 serie-motors, for which we pls you to contact us.
60
24
24
25
25
21
22
20
20
18
90-100
0.3
0.6
112-132
0.4
0.8
160
÷
200
0.5
1.0
225
0.6
1.2
Frame Size
Min Air Gap [mm]
Max Air Gap [mm]
71-80
0.25
0.5