Lenze SDSGS - Manual (Page 28)

Mechanical installation
Holding brake (option)
Spring−applied holding brakes
5
l
28 BA 13.0011−EN 1.0
5.4.3 Spring−applied holding brakes
These brakes are used as holding brakes and serve to hold the axes without backlash at
standstill or in the deenergised state.
For permissible operating speeds and characteristics, please see the respective valid motor
catalogue. Emergency stops at higher speeds are possible, but high switching energy
increases wear on the friction surfaces and the hub.
(
Stop!
The friction surfaces must always be free from oil and grease because even
small amounts of grease or oil will considerably reduce the braking torque.
The formula below provides a simplified way to calculate friction energy per switching
cycle which must not exceed the limit value for emergency stops that depends on the
operating frequency (
^ motor catalogue; Lenze drive solutions: Formulas, dimensioning,
and tables).
Q + ½ @ J
ges
@ Dw 2 @
M
K
M
K
* M
L
Q [J] Friction energy
J
tot
[kgm 2 ] Total mass inertia (motor + load)
Dw [ 1 /
s
] Angular velocity w=2p n /
60
, n= speed [rpm]
M
K
[Nm] Characteristic torque
M
L
[Nm] Load torque
Depending on the operating conditions and possible heat dissipation, the surface
temperatures can be up to 130 °C.
The spring−applied brakes operate according to the closed−circuit principle, i.e. the brake is
closed in the deenergised state. The brakes can be fed with a bridge−rectified DC voltage
(bridge rectifier) or with a smoothed DC voltage. The permissible voltage tolerance is
±10%.
,
For more information on spring−applied brakes, please refer to the
corresponding catalogues and operating instructions of the brakes.
Wear on spring−applied brakes
Spring−applied brakes are wear−resistant and designed for long maintenance intervals.
However, the friction lining, the teeth between the brake rotor and the hub, and also the
braking mechanism are naturally subject to wear due to the way in which the equipment
functions. In order to ensure safe and problem−free operation, the brake must therefore be
checked regularly and, if necessary, replaced.
If the brake is used purely as a holding brake, the amount of wear on the friction surfaces
is only very small. Emergency stops increase wear on the friction surfaces.
The following table describes the different causes of wear and their effect on the
components of the spring−applied brake. In order to calculate the service life of the rotor
and brake and determine the required maintenance intervals, the relevant influencing
factors must be quantified. The most important factors are the applied friction energy, the
starting speed of braking and the switching frequency. If several of the indicated causes of
wear on the friction lining occur in an application, their effects are to be added together.