5 Mechanical installation
Holding brake (option)
Spring-applied holding brakes
5.4.2 Spring-applied holding brakes
These brakes are used as holding brakes and serve to hold the axes w ithout backlash at
standstill or in the deenergised state.
For perm issible operating speeds and characteristics, please see the respective valid
m otor catalogue. Em ergency stops at higher speeds are possible, but high sw itching
energy increases w ear on the friction surfaces and the hub.
@ Stop!
The friction surfaces m ust always be free from oil and grease because
even small am ounts o f grease or oil w ill considerably reduce the braking
torque.
The form ula below provides a sim plified w a y to calculate friction energy per switching
cycle w hich must not exceed the lim it value fo r emergency stops that depends on the
operating frequency (Ш m otor catalogue; Lenze drive solutions: Formulas,
dim ensioning, and tables).
2 MK
Q = к ■ Jges ■ Аш2 ■ M KM
Q [J]
Friction energy
Jtot [kgm2]
Total mass inertia (motor + load)
Аш [7s]
Angular velocity ш=2я n/60, n= speed [rpm]
MK [Nm] Characteristic torque
ML [Nm] Load torque
Depending on the operating conditions and possible heat dissipation, the surface
tem peratures 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 w ith a bridge-rectified DC
voltage (bridge rectifier) or w ith a sm oothed DC voltage. The perm issible voltage
tolerance is ±10%.
For more inform ation on spring-applied brakes, please refer to the
corresponding catalogues and operating instructions of the brakes.
W ear on spring-applied brakes
Spring-applied brakes of the INTORQ BFK458, BFK460 series and the spring-applied
brake of the M Q A m otors are w ear resistant and designed fo r long m aintenance
intervals.
However, the friction lining, the teeth between the brake rotor and the hub, and also the
braking mechanism are naturally subject to function-related w ear w hich depends on
the application case (see table). In order to ensure safe and problem -free operation, the
brake m ust therefore be checked and m aintained regularly and, if necessary, replaced
(see brake maintenance and inspection).
The fo llow in g table describes the different causes of wear and their effect on the
com ponents of the spring-applied brake. In order to calculate the useful life of the rotor
and brake and determ ine the m aintenance intervals to be prescribed, the relevant
influencing factors m ust be quantified. The most im portant factors are the applied
friction energy, the starting speed of braking and the sw itching frequency. If several of
the indicated causes o f wear on the friction lining occur in an application, their effects
are to be added together.
26
Lenze • BA 33.0006 • 3.0
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