Technical data
Holding brake (option)
Spring-operated brakes
3
23
BA33.0001 E N 2.0
3.4.2 Spring-operated brakes
The spring-operated brakes serve as a holding brake to hold the axles when the machine
is at standstill or deenergised. Permissible operating speeds and characteristics
(Ecatalogue for spring-operated brakes). Emergency stops at higher speeds are possible
but high switching energy increases wear on the friction surfaces and hub.
Stop!
In any case, the friction surfaces must be kept free of lubricant and grease,
since even small amounts can d rastically reduce the braking torque.
When used solely as a holding brake, very little wear occurs on the friction surfaces.
Emergency stops lead to wear on the friction surfaces and also lead to the creation of dust.
The lenze BFK 458 spring-operated brake can be adjusted up to 5 times. The BFK 418, 457
and 460 cannot be adjusted (Details Ecatalogue and operating instructions for
spring-operated brakes). Brakes that cannot be adjusted must be replace once the wear
limit has been reached.
The friction energy per switching cycle can be calculated using the formula below and may
not exceed the limit value (depends on the switching rate) for emergency stops
(E catalogue on spring-operated brakes).
Q[J] Friction energy
Q = ½ ⋅ J
total
⋅ ∆ω
2
⋅
K
M
K
− M
L
J
total
[kgm
2
] Total mass moment of inertia (motor + load)
∆ω [
1
/
s
] Angular sp eed ω =2π
n
/
60
, n = speed [min
-1
]
M
K
[Nm] Characteristic torque
M
L
[Nm] Load torque
Depending on the operating conditions a nd possible heat removal, the surface
temperatures can reach up to 130 °C.
The spring-operated 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 bridged DC voltage (bridge
rectifier) and a smoothed DC voltage. The permissible voltage tolerance is ±10%.
Note!
For additional information see the catalogues and operating instructions for
spring-operated brakes.
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