Allen-Bradley ClutchBrake PLC-5 Series - Soft Clutch and Brake

4–13Write Ladder Logic
Publication 65566.5.1 - October 1996
Soft" Clutch and Brake
A “soft” clutch/brake provides smoother starting and stopping of
press motion. The clutch and brake are activated with a 2-step valve
sequence using auxiliary pressure-relief valves in series with the
main clutch/brake valves. You preset auxiliary-valve time delays to:
• provide a brief interval of pressure-relieved slip action
• turn auxiliary valves ON or OFF for full pressure at time-out
You select time-delay presets in the range of 0.1 – 1.0 seconds
according to the speed of the press, as shown in the following
example timing diagram:
Clutch/Brake
Aux
1
Engage clutch
to start the press
Disengage clutch and
engage brake
to stop the press
Aux 2
/ /
/ /
/ /
soft clutch time delay
soft brake time delay
clutch engaged
brake engaged
slip action (pressure relief)
full pressure
slip action (pressure relief)
full pressure
Time
Cycled V alves:
To program a soft clutch and brake, use control bits
B151/16, 17, 19, and 22.
Important: The sequence and logic of these bits are application
dependent. For example:
Bit: B151/ Bit Function Note
16 Auxiliary 1 Cycles With Clutch remains ON to energize with clutch valve
17 Auxiliary 2 Cycles With Clutch remains OFF to energize with brake valve
19 Auxiliary 1 Enabled valve relieves pressure when OFF
22 Auxiliary 2 Enabled valve relieves pressure when ON
Sequence of Events Bit 19 Bit 22 Aux 1 Aux 2
clutch valve energized OFF OFF OFF OFF
soft clutch timer timed out ON ON ON OFF
clutch valve deenergized
and brake engaged
ON ON OFF ON
soft brake timer timed out OFF OFF OFF OFF