Unimotor Brake Information

Fail safe Parking Brakes

Any Unimotor may optionally be ordered with an internal rear mounted parking brake. The brake works on a fail safe principle: the brake is active when the supply voltage is switched off and the brake is released when the supply voltage is switched on. The table below shows the delay times that occur when the brake is switched on or off. Shunting the brake with an external diode to avoid switching peaks increases the coil's decay time (OUT) considerably.

If a motor is fitted with a fail safe brake, take care not to expose the motor shaft to excessive torsional shocks or resonances when the brake is engaged or disengaged. Doing so can damage the brake.

SAFETY NOTE: The Fail-Safe Brake is for use as a holding brake with the motor shaft stationary. Do NOT use it as a dynamic brake, except for emergencies such as a mains supply failure.

Technical Details

MOTOR FRAME SIZE	VOLTS	POWER	STATIC TORQUE	RELEASE TIME (Coil Energized)	BRAKE ON-TIME (Coil de-energizing no diode)	BRAKE ON-TIME (Coil de-energizing with diode)	INERTIA ^*2	BACKLASH
(mm)	DC	W	(Nm)	(ms nominal)	(ms nominal)	(ms nominal)	(Kgcm²)	(degrees)
75	24	6.3	2	22	24	100	0.03	0.75
95	24	16	6^*1	30	20	140	0.29	0.75
115	24	16	12	40	10	60	0.49	0.75
142	24	23	20	85	30	200	1.28	0.6
190(A/B)	24	25	40	95	15	85	1.28	0.6
190(C/D)	24	25	60	120	20	150	2.5	0.6

Note that the brake response time is extended when a diode is fitted across the brake coil at the driver (customer) end. This is usually required to protect solid state switches, or to reduce arcing at the relay contacts

Special Brakes

Where volumes have justified it, CTD have designed a number of custom products with customer specific brakes. Please contact CTD if you have a requirement for a special application.

^*1Brake rating changes to 12Nm after mid-2003
^*2 1 Kgcm² = 1x10^-4 kgm²