Electromagnetic Power Off & Power On Brakes

Servo2Go supplies electromagnetic power off & power on brakes from Inertia Dynamics, including FB, MPC, and other types. Learn more about each type of electromagnetic brake or browse our products below.

What is an Electromagnetic Brake?

An electromagnetic brake slows or stops motion via an electromagnetic force that is created to apply mechanical resistance. The key components of an EM brake are: field coil, armature, and hub. When voltage or current is applied to the EM brake, the coil becomes an electromagnet, producing magnetic lines of flux. This flux travels through the gap that exists between the field coil and the armature, magnetically pulling the armature against the hub, creating a holding force. When torque is fully engaged, torque transfer is 100% efficiency. When current is removed, springs pull the armature away from the hub surface, creating a gap. In most industrial applications, a friction material is used to help slow down the wear in a clutch or brake.

The amount of time it takes to develop the magnetic field of an EM brake is determined by the amount of turns in a coil (determines how quickly the field is generated) and the air gap between the armature and the face of the brake (magnetic lines of flux diminish quickly in air).

The stopping time of an electromagnetic brake is determined by several factors such as: the strength of the magnetic field, amount of inertia, size of the air gap between the armature and hub, and the temperature.

Power Off vs. Power On Electromagnetic Brakes

There are two types of electromagnetic brakes: power off and power on. Power Off brakes stop or hold a load when electrical power is either accidentally or intentionally disconnected. These brakes were previously known as “fail safe brakes.” Power off brakes control unbalanced or vertical loads, handle occasional load holding needs, and, for high cycle rates, stop and hold a load. They are typically used on or near an electric motor and can have either standard or zero backlash hubs. Power off brakes have applications in robotics and servo motor brakes.

Power on brakes are used to stop a rotating load when the electrical power is turned on. This brake has a single face and is backlash-free (torsionally rigid). Power on brakes feature long life expectancies and durable construction. They find applications in industries such as automation, military, medical, food processing, and packaging.

You can view our selection of electromagnetic brakes below!  

Power-Off Brakes are designed to decelerate or park inertial loads when the voltage is turned off either intentionally or accidentally, as in the case of a power failure. 

Electromagnetic Brakes We Carry:

Flange Mounted Spring Applied Brakes

Type FSB

Inertia Dynamics type FSB brakes are designed to decelerate or hold inertial loads when the voltage is turned off.  These brakes can be mounted to a bulkhead or motor.

Flange Mounted Spring Applied Brakes

Brake Only Module (Power-Off) with Output Shaft C-Face

Type MPC

The MPC is a power-off brake module with an output shaft.  The unit mounts on a C-Face motor and the output can be coupled to a C-Face gear reducer.  Ideal for creating brake motor packages on smaller servo and stepper frame motors.

Brake Only Module (Power-Off) with Output Shaft

Spring Applied Brakes

Type SAB

Inertia Dynamics features a type SAB spring applied brake. SAB brakes are designed to be engaged and disengaged in a static condition at zero RPM.  They are best used as a parking brake to hold a load in position.  These brakes can be mounted to a flange or motor using thru-holes or tapped holes in the field cup.  A conduit box is optional.  SAB brakes have been used extensively for servo brake applications.  High temperature coil insulations are available upon request.

Spring Applied Brakes

Manual Release, Spring Applied Brakes


Inertia Dynamics features a type FSBR015 spring applied brake with a manual release lever.  The brake incorporates a lever which is rotated to mechanically engage the clapper plate.  The clapper plate acts against the compression springs and allows the armature disc to spin freely.  The brake is now free of torque.  An optional microswitch is activated on the field assembly to disconnect power to your system in case of an accidental start-up with the brake manually released. To return the brake to normal operation, rotate the lever to re-engage the brake and produce torque.

Manual Release, Spring Applied Brakes

Reverse Mounted Spring Applied Brakes


Inertia Dynamics type FSBR brakes are designed for applications requiring minimum space (short axial length) or on motors with short shaft extensions. When mounted, the armature hub is installed on the shaft first, then the brake is installed over the hub and attached to the motor.

Reverse Mounted Spring Applied Brakes

Flange Mounted Brakes

Type FB

FB series power-on brakes are used to stop or hold a load that is coupled to the armature hub assembly.  The armature hub is attached to the load shaft.  The field assembly is mounted to a bulkhead that is perpendicular to the shaft.

Flange Mounted Brakes

Shaft Mounted Clutches/Power-On Brakes

Type SLB and SOB

The SLB and SOB series are shaft-mounted Clutch/Power-On Brake packages that are used to couple two parallel or in line shafts.  The Clutch/Brake package combines the features of our model SL or SO with an FB into one unit for easy installation.  The clutch armature hub accommodates a pulley, gear, sprocket, etc., to transmit torque to the second shaft.  The brake is used to stop or hold the load.  The Clutch/Brake package is shaft mounted and retained by a loose-fitting pin or bracket through the anti-rotation tab.

Shaft Mounted Clutches/Power-On Brakes

C-Face, Power-Off Brakes

Inertia Dynamics' Single C-Face Power-Off Brakes are designed to decelerate or hold inertia loads when the power is turned off. The single C-Face mounts on the fan or non-driven end of a motor. Brakes are available from 3 lb.-ft. to 15 lb.-ft.

c-face brakes from inertia dynamics

C-Face, Power-Off Brakes with Heavy-Duty Enclosures

Our Single C-Face Power-Off Brake is also available with cast iron housing for applications involving corrosive environments. The heavy-duty housing also includes o-ring seals to create a dust-tight brake. Brakes are available from 3 lb.-ft. to 15 lb.-ft.

C-Face Heavy Duty Brakes from Inertia Dynamics

Double C-Face, Power-Off Brakes

The Double C-Face Brake is designed for use as a coupler between standard C-Face motors and C-Face gear reducers. An optional foot mount kit is also available with this unit.

Double C-Face Brakes from Inertia Dynamics