In a common spring-applied electromagnetic friction brake, the brake engages when electrical power is off and releases when its coil is energized. Current creates a magnetic field that pulls a movable armature against the spring force. When power is removed, springs clamp friction surfaces; that contact generates torque and transfers it through a hub to the shaft. Other electromagnetic brakes, such as hysteresis brakes, produce torque by a different mechanism and do not follow this power-off behavior.
How a spring-applied electromagnetic brake works
A typical spring-applied, single-disc brake contains a field coil, a magnetic circuit, a movable armature, springs, friction surfaces, a disc or lining, and a hub connected to the shaft. The coil moves the armature; the springs and friction surfaces create and transmit the braking force. Kendrion’s spring-applied brake description and Oriental Motor’s brake-motor explanation describe this general arrangement.
With coil power: the brake releases
Applying DC voltage to the field coil produces a magnetic field in the brake’s magnetic circuit. The magnetic force attracts the armature across the small air gap, opposing the springs and moving the armature away from the friction surfaces. With those surfaces separated, the shaft can rotate without the brake clamping it.
Without coil power: the brake engages
When coil power is removed, the magnetic field no longer holds the armature in the released position. Springs press the friction disc or lining against the mating surface. Friction resists rotation, and the brake’s disc-and-hub connection passes that torque to the shaft.
Recommended Free Tools
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
This is an electrically actuated brake, but in this design the braking torque is transmitted mechanically by friction. The magnetic field positions the armature; it is not itself the source of the clamping force.
Why “electromagnetic brake” does not always mean the same thing
The term covers different mechanisms and operating states. A spring-applied friction brake uses coil power to release its clamp. A hysteresis brake instead creates magnetic drag across an air gap, without friction or shear contact between its active rotating and stationary members. Its coil field magnetizes and restrains the rotor, producing braking torque. Magtrol’s HB/MHB datasheet says torque in that product family is controlled by DC field-coil current, is proportional to that current, and is available at zero slip speed.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
These are different brake architectures, not two versions of the same clamping action. Do not assume that every electromagnetic brake engages when power is removed: check the specified design and the manufacturer’s instructions for the actual unit.
What to check when comparing or selecting a brake
Start with the function the machine needs, then verify that the brake’s electrical and mechanical specifications fit. Manufacturer examples differ, so product-level data—not the broad category name—should guide selection.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsRank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
- Operating state: Determine whether the brake engages when de-energized or when energized.
- Torque mechanism: Establish whether it clamps friction surfaces or creates magnetic drag across an air gap without contact.
- Purpose: Check whether the specific product is intended to stop a moving load, hold a shaft at rest, or provide controlled drag or tension.
- Electrical and mechanical fit: Match the exact model’s supply voltage and current, torque, speed, inertia limits, mounting, and duty cycle. Specifications vary by product and size; for example, SEPAC’s brake listings provide model-specific data, while Kendrion documents multiple voltage options for its brake range.
- Control and heat: Check whether the brake needs current regulation or separate pull-in and holding levels. SEPAC says its SEB-Max brake should transition from pull-in to holding voltage after about one second; it describes the lower holding voltage as reducing power use and heat. That timing and control method are specific to that product, not a universal brake rule. Magtrol recommends a current-regulated DC supply for optimum torque stability with its hysteresis brakes.
Use lifetime figures only in their stated context
Oriental Motor states that the cited AC motor brake has a lifetime of 2 million repeated braking cycles when braking a load within its permissible inertia. The page does not state a publication year. This figure belongs to that product and condition; it is not a general lifespan for electromagnetic brakes. See Oriental Motor’s brake-motor page for its product context.
Quick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
