Every machine that starts, stops, holds, or controls a rotating load needs a clutch or brake. The question engineers and procurement teams face isn't whether to use one — it's which technology, from which manufacturer, will deliver the reliability, torque range, and control behavior the application actually demands.
Ogura Industrial Corp. has been answering that question since 1938. With over 5,000 models in production, ISO 9001:2015, ISO 14001:2015, and IATF 16949:2016 certifications, and a torque range spanning from under 10 mNm to 12,000 Nm (8,851 lb-ft), Ogura manufactures electromagnetic clutches and brakes for virtually every industrial motion control scenario. The challenge for buyers isn't finding a product — it's navigating the product families to find the right one.
This guide maps Ogura's electromagnetic clutch and brake portfolio to the four fundamental categories of industrial need, with a plain-language decision framework at the end. Each category links to a dedicated deep-dive article for engineers who need full technical specifications, and for procurement teams who need to understand what they're buying and why.
How Electromagnetic Clutches and Brakes Work
Before comparing product families, it helps to understand the shared operating principle all electromagnetic devices in this line have in common.
Every electromagnetic clutch and brake is built around a coil, a rotor, and an armature. When DC voltage is applied to the coil, it generates magnetic flux. That flux crosses an air gap to magnetize the rotor, which in turn attracts the armature. The armature engages the rotor — either through friction, interlocking teeth, magnetic particles, or hysteresis forces depending on the product type — and torque is transmitted or resisted.
Remove voltage, collapse the field, and the armature disengages. Cycle the voltage on and off and you cycle the clutch or brake. The electrical actuation signal is small — a PLC output or relay — while the mechanical torque transmitted can be enormous. That separation of control signal from mechanical power is what makes electromagnetic devices the right answer for remote, automated, and high-cycle applications.
Ogura's portfolio spans four technology families, each with distinct operating characteristics suited to different application requirements.
The Four Technology Families
1. Friction Clutches and Brakes: The Industrial Workhorses
Best for: High cycle rate applications, general industrial automation, packaging, printing, conveyors.
Single face and multiple disk electromagnetic clutches and brakes are the most widely deployed electromagnetic devices in industrial machinery. A single friction interface (single face) or a stack of friction disks (multiple disk) engages when the coil energizes — transmitting or arresting torque across the contact faces.
Single face designs are the fastest-responding and most cost-effective option for moderate torque at high cycle rates. Multiple disk designs multiply the torque capacity in the same radial envelope by adding friction surfaces — the right choice when torque requirements exceed what a single face can deliver without upsizing the outer diameter.
The tooth clutch is a specialized friction variant that replaces the flat friction surface with interlocking teeth, delivering the highest torque-per-size of any electromagnetic clutch type. The trade-off is an engagement speed limit of 30–50 RPM — tooth clutches must be engaged near zero speed. Within that constraint, lockup is 100% with zero slip: the right tool for machine tool gearboxes, NC lathes, and any application where even transient slip is unacceptable.
→ Deep Dive: Single Face, Multiple Disk & Tooth Clutches and Brakes
2. Failsafe Brakes: Safety-Critical Stopping
Best for: Robots, vertical axes, medical equipment, cranes, mobile machinery, any application where loss of power must result in braking.
Standard electromagnetic brakes are power-on devices: apply current to engage, remove current to release. For most applications, this is exactly right. But for any machine where an unexpected power loss, cable failure, or emergency stop must result in the brake engaging — not releasing — standard power-on logic is fundamentally unsafe.
Failsafe brakes invert that logic. They are engaged at all times by default — either by mechanical springs (spring applied brakes) or by a permanent magnet (power-off permanent magnet brakes). The coil is energized to release the brake and allow rotation. Lose power, and the brake immediately engages.
Spring applied brakes provide robust, high-torque failsafe braking with well-understood failure modes. Permanent magnet power-off brakes achieve the same safety function while consuming zero power in the holding state — making them the preferred choice for battery-powered mobile robots, servo axes with aggressive energy efficiency targets, and compact robotic joints where the heat generated by a continuously energized spring applied release coil creates thermal problems.
→ Deep Dive: Spring Applied & Power-Off Permanent Magnet Brakes: Engineering Failsafe Motion Control
3. High-Torque Compact Solutions: Multiple Disk and Tooth Clutches
Best for: Machine tools, gearboxes, servo drives, high-inertia conveyor systems, applications where maximum torque must fit in minimum space.
When the torque requirement exceeds what single face designs can deliver — or when the outer diameter constraint is tight — engineers reach for multiple disk and tooth clutch designs. Multiple disk clutches stack friction surfaces axially, multiplying torque without increasing radial envelope. Tooth clutches deliver the absolute maximum torque density of any electromagnetic clutch design, at the cost of a low-speed engagement constraint.
Both types are extensively used in machine tool applications where spindle and gearbox envelopes are constrained, torque demands are high, and cycle counts may be moderate but shock loads are significant. Ogura's MZ series tooth clutches cover a torque range of 25 to 4,000 Nm in a three-component package.
4. Tension Control: Particle and Hysteresis Devices
Best for: Web handling, winding/unwinding, tension-critical converting lines, precision torque limiting, cleanroom and contamination-sensitive applications.
Particle clutches and brakes, and hysteresis clutches and brakes, operate on entirely different principles from friction-based devices. Rather than engaging and disengaging on a cycle, they provide continuously variable, slip-capable torque — adjusted in real time by varying the coil current. This makes them the correct technology for tension control: maintaining consistent back-tension on an unwinding roll, a wire spool, or a web of film regardless of speed changes and roll diameter variations.
Magnetic particle devices use chains of ferromagnetic powder to transmit torque proportional to current — offering a wide torque range and high torque density. Hysteresis devices transmit torque through magnetic hysteresis effects in a specially alloyed disk, with no physical contact between input and output whatsoever. Zero wear, zero contamination, indefinite service life — at a higher unit cost that is routinely justified by maintenance savings and process cleanliness requirements.
Decision Framework: Matching Application to Product Family
| Application Requirement | Product Family | Key Constraint to Check |
|---|---|---|
| General automation, high cycle rate | Single Face Clutch/Brake | Torque range, engagement speed |
| Maximum torque, constrained envelope | Multiple Disk or Tooth Clutch | Engagement speed limit for tooth types |
| Failsafe — must stop on power loss | Spring Applied or PM Power-Off Brake | Available envelope, thermal load |
| Energy efficiency, battery-powered | PM Power-Off Brake | Torque range vs. spring applied |
| Adjustable torque, tension control | Particle Clutch/Brake | Slip heat dissipation |
| Zero wear, cleanroom, long life | Hysteresis Clutch/Brake | Torque range limits vs. particle |
| High torque, zero slip, low speed | Tooth Clutch | Engagement speed ≤ 30–50 RPM |
Competitive Interchangeability
A practical note for procurement teams replacing existing equipment: Ogura designs many of its product series to be direct drop-in replacements. Mounting patterns, bore dimensions, and torque ratings are intentionally matched. If you're replacing a worn or obsolete unit from any of these manufacturers, a direct Ogura equivalent very likely exists.
Electromate's engineering team can assist with specific cross-reference identification before you commit to a purchase.
Why Ogura
Three things distinguish Ogura from the field of electromagnetic clutch and brake manufacturers:
Breadth. Over 5,000 models means the right product exists for nearly every application without custom engineering. Torque coverage from micro-scale office automation devices to 12,000 Nm heavy industrial drives — all from a single manufacturer with consistent quality standards.
Longevity. Manufacturing since 1938 means the product line has been refined across decades of field feedback. Product series that have been in production for 20+ years have failure modes that are understood and designed out.
Certifications. ISO 9001:2015 quality management, ISO 14001:2015 environmental management, and IATF 16949:2016 automotive quality standards confirm that Ogura's manufacturing processes meet the requirements of the most demanding industries in the world.
Next Steps
The articles in this series each cover one technology family in full engineering depth — operating principles, torque and speed specifications, thermal considerations, application examples, and sizing guidance. Whether you're an engineer selecting a clutch for a new machine design or a procurement professional replacing a failed unit, each article gives you what you need to make the right call.
