Constricting clutches and brakes

Rugged tire-like constricting tube

Airflex expanding clutches and brakes are the go-to solutions for braking and tensioning applications. Available in four different series spanning a range of sizes and features, you’ll find the perfect fit for construction equipment, marine winches, laundry machines and more.

  • Long life - Rugged tire-like constricting tube
  • Even wear - Force applied uniformly at optimum radius
  • Many options - Wide torque capacity range

Four models excel at starting and stopping heavy-duty equipment in harsh conditions

  • CB – the perfect fit for high-speed cyclic operations, coupling and general power transmission
  • CM – specifically engineered for the marine industry on diesel-driven, reverse-reduction gears
  • VC – handle large inertia loads and sustained slippage on heavy-duty applications
  • HEVC – increases energy capacity and allows for longer slip times in severe clutching and braking applications

How constricting elements work

Airflex constricting drum clutch and brake elements use a rugged, tire-like neoprene and cord tube that expands radially inward when pressurized. The expansion forces a friction surface against a cylindrical drum to create torque.

Force applied at maximum radius from axis

Instead of the reduced radius that occurs in plate clutches, constricting drum clutches concentrate the frictional force on the outside drum diameter to achieve maximum torque. The drum radius acts as the torque lever arm to generate and apply force uniformly around the drum circumference.

Uniform contact velocity

In Airflex constricting drum clutches and brakes, friction shoe contact occurs across the cylindrical surface of the drum where the contact velocity is constant. This is an advantage over plate-type clutches where the contact velocity varies across the friction plate face.

Self-adjusting to compensate for wear

As friction surfaces wear, the tube simply expands farther as needed. Normal wear does not reduce torque capacity.

No lubrication required

Constricting drum clutches and brakes do not need lubrication because they lack close-fitting sliding components.

Operates in any plane

Unlike plate clutches that operate best in a vertical plane, a constricting design combined with its centrifugal effects allows for clutch operation in any plane.

Features and benefits

CB series

  • Tube is the only moving component
  • Cushioned action protects drive components
  • Flexible coupling
  • Torque capacities up to 1,160,000 lb•in (131,000 N•m)
  • Available in 20 sizes

HEVC series

  • Same basic features and size as VC elements but with 25% higher torque
  • Allows for longer slip times
  • Safeguards driveline components during startup
  • Increased start times – over 15 seconds at highest energy
  • Low friction wear for longer clutch life
  • Sustained torque at high temperatures
  • Torque capacities available up to 11,904,000 lb•in (1,344,971 N•m)
  • Available in 6 sizes

CM series

  • Same basic features as CB elements
  • Ventilated construction for greater heat dissipation
  • Allows for double- and triple-element assemblies
  • Torque capacities up to 3,236,000 lb•in (365,000 N•m)
  • Available in 5 sizes

VC series

  • Ideal for modernizing existing equipment
  • Smaller diameters reduce contact velocity
  • Ventilated open construction dissipates heat rapidly
  • Shock-free engagement
  • Torque capacities available up to 9,300,000lb•in (1,050,759 N•m)
  • Available in 24 sizes
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In our digital catalog you can find product specifications, literature and helpful tools like product configurators, 2D/3D models, cross reference, crimp specs and many more.