S.S. White® Technologies Inc.

What is a Flexible Shaft?

Flexible Shaft

A flexible shaft transmits rotary motion much like a solid steel shaft. But, it can be routed over, under, and around obstacles that would make using a solid shaft impractical. A “Flexible Shaft Assembly” consists of a rotating shaft (sometimes called a core) with metal end fittings for attachment to mating parts. A protective outer casing is used when necessary. This casing has its own fittings (called ferrules) that keep it stationary during use.

Typical Flex Shaft ConstructionTypical Flex Shaft Construction

Flexible Shaft

The Principle Advantages of Flexible Shaft:

  • Eliminates alignment problems: Flexible Shafts have no need for the tight tolerance that solid shafts require.
  • Greater design freedom: Limitless possibilities in position motor and driven components.
  • High efficiency: Flexible Shafts are 90 %-95% efficient. Gears, U-Joints, Belts and Pulleys have much lower efficiencies due to greater frictional losses.
  • Large off-sets: Flexible couplings allow only 5 degrees of off-set and U-Joints 30 degrees, but with a 40%-50% decline in efficiency. Flexible shafts permit a full 180 degree off-set while maintaining their high efficiency.
  • Light weight and powerful: Flexible Shafts have a 3:1 weight advantage over other design solutions while transmitting greater power loads.
  • Lower installation cost: Flexible Shafts install in minutes without special tools or skills. Solid Shafts, Gears, Pulleys, and Universal Joints require precise alignment and skilled mechanics for their installations.
  • Reduced parts cost: Bearings and housings for Solid Shafts and Gears require precise machining operations. Flexible Shafts eliminate the need for such demanding tolerance and their excessive costs.


Flexible shaft assemblies are successfully used in everything from 747 airplanes to toys. Their exceptionally long lives are not affected by continuous operation at speeds up to 50,000 RPM and temperature extremes ranging from as high as 1000 degrees Fahrenheit, to as low as –300 degree Fahrenheit. Some of the major industries using them are:

  • Aircraft/ Aerospace
  • Medical/Surgical Equipment
  • Marine
  • Construction
  • Farm/Garden Equipment
  • Office Equipment
  • Automobiles/Transportation
  • Consumer Products/Toys
  • Power Tools

Flexible Shaft

Flexible Shafts in Aerospace Flap & SlatsCommercial Use:

Aerospace Flap & Slats

Flexible Shafts in Aerospace Flap & SlatsFlaps are hinged surfaces mounted on the trailing edges of an aircraft wing. Flaps are what help reduce the speed of an aircraft while landing. Slats are the surfaces on the front edge of the aircraft wing. They are used to improve airflow at high angles and also for landing. S.S. White Flexible Shafts drive the actuators that enable the Flap & Slats to extend and retract; therefore ensuring a safe takeoff or landing after flight.

Aerospace Thrust Reverser Actuation System (TRAS)

The “thrust reverser” is used in aircraft engines to slow down the plane after landing. S.S. White manufactures highly engineered Flexible Shafts that are used to power Thrust Reverser Actuation Systems (TRAS). The shafts synchronize and connect the actuators and open both halves of the Thrust Reverser and lock the system while in flight.