Universal joints, or u-joints are flexible mechanical connectors used to transmit rotary motion from one shaft to another shaft that is not in line with the first, or when alignment varies during service.

There are two types of universal joints, defined by their number of bending joints:

• Single joint: has only one bending aspect and is capable of operating at up to a 45-degree angle.
• Double joint: utilizes two bending joints, the double u-joint can operate at angles up to 90 degrees. Additionally, it also accommodate parallel offset between 2 shafts with an operating angle of the central section from 0 to 45 degrees.

Universal joints vary based on their material composition, hub type and the applications for which they are designed.

Steel is the most common material used, either in stainless form; or alloyed with other metals to handle greater torque and temperature.

Plastics and thermoplastics are often used in constructing universal joints, as this lends greater rust and corrosion resistance, as well as electrical and magnetic insulation in applications where this is required.

Hub Styles

U-joints are available with two hub styles:

• Solid: solid hub universal joints are solid and have not been machined, and as a result, do not have a hole.
• Bored: bored styles of u-joints generally derive their name from the shape of the hole in their hub, as with round, hex or square styles.

The two bored styles that deviate from the convention of round, hex or square styles are:

• Splined: has longitudinal grooves inside of the bore.
• Keyed: has keyways to prevent rotation of the u-joint on the corresponding shaft.

Specifications

Mechanical Components

Mechanical components covers a wide range of items and devices designed to handle, induce, or drive mechanical systems. In almost all cases, these components were manufactured to be part of a greater system, and do not have the ability to function on their own.

The mechanical components family includes the following products:

• Bearings and bushings
• Belts and pulleys
• Chains and sprockets
• Clutches and brakes
• Couplings
• Collars and universal joints
• Enclosures
• Fans and electronic cooling
• Gears
• Industrial heaters and heating elements
• Industrial tools
• Limit switches
• Mechanical fasteners
• Power transmission (mechanical)
• Process equipment
• Pulleys and belts
• Seals
• Solenoids
• Springs
• Switches

Power Transmission

Power transmission areas cover the wide spectrum of gears, locknuts, and other couplings that are used to secure shafts or transmit power throughout drive systems. The gears included in this family are:

• Bevel
• Herringbone
• Worm
• Helical
• Hypoid
• Miter
• Spur and strait tooth
• Gear stocks and blanks
• Belts and belt pulleys
• Sprockets
• Ratchets and pawls

All of these gears are available in both English and metric configurations.

Standards

AD 46-41-03 - Control wheel universal joints\bellanca aircrft\14-13-2\14-13.

GME L-9A-18 - Determination of radial elasticity of universal joints and intermediate spindels.

GMI L-9A-19 - Determination of static torsional strength of universal joints and intermediate spindels (itdc release, draft for harmonization).

GOST 8059 - Universal joints with sliding liners for rolling-mill equipment. general requirements.

SAE J901 - Universal joints and driveshafts - Nomenclature - Terminology - Application

Image credits:

KTR Corporation | Oren Elliott Products, Inc. | Ondrives US Corporation