The main aspect for selecting the universal joints configuration is the type and extent of misalignment between the driving and driven shafts. Angular misalignment occurs when the driving and driven shafts are positioned at an angle to one another. Axial misalignment is the horizontal distance between the two shafts. Parallel misalignment is the parallel offset or movement between shafts.
Single joints can compensate for angular misalignments of up to 45°. In contrast, double joints and drive shafts can compensate for up to 90° angles — 45° per joint) or compensate for parallel misalignment.
This single universal joint can compensate for angular misalignments up to 45°.
Propeller shafts are essentially elongated double joints — suitable for compensating parallel and angular misalignments as well as overcoming greater axial misalignments.
Typical drive shafts feature a telescoping expandable middle portion that also allows for easy replacement of the assembly.
Friction bearing versus low-friction bearing components The term friction bearing refers to the friction created between the moving components of the central connector during operation. The higher the friction, the more stress and wear asserted onto the joint — in turn resulting in heat, premature wear, and loss of precision.
Friction-bearing joints operate with significant friction between the pins and the block of the joint. They are suitable for many standard applications and can carry high loads at moderate bearing speeds.
Lubrication can help reduce friction, heat generation, and wear — in the form of regular re-lubrication or oil-drips as well as grease-packed or oil-filled boot covers fitted to these joints to extend their expected life.
Needle-bearing universal joints use roller bearings at the contact points between pins and yokes, which significantly lowers friction, heat, stress and wear on the moving components. As a result, needle-bearing joints can sustain higher operational speed and precision for extended periods of time.
Needle-bearings can be packed with lubricants and sealed for the lifetime of the joint; a method requiring less space and lubrication than the addition of lubricant-retaining boots. For these qualities, needle-bearing joints are suitable for high-precision, high-speed applications, such as automation and robotics.
