Gear couplings, also known as curved tooth couplings, consist of a hub and a casing. The torque is transferred by means of a special toothing on the hub and on the inside of the casing. These couplings are usually lubricated with grease and are used in actuators where high torques are transferred.
A gear coupling is torsion-resistant, rupture-proof and can compensate well for angular, radial or axial deviations. These couplings also produce minimal noise and vibration, giving them an impressively long service life.
Gear couplings are available for both simple and double cardan drives.
There are a number of different types, including models with spacers and a design where the casing consists of two supporting saddles, which simplifies installation and removal as no special tool is required. The advantage of the latter variant is that an existing older actuator can also be retrofitted without detachable saddles.
A gear coupling can either be manufactured completely from steel, or can be made of up a steel hub and a polyamide (nylon) casing. This type of combination has very good frictional properties between the tooth surfaces and requires no maintenance, even in continuous use. Polyamide is also highly resistant to heat, lubricants, (hydraulic) oil and solvents. In addition, the hard, smooth polyamide surface gives it the ideal sliding properties. Unlike couplings which are made entirely of metal, the teeth in this type of combined coupling are less likely to "jam" when running dry.
Current standards for shaft couplings are DIN 740, DIN 115 and DIN 116.
