Heidenhain - Measuring angles with rotary encoders

Mounting variants

In rotary encoders which have integral bearing and stator coupling, the graduated disk of the encoder is connected directly to the shaft to be measured. The scanning unit is guided on the shaft via ball bearings, supported by the stator coupling. During angular acceleration of the shaft, the stator coupling must absorb only that torque resulting from friction in the bearing, thereby minimising both static and dynamic measuring error. Moreover, the coupling mounted on the stator compensates for the axial motion of the measured shaft. Other benefits of the stator coupling are:

  • Simple mounting
  • Short overall length
  • High natural frequency of coupling              
  • Hollow shaft option  

Rotary encoders with integral bearing that are designed for separate shaft coupling and are designed with a solid shaft. The recommended coupling to the measured shaft compensates radial and axial tolerances. Angle encoders for separate shaft couplings permit higher shaft speeds.

Rotary encoders without integral bearing operate without friction. The two components - the scanning head and the scale disk, drum, or tape - are adjusted to each other during assembly. The benefits are:

  • Large diameter of hollow shaft
  • Good for high shaft speeds
  • No additional starting torque

Rotary encoders with integral bearing

The HEIDENHAIN - ERN, ECN and EQN rotary encoders with integral bearing and mounted stator coupling are characterised by simple mounting and short overall length. Possible applications range from simple measuring tasks to position and speed control on servo drives. The hollow shaft of these encoders is slid directly onto and fastened to the shaft to be measured.

ROD, ROC and ROQ rotary encoders have their own bearings, which are sealed. They are robust and compact. These encoders are coupled by the rotor to the measured shaft through a separate coupling that compensates axial motion and misalignment between the encoder shaft and measured shaft.

Rotary encoders with integral bearing, for mounting by stator coupling


Rotary encoder without integral bearing

In addition to the system accuracy, the mounting and adjustment of the scanning head normally has a significant effect on the accuracy that can be achieved with rotary encoders without integral bearings. Of particular importance are the mounting eccentricity and radial run-out of the measured shaft.

The inductive rotary encoders ECI/EQI 1300 are mechanically compatible with the photoelectric encoders ExN 1300 where the shaft is fastened with a central screw. The stator of the encoder is clamped by an axially tightened screw in the location hole.

The photoelectric ERO modular rotary encoder from HEIDENHAIN consists of a graduated disk with hub and a scanning unit. They are particularly well suited for limited installation space or for applications for which there must be no friction.

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Heidenhain - Measuring angles with rotary encoders
Heidenhain - Measuring angles with rotary encoders
Heidenhain - Measuring angles with rotary encoders
Heidenhain - Measuring angles with rotary encoders