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Optical hollow shaft encoder with up to 50 millimeter bore

The optical hollow shaft encoder FGH 6 is supplied with a large hollow shaft bore up to 50 millimeters in size. The stable, ribbed cast aluminium design and the flat style of construction ensure the encoder is particularly suitable for fitting other devices such as speed switches and absolute encoders or combinations of both. The device is available with radial shaft seals and high protection class rating up to IP56 (IP66) for use in permanently oily/wet environments. The precision nickel pulse disk offers up to 4096 pulses; the electronics are integrated in the encoder or rather the replaceable scanning head. A redundant version is available with two identical scanning and evaluation electronics. The encoder is insensitive to the effects of mechanical stress factors such as vibration, axial bearing play and thermal expansion.


Diameter hollow shaft

up to 50 mm

Supply voltage

12 - 30 VDC

Signal amplitude


Standard pulse rates

1000, 1024, 1200, 2000, 2048, 2400, 2500

Output signals

0° channel

Maximum frequency

100 kHz

Device temperature range

-25 °C to +85 °C

Degree of protection

up to IP66


approx. 6 kg

Option 90

Second pulse channel as basic channel, however, electrically phase shifted by 90°

Option N/N2

Mechanically fixed reference pulse (N), one square pulse per revolution, with inverted signal

Option G

Additional inverted output signals for basic channel, 90° channel, reference pulse including LED check

Option 2F

Twice as many pulses as basic channel by combining the 0° and 90° channels

Option B

Rapid direction of rotation sensing at each edge of 0° and 90° channels

Option B2

Rapid direction of rotation sensing at each edge of 0° and 90° channels; additional standstill detection

Option V

Electronic doubling of basic channel pulse and the 90° channel through multiple evaluation

Option L2

150 mA power output for basic channel, 90° channel and the corresponding inverted signals

Option J

Optically adjusted pulse disk to reduce rotational frequency modulation

Option S

Electronic overspeed switch with two mutually independent, programmable switching points

Option FOC

As an alternative to conventional signal transmissions via copper cables it is also possible to transmit encoder signals via fiber optic cables

Operating and Assembly Instructions (PDF, 6.86 MB) Download
Catalog - Incremental hollow shaft encoders (PDF, 7.72 MB) Download
Inquiry form - Incremental encoders (PDF, 165 KB) Download
Case Study - Safely-limited speed, rolling mill (PDF, 262 KB) Download


Standard dimension drawings and connection diagrams are provided in the Operating and Installation Instructions. We would be pleased to send you individual variations as well as DXF/STEP files on request.