SensorsStandard Rotational Speed Sensors

rotec GmbH · Joseph-Dollinger-Bogen 18 · D-80807 Munich · GermanyTel: +49 (0) 89 323 651-0 · Fax: +49 (0) 89 323 651-56 www.rotecmunich.de

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The rotec sensors described here are designed for non-contact measurement of the rotational speed of a toothed

wheel. Each sensor consists of two magnetoresistive elements and a permanent magnet enclosed in a stainless

steel cylindrical housing with M10x1 outer thread. The sensors themselves are entirely passive. For operation they

require an accompanying electronic unit which converts their analogue output to a TTL signal. The sensors ex-

hibit minimal temperature dependence and their operation is not impaired by dirt or oil films. The output signal

amplitude is independent of the rotational speed. A variety of lengths and designs is available.

The sensors' stainless steel cylindrical housing has an M10x1 outer thread. The target wheel should have a gear

module in the range 0.6 to 2.4mm, a pitch between 1.9 and 7.7mm and a thickness of at least 5mm. A sensing

gap from sensor to wheel of up to 5mm is allowed for. The electronic unit operates for the tooth frequency range

0.1Hz to 20 kHz, i.e. a tooth must be detected at least once every ten seconds. Differential magnetoresistive sen-

sors need to be carefully positioned for both optimal adjustment of orientation w.r.t. the target wheel and setting

of sensing distance.

Measurement Principle Main Features:

◗ M10x1 outer thread

◗ Target wheel: ferromagnetic material

Gear module: 0.6mm to 2.4mm

Pitch: 1.9mm to 7.7mm

◗ Sensing gap up to 5mm

◗ Tooth frequency range: 0.1Hz to 20kHz

◗ Sensor electronic unit: input 5mV to approx 80V,

output TTL level (0/5V)

SensorsStandard Rotational Speed Sensors

rotec GmbH · Joseph-Dollinger-Bogen 18 · D-80807 Munich · GermanyTel: +49 (0) 89 323 651-0 · Fax: +49 (0) 89 323 651-56 www.rotecmunich.de

Sensor Type A

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Cable for Sensor Type B and C

Inline Sensor Electronic Unit

Sensor Type B

Standard Sensor Electronic Unit

Sensor Type C

SensorsFourfold Rotational Speed Sensors

rotec GmbH · Joseph-Dollinger-Bogen 18 · D-80807 Munich · GermanyTel: +49 (0) 89 323 651-0 · Fax: +49 (0) 89 323 651-56 www.rotecmunich.de

Main Features:

◗ Outer thread M10x1

◗ Target wheel: ferromagnetic material

Gear module: 1mm to 2.5mm

Pitch: 2mm to 6mm, ideally 2.5mm

◗ Tooth frequency range: 1Hz to approx. 45kHz

◗ Sensing gap up to approx. 1.5mm

The sensor's stainless steel cylindrical housing has

an M10x1 outer thread. The target wheel should have

a gear module in the range 1 to 2.5, a pitch between

2 and 6mm and a thickness of at least 5mm. A sens-

ing gap from sensor to wheel of up to approx. 1.5mm

is allowed for. The electronic unit operates for the

tooth frequency range 1Hz to approx. 45 kHz. The

magnetoresistor arrangement demands that the sen-

sors need to be carefully positioned for both optimal

adjustment of orientation w.r.t. the target wheel and

setting of sensing distance. An 'eightfold sensor'

which provides eight pulses per tooth is also avail-

able.

Measurement Principle

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The rotec 'fourfold sensor' is used in order to increase the angular resolution of rotational-speed measurements.

The sensors are used when the target wheels have a relatively small number of teeth, e.g. chain sprockets or

gears within a gearbox. Each scanned tooth provides four data points. The sensor comprises 4 magnetoresistive

elements with a permanent magnet enclosed in a stainless steel casing with M10x1 outer thread. The sensors re-

quire an accompanying electronic unit which converts their analogue output voltage to square wave TTL level. The

sensors exhibit minimal temperature dependence and their operation is not impaired by dirt or oil films.