That is what I thought but I made a big mistake,because when I converted from RPS to RPM I divided by 60 instead of multiplying it that is why I could not figure it.Thanks,you are very knowledgable CSA.I wonder for how many years you have been workingThe speed sensor doesn't have teeth. The speed sensor is usually a magnetic pick-up of some type (active (powered) or passive (unpowered)) that senses changes in magnetic density--such as occusr when a piece of metal passes by the speed sensor followed by a lack of metal. This creates pulses that can be used to determine speed of rotation.
By using a toothed wheel under the speed sensor the accuracy of the speed measurement can be improved, especially at low speeds. By using a wheel with 60 teeth, the number of pulses per second generated is directly proportional to the speed in RPM.
For example, a shaft rotating at 300 RPM with a 60-toothed wheel will be spinning at 5 revolutions per second. At 5 revolutions per second, the number of teeth passing under the speed sensor will be 300 (60 teeth per revolution times 5 revolutions in each second). This means a frequency meter or frequency counter can easily be used to measure RPM where each pulse is equal to one RPM.
The same shaft spinning at 50 revolutions per second would produce 3000 pulses in one second. 50 RPS equals 3000 revolutions per minute.
Do the maths with units. Using a 60-toothed wheel makes it convenient to measure speed (in RPM) with just about any off-the-shelf frequency meter or frequency counter--no conversion factors required.
Try doing that with a 20-toothed wheel and a frequency meter....
Hope this helps. The speed sensor (often called a speed pick-up) doesn't have teeth; it just "counts" the number of teeth on the shaft (or a wheel attached to the shaft) and produces pulses that can be measured using some device. A frequency meter is a common and easily used and understood device.
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by Seth Price