Engineering Resources for Motion Control Systems
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Engineering Resources for Motion Control Systems |
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Encoder Installation InstructionsInstallation OVERVIEW | Shafted Encoders | Hollow-Shaft Encoders with Tether | Hollow-Shaft Encoders with Block & Pin Tether |
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Overview Within this framework, certain physical properties associated with mechanical coupling must be observed to ensure a long operating life. The mechanical structure of the encoder shaft, as well as the shaft that is being coupled to are both supported with some form of rotary bearing (typically ball or roller bearings). Mechanical processes are not perfect and no matter how smoothly a rotating shaft may appear to turn, it will wobble when rotated. This small amount of movement is referred to as runout and is usually a few thousandths of an inch (maximum) for most industrial installations. This same principle applies to the encoder shaft as well. And here is where the installer needs to pay special attention. If you were to hard couple the encoder shaft to a motor shaft and also hard couple the encoder body to the motor casing, the runout of the motor shaft would fight against the smaller, more accurate encoder bearings. This is a perfect "bearing grinding" machine! The motor bearings will "win" in this contest and you will be replacing encoders on a regular basis. The solution, of course, is to ensure that some part of the encoder's position sensing assembly is flexible to minimize the stress on the encoder bearings. In the case of a shafted encoder, there is typically a flexible coupling between the encoder shaft and the motor shaft. For hollow shaft encoders, a flexible tether is used between the encoder body and the motor casing, or it may be secured with a block and pin tether. Armed with this knowledge, you are ready to install your encoder. For more detailed information, call our engineering department at 800-350-2727.
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