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Gear Motors

The two most common type of gear motors used in automatic labeling systems are alternating current (A.C.) and direct current (D.C.).

The two most common type of gear motors used in automatic labeling systems are alternating current (A.C.) and direct current (D.C.). Even though there are several other types of gear motors available we will discuss just those that most readily apply to labeling systems.

While A.C. gear motors are not used in the majority of labeling systems, it is important to know about them as they are long lasting and relatively inexpensive when compared to D.C. gear motors. When it comes to labeling systems you can find them in two speed types, vari-cone which has a mechanically adjustable pitch pulley that utilizes a belt drive, or a special control driver that electrically changes speeds. One of the main drawbacks of an A.C. gear motor is that there is a loss of rpm as the load increases, a factor called slippage. This slippage can result in labeling errors, especially in systems that utilize timers to dispense labels, as many systems do. This site does not recommend labeling systems that utilize either timers or A.C. gear motors.

Labeling equipment manufacturers overwhelmingly choose to use D.C. gear motors in their products. You should be aware, however, that there is a vast difference in the level of quality of the various D.C. motors and the devices used to control them. The industry leader in the production of quality factional horsepower motors is Bodine, so it is wise to look for products that incorporate Bodine motors.

Every D.C. motor will need a controller to change alternating current to direct current. Most D.C. controllers will allow you to alter the conveyer speed through the use of an adjustable speed pot which will need to be set manually. Many of the D.C. controllers you will find today actually include multiple speed pot knobs which allow an operator to manually coordinate the speeds of the conveyer, wrap belt, and drive roller. While this set up process in often tiresome and labor intensive they will usually result in fairly high accuracy. There are, however, other ways to get high accuracy without all the time and bother.

With a closed loop D.C. control you replace the speed pot with two components: a generator or encoder which is often placed on either the end of the motor or on the output shaft, and a microprocessor or PLC. These components monitor the voltage or pulse, compare it against the preset setting, and then automatically make any necessary adjustments. At full motor speed these systems have the capacity to hold speed regulation to within +/- 1/2 rpm or 0.06%.

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