Mechanical Variable Speed – Selection

“TD” Series

In general, proper selection of a ComTrac drive is as easy as the drive is to operate.

Operation
Because of its mechanical operation, the ComTrac drive generally produces constant output torque, while the induction motor produces constant horsepower and constant speed. Combined they provide optimum utility and economy.

The ComTrac drive has two operating regions.

  • Constant torque between the drive’s absolute minimum speed and transition speed.
  • Constant horsepower between the transition speed and the maximum speed.

When selecting a ComTrac drive, it is important to choose a unit which will not allow the cone and ring system to be overpowered by the motor. As shown in the ComTrac Performance Chart, ComTrac drives should always be selected so that the output torque required is well below the torque capability of the cone and ring system.

General Selection Considerations
The ComTrac drives shown in the selection tables are rated for constant torque operation - where required horsepower varies directly in proportion to the speed of the driven machine.

In general, proper selection of a ComTrac drive begins by establishing the maximum horsepower required by the driven machine at maximum speed. A ComTrac drive is then selected with a maximum speed and horsepower rating that meets or exceeds that of the driven machine. Since the typical ComTrac application requires constant torque over the entire speed range, there will be an adequate service factor to protect the traction ring from damage.

Non-Standard Application Conditions
For constant horsepower applications, or any of the non-standard application conditions shown below, please contact the STOBER Technical Support group for ComTrac Selection.

Unusual Loading Conditions

  • Heavy shock loading
  • High inertia loads
  • Load reversals or overhauling loads
  • More than ten starts per hour

Unusual Environmental Conditions

  • High altitudes - above 5000 feet
  • Explosive fumes or corrosive chemicals
  • Excessively dusty or abrasive environments
  • Ambient temperatures below 25 degrees or above 125 degrees Fahrenheit

Non-Standard Motors

  • Motor frame sizes other than those shown in the selection tables in the catalog.
  • Motors other than NEMA Design B

Non-Standard Mounting

  • Shaft up or shaft down vertical mounting

Application-Matched Options
Several options for ComTrac drives such as washdown duty, remote speed controls, etc. are available. In addition the following options are also available:

  • 50 Hz Operation for export
  • Various Motor Enclosures

For application and selection assistance, for these options and more, contact your local STOBER Drives distributors.

Horsepower Ratings: 0.5 to 10

Output Speeds: 2180 to 311 RPM. Combine with MGS "C", "F", or "K" to get down to .6 RPM>

Speed Range: 5:1 or 7:1

Output Torques: Up to 496 in.lb.

NEMA C-Face Inputs: 56C through 215TC

NEMA C-Face Outputs on 0F: 56C through 182/184TC