The setup is a DC motor directly connected via its shaft to a drum which drives a horizontal conveyor belt. There is a load of mass, M, on the conveyor belt. I am stuck on trying to figure out what 'D' in the equation below means.

Title: Pulley, Conveyor Belt & Load system

Description: Load-Inertia to the motor consists of pulley (of radius r) and mass of load (M) on conveyor belt. The load-torque, to be delivered by the motor is given as:

torque load


M is the mass of load on the conveyor belt.

r is the drum radius

ω = angular velocity

But i don't know what D means and i cannot figure out how that equation was derived in the first place. Any help would be much appreciated.

  • \$\begingroup\$ you need torque to accelerate the loaded-belt. How fast must that belt speed change? All the energy of the loaded belt must come from the motor, which you provide with volts and amps into the motor. \$\endgroup\$ – analogsystemsrf May 18 at 23:50
  • \$\begingroup\$ I don't have any values to work with. I just need to understand how that formula was derived, and i cannot figure out what D means in that equation, so that makes things more complicated as i have written a few pages of equations here but i could not find a similar relation between the torque, mass, radius of drum and angular velocity/speed. It seems like D is constant?? Maybe it represents moment of inertia? \$\endgroup\$ – WiredMaker May 18 at 23:56
  • 1
    \$\begingroup\$ \$\small D\omega =\large \frac{d\omega}{dt}\$ \$\endgroup\$ – Chu May 19 at 0:01
  • \$\begingroup\$ It finally makes sense now. Thanks a bunch for the clarification. \$\endgroup\$ – WiredMaker May 19 at 0:12
  • \$\begingroup\$ Related: Sizing a motor for a conveyor. \$\endgroup\$ – Dave Tweed May 19 at 1:38

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