Torque and Speed Relationships in Gears | Motor Driving Winch Through Geartrain

LECTURE 06
Here the relationships are derived for torque and speed between mating gears in terms of radius, diameter, circumference, and numbers of teeth. It is shown that there is a direct ratio between gear size and torque and a negative inverse relationship between gear size and torque. (The negative indicates that the rotational direction changes at each mesh.) The concept of pitch circles is presented as a way of modeling gear action as simple friction rollers. The idea is presented that gears must have the same pitch (number of teeth per unit of circumference or diameter) in order to properly mate. A problem is solved in which a known mass must be lifted at a specified speed by a specified spool diameter using a specified set of gears with specified numbers of teeth. The required torque, speed, and direction of rotation is determined for the motor that drives the geartrain. It is explained that the "lossless" assumption utilized in the example is a good starting point for understanding, but fails to account for torque loss that would happen due to friction in any real geartrain.

ENGR 122 Playlist (Engineering Problem Solving III):
   • ENGR 122: Engineering Problem Solving...  

ENGR 121 Playlist (Engineering Problem Solving II):
   • ENGR 121: Engineering Problem Solving II  

ENGR 120 Playlist (Engineering Problem Solving I):
   • ENGR 120: Engineering Problem Solving I  

This lecture segment was recorded on March 26, 2018. All retainable rights are claimed by Michael Swanbom.

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