Sample Problems

A few typical Rotac application problems are presented here along with simplified solutions which can be used to approximate the torque requirement for a specific job. These formulas should be used only as a guide in the selection of an actuator since friction and other system characteristics are not considered.

The symbols used in the sample problems are defined as follows:



Problem #1
Find the torque required to rotate a rectangular load (horizontally) thru a given arc in a specified time. (See fig. 1)



Example #1



Example #2



Problem 1A:
Find the torque required to lift a weight and rotate it vertically thru a specified arc in a specified time.

Solution:





Problem 2:
Find the torque required to rotate a thin hollow pipe about its transverse axis through a given angle in a specified time.



Solution:



Assume:
50% ( t ) for acceleration
50% ( t ) for deceleration

Therefore,



Example:
Assume:



Problem 3:
Find the torque required to open or close a door through a given angle in a specified time.



Solution:

Assume:
50% (t) for acceleration
50% (t) for deceleration

Therefore,



Example:
Find the torque necessary to open a 350 Lb. door 100° in
.8 secs.

Assume:

Problem 4:
Find the torque required to rotate several plates of various thicknesses through a given angle in a specified time.

Solution:



Assume:
50% (t) for acceleration
50% (t) for deceleration

Therefore,



Example:
Rotate three plates as shown, 180° in 2 sec.

Assume:



Problem 5:
Find the torque required to produce a given force as shown in the figure below.



Solution:



Problem 6:
Find the torque required to produce a given force in a typical die closer application.



Solution: