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Belt, Path-Joint, Pulley-Rocker

Add Pulley makes a motion relationships between a Rocker, a Motion-Point on a sketch-loop and the radius of a Pulley.

There are two Pulley types:

Drive-Pulley - its motion is given by a kinematically-defined Part.

Driven-Pulley - its motion is given by the speed of the Belt.

The linear speed of the Motion-Point along a sketch-loop is equal to the product of the angular velocity of the Pulley and the Pitch-center-Radius of the Pulley.


You can add one Drive Pulley and one or more Driven Pulley to each sketch-loop.

For the Drive-Pulley

Specify a Drive Pulley at an Arc in a sketch-loop with a Rocker joined to its center.

VMP = Velocity of the Motion-Point  - calculated by MechDesigner

RP = Radius of the Drive Pulley - specified by the Pulley dia Example Kinematic-Chains log-box

ωP = Angular Velocity of a Rocker - specified by Kinematic FBs

For each Driven-Pulley

Specify a Driven Pulley at an Arc with a Free-Rotating-Part joined at its center.

VMP = Velocity of the Motion-Point  - specified by the Drive-Pulley

RP = Radius of the Driven Pulley - specified by the Pulley dialog-box

ωP = Angular Velocity of the Free-Rotating-Part becomes a Pulley-Rocker - calculated by MechDesigner

The Pulley-Rocker is a kinematically-defined Part.

tog_minusThe Pulley-Rocker in the Kinematics Tree

tog_minusAdd Pulley

Design Arrangements

Fixed Pulley centers : Two or more Pulley Sets


Use two Belts to:

Give a larger Speed Reduction

Reduce Belt Span

The image to the left shows a Simple Belt with the three Pulleys and two Belts

tog_minusStep 1:  First Belt

tog_minusStep 2:  Second Belt