Option 1: Fixed Pulley Centres


Fixed Pulley Centres : the centre of each pulley does not move relative to the machine frame (Base-Part). It is the most common belt and pulley arrangement.


The sketch-loop/path is a sketch-loop in the Base-Part.
Each Pulley is a Part that is joined to the Base-Part with a Pin-Joint.

A Pulley Part can be a:

Driving Pulley
The Driving Pulley is kinematically-defined (Green Part-Outline)  before you use Add Pulley.
The Driving Pulley rotates to move the Belt.

Linear Motion of Belt =  Drive Pulley Radius x Drive Pulley Angular Motion

Driven Pulley
The Driven Pulley is not kinematically-defined (Blue Part-Outline) before you do Add Pulley.
The Driven Pulley is rotated by the Belt. It becomes kinematically when you do Add Pulley.

Angular Motion of Pulley = Linear Motion of Belt / Pulley Radius.

Pulleys that have 'Fixed-Centres' rotate with their centres fixed to the Base-Part.

It is possible to have:


Pulleys and Fixed Centres:


Pulleys are Rotating-Parts, with Pin-Joints at the centre-Points of the Arcs in the sketch-loop in the Base-Part
Use the Pulley dialog-box to edit the Number-of-Teeth of each


The Belt is a sketch-loop
When the Pulleys are on fixed-centres, add the sketch-loop to the Base-Part


The Pulleys or the Belt move with a specified motion.

When the motion is specified for the:

Belt: We use a Motion-Path FB to define the motion of a Motion-Point along the sketch-loop on the Base-Part. Then, the Pulley's motion comes from the Belt's motion.
Pulley. The Pulley PArt is a kinematically-defined Part - for example, we can add a Motion-Dimension FB to define the rotation of the Pulley directly.  Then, the Belt's motion comes from the Pulley's motion.

Tutorials and Reference Help Files for MechDesigner and MotionDesigner 14.2 + © Machine, Cam, Mechanism, and Motion Design Software by PSMotion Ltd