<< Click here to display Table of Contents for MechDesigner Help and Tutorials >> Navigation: Getting Started Tutorials - MechDesigner > Tutorial 17: Belts and Pulleys > Option 1: Fixed Pulley Centres:

Pulleys Driven By Belt

Contents

Fixed Pulleys Centres: Pulleys become driven by a Belt

This design arrangement is a little more unusual than the Belt driven by a Pulley.

Physically, the Belt is wrapped around freely rotating Pulleys. The Belt is driven by motion-values at the input-connector to the Motion-Path FB.

Free Running Pulleys that are driven by a Belt

Preparation:

GA-AddPulley-0

STEP 1:

Edit the Base-Part

STEP 2:

Add a sketch-loop - with lines and arcs only - to represent the Path for the Belt

Hover+Drag to merge the Points at the end of each Line and Arc to give a sketch-loop.

STEP 3:

Add a dimension to each Arc

The radius of the Arc is not important. MechDesigner adds a Pulley with an integer number-of-teeth with a Pulley that has a radius that is near to the starting dimension.

STEP 4:

Close the Part-Editor

GA-AddPulley-1

STEP 5:

Click Kinematic-FB toolbar > Add Motion-Path FB

The Command-Manager has one selection-box:

Click a sketch-element in the sketch-loop.

Click in the Command-Manager.

GA-AddPulley-2

A Motion-Point shows at the start-Point of the sketch-element you select in the sketch-loop. It is a small triangle inside the Point-Symbol.

STEP 6:

Add a Linear-Motion FB

Connect the Linear-Motion FB to the Motion-Path FB with a wire.

Motion-values of 0 - 360 (at the output of the Linear-Motion FB) move the Motion-Point the total length of the sketch-loop.

You can use motion-values from any Function-Block,of course. E.g.: Motion FB .

GA-AddPulley-3

STEP 7:

Add Parts

: one part for each Pulley / Arc

The length of each Part is not important for the Pulley or belt.

STEP 8:

Add a Pin-Joint

between the start-Point of each Part and the centre-Point of each Arc

The Pin-Joint will be at the centre of the Pulley.

Add Pulley command

Do Kinematic-elements > Add Pulley to add each Pulley.

Click Add Pulley in the:

•	Mechanism menu

- or -

•	Kinematic-elements toolbar

Add Pulley opens in the Command-Manager.

Select the four element in the graphic-area.

Note:

See Preparation, above, to identify the four elements.

CM-AddPulley-3

CM-AddPulley-3A

Click the Pin-Joint

Click the Motion-Path FB (not the Motion-Point)

The Part-Editor opens to show the sketch-loop

Click the radius Dimension of one of the Arc sketch-element

The Part-Editor closes.

Click the Part, with a Pin-Joint at the centre-Point of the Arc.

Click to close the Command-Manager

Do Add Pulley again, to add a Pulley at the other Arc.

Two Pulleys Driven by the Belt'

Notes:

The Pulleys are Driven Pulleys.

The angular-velocity of each Pulley is defined by the linear-speed of the Motion-Point along the sketch-loop (Belt) and the radius of each Pulley.

•	When you add a Pulley, the radius of the Arc will change a little to give an integer number-of-teeth

•	The Parts are horizontal when the MMA is zero.

•	Driven Pulleys are Purple

•	Edit the number-of-teeth with the Edit Pulley dialog.

•	Edit the Tooth-Pitch in the Motion-Path FB.

KT-Pulley-Rocker2

Kinematics Tree of the Pulley-Rocker element.

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