Pulleys Driven By Belt

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Pulleys Driven By Belt

Fixed Pulleys centers: 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



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 ArcRed-14-1b

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


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 OK-tiny-11-15 in the Command-Manager.


A Motion-PointRed-14-2 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 FBRed-14-2 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 .



STEP 7: Add PartsRed-14-3 : one part for each Pulley / Arc

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

STEP 8: Add a Pin-JointRed-14-4 between the start-Point of each Part and the center-Point of each Arc

The Pin-Joint will be at the center 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.


See Preparation, above, to identify the four elements.




Red-14-1b Click the Pin-Joint  

Red-14-2 Click the Motion-Path FB (not the Motion-Point)

The Part-Editor opens to show the sketch-loop

Red-14-3 Click the radius Dimension of one of the Arc sketch-element

The Part-Editor closes.

Red-14-4 Click the Part, with a Pin-JointRed-14-1b at the center-Point of the Arc.

Click OK-tiny-11-15 to close the Command-Manager

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

Two Pulleys Driven by the Belt'

Two Pulleys Driven by the Belt'


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.


Kinematics Tree of the Pulley-Rocker element.