Under the Model element in the Project tree, right-click Connections and select Insert > Joint.

A new Joint is created under the Joints group.

Right-click the new Joint and Rename it as Revolute_Drive.

In the Details panel, under Definition, set Connection Type to Body-Ground.

Set Type to Revolute.

In the Details panel, under Mobile, click in the Scope field.

Using the Face selection tool, select the inner face of Sprocket and click Apply.

The Details for the Revolute_Drive joint should appear as shown below:

In the Project tree, under Connections, right-click the Joints group and select Insert > Joint to insert two more Revolute Joints named Revolute_Driven and Revolute_Sprocket_Guide, as shown below: