Here's the simple way to get Gear Joints
Click the Gear Joint icon in the Kinematics Joints toolbar or select Insert -> New Joint ->Gear... from the Menu bar.
The Joint Creation: Gear dialog box appears.
The Mechanism is identified in the specification tree.
Now you need to select two Revolute joints.
Select Revolute.1 either in the specification tree or in the geometry area.
Create Revolute.2 within the Gear command. For this: click Create button
The Joint Creation: Revolute dialog box appears automatically:
Select line .1 (Gear1 axis) and line.2 (Gear2 axis) as shown below in the geometry area:
Select plane.1 (Gear1 face) and plane.2 (Gear2 face) either in the specification tree or in the
Select the Offset option button and keep the default value. When done, click Ok.
Assign a command, select for instance the Angle driven for revolute1 check box.
Click "define" button to define the ratio parameter automatically. The Gear Ratio Definition dialog box is
Select the two circles in the geometry area. each one for Gear 1 and Gear 2.
The calculated ratio appears in the Joint Creation: Gear dialog box.
Change the rotation direction option if needed.
The default is Same (positive)
Opposite is negative
Click Ok when done