To Create a Rack and Pinion Gear Pair
1. Click
Gears. The
Gear Pair Definition dialog box opens.
2. Under Type, select Rack and pinion.
3. Enter the following information on the Pinion tab:
◦ Select a rotational motion axis. A magenta arrow appears on the joint, indicating the positive direction for the axis. Use the right-hand rule to determine the direction of rotation.
The names of the bodies connected by the joint appear in the
Body area of the tab. By default, the first body in the connection is called the
Gear, and the second body is the
Carrier. To reverse the body order, click
. You can view the body order associated with a given gear in the Mechanism Tree by clicking
Gears in the
Connections folder, and then clicking the arrow next to the name of the gear.
◦ Under Pitch Circle, type a value for the diameter of the pitch circle in the Diameter box.
◦ Next to
Icon location, click
and select a point, a vertex, a datum plane or a surface perpendicular to the axis for the location of the pitch circle icon. The default location is at the root of the Pinion joint.
4. Enter the following information on the Rack tab:
◦ Select a translational motion axis. A shaded arrow appears indicating the positive translation direction. This translational motion axis must be perpendicular to the rack axis. To reverse the direction, click
.
The names of the bodies connected by the joint appear in the
Body area of the tab. By default, the first body in the connection is the
Rack, the second is the
Carrier. To reverse the body order, click
.
◦ The rack pitch plane is automatically placed tangent to the pinion pitch circle, in the direction of the rack axis.
When you press ENTER, two circles of this diameter are displayed on the pinion and are centered on the selected motion axis. The two circles are connected by smaller segments that represent the helix angle of the rack and pinion pair. A straight line from the center of the pinion to its circumference indicates the zero reference point of the motion axis. The rack pitch plane is displayed as a rectangle, tangent to the pitch circle, whose width is the same as the radius of the pitch circle and whose length is the distance the rack can move.
5. Click Rack Ratio on the Properties tab to define the value of the pitch circle diameter. If you select Pitch circle diameter (the default), diameter of the pitch circle is displayed on the Pinion tab. Select User defined and enter a real number for the rack ratio to set the distance the rack will travel for each turn of the pinion. The diameter of the pitch circle of the pinion is automatically calculated and the corresponding pitch plane of the rack is adjusted.
6. Enter values for the Pressure angle (default = 20°) and the Helix Angle of the gear pair. The helix angle is set for the pinion and is automatically used to define the corresponding slant angle on the rack.
|  A positive helix angle indicates that the spiral is right-handed. |