MechDesigner Reference & User Interface > 2.2 Mechanism-Editor: > Machine elements > Mechanism

Add Rack and Pinion / Ball-Screw

Terminology

Rack -Pinion :

A Rack-Pinion is the term for a sliding, linear-gear (Rack) that is in mesh with a rotating, circular-gear (Pinion).

The motion of the two Parts are kinematically-related by the module and number-of-teeth on the Pinion.

Ball-Screw :

A Ball-Screw is a device in which a Screw rotates to move a Nut, or vice-versa. The Linear-Motion of the Nut and the rotation of the Screw are related by the lead of the screw-thread.

Kinematic State before you do Add Rack-Pinion.

Either the Part with the Pin-Joint or the Part with the Slide-Joint is not kinematically-defined.

Kinematic State after you do Add Rack-Pinion.

The Part with the Pin-Joint and the Part with the Slide-Joint are kinematically-defined.

Add Rack-Pinion removes one degrees-of-freedom.

Preparation (typical)

When the movement of the Rack will come from the Pinion (Driving Pinion)

MD-GA-RackPinion-Prep-0

Elements before you do Add Rack-Pinion

Line - in a rotating-Part that is kinematically-defined

Line - in a Sliding-Part that is not kinematically-defined

When the movement of the Pinion will come from the Rack (Driving Rack)

Elements before you do Add Rack-Pinion

Line - in a Sliding-Part that is kinematically-defined

Line - in a Rotating-Part that is not kinematically-defined

Add Rack and Pinion

When the movement of the Rack comes from the Pinion (Driving Pinion)

STEP 1: Click Add Rack-Pinion

1.Add menu > Mechanism menu > Add Rack-Pinion

- or -

1.Machine-elements toolbar > Add Rack-Pinion

There are two elements to select in the Command-Manager.

STEP 2: Select the two elements in the graphic-area

1.Click Line - it is in the Part that is kinematically-defined.

2.Click Line - it is in the Part that is NOT kinematically-defined.

STEP 3: Complete the Command

1.Command-Manager: Click to complete Add Rack-Pinion.

Result :

The Pinion is on the Rotating-Part.

The Rack is on the Sliding-Part.

The Rack is parallel to the Line you select in the Sliding-Part.

The Pitch-Line of the Rack is offset from the center of the Pinion by the Pitch-Circle Radius of the Pinion.

The Sliding-Part is now a Part that is kinematically-defined.

When the movement of the Pinion comes from the Rack (Driving-Rack)

STEP 1:Add Rack-Pinion

1.Add menu > Mechanism menu > Add Rack-Pinion

- or -

1.Machine-elements toolbar > Add Rack-Pinion

The Command-Manager indicates you must select two(2) elements

STEP 2:Select the two elements in the graphic-area

2.Click Line - it is in the Part that is kinematically-defined.

3.Click Line - it is in the Part that is NOT kinematically-defined.

STEP 3:Complete the Command

4.Command-Manager: Click in the Command-Manager.

The Rack-Pinion is now in the Assembly-Tree and Graphic-Area.