Trying to create an assembly of a rack and pinion? In this case select the “Rack Pinion” mate option in “Mechanical Mates”. This tutorial will detail how to use the rack pinion mate in SolidWorks.
Begin by inserting a rack and spur gear into an assembly. Use the following properties:
Rack – Module 10, 20° pressure angle, pitch height 40mm and length 250mm.
Spur Gear – Module 10, 10 teeth and 20° pressure angle.
Mate the front face of the rack coincident with the front plane of the assembly. Apply a coincident constraint between the bottom face of the rack and the top plane. With these mates applied, the rack is able to move linearly left and right.
Mate the front face of the spur gear flush with the front face of the rack. Apply a coincident mate, use the origin of the spur gear and right plane of the assembly as the references.
To determine the height of the spur gear, add half of the pitch diameter and the pitch height. Position the gear 90mm above the top plane, using a distance mate. The references for the mate are: the origin of the gear and top plane of the assembly.
Rack Pinion Mate
If the rack and pinion are positioned correctly, the sketch of the pitch height should be tangent to the pitch diameter.
Expand the gear and ensure the “TooCutSke” sketch is set to visible. Do the same for the rack, ensure that the sketch “TooCutSkeSim” is set to visible. Create and new mate and select “Rack Pinion” from the “Mechanical Mates” section. Use the pitch height sketch line and pitch diameter as the mate references, click the green check mark to complete the mate. Tick “Reverse”, if movement is in the wrong direction.
For a rack pinion mate a line and circular edge are the only requirements. Use the rack and pinion mate to convert rotational motion to linear, or vice versa.
The image below uses two rack pinion mates, one of which is reversed, to simulate an object passing through a set of rollers.
Issues with Rack Pinion Mate
If either the rack or pinion are moved, with the mate suppressed, this may result in tooth overlap or no contact. Their positions are determined when the mate is unsuppressed.
The mate still functions when there is no contact.
There is no check to determine suitability. Changing the module of the spur gear does not affect the mate.