﻿ Getting Started Tutorials - MechDesigner > Tutorial 2A: Four-bar Kinematic-Chains > Step 2.8: Model a 'Pin in a Straight Slot'

# Step 2.8: Model a 'Pin in a Straight Slot'

## A 'Pin-in-a-Slot' Mechanism

 You may think a Pin-in-a-Slot is a special type of joint. Note: A Pin-in-a-Slot is term a joint in which a Pin-Joint appears to move along a Slide-Joint. The mechanical-design of a Pin-in-a-Slot might be actually be similar to Diagram A, in which we see two Parts : •Part : a lever with a pin roller at its end•Part : a part with a linear slotHowever, the kinematic-design of a Pin-in-a-Slot is always three Parts. Diagram B shows a different mechanical configuration, with three Parts: •Part : a lever, with a pin-joint at its end•Part : a part with a slot•Part : (the new Part) - a block (or a piston) that slides along the slot (Slide-Joint), AND is also joined to the lever (Pin-Joint)It helps me to imagine that Part is a Slide-Rail, and Part is a Sliding-Block that slides along the Slide-Rail. Diagram C shows a system that is a similar construction to Diagram B. Diagram C shows the Pin-Joint is that is offset to one side of the Slide-Joint.

### Video:

 Tutorial 2; Step 2.6 Pin-in-Slot Example Geneva

### General: To model a Pin-in-a-Slot

 Dyad only: STEP 1: Draw a Line† in Part - in this case, it is in the Base-Part Add dimensions and constraints to the Line. It will be the 'Slide-Rail'. STEP 2: Add a Part STEP 3: Join Part to Part with a Slide-JointPart is now the 'Slide-Block'. STEP 4: If necessary, edit Part to add a Point‡ to set the position of the Pin-Joint in Part STEP 5: Join Part to the Point in Part with a Pin-JointNotes: † You can add a CAD-Line in a Part or use the CAD-Line along the center of the Part. ‡ STEP 4 may not be necessary as you can use the start-Point or end-Point CAD-Line in Part when you do STEP 5.