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.

Pin in a Slot Design Options

The mechanical-design of a Pin-in-a-Slot might be actually be similar to Diagram A, in which we see two Parts :

Part1s-red : a lever with a pin roller at its end
Part2s : a part with a linear slot

However, the kinematic-design of a Pin-in-a-Slot is always three Parts.

Diagram B shows a different mechanical configuration, with three Parts:

Part1s-red : a lever, with a pin-joint at its end
Part2s : a part with a slot
Part3s : [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 Part2s is a Slide-Rail, and Part3s 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.


There are two examples of the Pin-in-a-Slot mechanisms, below.

Cam-Follower in a Slot - Geneva Mechanism

 

'Expand' then 'Play'

How to...Add a new Mechanism-Editor.

 

'THK' Slider and Rail - Dwell Mechanism

Pin-in-Slot Dyad and Mechanism How to...Add a new Mechanism-Editor.

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

One of eight kinematic options for a Pin in a Slot

Dyad only:

STEP 1: Draw a Line† in Part1s-red - in this case, it is drawn in the Base-Part

Add dimensions and constraints to the Line. It will be the 'Slide-Rail'.

STEP 2: Add a Part2s
STEP 3: Join Part2s to Part1s-red with a Slide-Joint3s

Part2s is now the 'Slide-Block'.

STEP 4: If necessary, edit Part2s to add a Point5s to set the position of the Pin-Joint in Part2s
STEP 5: Join Part4s to the Point5s in Part2s with a Pin-Joint5s

Notes:

You can add a CAD-Line in a Part1s-red or use the CAD-Line along the centre of the Part.

STEP 4 may not be necessary as you can use the start-Point or end-Point CAD-Line in Part2s when you do STEP 5.

Eight Possible Pin-in-a-Slot Kinematic-Chains

The Pin-in-a-Slot is actually two joints [of the three total joints] in a Dyad.

In the Dyads we describe below, the letters R-P represent the two joints.

The R is a Pin-Joint - R for Revolute-Joint, which is the kinematic-term for Pin-Joint.
The P is a Slide-Joint - P for Prismatic-Joint, which is the kinematic term for Slide-Joint.

When you add a third joint, which may be a Slide-Joint(P) or a Pin-Joint(R), the Dyad is complete.

You can also join the Dyad to a Rocker or a Slider. Thus, it is possible to build eight different kinematic-chains.

Configurations:

1  & 2: RP+R + Rocker OR  RP+R + Slider. The Dyad is an RPR Dyad.

3 & 4: RP+P + Rocker OR RP+P + Slider. The Dyad is an RPP Dyad.

5 & 6: R+RP + Rocker OR R+RP + Slider. The Dyad is an RRP Dyad.

7 & 8: P+RP + Rocker OR P+RP + Slider. The Dyad is a PRP Dyad.

Remember also, it is possible for each Dyad to have a maximum of four different closures. See Change Dyad Closure.

KinematicChain-PinSlot1

Configuration 1 (See Step 2.7)

This is a Rocker and an R-P-R Dyad

Join Part1s-red to the Base-Part with a Pin-Joint

Join Part2s to Part1s-red with a Slide-Joint3s. The Joint uses the CAD-Line in the two Parts.

Join Part2s to Part4s with a Pin-Joint5s

Join Part4s to the Base-Part with a Pin-Joint.

[A Motion-Dimension FB identifies the Part we will move with a specified motion.

The motion-values at the input-connector to the Motion-Dimension give the rotation to the Part4s]

KinematicChain-PinSlot2

Configuration 2

This is a Rocker and an R-R-P Dyad (or P-R-R if you prefer to start from the Motion Driven Joint)

Part1s-red is joined to the Base-Part with a Pin-Joint

[A Motion-Dimension FB identifies Part1s-red as the Part we will move with a specified motion.

The motion-values at the input-connector to the Motion-Dimension give the rotation to the Part1s-red]

Part2s is joined to Part1s-red with a Slide-Joint3s. The Joint uses the CAD-Line in the two Parts.

Part2s is joined to Part4s with a Pin-Joint5s .

Part4s is joined to the Base-Part with a Pin-Joint.

KinematicChain-PinSlot3

Configuration 3 (See Step 2.6)

This is a Rocker and an R-P-P Dyad

Join Part1s-red to the Base-Part with a Slide-Joint

Add a Line to Part1s-red. Use the new Line to join Part2s to Part1s-red with a Slide-Joint3s.

Join Part2s to Part4s with a Pin-Joint5s

Join Part4s to Base-Part with a Pin-Joint.

[A Motion-Dimension FB identifies Part4s as the Part we will move with a specified motion.

The motion-values at the input-connector to the Motion-Dimension give the rotation to the Part4s]

KinematicChain-PinSlot4

Configuration 4

This is a Slider and an R-R-P Dyad (or a P-R-R if you prefer to start from the Driven Joint)

Join Part1s-red to the Base-Part with a Slide-Joint

[A Motion-Dimension FB identifies Part1s-red as the Part we will move with a specified motion.

The motion-values at the input-connector to the Motion-Dimension give the displacement to the Part1s-red]

Add a Line to Part1s-red. Use the new Line to join Part2s to Part1s-red with a Slide-Joint3s.

Join Part2s to Part4s with a Pin-Joint5s

Join Part4s to the Base-Part with a Pin-Joint.

KinematicChain-PinSlot5

Configuration 5

This is a Slider and an P-R-P Dyad

Join Part1s-red to the Base-Part with a Slide-Joint

[A Motion-Dimension FB identifies Part1s-red as the Part we will move with a specified motion.

The motion-values at the input-connector to the Motion-Dimension give the displacement to the Part1s-red]

Add a Line to Part1s-red. Use the new Line to join Part2s to Part1s-red with a Slide-Joint3s.

Join Part2s to Part4s with a Pin-Joint5s

Join Part4s to the Base-Part with a Slide-Joint. This Slide-Joint is at a fixed angle of approximately 60º

KinematicChain-PinSlot6

Configuration 6

This is a Rocker and an P-R-P Dyad

Join Part1s-red to the Base-Part with a Pin-Joint

[A Motion-Dimension FB identifies Part1s-red as the Part we will move with a specified motion.

The motion-values at the input-connector to the Motion-Dimension give the rotation to the Part1s-red]

Add a Line to Part1s-red. Use the new Line to join Part2s to Part1s-red with a Slide-Joint3s.

Join Part2s to Part4s with a Pin-Joint5s

Join Part4s to the Base-Part with a Slide-Joint. The Slide-Joint is at fixed angle of approximately 60º

KinematicChain-PinSlot7

Configuration 7

This is a Slider and an R-P-R Dyad

Join Part1s-red to the Base-Part with a Pin-Joint

Add a Line to Part1s-red. Use the new Line to join Part2s to Part1s-red with a Slide-Joint3s.

Join Part2s to Part4s with a Pin-Joint5s

Join Part4s to the Base-Part with a Slide-Joint. The Slide-Joint is at a fixed angle of approximately 60º

[A Motion-Dimension FB identifies Part4s as the Part we will move with a specified motion.

The motion-values at the input-connector to the Motion-Dimension give the displacement to the Part4s]

KinematicChain-PinSlot8

Configuration 8

This is a Slider and an R-P-P Dyad

Join Part1s-red to the Base-Part with a Slide-Joint

Add a Line to Part1s-red. Use the new Line to join Part2s to Part1s-red with a Slide-Joint3s.

Join Part2s to Part4s with a Pin-Joint5s

Join Part4s to the Base-Part with a Slide-Joint. The Slide-Joint is at a fixed angle of approximately 60º

[A Motion-Dimension FB identifies Part4s as the Part we will move with a specified motion.

The motion-values at the input-connector to the Motion-Dimension give the displacement to the Part4s]

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