Why A Retractable Pen?
APR 2026
Click! Click! Retractable pens feature a very clever mechanism called a "push-push" mechanism. This type of mechanism exists in many forms: old push light switches, cabinet latches, sim card readers, and more. But this is probably the most recognizable implementation.
The main question: why does the pen tip press out when you push the pen down, but the pen tip retracts when you push down again? Let's get into it.
What is A Push-Push Mechanism?
A Push-Push mechanism allows the user to toggle between two states (on/off or open/closed) with the push of one input. In this case, the push of the pen's plunger moves the pen tip out and then back in.
The bottom of the Pen is home to some important parts that help transfer ink onto paper. But those parts don't actively contribute to the push-push mechanism. To see the parts of the mechanism, we need to look inside the top of the pen.
Let's explore how these parts move
To better understand the mechanism, let's look more closely at three critical parts.
Okay, Time to Walk Through the Mechanism
Now that we're familiar with the main parts and the flattened view, let's walk through the mechanism, step by step.
