Crank Mechanism

A quick return mechanism such as the one seen opposite is used where there is a need to convert rotary motion into reciprocating motion. As the disc rotates the black slide moves forwards and backwards.

---

As the slider moves to the right the connecting rod pushes the wheel round for the first 180 degrees of wheel rotation. When the slider begins to move back into the tube, the connecting rod pulls the wheel round to complete the rotation.

One of the best examples of a crank and slider mechanism is a steam train. Steam pressure powers the slider mechanism as the connecting rod pushes and pulls the wheel round. The cylinder of an internal combustion engine is another example of a crank and slider mechanism.

---

This diagram shows how the crank linkage or slider can be made to give a side to side movement. By adjusting the height from the opening you can increase or decrease the amount of sideways movement. Adjusting the size or aperture of the opening will also have an effect on the amount of lateral movement. Trial and error play a big part in making things work.

---