Piston
Tap (the Piston icon) to add piston support to your diagram. The piston support enables rotation and movement at its tip point. It forces the element to slide through one particular point, which is the only difference from Sliding Support. Piston support decreases the degrees of freedom (DOF) by 1.
To place a piston support, tap at any point on an existing element. Drag to move it to a different location.
To replace an existing support with a piston support, tap the Piston command in the context menu of the support you want to replace.