# Rotational Spring

Ideal spring in mechanical rotational systems

## Library

Mechanical Rotational Elements

## Description

The Rotational Spring block represents an ideal mechanical rotational linear spring, described with the following equations:

`$T=K·\phi$`
`$\phi ={\phi }_{init}+{\phi }_{R}-{\phi }_{C}$`
`$\omega =\frac{d\phi }{dt}$`

where

 `T` Torque transmitted through the spring `K` Spring rate φ Relative displacement angle (spring deformation) φinit Spring preliminary winding (spring offset) φR, φC Absolute angular displacements of terminals R and C, respectively ω Relative angular velocity `t` Time

The block positive direction is from port R to port C. This means that the torque is positive if it acts in the direction from R to C.

## Dialog Box and Parameters

### Parameters Tab

Spring rate

Spring rate. The default value is `10` N*m/rad.

### Variables Tab

Use the Variables tab in the block dialog box (or the Variables section in the block Property Inspector) to set the priority and initial target values for the block variables prior to simulation. For more information, see Set Priority and Initial Target for Block Variables.

## Ports

The block has the following ports:

`R`

Mechanical rotational conserving port.

`C`

Mechanical rotational conserving port.