=========
Worm Gear
=========
*Introduced in MORe v4.3*

Worm gear link properties implement a worm drive. Only the linear elastic behaviour is modelled, non-linearities are neglected. The simplifications are:

- any kind of backlash is neglected
- the force pushing the worm and the wheel apart (due to the pressure angle of the teeth) is not modelled and has to be added as load in an analysis if desired
- irregular transmission due to the teeth is not modelled
- local deformations of the worm and the wheel are not modelled

----------
Definition
----------

Source and target interfaces should be chosen as shown in following figure:

   .. image:: media/lp_worm_gear.png
      :alt: Worm gear link definition
      :scale: 100 %


^^^^^^^^^^^^^^^^^^^^
Source interface
^^^^^^^^^^^^^^^^^^^^

==============  ===========================================================================================
Type            Stationary interface (6dof)
Topologies      Peripheral face of the worm
Location        Center of worm
u direction     Axial, along center line
v direction     Transversal
w direction     Normal, towards the wheel
==============  ===========================================================================================

^^^^^^^^^^^^^^^^^^^^
Target interface
^^^^^^^^^^^^^^^^^^^^

==============  ===========================================================================================
Type            Stationary interface (6dof)
Topologies      Peripheral face of the wheel
Location        Center of wheel
u direction     Axial, along center line of the worm
v direction     Parallel to the v-direction of the source interface
w direction     Parallel to the w-direction of the source interface
==============  ===========================================================================================

^^^^^^^^^^^^^^^^^^^^^^^^^
Recommended link settings
^^^^^^^^^^^^^^^^^^^^^^^^^

==========================  ==========================
Use ground for source       unchecked
Location master             none
Orientation master          either source or target
==========================  ==========================

----------
Parameters
----------

=====================  =========  =======================================================================
Parameter              Unit       Description
=====================  =========  =======================================================================
Worm number of starts             Number of starts on the worm shaft
Wheel number of teeth             Number of teeth on the worm wheel
Wheel radius           m          Radius of the pitch line of the wheel
Contact stiffness      N/m        Stiffness of the contact between the teeth
Contact damping        Ns/m       Damping of the contact between the teeth
=====================  =========  =======================================================================