part is located here Realistic Movement Spring
Answered with a tutorial: https://grabcad.com/tutorials/how-to-model-spring-of-realistic-movement-in-solidworks-2012
that is interesting - i always make springs at various states of compression from free to solid (profile swept along a helix). i add configurations based on loading conditions (from manufacturer spring rate data). then i can see what my design does under load if the assembly is mated to the spring that changes lengths. what purpose does having the assembly above serve in designing actual mechanisms? how/why do you use it?