Need Electromechanical examples

Hi,
I will have a class test soon on transfer functions regarding electromechanical systems. I need examples to workout and compare the with solutions.
does anyone know of a good source or workbook?

I am given differential equations and a diagram. I convert them into s-domain, isolate the out/in to put in the blocks in the block diagram of the system with gain, error, etc. The most complicated can be the load speaker analysis.

thanks