Depending on the position you are applying to, you may be asked to take an assessment test. If you are applying for an entry-level technical position, then you may be asked to take a mechanical aptitude test, such as the Bennett Test of Mechanical Comprehension to see if you understand the basics of your position.
More experienced positions such as maintenance mechanics may be required to take a Ramsay Mechanical Test, where theoretical and practical knowledge of various mechanical and electrical topics is assessed.
If the job you are applying for has to do with customer care you may be asked to take a situational judgment test to assess how you would do in real-world situations and how you would react. The assessment tests are given by Aon Hewitt. For other positions, you may be required to take other tests such as the Hogan personality test, in-basket, and more.