I am sorry but this question is puzzling. Coaching centres are places that generally coach students for the preparation for an entrance exam. Carrying it futher, coaching centres may also help out in specific subjects. But I havent heard of coaching centres and placements as coaching centres are not recognized places and so their very validity is in question. So please dont look for coaching centres for any study with regard to placements. 

If you are interested in mechanical engineering, well drawing is a subject that you need to study so you can take coaching to help you understand better. This will be once you are studying mechanical engineering. 

Please clearly specify the purpose for which you need coaching and we could get back with the right kind of information.