Hello Mayur,
Well Internship in Indian Railways is very helpful, especially if you are a mechanical Engineering student. Rail Coach factory is also a body of Indian Railways.Having an industry experience and recieving training from professionals, can not be compared with theory classes and online video tutorials.
For internship/training, you will have to apply in RCF.
https://rcf.indianrailways.gov.in/view_section.jsp?lang=0&id=0,294,468
There will be a training session organised in kapurthala, in which you will be trained. Ussually it will be a summer training of 40 days.
Having some source or relative who can recommend your name for internship is highly beneficial, otherewise there are provisions, where you will have to collect the forms from internship centre or fill online.
Hope this helps
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