My CUSAT CAT rank is 1897,will I get Mechanical in the main campus?

Your CUSAT CAT rank is decent. You’ll need to wait patiently in the counseling process. You have a high chance of being called for counseling. You might need to stick to Mechanical as your first option until the third shortlist is out.

The next thing you should be careful about is that of choosing the lower options. The reason behind this step is that sometimes you will be selected for your lower options and might get a chance to upgrade to Mechanical although there is no surety for this to happen at all times. So, choose branches like IT, civil as your lower options carefully based on your preferences. Keep your hopes high patiently and wait for the allotment positively.

A word of advice, if you are getting admission for Mechanical Engineering at any other colleges, go for it. Rather than waiting around for the opportunity to get Mechanical at CUSAT. The institute does not have a good placement record for Mechanical. You will most likely get recruited by IT firms after the completion of the course. And to get core companies you will need to score well in GATE.