Company Follows wrong practice to not pay Gratuity

My company in Delhi not in a Practice to Pay Gratuity. I want to Claim my Gratuity after a Gap of 5 months as I Resigned on 10 February 2016 after serving 15 days notice period. I carry all document like appointment letter, relieving letter, my resignation letter. As i have not claimed immediately is it possible to claim it now and what is the maximum duration till when can I claim my gratuity amount e.g. like after which i cannot claim my gratuity. Also to bring one more thing in your notice that as i mentioned that company is not in practice to pay gratuity they follow a very smart trick that for the employees who are about to complete 5 yrs in a company, they simply pay salary in cash or from some other personal(saving) account so that break can be shown in employees service and even they do not pay pf for these months so that in no case employee can prove his existence in a company. So, same happened to me as company transferred 2 months salary i.e. 4.11 & 4.12 months from some saving account (through cheque) However, i have completed full 8 years in a company. (with 2 month gap in between.) I have relieving which clearly mentioned my joining & Leaving date and i have one PF account. (as for few employees they issue a 2nd pf no. to show rejoiining). So, my question is that can i claim gratuity even smart tricks and wrong practice followed by the company..