Applicability of Service Tax

Sir I am accountant of one propretory concern. I have one doubt regarding service tax. Please clarify me. My question is , "Is Service Tax is applicable to transport contractors?. My boss is running some 50 transit mixers (schwing stetter) and Pump for overlifting the concretes. We are Billed in Hire Charges for transit mixtures in kilo metre running basis and also some contract basis that is roundsum basis (that is diesel is supplied by the company not ours) my question whether service tax is applicable to this transaction or not. All transport vehicles and pumps are worked in Consortium Construction Ltd. Please someone help me and suggest me