Regarding GST ON TRANSPORT

Sir,we have the union of Tralla transportation and have been applied for GST registration and the style of working is that on the pukar of vehicle we send the said vehicle for transportation of goods of factory and as per bills/invoices our said Tralla delivers the good as per invoices/bills to the concerned dealer.Sir in view of the above said working we are not in knowledge who is liable to pay the GST and what is roll of our union.Sir please guide us in the matter cited.We shall be highly appreciated to your expert opinion Sir please guide us briefly.Thanks.