the present invention describes an improved grip belt drive system for use in sealing machines used to wrap articles in thermoplastic film . briefly , a timing belt is used in place of the traditional flat or v belt . the presence of teeth on the pulleys , coupled with the use of a timing belt eliminates the possibility of slippage between the belt and the pulleys . to protect the system in the case of a film jam or misplaced article , a torque - limiting mechanism is included , which disengages the drive system if there is excessive counterforce . furthermore , the outer surface of timing belt contains a pattern , which when mated with a second belt having the same or a complementary pattern , meshes in such a way so that the two belts are positively locked in both the longitudinal and transverse directions .