In a ratchet type chain tensioner, having a toothed rack on its plunger and a pawl cooperable with the rack, a recess is provided between the front end of the rack and the protruding end of the plunger. The output negative terminal is connected directly to the input negative terminal. The control system is configured to receive a driver input relating to a brake pressure sought to be applied. Thus, a VAS platform of the second network can receive the address of the second network and the subscriber identity of the subscriber, such that subscriber accessing services of the VAS platform can be identified for charging andor addressing purposes.