together with the end of the striking rod 60 the striking rod 60 extends through an opening 64 formed in a transmission housing 66 the switch box 42 is secured on the transmission housing 66 with a screw 68 passing through an opening 44 formed in the flange section 46 of the switch box 42 and engaged with a threaded bore 70 formed in the boss section 72 the switch box 42 is provided with a sealing ring 48 on the outer periphery which sealing ring 48 abuts the transmission housing 66 for a seal therebetween the switch box 42 is equipped with stationary contacts 50 52 54 56 and 58 on the internal periphery thereof the stationary contact 50 is connected with an electric power source not shown for supplying electric power to the switch arrangement the contacts 52 54 56 and 58 are arranged as shown in fig3 and respectively adapted to respective transmission gear positions namely the contact 52 is adapted to the neutral gear position the contact 54 is adapted to the fourth speed gear position the contact 56 is adapted to the over drive gear position and the contact 58 is adapted to the reverse gear position the contact section 30 of the movable contact element 24 contacts either one of the contacts 52 54 56 and 58 corresponding to the transmission gear position it will be appreciated that the hereabove shown and described embodiment shows an.