The invention relates to improvements to the operation of a broadcast data receiver and, in particular, to the provision of a video data amplifier and driver circuit for the processing of a received video data signal. The first exhaust treatment device is disposed in front of the engine and lower than the upper surface thereof. The suspension device for front wheels has a front convex shape and a rear concave shape and covers the front end of the casing, and pivots to the middle of the front end of the casing.