Ride on mower mulching mower series stiga park rotational speed 3 200 rpm power hp 1618 hp power watt 11 900 watt engine make briggs stratton engine model b s vanguard displacement 570 cc cylinder 2 engine cycles 4 stroke battery voltage 12 v battery capacity 24 ah gear hydrostatic transmission antriebsfunktion variable speed start system electric start features central cutting height adjustment headlights housing material steel power