Trolleybus burnout

A trolleybus having troubles and slipping due to wet snow mud on a light grade. But this is quite unexpected behavior for usual trolleybus because there are many buses with automatic transmission, as well as ones with manual gearbox, including articulated with mid or tail driving axle, all of them climbing the same grade without such hard wheelslip. Hence, the road surface isn't really so slippery to completely prevent climbing. The only reason should be that this specific type of trolleybus has a feature always to start very roughly and couldn't do it in a more soft manner :)