Posted By Stuart Nagle Stephen. Going back in years to my days spend shivering on cold winter mornings/nights on gritting vehicles, I am suprised to hear of this accident. As far as I am aware, once the gritter unit (fixed or demountable type) is disengaged, the spinner at the rear that 'spreads' the grit should stop revolving. Once it had stopped revolving, there was a pin at the side,which, once removed opened the spinner and blockages could be removed. the unit was then closed, pin reinserted, and the unit restarted. A quite safe operation as I recall - except on the motorway hard shoulder at 03.00 hours in the snow !! You may have several problems; 1) disengaging the unit is not stopping the spinner - this can and should be rectified by mechanical maintenance. 2) Blockages are always a nuisance, and best avoided. Is the grit being loaded correctly and is there a grid atop the gritter body to prevent 'lumps' entering the hopper ? 3) What is the condition and storage facility of the grit like. If the grit get excessively wet, it will form into lumps, especially over long periods of storage (how old is it). Improvements to storage facilities and 'working the grit over' with machinery, such a a bucket loader can work wonders. If the grit is not 'de-crusted' and just taken and placed in a hopper, you're always going to get problems !! Hope this is of assistance... Stuart Nagle