Today’s invention is a system which might best be used on railway engines.
If an individual wheel is sensed to be losing traction (often a problem on icy tracks or when under emergency braking conditions), its contact pressure on the rail can be temporarily increased by pumping a measured amount of heavy fluid (perhaps lubrication oil) from a central reservoir into a circumferential channel within the wheel.
This would also have the effect of suddenly increasing the moment of inertia of the wheel and thus reducing its rotational velocity when starting to spin. The volume of flow to each wheel could be precisely controlled in order to ensure an optimal distribution of grip and rotational inertia.
In addition, the frictional heating of the wheels could be lessened by withdrawing the fluid from them when the train had halted.