vibration in stering wheel and engin

When my discovery hits a pot hole or bump in the road ( e.g cat eye) the steering wheel, gear stick and engine shakes vigorously as thought the wheels are out of line , i have taken it to a garage and they didnt know what was wrong with it. It tends to happen more on motorways or when goingat higher speeds, i've found that when it happens to take my foot off the accelerator pedal and to press the brakes lightly to stop the wheels spinging.

hope that somebody can be of help.

thanks Ian.

yes of course we can. DO A SEARCH FFS!!!