steering shake

hi i,m new to the forum and would like to ask some advice when driving my landrover discovery (k reg) the steering some times starts to shake realy bad, it does not happen all the time just now and again,but is pretty scary when it does,and it is not just at a certain speed either it can happen at any speed,,i have lowerd the tyre pressure and this seems to help a bit,it still shakes now and then but not a bad,,just wondering if you could give me any ideas of what it could be any help would be greatly appreciated many thanks.

the steering column uj is a common problem.
also check all the steering joints. check your front wheel balance too.

and the swivels need to be set correctly.