Here are your parts
http://www.appliancepartspros.c....aspx?model=DBSR453EB2WW

By shut off I am assuming you mean that the motor stops.

Can you restart it right away or do you have to wait several minutes?

If you have to wait then it is probably the motor overheating.
The motor's thermal protect is opening and you have to wait for the motor to cool down so it resets.

Could be:
That the motor is clogged with lint and not cooling.

That there is too much drag on the motor. Try turning it in the correct direction manually. It should turn fairly easily. You may want to try this on a couple other units to get a feel for it. If there is too much drag it could be either the rear or the front drum bearings.

That the motor is on it's last legs.