It sounds like the motor is overheating.
It has an internal thermal protect that opens if the motor overheats.
Then the motor has to cool down before it resets. Though an hour does seem very long.

Try turning the drum by hand, it should turn fairly easily.
If not you will have to open it up and find out what is going on.

Also the motor has two centrifugal switches on it, one of them switches out the start winding once the motor is close to operating speed. If this does not happen the motor will overheat. Since you get machine heat the centrifugal mechanism is probably OK, since the other switch switches in the heater.
So odds are that the switch is toast. Usually the motor has to be replaced as the switches are not available separately. Cannot say for sure as you did not post a Model Number.

Also if the voltage to the unit is low it will cause the motor to overheat, though this is very rare.

One other thing to try is push the door closed and try to restart it. Could be the door switch is just making so the whole unit has to cool down before it makes contact again.

Here is a good site with additional help
http://www.applianceaid.com/dryers.html