Hafner motors wind in a different manner. On the vast majority of non-Hafner windup motors, the outer end of the mainspring is attached to the motor's frame, and the inside end attached to a hub. The hub rotates one direction when the mechanism is running , and has to rotate the opposite direction when winding. However, Hafner has the outer end of the mainspring attached to a four-fingered "basket" that not only encases the spring, but also rotates with the key to wind the mainspring from the outside-in. The basket has a ratchet mechanism so that it can only rotate one way. So, when a Hafner motor runs, the key stands still, whereas when a Marx motor runs, the key will spin, too. However, the rest of the Hafner motor is conventional, so you should still be able to turn the wheels by hand with the brake off (if it has a brake - some do, some don't). But, the key will not spin when you turn the wheels.
I like Hafner motors - they are fairly reliable, well governed and run nice - but they are one of the more difficult motors to work on. The basket makes mainspring replacement a bit difficult. Any internal work on the mechanism will require cutting the back axle to remove it just so there is room to spread apart the motor sideplates, and then a new axle has to made and the ends peened over to hold the wheels. Their main weaknesses are the mainspring (of course) and the mainspring hub - which is die cast, and being under a lot of stress, is prone to breaking at the first sign of zinc pest. But, overall, they are still a good motor.
