Klassische Schraubkranzfreiläufe: Unterschied zwischen den Versionen

The outer body of a freewheel can turn freely in one direction relative to the inner body, but not in the other direction. Most freewheels achieve this by means of pawls which engage a ratchet. The photo below shows the inner body (the part that threads onto the hub) of a freewheel. The outer body (the part that holds the sprockets) has been removed. The red arrow points to one of the two pawls of this freewheel. Small wire springs, visible in the photo, rotate the pawls outward.

The photo below shows the outer body from the back (left) side. The ratchet is the circular stepwise arrangement near the center of the photo. When the cyclist coasts, the pawls slip forward (counterclockwise in the photo) over the rachet. The freewheel makes a characteristic tick-tick-tick sound as the pawls spring into place behind ratchet teeth. When the cyclist is pedaling, the outer body also turns (counterclockwise in the photo), the pawls engage the ratchet teeth and the freewheel is silent. This particular freewheel has two pawls directly opposite one another and an odd number of ratchet teeth, 15, so only one pawl engages at a time.

The photo also shows bearing balls in a bearing race, embedded in grease to hold them in place during assembly (also a few bearing balls that got away). The bearing balls roll between this bearing race and one on the inner body. In the previous photo, part of the inner body's bearing race is visible as a polished arc (blue arrow). The front (right) side of the freewheel has another bearing assembly, not shown in these photos. The bearings center the outer body on the inner body, and allow the inner and outer body to turn freely relative to each other when the cyclist is coasting.