?A shear pin (also known as a shear bolt) is a weak bolt that connects your auger to the auger shaft. That connection allows the augers to rotate, collect snow and send snow into the impeller fan where the snow is thrown from the chute. If a large object gets wedged between your augers and the housing, the pins break as designed to protect your auger gearcase from incurring damage. All two-stage snow blowers have at least one shear pin on each side of the auger gear case. A shear pin is different from a regular bolt because it is designed to break, or "shear," which in this case is a good thing. Shear pins are made with a weak point that snaps if a jam occurs between the auger and the housing. Lets say a rock gets between the rotating auger and the housing. It stops the auger, but the auger shaft, which the auger is connected to by a shear bolt, wants to keep turning. If the jam by the rock is too severe and outmatches the force supplied by the gearcase to the rotating auger shaft, the shear bolt breaks, allowing the gearcase and the shaft to continue moving, undamaged. These jams that interrupt the auger rotation cause the shear pins to break, releasing the auger shaft from the auger. While this stops the auger from rotating, this also prevents damage to the snow blower gearcase.