Reinforced spool assembly

A reinforced spool assembly has a shaft, a spool member coaxially mounted around the shaft, and two ratchets mounted on two axial ends of a combination of the shaft and the spool member. Each one of two ratchets has a body having an inner surface. The two inner surfaces of the two bodies face each other. In each one of the ratchets, the body has a reinforced supporting structure. The reinforced supporting structure is located between the shaft and the spool member and is offset from the inner surface of the body. A reference plane is defined on and extends along the inner surface of the body, is perpendicular to a central axis of the shaft, and passes through the reinforced supporting structure. Mechanical strength of the reinforced spool assembly is increased by the reinforced supporting structure.