A cam assembly includes a wheel member fixed to a shaft and a cam member removably attached to the wheel member. By attaching the cam member to the wheel member while arranging the cam member in a first orientation, a first cam shape is given to the cam assembly. Moreover, by attaching the cam member to the wheel member while vertically inverting the cam member to set the cam member in a second orientation, a second cam shape different from the first cam shape is given to the cam assembly.