Abstract: A paper shredder includes an upper cover and a pressing structure. The pressing structure includes a base plate and a retractable member. The retractable member includes a push rod, a first sleeve, and an elastic element. The first sleeve includes a first hollow portion. The push rod is inserted into the first hollow portion of the first sleeve. The elastic element is disposed within the first hollow portion of the first sleeve. When the paper stack is contacted with the base plate to push the push rod, the push rod is transferred through the first hollow portion of the first sleeve and the elastic element is pushed by the push rod. Consequently, the elastic element generates an elastic force to press the paper stack.

Abstract: A paper shredder includes an upper cover and a pressing structure. The pressing structure includes a base plate and a retractable member. The retractable member includes a push rod, a first sleeve, and an elastic element. The first sleeve includes a first hollow portion. The push rod is inserted into the first hollow portion of the first sleeve. The elastic element is disposed within the first hollow portion of the first sleeve. When the paper stack is contacted with the base plate to push the push rod, the push rod is transferred through the first hollow portion of the first sleeve and the elastic element is pushed by the push rod. Consequently, the elastic element generates an elastic force to press the paper stack.

Abstract: A shaft positioning device is provided. The shaft positioning device includes a first supporting part, a second supporting part, and a position-limiting structure. The first supporting part includes a first hole. The second supporting part includes a second hole. After two ends of a shaft are penetrated through the first hole and the second hole, respectively, the position-limiting structure is located beside the first supporting part to limit the axial position of the shaft. Consequently, the shaft positioning device of the present invention is capable of positioning various types of shafts without the need of reserving a large installation space.

Abstract: The shaft positioning device includes a first supporting part, a second supporting part, and a position-limiting structure. The first supporting part includes a first hole. The second supporting part includes a second hole. After two ends of a shaft are penetrated through the first hole and the second hole, respectively, the position-limiting structure is located beside the first supporting part to limit the axial position of the shaft. Consequently, the shaft positioning device of the present invention is capable of positioning various types of shafts without the need of reserving a large installation space.