| 摘要 |
A simple, inexpensive jack that can be used in severe working environments and can check an amount of raising and lowering movements of a piston of the jack at any time during working. The jack includes a cylinder, a piston capable of raising and lowering movements within the cylinder and a protective cover for covering at least a part of the outer circumference side surface of the cylinder, the protective cover having an inner circumference larger than the outer circumference of the cylinder and having one end fixed adjacent to the top end of the piston via a saddle and the other end being open, and a scale on the outer side surface of the cylinder. The amount of the raising and lowering movements of the piston is indicated by the relationship between the open end of the protective cover and the scale.
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