Fastener driving tool with dual safety mechanism

Abstract

A fastener driving tool with a check valve installed on a piston includes a driving device and a returning device. The driving device includes a main body, a driver member and a first check valve. The main body includes a gas vessel, a cylinder, an upper cover and an annular wall, a chamber is formed between the gas vessel, the cylinder and the annular wall, a second hole is formed on one of the annular wall and the cylinder or a second hole is formed between the annular wall and the cylinder, and the second hole communicates with the chamber. The driver member includes a piston and a driver, the piston has a first sealing ring, a second sealing ring and a third sealing ring and is formed a first hole, and the driver is connected to the piston. The returning device is connected to the driver. The first check valve is disposed outside the opening of the first hole. When the first safety mechanism fails, the second safety mechanism is the main one, thereby improving the operational safety of the fastener driving tool of the present invention, and the structure is simplified.