Abstract: A pneumatically operated nail gun having a safety device which prevents a trigger lever from being accidentally manipulated. The gun has a nail guide movably disposed over a bit guide. A movable segment having a pipe-shaped portion and an arm portion formed integrally therewith is provided. The pipe-shaped portion is disposed movably in the nail guide, and the arm portion is movable in a slit of the nail guide. The arm portion is coupled to the safety arm whose end portion is engageable with the trigger lever. A spring is provided to urge the safety arm in a direction to maintain engagement between the end portion and the trigger lever. When the nail inserted in the nail guide is depressed onto the workpiece, the pipe-shaped portion moves against the biasing force of the spring, so that the end portion of the safety arm disengages from the trigger lever, whereupon the trigger lever can be operated.

Abstract: A pneumatic fastener driving tool including a start valve adapted to be open for start a fastener driving operation by pneumatically driving a driving rod forwardly, and a vent hole for connecting to start valve to atmospheric air to let compressed air escape to atmosphere when compressed air is accidentally supplied through the start valve after one cycle of fastener driving operation is completed due to bouncing of the piston, for example.