Pneumatic puller

A pneumatic puller comprising:

• a shell unit defining a sliding space;
• a pulling member fixedly connected to the shell unit, and having a fixed section that extends in the sliding space and an exposed section that is opposite to the fixed section;
• a valve unit including a piston that is fixedly connected to the fixed section, and a directional valve assembly that is movably mounted to the piston and that is adapted for controlling a gas flow direction;
• and
• a cylinder movably disposed in the sliding space, sleeved on the fixed section, and including a cylinder wall that surrounds the piston and that is in airtight contact with the piston, the cylinder and the piston defining a first chamber and a second chamber, the cylinder being movable along the fixed section between a first reverse position and a second reverse position relative to the piston when urged by pressure of a gas, the cylinder abutting against one side of the piston and the directional valve assembly releasing the gas into the second chamber when the cylinder is in the first reverse position, the cylinder abutting against another side of the piston and the directional valve assembly releasing the gas into the first chamber when the cylinder is in the second reverse position, the cylinder moving along the fixed section away from the exposed section and hitting the piston when moving from the first reverse position to the second reverse position.