Oil Pulse Wrench

Structure of Pulse Unit 
& Pulse Mechanism

A series of EYP model pulse wrench presents highest efficiency with simple mechanism of pulse. Oil is filled everywhere inside of the Cage which is combined with built-in Shank-anvil. Shank-anvil has two Pistons that are located 180? opposite. Each Piston is fitted on with a Roller which is always contacting inside wall of the Cage. There are two mounted portions that are protruded from inside wall of the Cage. Those two mounts are located 180? opposite, also. Shank-anvil is not directly connected with the airmotor, but the Cage is dirctly connected with it.
When Shank-anvil is under no load ie., free running, it is rotating together with the Cage. Once Shank-anvil is on load, it begins to stop rotating but the Cage keeps rotating. Then, two mounted portions in the Cage begin to push a pair of Rollers together with the Pistons towards the center of the Cage and then, this movement of pistons forms a pair of sealed chambers in the Shank-anvil where oil flow will be intercepted. After oil flow is intercepted, oil in the chambers where a pair of Pistons are moving will be compressed and will generate pulse in a moment to transfer energy from the Cage to the Shank-anvil.


New EYP model pulse unit recently developed has a pair of pistons. Oil is filled in the cage and shall be efficiently compressed in the sealed chambers in the shank-anvil. A pair of pistons and a pair of balls-steel will form a pair of sealed chambers in the shank-anvil. (Patented)
This simple mechanism helps to lower the number of parts required, and makes it easy to perform repair work. EYP model pulse unit simply generates single pulse per single rotation without using any mechanical cams. Shank-anvil has a pair of pistons, and each piston is located 180? opposite. There are two mounted portions in the cage that are protruded from inside wall of the cage. These protruded mounts in the cage are corresponding with a pair of pistons. (Patented)

Shut off mechanism to intercept supply-air is directly related to main valve. After reaching pre-set torque, supply-air shall be automatically shut off. (Patent Pending)
Shut off mechanism provides most reliable and stable performance in terms of torque accuracy even if the suppy-air pressure should be 0.4MPa.

Oil seals are to intercept lower pressure oil. This mechanism helps to extend life of seals much longer than the case as oil seals are to intercept higher pressure oil. Relief valve to adjust range of torque is positioned in the center bore of shank-anvil, which provides easiest handling for torque adjustment.

Shank-anvil has two-pieces structure consisting of the cap-anvil which forms square end and the body which forms substance to generate pulse. (Patent Pending)

This structure is adopted on the EYP-80AS, EYP-300AS and EYP-380AS models. In case of the EYP-80AS, for example, the square end can be selected among 3/8 inch, 1/2 inch and the one to accept bit-driver. Changing cap-anvils can be easily executed on the job site without using any special tools.

Ergonomic requirements like less vibration or less reaction force are realized on the EYP model pulse wrenches. To enhance these features, the grip-handle is covered with the same rubber that is used on the tennis racket. This rubber grip is supplied as a standard equipment to help to reduce burden on wrist, arm and shoulder of the operator.