US Patent 7395688 Hog ring fastening device

A hog ring fastening device includes a body member, a main pneumatic cylinder attached to the body member, a first swing member supported for turning on the body member, a push means supported on the first swing member, a feed pneumatic cylinder fixed to the first swing member and connected to a port of the main pneumatic cylinder, a second swing member supported for turning on the body member so as to be in contact with the free end of the piston rod included in the feed pneumatic cylinder, a feed means supported on the second swing member, a spring seat fixed to the body member, a compression spring extended between the spring seat and the first swing member, and an extension spring extended between the first and the second swing member.