The present invention eases possible rubbing between an upper cutting edge and a work cutting surface during the elevation of the upper cutting edge to prevent the upper cutting edge from being worn in order to increase its lifetime. A polychloroprene latex composition which has a low viscosity and which can be made to have a high solid content, can be obtained by emulsion polymerization of chloroprene alone or chloroprene and a monomer copolymerizable with chloroprene in the presence of a polyvinyl alcohol and a nonionic emulsifier. The conduit defines a conduit passageway having a conduit inlet and a conduit outlet. The drive wheel engages the guide wheel.