Abstract: A chain comprising links and pins formed from fiber reinforced thermoplastic resin is disclosed. Each link has bores, and each pin has a body for insertion through the bores of adjoining links to connect the links pivotally. The body has two diametrically opposite rows of grooves formed in its peripheral surface, has a front end from which an annular shell projects coaxially and an axial protrusion extends through the shell coaxially, and has a rear end formed with a flange. The shell has a radially outwardly projecting shoulder formed around its mid-portion, has a frustoconical front end portion, and has radially extending slits which makes the shell radially compressible. The link which has a bore positioned at the inlet for the insertion of the pin, has bosses which are engageable with the flange for holding the pin against rotation to maintain the rows of grooves at right angles with respect to a longitudinal direction of the links.

Abstract: A sprocket wheel having replaceable teeth includes a wheel body, a plurality of replaceable teeth, and fixing members to fix each tooth to the wheel body. In the outer periphery of the wheel body are formed a plurality of notches regularly spaced from each other. Each replaceable tooth consists of a central portion which forms a tooth groove on the upper surface and which fits into the notch of the wheel body, and two flanges formed in right and left sides of the central portion. The right and the left flanges can be formed ahead of and behind the central portion of the tooth respectively. Each fixing member can consist of an internal thread formed in each flange of the tooth, a bolt hole formed in each side of the notch, and a bolt having a head thinner than the flange.

Abstract: A flight for collecting sludge by sweeping comprises a roller shoe, comprising (a) a frame having a substantially U-shaped cross section and having a pair of side plates, (b) a shaft having a diameter-enlarged portion at one end and a threaded portion at the other end, and fixed to the side plates, and (c) a roller rotatably supported by the shaft between the side plates, wherein the frame is constituted by an injection-molded synthetic resin, and the roller is made of a synthetic resin.