Abstract: A process for manufacturing a petroleum resin is disclosed. The process comprises, polymerizing a petroleum fraction containing unsaturated hydrocarbons in the presence of Friedel-Crafts catalyst, and washing the polymerized product with water or an alkaline solution in the presence of 1-200 ppm of a polymer having a hydroxyl value of 40-120 mg KOH/g and represented by formula (I): ##STR1## wherein R.sub.1 represents a C.sub.4-16 alkyl group, each R.sub.2 individually represents H or a methyl group, each X individually represents H, an alkyl or an aminomethyl group, n is an integer of 0-8, and m is an integer of 8-20. The process can remarkably shorten the time required for the separation of oil from water after the polymerization, producing transparent, light-colored, petroleum resins with a low ash content.

Abstract: An improved chain comprising inner link plates, sintered oil-retaining bushings secured to the inner link plates, outer link plates, connecting pins secured to the outer link plates and the pins being rotatable within the bushings, the improvement comprising: the sintering density of the bushings being in the range of approximately 6.0 g/cm.sup.3 to 7.1 g/cm.sup.3 ; and, a roller rotatably supported on each bushing.

Abstract: A continuous push-drive chain formed by a plurality of blocks, each of the blocks having a letter V-shaped configuration in side elevation, defining large engagement surfaces relative to overall block size; and, structure for connecting adjacent blocks to one another disposed at one distal end of the V-shaped configuration, whereby large pushing forces between the blocks may be transmitted substantially unidirectionally and independently of the connecting structure, simultaneously increasing chain load capacity and reducing chain wear.

Abstract: A conveyor or chain having a tubular filament-wound cylindrical element used as the pins interconnecting the link plates and/or as rollers or bushings in the chain assembly. The element is formed from a length of tubular material which is wound on a mandrel having an outside diameter equal to the inside diameter of the tubular element. The filament of the winding is a long aramid fiber which is integrated in the tubular material by an adhesive agent.