Abstract: An oil separating apparatus of an engine mounted on a shaking machine such as a rammer, for separating oil mist from blow-by gas and for feeding liquefied oil back to a crank chamber comprises a rocker chamber having an enlarged volume and mounted on a cylinder head, a breather chamber mounted on the rocker chamber, a blow-by gas port provided on the locker chamber for communicating the rocker chamber with the breather chamber, and an oil passage having an enlarged passage area for communicating the crank chamber with the rocker chamber. The constituted oil separating apparatus separates oil mist from blow-by gas almost completely and returns liquefied oil to the crank chamber swiftly, even when the engine produces a large amount of oil mist due to violent vibrations of the shaking machine.

Abstract: An injection-molded gear for an utility engine has a high reliability, tenacity, and accuracy, capable of being manufactured at low cost without requiring cutting, and ensuring a substantial reduction in noise. An inner part of a cam crankshaft gear is formed of an insert ring of a sintered iron alloy. An outside portion and a toothed crest portion of the gear are formed by injection-molding a polyamide resin such as nylon 66 and heat-treating the resulting molded product so that its relative viscosity is equal to or larger than 3.5. The relative viscosity is defined as .eta./.eta..sub.0 where .eta..sub.0 is a viscosity of sulfuric acid of 98% concentration and .eta. is a viscosity of a solution of the 98% sulfuric acid in which the polyamide resin is dissolved at a concentration of 1.0%.

Abstract: An engine exhaust apparatus comprises a sound suppressing section for lowering the exhaust noise level as an exhaust gas discharged from the exhaust port passes through it. The exhaust apparatus is provided with an ejector section for introducing secondary air into the exhaust gas delivered from the sound suppressing section and mixing the gases, and a post-treatment section for purifying the gas mixture delivered from the ejector section. The exhaust gas discharged from an exhaust manifold gets into the ejector section through the sound suppressing section, and is then purified in the post-treatment section. Therefore, the ejector effect cannot be reduced by the sound suppressing section which is subject to high flow resistance. Thus, the exhaust noise level can be lowered with the ejector effect of the introduction of the secondary air improved considerably, and low cost and simple construction can be enjoyed.