| 摘要 |
PURPOSE:To aim at the miniaturization of an engine by installing a reduction gear consisting of an inverted cam circumscribing a peripheral surface of a cam being driven by a crankshaft, and installing a tappet valve cam and a decompression cam parallelly on the peripheral surface of the inverted cam. CONSTITUTION:There is provided with a reduction gear R consisting of a driving cam Ca1 being driven by a crankshaft 13 and an inverted cam Ca2 circumscribing a peripheral surface of this driving cam and driven at a 1/2 reduction gear ratio. A tappet valve cam 50 and a decompression cam 51 are parallelly installed on the peripheral surface of the inverted cam Ca2. Inside the reduction gear R, there is provided with a Governor G which control axial movement of the inverted cam according to its revolution, whereby decompressing action takes place at time of starting. With this constitution, a part of the reduction gear is usable for a decompression device in combination so that an engine can be miniaturized.
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