Patent ID: 7484580

Claim:
A tractor comprising a transmission casing, a traveling-system power transmission mechanism provided in the transmission casing and interposed between an engine and an axle, a PTO-system power transmission mechanism provided in the transmission casing and interposed between the engine and a PTO shaft, and a changeover mechanism provided in the transmission casing and interposed between both power transmission mechanisms, wherein when the power transmission of the PTO-system power transmission mechanism is interrupted at a middle portion thereof by the changeover mechanism the changeover mechanism is configured so as to be capable of performing a changeover manipulation to connect a downstream side portion of the PTO-system power transmission mechanism and a downstream side portion of the traveling-system power transmission mechanism, the changeover mechanism is comprised of a traveling-system power transmission gear which is mounted on a traveling-system power transmission shaft which constitutes a portion of the traveling-system power transmission mechanism, a PTO-system power transmission gear which is mounted on an upstream-side PTO-system power transmission shaft which constitutes a portion of the PTO-system power transmission mechanism, and a shift gear body which is arranged coaxially with the upstream-side PTO-system power transmission shaft and is mounted on a downstream-side PTO-system power transmission shaft which constitutes a portion of the PTO-system power transmission mechanism, and the shift gear body is formed by mounting a slide member on the downstream-side PTO-system power transmission shaft in an axially slidable manner and by forming a PTO-system side shift gear which is meshed with the PTO-system power transmission gear and a traveling-system side shift gear which is meshed with the traveling-system power transmission gear on the slide member thereby, with the sliding of the slide member, enabling a manipulation to selectively change over the meshing between the PTO-system power transmission gear and the PTO-system side shift gear and the meshing between the traveling-system power transmission gear and the traveling-system-side shift gear.