Full-bridge valve element and hydraulic system

The utility model relates to a hydraulic valve, in particular to a full-bridge valve core and a hydraulic system, and aims to solve the problem that a piston rod of an idle oil cylinder in an existing hydraulic system possibly extends out automatically due to leakage of a full-bridge valve core. The full-bridge valve core is provided with an oil inlet channel, an oil return channel, a first working oil channel and a second working oil channel in a valve body; a first oil inlet sealing shaft shoulder, a second oil inlet sealing shaft shoulder, a first oil return sealing shaft shoulder and a second oil return sealing shaft shoulder are arranged on the valve rod; when each sealing shaft shoulder is in sealing fit with the wall of the valve cavity, the fit clearance between the first oil return sealing shaft shoulder and the wall of the valve cavity is larger than that between the second oil return sealing shaft shoulder and the wall of the valve cavity; the fit clearance between the first oil inlet sealing shaft