A track tension system including a hydraulic cylinder coupled between a drive frame and idler of a track system, an accumulator and a hydraulic valve that controls flow between the cylinder and accumulator. The cylinder extends and retracts to change the distance between the drive frame and idler which increases and decreases, respectively, tension on the track system. The hydraulic valve can be opened to allow flow between the cylinder and accumulator, and closed to block flow between the cylinder and accumulator. Control factors can be monitored to control valve position. An overload pressure relief can allow flow between the cylinder and accumulator when the hydraulic valve is closed and pressure in the cylinder reaches overload pressure. An orifice can allow constricted flow between the cylinder and accumulator when the hydraulic valve is closed. A check valve can connect the track tension system to a vehicle hydraulic system.