In a telecommunication network, pilot signals are provided in orthogonal frequency division multiplexing frames to enable a single-carrier frequency division multiple access method to work substantially harmoniously with an orthogonal frequency division multiplexing access method in uplink. The instrument includes a microwave-transparent reaction vessel with an open mouth, a pressure-resistant seal on the mouth of the vessel, and a needle, portions of which penetrate the seal with a first end of the needle and provide fluid communication into the vessel. Accordingly, it is possible to provide a work vehicle capable of inhibiting a hydraulic oil from spilling out in exchanging the filter. A damping orifice restricts flow of hydraulic fluid to and from the servo piston.