Study of the subject will provide knowledge from field of the diagnostics of hydraulic components and equipment with a sight on free of disassembly diagnostics. Parametric, vibrodiagnostic, tribotechnical and thermodynamic diagnostic methods of technical diagnostics are discussed. There are considered problems of reliability of hydraulic components and systems in the subject. There are described the instruments of technical diagnostics in terms of subject. Physical principles and metrological characteristics of sensors including the requirements on the sensors are given. There are described the sensors of diagnostic variables: pressure, flow, temperature, trajectory, speed, acceleration, force, moment, revolutions, noise and vibration. The basic diagnostic measurements of hydraulic and pneumatic components (hydro-generators, rotary hydro-motors, linear hydro-motors, compressors, pneumomotors, pressure valves, distributors and other flow elements) and systems are discussed. The subject also deals with operation simulation and monitoring of machines.