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One of the most common complaints about noise in small vehicles is related to the hydraulic steering pump, which is strongly used during parking maneuvers, and produces a noise that overcomes the one coming from the engine, due to its low speed. This noise can be eliminated by the introduction of two resonators inside the high-pressure tube designed to coincide with the tube's resonance frequency. Here I present a bench test for measuring and evaluating the resonance frequencies of high-pressure tubes of hydraulic steering systems with and without resonators, and the resulting attenuation level of the steering pump noise by measuring the pressure peaks at the entry and outlet of the tube. Adopting this bench test eliminates some confounding variables that can interfere with the measurement such as engine vibration, others components' frequency orders (the engine itself, compressor, alternator, etc.), speed control, among others.

One of the most important complaints about noise in small vehicles is related to the hydraulic steering pump, which is used strongly during parking maneuvers, and produces a noise that overcomes the one coming from the engine, due to its low speed. This noise can be eliminated by the introduction of two resonators inside the high-pressure tube designed to coincide with the tube's resonance frequency. However, in some cases, as in tubes with short rubber pieces, these resonators may be not sufficient to reduce the noise to non-audible levels, due to its low ability to absorb the pressure peaks coming from the pump. In these cases it is possible to introduce orifices at each resonator to maximize its effect. Here we present the theory related to the use of these orifices and the results obtained in tests on bench.