ISO 10767-3:1999

Overview

ISO 10767-3:1999 - part of the ISO 10767 series on hydraulic fluid power - specifies a laboratory method for measuring and rating the pressure ripple and related dynamic characteristics generated by positive-displacement hydraulic motors. The standard defines how to isolate the motor’s contribution to flow and pressure fluctuations (the source flow ripple and source impedance) from circuit interactions, using a secondary‑source technique and plane‑wave transmission-line analysis. Results include harmonic-by-harmonic ratings and overall r.m.s. values that enable objective comparison of motors.

Key topics and technical requirements

• Scope & applicability: Positive-displacement motors (including bi-directional) operating under steady-state conditions; motoring frequency range 50 Hz–400 Hz.
• Ratings produced:
  • Source flow ripple amplitude (over 10 harmonics)
  • Source impedance amplitude and phase (over 10 harmonics)
  • Anechoic and blocked acoustic pressure ripple amplitudes and overall r.m.s. values
• Instrumentation:
  • Static instruments (mean flow, pressure, speed, temperature) at industrial (class C) accuracy.
  • Dynamic pressure sensors: resonant frequency > 30 kHz, linearity within ±1%.
  • Frequency analysis able to measure amplitude and phase for at least ten harmonics, synchronized across sensors.
  • Harmonic measurement tolerances: amplitude within ±1%, phase within ±1°, frequency within ±0.5% (overall r.m.s. uncertainty ≈ ±10%).
• Test conditions: Maintain mean flow ±2%, mean pressure ±2%, shaft frequency ±1%, temperature ±2 °C. Fluid property accuracies: density ±2%, viscosity ±5%, bulk modulus ±5%.
• Test rig & procedure:
  • Secondary‑source circuit configuration with a straight, rigid supply pipe and pressure transducers positioned along it.
  • Motor installed “as-delivered”; reference pulse once per shaft revolution for synchronization.
  • Two alternative supply‑line methods depending on knowledge of fluid bulk modulus.
• Data processing: Mathematical isolation of motor source terms requires digital processing; Annexes A/B are normative (errors, data‑reduction algorithms) and Annex C lists software sources.

Practical applications

• Objective laboratory rating and comparison of hydraulic motors for noise, vibration, and pressure–flow quality.
• R&D and design validation to evaluate effects of motor design changes on pressure ripple.
• Component qualification and acceptance testing for OEMs and suppliers.
• System design guidance to select motors that minimize hydraulic pressure ripple and downstream vibration/noise.

Who should use this standard

• Hydraulic motor designers and test engineers
• Fluid power system designers and OEMs
• Independent test laboratories and certification bodies
• R&D teams focusing on NVH (noise, vibration, harshness) and hydraulic system reliability

Related standards

• ISO 10767-1 (Precision method for pumps) and ISO 10767-2 (Simplified method for pumps)
• ISO 1219-1 (Graphic symbols)
• ISO 5598 (Fluid power vocabulary)

Keywords: ISO 10767-3, hydraulic fluid power, pressure ripple, positive-displacement motor, source flow ripple, source impedance, anechoic pressure ripple, test rig, harmonics, motor testing.