scope:

Note: Nothing in the specification supersedes applicable laws and regulations unless specific exemption has been obtained.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose. Determination of hydraulic power steering system noise.

Forward. This procedure describes the noise measurement of the hydraulic-assisted power steering system.

Applicability. The test is applicable to passenger vehicles with hydraulic-assisted power steering system. Specific noise covered in this procedure includes:

1. Hydraulic Power Steering Pump Noise

2. Hydraulic Power Steering Gear Noise

This test procedure includes quantification of typical hydraulic power steering gear noises, such as hiss, squawk, and whistle. The frequency range for hiss is 1-4 kHz for structure borne noise and 4-12.5 kHz for airborne noise. Squawk, a type of closed loop instability, has a frequency range of 100-350 Hz. The frequency range for whistle is 4-9 kHz.

Definitions.

LFRE: left front seat, right ear (left hand drive vehicle, driver's seat occupied)

RF: right front (seat vacant, microphone placed in center of seat position)

RFLE: right front seat, left ear (right hand drive vehicle, driver's seat occupied)

LF: left front (seat vacant, microphone placed in center of seat position)