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DID YOU KNOW: Advice for the professional

The main role of a bush is to absorb the various forces applied to the control arm. It achieves this through its elasticity:

MOOG - Hydrobushing - Rubber Elasticity
  • The rubber in the bushing becomes twisted or deformed under the forces created by shock absorber movement e.g., when a vehicle is cornering or driving over bumps or potholes
  • The rubber in the bushing is compressed due to vehicle weight displacement under braking and acceleration forces

Through its damping properties, the bush must also be able reduce the magnitude of force transferred to the chassis from wheel vibrations resulting from:

MOOG - Hydrobushing - Rubber Frequency
  • Brake judder caused by irregularities on brake disc (e.g. lateral run-out, disc thickness variation, surface roughness)
  • Transfer of vibrations from rough or irregular road surfaces or the similar effects of some tyre surface designs e.g. snow or off-road tyres

The main weakness of rubber is its limitation to dampen oscillations of high amplitude and low frequency. Typically, these are also the main type vibrations that a control arm bush must attenuate. To address this weakness which is inherent to standard ‘rubber-to-metal’ bushes, hydroelastic bushings have been developed (these are also known as ‘hydro bushes’). These bushes offer outstanding fluid damping performance for high amplitude and low frequencies.

MOOG - Hydrobushing - Rubber Weakness

In addition to enhanced dampening properties, hydro bushes also limit the deterioration of other vehicle steering and suspension system components.

To ensure continued driver comfort and safety, MOOG provides hydro bushes whenever this is the original design technology deployed by the vehicle manufacturer.

MOOG - Typical Hydroelastic Bushing Construction

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The content contained in this article is for entertainment and informational purposes only and should not be used in lieu of seeking professional advice from a certified technician or mechanic. We encourage you to consult with a certified technician or mechanic if you have specific questions or concerns relating to any of the topics covered herein. Under no circumstances will we be liable for any loss or damage caused by your reliance on any content.

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