Light Vehicle Products | Motor Mounts

Passive Switchable Hydro Motor Mount

The hydro motor mount with a passive switching function is a suitable solution for three- and four-cylinder combustion as well as hybrid engines. This solution adapts its damping performance based on the excitations coming from the engine and thus secures the driving comfort of the vehicle without the need for external electric or hydraulic switches. This significantly reduces the component complexity while offering excellent driving comfort.

Damping and stiffness are two key characteristics for motor mounts since they have to both absorb vibrations coming from the engine and at the same time support its static weight and dynamic forces.

The hydro mount with passive switching function accomplishes a stiffness reduction in idle mode through the integration of an additional channel. A membrane opens or closes the connection to the second channel depending on the amplitude of the excitations coming from the engine. When the excitation amplitude exceeds a certain level, the membrane closes, which increases the pressure on the fluid and forces the fluid through the main channel, thus providing a high damping level of the part and securing good driving comfort – shake performance – for the vehicle.

When the amplitude of the excitation is below a certain level, for example when the engine is in idle mode, the membrane opens and lets the glycol flow through the second channel. The moving fluid is acting as a damper and generates a stiffness dip below the resonance frequency. That allows the part to adapt the damping performance and decreases the unwanted vibrations transferred to the car body. This frequency of the stiffness dip can be tuned to the needs of the engine, making this solution applicable to both petrol and diesel engines as well as to hybrid powertrains.

About Motor Mounts

Motor mounts carry the static and dynamic loads of the motor throughout its entire service life and are also an important factor for isolating low to high frequency vibrations. Downsized and turbocharged motors are state-of-the-art to reduce fuel consumption but lead to high vibration levels.


Motor and transmission mounts consist of a motor or gearbox support arm, an isolation element and a body-side connecting element. The critical element is the rubber spring that dampens vibrations, supports drive torques and isolates noise during start-up. The motor mount prevents booming noises and load-change shocks. Vibrations of the body and drive train are improved by using a hydraulic damping system. Motor mounts effectively isolate motor vibrations and dampen road excitations to ensure a comfortable driving experience.

The product portfolio ranges from conventional rubber mounts and hydro motor mounts, through electrically or pneumatically switchable motor mounts, to gearbox mounts and torque rods.