Passive Engine Suspension
Special demands are made on the mountings of the transverse engine. In diesel engines they should absorb, through large-sized rubber insulators, the vibrations over the entire RPM range, and with petrol engines,
during idling, but nevertheless, not allow the engine too much freedom of movement. For this reason, a further pendulum support or torque prop, mostly found up front in the center of the engine compartment, joins the
two mountings found on the right of the engine, and on the left on the gearbox. It comes into play when the engine makes a movement opposite to the drive shaft rotation, e.g., when pulling off quickly (jack-rabbit-
starting). Only then are more vibrations transfered. Afterwards, a space again exists in the torque prop. The engine is suspended solely by these two bearings (see figure).
Of course, also longitudinally mounted engines at least rubber mountings and possibly torque support arms. In the early days the automobile engine is still firmly connected to the chassis, in motorcycles and Formula
One racing cars even part of it (picture above). Today the inner workings of an engine suspension is mostly beyond vulcanized rubber to metal materials. Single engine bearings connected via electrical or vacuum lines
to a controlling system does not mean that it is an active engine bearing system. As long as it's about mitigating the effects of vibrations or noises, and not countersteering, motor bearings are considered passive.
It started with the hydraulic fluid, which was given into the rubber cavities in optimized amount during production process. Then was added a bypass between empty and filled spaces in which the damping could be
adjusted by opening or closing. This could be controlled by engine management depending on engine and/or vehicle speed. High-torque engines generally have more often need for a more bearing control. Fuel is
saved by such constructions, if thereby the idling speed of e.g. a V8 can be lowered to 500 rpm. 01/16