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Engine mountings

Engine mountings


Background

The balancer shafts are most effective within the normal working range of the engine, from 1800 rpm and above. At slower engine speeds, from idling up to 1800 rpm, the balancer shafts are unable to counteract engine vibration. To provide effective damping of engine vibration at speeds below 1800 rpm, the rear and right-hand front engine mountings are of hydraulic type. They are designed to provide the maximum damping effect between idling speed and about 1800 rpm. Hydraulic engine mountings confer the following advantages:


• improved damping of horizontal engine movements during acceleration

• improved damping of vertical engine movements on bumpy roads

• Improved damping of engine movements when idling

• Reduction of structure-borne noise between engine and body.


Description

The hydraulic mounting has two chambers containing a special damping fluid. Interposed between the two chambers are a diaphragm and a passage, the length and cross-sectional area of which determine the dampening characteristics of the mounting. The diaphragm absorbs the forces generated by normal small movements of the engine. If engine movement is more pronounced, the damping action of the diaphragm will be insufficient. Fluid is then forced from the upper into the lower chamber, equalizing the pressure. This gives the hydraulic mounting a progressive damping action in that the resistance of the mounting increases with increased load.