bearings must operate under tremendous loads, severe temperature variations, abrasive
action, and corrosive surroundings. Essential bearing characteristics include the
LOAD STRENGTH is the ability of a bearing to withstand pounding and crushing during
engine operations. The piston and rod can produce several TONS of downward force. The
bearing must not fatigue, flatten, or split under these loads. If the bearing load
resistance is too low, the beating can smash, fail, and spin in its bore. This ruins the
bore or the journal.
CONFORMABILITY is the ability of a bearing to move, shift, conform to variations in
shaft alignment, and adjust to imperfections in the surface of the journal. Usually, a
soft metal is placed over hard steel. This lets the bearing conform to the defects in the
EMBEDABILITY refers to the ability of a bearing to permit foreign particles to become
embedded in it (fig. 3-72). Dirt and metal
are sometimes carried into the bearings. The bearing should allow the particles to sink
beneath the surface into the bearing material. This prevents the particles from
scratching, wearing, and damaging the surface of the crankshaft or camshaft journals.
CORROSION RESISTANCE is the ability of a bearing to resist corrosion from acid, water,
and other impurities in the engine oil. Combustion blow-by gases cause engine oil
contamination that can also corrode engine bearings. Aluminum-lead and other alloys are
commonly being used because of their excellent corrosion resistance.
of a metallic particle embedded in bearing material (Babbitt lining).