Page 138 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

2
122 Automobile mechanical and electrical systems

Figure 2.78 Bearings

Figure 2.79 Signs of ‘nip’

manufacturers’ original specifi cation must always be fi tted. Bearing shell halves,
when correctly fi tted and tensioned in the bearing caps, form a perfectly round
Key fact profi le with equidistant clearance around the bearing journal. The bearings are
Bearing shell halves, when correctly ‘nipped’ and held in position when fi tted into the tightened bearing caps ( Fig.
fi tted and tensioned in the bearing 2.79 ). The bearing shell is also fi tted with a locating lug on the back that mates
caps, form a perfectly round profi le. with a slot in the bearing locating ‘half-bores’ ( Fig. 2.80 ). This ensures that the
bearing cannot rotate. Oil supply holes and slots are machined in the bearing
surface to supply appropriate lubrication.
Axial displacement of the crankshaft is controlled by thrust bearings to limit the
axial movement. These are fi tted at a main bearing journal either as two semi-
circular rings or as part of a main bearing shell.
A fl ywheel is fi tted on the end of the crankshaft to reduce vibration by
Key fact maintaining the engine rotation between power strokes. The clutch on a manual
transmission vehicle is mounted on the fl ywheel. On automatic transmission
A dual-mass fl ywheel splits the
mass of the fl ywheel into two parts vehicles the torque converter also works as a fl ywheel. Particularly on modern
and reconnects them by damping small but high-torque diesel engines, a dual mass fl ywheel can be used as
springs to reduce vibration. shown in Fig. 2.81 . Vibration on these systems is reduced considerably by
splitting the mass of the fl ywheel into two parts and connecting them by
damping springs.