Chapter 22. -DIESEL AND GASOLINE ENGINES 



I. MAIN BEARING JOURNAL- FRONT 



2. COUNTERWEIGHT 



3. MAIN BEARING JOURNAL- 

 INTERMEDIATE 



4. CONNECTING ROD JOURNAL- NO. 3 



5. MAIN BEARING JOURNAL- REAR 



6. BOLTING FLANGE -TIMING GEAR 



7. DOWEL- FLYWHEEL 



8. RING GEAR 



9. RETAINING BOLT HOLE 



10. DOWEL HOLE 



I I. PULLER SCREW HOLE 



12. FLYWHEEL 



13. LUBRICATING OIL HOLES 



75.81X 



Figure 22-19.— One-piece six-throw crankshaft with flywheel. 



are finished, are commonly referred to as the 

 intake and exhaust systems . These systems are 

 closely related and, in some cases, are referred 

 to as the air systems of an engine. A cross- 

 sectional view of the air systems of one type 

 of high-speed diesel engine is shown in figure 

 22-20. 



The following information on air systems 

 deals primarily with the systems of diesel en- 

 gines; nevertheless, much of the information 

 dealing with the parts of diesel engine air sys- 

 tems is also applicable to most of the parts 

 in similar systems of gasoline engines. How- 

 ever, the intake event in the cycle of operation 

 of a gasoline engine includes the admission of 

 air and fuel as a mixture to the cylinder. For 

 this reason, the intake system of a gasoline 

 engine differs, in some respects, from that of 

 a diesel engine. (See subsequent section on fuel 

 systems.) 



A discussion of the air systems of deisel 

 engines frequently involves the use of two terms 

 which identify processes related to the functions 



of the intake and exhaust systems. These terms- 

 scavenging and supercharging — and the proc- 

 esses they identify are common to many modern 

 diesel engines. 



In the intake systems of all modern 2-stroke 

 cycle engines and some 4-stroke cycle engines, 

 a device, usually a blower, is installed to in- 

 crease the flow of air into the cylinders. This 

 is accomplished by the blower compressing the 

 air and forcing it into an air box or manifold 

 (reservoir) which surrounds or is attached to 

 the cylinders of an engine. Thus, an increased 

 amount of air under constant pressure is avail- 

 able as required during the cycle of operation. 



The increased amount of air available as a 

 result of blower action is used to fill the cylin- 

 der with a fresh charge of air and, during the 

 process, aids in clearing the cylinder of the 

 gases of combustion. This process is called 

 scavenging . Thus, the intake system of some 

 engines, especially those operating on the 2- 

 stroke cycle, is sometimes called the scaveng- 

 ing system. The air forced into the cylinder 



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