ENGINEMAN 1 & Cinstruments. The instruments give the mostreliable indication as to what an engine is doingand what adjustments should be made.OIL LINES AND PASSAGESTroubles occurring in the oil passages and oillines are usually in the form of plugged orcracked lines. The former is generally the resultof carelessness, while the latter is usually a resultof improper support of the line.Even though clogged passages may beindicated by increased pressure gage readings, itis dangerous to rely wholly on such indications,since stoppage occurring beyond the pressureregulating valve and pressure gage may cause verylittle, if any, pressure increase on the gage. Youcan best determine if a bearing is receiving oil byinspecting it occasionally, just after engineshut-down. There should be plenty of oil in thevicinity of the parts being lubricated. Anothermethod for checking bearing lubrication is to notethe temperature of the bearings by feeling themwith the hand after engine shut-down. You shouldbe able to keep your hand on them for at leasta few seconds.3-16You can help prevent most oil line stoppageby observing the following rules:1. Never use cotton waste or paper towels forcleaning an engine. They may leave lint or smallbits of material which later may collect in the lines.2. Service the oil filters at specified intervals.Clean the case properly and when the lines areremoved, blow them out with compressed air.FUEL INJECTION EQUIPMENTAND CONTROLSThe fuel system is one of the most complicatedof all engine systems; therefore, special care mustbe exercised when making adjustments andrepairs.Even though manufacturers havedesigned many different fuel systems, the basicprinciple involved is the same in all of them. Ifyou understand the basic principle for one system,you will have no difficulty in becoming familiarwith other systems. The procedures for themaintenance and repair of the various systems arealso similar.Let’s review briefly not only the function ofa fuel system but also the various types of fuelsystems. As you know the function of a fuelinjection system is to deliver fuel to the enginecylinders under specific conditions: at a highpressure, at the proper time, in the proper quan-tities, and properly atomized. This function maybe carried out by either one of two types ofsystems: the air injection type or the solid injec-tion type. Since there are few air injections systemsnow in use, we will consider only the solid(mechanical) injection type systems.Solid injection systems may be classified asjerk pump systems and common rail systems.Variations are to be found in each of thesesystems. The following examples show some ofthe basic differences between the various solidinjection systems.Systems of the JERK PUMP type may beidentified as either individual pump systems orunit injection systems. Some jerk pump systemsuse a separate pump and fuel injector for eachcylinder, while the unit injection systems combinethe pump and injector into a single unit.The Bosch system is an example of an in-dividual pump system. The pump is a cam-actuated, constant stroke, lapped plunger andbarrel pump. The pump times, meters, distributes,and provides the necessary pressure to inject thefuel into the cylinder through a separate nozzle.The General Motors unit injector is an exam-ple of a unit injection system. It embodies a cam-actuated, constant stroke, lapped plunger andbushing, a high pressure pump, and an injectionnozzle, all in one unit.In the Cummins injection system, a cam-actuated injector and nozzle assembly is mountedin each cylinder. This system employs a commonmetering device that distributes a measured quan-tity of fuel to each of the injectors. TheCummingsinjectionsystemembodiescharacteristics of the unit injector and issometimes classified as such, although it is alsocalled a distributor system.The Fairbanks-Morse injection system isanother example of a jerk pump system.The injection system known as the COMMONRAIL system includes two types: the basic
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