gasoline, or solvent and never use compressed air to drythe element.during a crew turnover. The effort to check the lube oilsis easier than explaining to the chain of command whyan engine or part of the power train locked up or seized.Oil Bath Air CleanersENGINE OILOil bath air cleaners (fig. 1-38) draw air down acenter tube where it strikes the surface of oil in the oilreservoir. As the air strikes the oil reservoir, most of theparticles in the air do not make the 180-degree-upwardturn. The dirt particles remain trapped in the oil. As theair continues upward and passes to the filter element, thesmaller particles that bypassed the oil are trapped. Theair keeps the filter element soaked with oil by creatinga fine spray as it passes the reservoir. The air then makesanother 180-degree turn and enters the intake system ofthe engine.NOTE: It is the operator’s responsibility to keep theoil cup filled to the proper level with the correct weightof oil and to document when the oil is dirty or hasthickened, reducing its ability to clean particles from theair.LUBRICATION SYSTEMThe engine lubrication system (fig. 1-39) reducesfriction between moving parts, absorbs and dissipatesheat, seals the piston rings and cylinder walls, cleans andflushes moving parts, and helps deaden the noise of theengine.Checking the lubrication oils on a piece of equip-ment is part of the prestart check and the operator’sresponsibility. Also, it is a good professional practiceto recheck the lube oil levels after a lunch break orBesides reducing friction and wear, engine oil actsas a cooling agent by absorbing heat from the surfacesover which it is spread. Engine oil carries heat to theengine sump where it is dissipated. The watercirculating through an oil cooler also helps to reduce thisheat (not all engines have oil coolers).Engine oil is also used as a sealing agent. It fills thetiny openings between moving parts and cushions themagainst damage and distortion from extreme heat.Engine oil is very important as a cleaning agent. Gritand dirt in engine parts are often removed by the oilbefore damage can result. The foreign matter and thegreases in the bottom of the crankcase are evidence thatengine oil cleans. Some oils have chemicals, known asadditives, added to make them even better cleaners.Oil Level IndicatorThe oil level indicator consists of a rod, known as adipstick. The dipstick extends through a tube into thecrankcase (fig. 1-40). Marks on the dipstick indicatewhen the crankcase is full or, if low, how much oil isneeded. To take readings, you should perform thefollowing procedure: pull the dipstick out, wipe thedipstick with a rag, stick it back in, pull it out once again,and note how high the oil level is on it. On some engines,the correct oil level is achieved after the engine hasFigure 1-40.-Oil level indicator.1-29
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