When you are operating in dirty atmospheric conditions,grease seals out dust, dirt, and water from enteringbearings and bushings.Grease lube charts are either mounted on theequipment or are in the operator’s manual. Grease lubecharts state locations of grease fittings and how oftenthe fittings should be lubricated. Over greasing ofequipment blows seals and the excess grease collectssand and dirt that acts as a grinding compound on thelubricated surfaces. Under greasing allows excessivewear caused by metal-to-metal contact.NOTE: Greasing equipment is the responsibility ofthe operator.A water-resistant grease can prevent water fromentering bearings and bushing joints. The grease com-monly used on equipment is lithium-based. Lithium-based grease is water-resistant and has a wide range ofoperating temperatures. Care should be taken to keepgrease clean. Always keep the grease container coveredto prevent dirt and water from contaminating it.ENGINE COOLING SYSTEMSAll internal combustion engines are equipped withsome type of cooling system because of the hightemperatures they generate during operation. Thetemperature in the combustion chamber during theburning of fuel is much higher than the melting point ofiron. Therefore, if nothing is available to cool the engineduring operation, valves burn and warp, lubricating oilbreaks down, and bearings and pistons overheatresulting in engine seizure. At the same time, the enginemust not be allowed to run too cold. An engine runningcold does not burn all the fuel taken into the combustionchamber, causing carbon deposits to form that reducefuel mileage, increase wear, and reduce engine power.Three functions of the cooling system provide asatisfactory temperature operating range for the engine.First, the system removes the unwanted heat. Second, itregulates the engine temperature to keep it just rightduring all operating conditions. Third, when the engineis first started, the cooling system assists the engine inwarming up to its normal operating temperature as soonas possible.The two types of cooling methods are liquid coolingand air cooling. The liquid-cooling system is the mostpopular for automotive use, because it provides the mostpositive cooling and it maintains an even enginetemperature. Air cooling is used for small vehicles andequipment; however, air cooling is not used if watercooling is practical. This is because air-cooled enginesdo not run at even temperatures and require extensiveuse of aluminum to dissipate heat.Other means of heat dissipation for the engine, inaddition to the cooling system, are as follows:. The exhaust system dissipates as much, if notmore, heat than the cooling system, although that is notits purpose.l The engine oil removes heat from the engine anddissipates it to the air from the sump.. The fuel provides some engine cooling throughvaporization.. A measurable amount of heat is dissipated as theair passes over the engine.LIQUID-COOLING SYSTEMA simple liquid-cooled cooling system consists of aradiator, water pump, hoses, fan and shroud, thermostat,and a system of jackets and passages in the cylinder headand cylinder block through which the coolant circulates(fig. 1-44). Cooling of the engine parts is accomplishedby keeping the coolant circulating and in contact withthe metal surfaces to be cooled. The pump draws thecoolant from the bottom of the radiator, forces it throughthe jackets and passages, and ejects it into the upper tankon top of the radiator. The coolant then passes througha set of tubes to the bottom of the radiator from whichthe cooling cycle begins again. The radiator is situatedin front of a fan that is driven either by the water pumpor an electric motor. The fan ensures an air flow throughthe radiator at times when there is no vehicle motion.RadiatorMost radiators have two tanks with a heatexchanging core between them. The upper tank containsan outside pipe, called an inlet, and on top is the fillerneck. Attached to the filler neck is an outlet to theoverflow pipe. The overflow pipe provides an openingfrom the radiator for escape of coolant or steam ifpressure in the system exceeds the regulated maximum.This prevents rupture of cooling system components.The lower tank contains an outside pipe that serves asthe outlet for the radiator.The radiator is usually mounted in the front of theengine compartment so cool air can pass freely throughthe core. The outlet on the bottom radiator tank isconnected to the water pump inlet. The top tank inlet ofthe radiator is connected to the outlet at the top of theengine. Rubber hoses and hose clamps are used to make1-32
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