2-8speeds and some are equipped with overdrive. Operatorcontrol is limited to the selection of the gear range bymoving a control lever.Part of the prestart operation is to check thetransmission fluid level when the engine is idling and atnormal operating temperature, when the vehicle is level,and when the transmission control lever is in park. Thetransmission fluid is used as a combination powertransmission medium, hydraulic control fluid, heat transfermedium, bearing surface lubricant, and gear lubricant.The manufacturer’s recomendations must be followedwhen servicing and filling the transmission with fluid.CAUTIONDo not overfill the transmission becauseoverfilling causes foaming and shiftingtroubles.Some transmission troubles you may encounter andmust document are as follows:. No drive in any selected positions.On standstill starts the engine speed acceleratesbut the vehicle movement lags.Engine speed accelerates during upshifts.Transmission will not upshift.Upshift and downshift are harsh.Vehicle creeps too much in drive.Vehicle creeps in neutral.Improper shift points.Unusual transmission noise.Oil leaks.Fluid CouplingsIn the past, fluid couplings were widely used withautomatic transmissions. Fluid couplings act like anautomatic clutch by slipping at idling speeds and byholding to increase power as the engine speed increases.There is no mechanical connection between the engineand transmission; power is transmitted by oil.Figure 2-6.—Automatic transmission cross-sectional view.2-5
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