2-8speeds and some are equipped with overdrive. Operator
control is limited to the selection of the gear range by
moving a control lever.
Part of the prestart operation is to check the
transmission fluid level when the engine is idling and at
normal operating temperature, when the vehicle is level,
and when the transmission control lever is in park. The
transmission fluid is used as a combination power
transmission medium, hydraulic control fluid, heat transfer
medium, bearing surface lubricant, and gear lubricant.
The manufacturers recomendations must be followed
when servicing and filling the transmission with fluid.
Do not overfill the transmission because
overfilling causes foaming and shifting
Some transmission troubles you may encounter and
must document are as follows:
. No drive in any selected positions.
On standstill starts the engine speed accelerates
but 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.
In the past, fluid couplings were widely used with
automatic transmissions. Fluid couplings act like an
automatic clutch by slipping at idling speeds and by
holding to increase power as the engine speed increases.
There is no mechanical connection between the engine
and transmission; power is transmitted by oil.
Figure 2-6.Automatic transmission cross-sectional view.