HYDRAULIC SYSTEMS
and APPLY DEVICES
Chapter 5
 Page 93
 Classroom Manual
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LAWS of HYDRAULICS
All hydraulic systems have a liquid, pump,
lines, control valves, and a output device.
 Hydraulics is the study of liquids in
motion.
 Liquids will conform to the shape of their
container.
 Liquids will react predictably to pressure
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exerted on them.
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PASCAL’S LAW
Pressure is equal in all areas of a sealed
hydraulic system.
 Hydraulics can be used to increase the
force available to do work.
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FLUID CHARACTERISTICS
Any leak will decrease pressure.
 Liquids have no shape of their own.
 Liquids seek a common level.
 Liquids are incompressable.
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MECANICAL ADVANATAGE
Hydraulics do work in the same way as
a gear or lever.
 Force x Distance = Work
 Increase force = Reduced distance.
 Decrease force = Increased distance.
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AUTOMATIC TRANS
APPLICATIONS
Fluid is used to apply bands and clutches.
 Servos are used to apply bands.
 Holding power is determined by band type
and pressure applied.
 A servo multiplies force through hydraulic
action.
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FLUID
All hydraulic systems use a fluid to perform
work.
 All domestic manufactures require a
petroleum-based fluid.
 Some import manufactures require the use of
a synthetic fluid.
 ATF is dyed clear red, and darken when
burnt, or become milky when contaminated
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by water.
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FLUID ADDITIVES
Zinc, phosphorus, and sulfur are commonly
added to reduce friction.
 Detergent additives, keep the parts clean.
 Dispersants keep contaminants suspended so
they can be trapped by the filter.
 ATF is subjected to many tests, oxidation
resistance, corrosion and rust inhibition,
flash and flame points, and resistance to
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foaming.
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FLUID REACTIONS
Chemicals in fluids may react with seals.
 Fluids are tested for compatibility with a
specific transmission.
 Incompatibility can result in swelling or
shrinking seals.
 ATF is also tested for the ability to mix
with other brands.
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RECOMMENDED
APPLICATIONS
There are several types of ATF.
 Fluid types include A, CJ, H, Dextron, and
Mercon.
 Types F and G do not contain friction
modifiers.
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FILTERING
Filters trap dirt and particles.
 Untapped particles can cause sticking valves
and premature wear.
 Deep pans will have a unique filter.
 Three types of filter media screen, paper, felt.
 Secondary filters for pumps, governors, ect.
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TRANS OIL FILTER
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RESERVOIR
Reservoir is the oil pan.
 Oil is drawn from the pan and returned after
being circulated through the selected circuits.
 Level must be maintained to prevent
aeration.
 All transmissions must have a vent to allow
air movement in and out of the trans.
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OIL PAN
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TRANS COOLERS
Keeping the ATF cool ensures that it
will be able to adequately lubricate and
cool the transmission.
 The trans cooler dissipates heat into the
air stream flowing though the radiator.
 Return oil is lube oil in most trans’s.
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OIL COOLER CIRCUIT
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OIL PUMPS
The oil pump provides circulation and
pressure.
 Oil pump is driven by hub of the torque
converter.
 Three types of pumps gear, rotor, vane.
 Vane type is variable displacement.
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GEAR PUMP
Page 103
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ROTOR PUMP
Page 103
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400 PUMP
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