
Automatic Transmission – 4L60E – General Information Page 7C1–16
Page 7C1–16
3.3 General Definitions
General Definition
Accumulator A component of the transmission that absorbs hydraulic pressure during the apply of a
clutch or band. Accumulators are designed to control the quality of a shift from one
gear range to another.
Adaptive Learning Programming within the PCM that automatically adjusts hydrau lic pressures in order to
compensate for changes in the transmission (i.e. component wear).
Applied An 'Applied Component' is one that is holding another component to which it is splined
or assembled to. Also referred to as "engag ed"
Apply Components Hydraulically operated clutches, servo’s, ba nds and mechanical one-way roller or
sprag clutches that drive or hold members of a pla netary gear set.
Apply Plate A steel clutch plate in a clutch pack, located next to the (apply) piston.
Backing Plate A steel plate in a clutch pack that is usually the last plate in that clutch assembly
(furthest from the clutch piston).
Band An apply component that consists of a flexible strip of steel and friction material that
wraps around a drum. When applied, it tightens around the drum and prevents the
drum from rotating.
Brake Switch An electrical device that provides sig nals to the powertrain control module or
transmission control module, (PCM), based on the positio n of the brake pedal. The
PCM uses this information to apply or release the torque converter clutch (TCC).
Centrifugal Force A force that is imparted on an object (due to rotation) that increases as that object
moves further away from a centre-point of rotation.
Check Ball A spherical, hydraulicall y controlled component (usually of steel) that either seals or
opens fluid circuits. It is also referred to as a check valve.
Clutch Pack An assembly of components generally consisting of clutch plates, an apply plate and a
backing plate.
Clutch Plate A hydraulically activated component that has two basic designs: (1) all steel, or (2) a
steel core with friction material bonded to one or two sides of the plate.
Control Valve Body A machined metal casting that contains valve trains and other hydraulically controlled
components that shift the transmission.
Coupling Speed The speed at which a vehicle is travelling and no longer requires torque multiplication
through the torque converter. At this point, the stator 'free wheels' to allow fluid leaving
the turbine to flow directly to the pump. (Also see Torque Converter).
De-energise(d) To interrupt the electrical current that flows to an electronically controll ed device,
making it electrically inoperable.
Direct Drive A condition in a gears set where the input speed and input torque equals the output
speed and output torque. The gear ratio through the gear set is 1:1.
Downshift A change in a gear ratio where both input speed and torque increases.
Duty Cycle In reference to an electronically controlled solenoid, it is the amount of time (expressed
as a percentage) that current flows through the solenoid coil.
Energise(d) To supply a current to an electronica lly controlled device, enablin g it to perform its
designed function.
Engine Compression Brakin g A condition where compressi on from the engine is used with the transmission to
decrease vehicle speed.
Exhaust The release of fluid pressure from a hydraulic circuit. (The words 'exh austs' and
'exhausting' are also used and have the same intended meaning.)
Fail-safe Mode A condition whereby a component (i.e. engine or transmission) will partially function
even if its electrical circuit is disabled.