- Accumulator (Transmission)A spring-loaded device used to dampen pressure fluctuations within the hydraulic system. The accumulator prevents shock loads by slowing the application rate of a clutch or band.
- Actuator (Transmission)A computer controlled output device that provides mechanical action in response to an electrical signal. An electronic pressure control valve is an example of an actuator.
- Apply SideRefers to the side of a piston on which force or pressure is exerted.
- BandA circular brake that wraps around a drum to stop the rotation of a planetary gear component. Bands are hydraulically operated by servos.
- Barometric PressureAtmospheric pressure expressed in terms of 'inches of mercury.'
- Battery Capacity TestA test used to determine a battery's ability to handle a sustained high-current load for a period of 15 seconds. When tested at 80¡F, a good battery will maintain a terminal voltage of at least 9.6V for the duration of the test.
- ChamferA beveled edge.
- Clutch PackA series of alternately stacked metal and composition plates.
- Coefficient Of FrictionA measurement equal to the force required to slide an object across a surface divided by the weight of the object.
- CoolantA blend of water and ethylene glycol-based antifreeze. A 50/50 mixture provides freeze protection down to -34¡F (-37¡C), and raises the boiling point to 265¡F (129¡C) when used in a system with a 15-psi pressure cap.
- Data Link Connector (DLC)The computer interface connector that accepts a scan tool; typically located below the instrument panel.
- Drive MemberA gear that transmits power to other members of a planetary gearset.
- Duty CycleThe ON-time of a controlled device expressed as a percentage.
- Friction ModifiersAdditives used to enhance an oil's lubricating properties.
- Gear PumpAn internal/external gear pump whose gears are separated by a crescent-shaped boss.
- ImpellerThe rear half of the torque converter shell that drives the turbine. The impeller is also called a pump.
- KOEOKey on, engine off
- kPa (kilopascals)6.895 kPa = 1 psi
- Manifold Absolute Pressure (MAP) SensorAn electronic device that converts intake manifold pressure into an electrical signal. In some electronic transmission/transaxles, the computer uses the signal from the MAP sensor to adjust line pressure according to changes in altitude.
- Manual ValveA spool valve operated by the shift linkage. The manual valve directs hydraulic pressure to the appropriate location to apply bands and clutches.
- Neutral Safety SwitchAn electrical device used to open the starter circuit when the transmission/transaxle is in gear.
- OrificeA precisely machined hole that controls the flow of fluid.
- Pascal's LawA discovery made by a sixteenth century scientist that proved that liquid is non-compressible, and that a force applied to the top of a liquid in a closed container is exerted equally in all directions.
- PorosityMinute holes in a casting that result when air bubbles form during the casting process.
- PreloadThe load applied to a bearing to eliminate looseness.
- Pulse Width ModulatedA computer command signal that allows a controlled device to be cycled on and off many times per second to achieve a specific output.
- Ravigneaux Gear TrainAlso known as a compound gear train, it consists of a single internal gear that houses two sets of planetary pinions mounted on a common carrier along with two sun gears.
- Reaction MemberThe part of a planetary gearset that is kept stationary so that output motion can occur.
- Rotary FlowThe oil flow that takes place in a torque converter when the impeller and turbine reach the coupling point.
- Rotor PumpA type of internal/external gear pump that utilizes rounded-toothed gears or lobes.
- ServoA hydraulically activated piston used to apply a band.
- Simpson Gear TrainA gear train composed of two simple planetary gearsets linked by a common sun gear.
- SlipRefers to the difference in speed between the impeller and turbine in a torque converter.
- Spool ValveA valve with a series of raised lands used to direct the flow of fluid throughout the valve body and transmission/transaxle case passages.
- SpragA 'dogbone' shaped holding element used in one style of overrunning clutch.
- Stall SpeedAn engine's maximum rpm with the transmission/transaxle in gear and the brakes applied.
- Throttle Position (TP) SensorA potentiometer that converts the movement of the throttle plate into an electrical signal. On an electronic transmission/transaxle, the computer uses the TP signal to regulate line pressure and shift points.
- Throttle ValveA spool valve that adjusts line pressure based on changes in engine load. The throttle valve is typically operated by a cable-actuated pushrod or plunger. In older transmissions that do not use a TV cable, the throttle valve is controlled by the vacuum modulator.
- Throttle Valve (TV) PressureThe hydraulic pressure applied to the boost side of the pressure regulator and the downshift side of the shifts valves.
- Transmission Range (TR) SwitchA device that indicates the selected gear to the on-board computer. The starter interrupt switch (neutral safety) is typically incorporated into the TR switch.
- TurbineThe part of a torque converter positioned in the front half (engine side) of the shell but not connected to it. The turbine drives the transmission/transaxle input shaft.
- ViscosityAn oil's resistance to flow.
- Vortex FlowA swirling oil flow that occurs between the impeller and turbine during torque multiplication.