Trannys Flashcards
(25 cards)
What are the major sub-systems of an automatic transmission?
Coupling, hydraulic system, apply devices, gearsets, and control systems.
What drives the hydraulic pump in an automatic transmission?
The torque converter, powered by the engine.
What are the main functions of hydraulic fluid in a transmission?
To apply clutches and bands, maintain the torque converter, and lubricate/cool parts.
What are the components of the torque converter, oil cooler, and lubrication circuit?
Torque converter pressure control, cooler flow, lubrication flow, bypass valves, and auxiliary filters.
What does a thermal and pressure bypass valve do?
Regulates fluid flow to adjust temperature and pressure; facilitates quicker warm-up or bypass when cooler is restricted.
What is the role of the valve body and spool valves?
To control hydraulic flow to clutches and apply devices using solenoids for electronic control.
What are the main components of a torque converter?
Impeller, turbine, stator, and torque converter clutch (TCC).
Describe the torque multiplication phase in a torque converter.
The stator locks, redirects fluid to assist the impeller, and multiplies engine torque.
What happens when the torque converter enters the coupling phase?
The turbine speed matches the impeller speed, and it acts as a fluid coupling.
What causes torque converter ballooning?
Overheating or inadequate fluid flow.
What are the three main types of compound planetary gearsets?
Simpson, Ravigneaux, and Lepelletier gearsets.
What is unique about the Simpson gearset?
It has two planetary gearsets with a common sun gear and provides three forward gears and one reverse.
How does a Ravigneaux gearset function in low gear?
The front clutch is applied, and the rear band holds the carrier, resulting in maximum forward reduction.
What is the configuration of the Lepelletier gearset?
It combines a simple gearset with a Ravigneaux gearset, providing six forward gears and one reverse.
What are the clutch applications for the Lepelletier gearset in first and second gear?
First gear: C1 applied, B2 holds. Second gear: C1 applied, B1 holds.
What is the role of one-way clutches?
They allow free rotation in one direction and lock in the other.
What sensors are commonly used in modern transmission control systems?
Throttle position sensor (TPS), wheel speed sensors (WSS), and input/output speed sensors.
What is the purpose of a manual lever position sensor?
To provide a shift lever position signal to the ECM/TCM for clutch preparation strategies.
How do solenoids function in electronic valve bodies?
Solenoids control hydraulic flow to clutches, shifting between normally open (NO) and normally closed (NC) states based on electronic signals.
What diagnostic capabilities do modern transmissions offer?
They provide DTCs, streaming data, clutch application timing, line pressure readings, and solenoid operation feedback.
What is a Clutch Volume Index (CVI)?
A measurement of fluid volume used to apply a clutch, monitored to diagnose wear or malfunction.
What are signs of low hydraulic pressure in a transmission?
Slipping, delayed engagement, and poor shift timing.
What does a stall test measure?
Torque converter performance by measuring maximum impeller speed with the turbine stationary.
What is the purpose of a thermal bypass valve?
To redirect fluid to help the transmission warm up faster or bypass restricted coolers.
