Wednesday, December 11, 2013
Components of a Toyota Transmission for a 1999 Camry
The automatic transmission in a 1999 Toyota Camry connects to the back of the engine, from which it delivers power to the wheels. The transmission keeps the engine operating at the speed at which it can develop its most efficient power. The transmission also moves the vehicle in reverse and disconnects the engine from the wheels in its neutral and park positions. The automatic transmission found in front-wheel-drive vehicles like the Camry is also called a transaxle.
Torque Converter
The torque converter, also called the torque converter clutch, mounts on the flywheel of the engine and provides an indirect link between the engine and the transmission. This link allows you to stop the vehicle and keep the engine idling without stalling. In the past, the torque converter continuously slipped during driving, causing less efficient operation. In the Camry, the torque converter has a lockup mode that operates while the vehicle travels at cruising speed. This mode prevents the torque converter from slipping, which increases operating efficiency.
Planetary Gears
Planetary gears consist of a system of gears with three parts. They have an outer ring gear --- a ring with teeth inside it. Three small gears, called planets, engage the teeth inside of the ring at opposite thirds of the ring gear, where they mesh with a third gear in the center called a sun gear. The transmission input shaft applies power to a component of the planetary gears. The band or brake holds one part from turning. The third component then turns, supplying power output to the output shaft. In one mode of operation, for example, the transmission input clutch applies power to the outer ring gear. A band holds the planet gears in place; the sun gear then turns, driving the output shaft. The component receiving the power and the output component vary depending on the gear ratio needed.
Clutches and Bands
The clutches and bands provide the holding and power application to the planetary gears. Bands activated by hydraulic pistons operate as brakes, squeezing a section of the planetary gears to stop them. The clutches consist of cylinders containing disks that, when pressurized with hydraulic fluid, lock in place to apply power as needed to the planetary gears. The 1999 Camry has forward and direct clutches, as well as three bands --- also called brakes.
Valve Body
The valve body consists of a series of passageways that allow hydraulic fluid to pass through to the clutches and pistons as needed. A solenoid valve releases hydraulic fluid into the valve body passages. The paths connect to various places in the transmission that require fluid pressure at different times. The 1999 Camry has two solenoid valves located in the valve body.
Other Components
The transmission has an oil pump that provides the pressure to make the hydraulic system operate correctly. Multiple seals and gaskets prevent the oil from leaking and to keep it flowing where it needs to go. Most modern transmissions also have multiple electronic components controlled by the power train control module.
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