Automatic Gearbox and Epicyclic Gear Train

Front

What is a common type of automatic gearbox?

Back

A common type of automatic gearbox uses an epicyclic gear train to provide various ratios.

Front

How is the epicyclic gear train operated?

Back

The epicyclic gear train is operated by brake bands and clutches, controlled by a hydraulic valve system or electronics.

Front

What connects the engine and gearbox in an automatic gearbox?

Back

A torque converter connects the engine and gearbox.

Front

What are the four main parts of a single epicyclic gear train?

Back

1. An annulus 2. A set of planet gears 3. A planet carrier 4. A sun gear

Front

How are gear ratios obtained in an epicyclic gear train?

Back

Gear ratios are obtained by locking certain parts of the unit and driving in and out on other parts.

Front

What is a compound epicyclic gear train?

Back

A compound epicyclic gear train has more than one set of each component, including one annulus, one planet carrier, two sets of planet gears, and two sun gears.

Front

What is the purpose of multi-plate clutches in an epicyclic gear train?

Back

Multi-plate clutches transmit drive to one of the parts of the epicyclic gear train to provide the necessary ratio.

Front

How do brake bands function in an epicyclic gear train?

Back

Brake bands prevent certain parts of the epicyclic gear train from rotating to provide the appropriate gear ratio, operated hydraulically.

Front

What is the role of the hydraulic control system in an automatic gearbox?

Back

The hydraulic control system operates brake bands and clutches using fluid supplied by an engine-driven pump and controlled by various valves.

Front

What is the difference between hydraulic and electronic control systems in automatic gearboxes?

Back

Hydraulic systems use fluid pressure for sensing and operation, while electronic systems use electronic sensors for sensing and an ECU for control.