Automatic Transmission Systems Flashcards

Which valve in the valve body primarily regulates main line pressure from the pump?

Answer: Pressure regulator valve

The pressure regulator valve balances pump output against spring force to set line pressure.

What is the main purpose of an accumulator in an automatic transmission hydraulic circuit?

Answer: Cushion clutch or band apply for smoother shifts

An accumulator absorbs part of the apply pressure briefly so the clutch or band engages gradually.

The manual valve in the valve body is positioned by which component?

Answer: The gear selector linkage or cable

The driver's shift lever moves the manual valve through linkage to route fluid for the selected range.

On a hydraulically controlled transmission, a throttle valve (TV) cable adjusted too loose will most likely cause what?

Answer: Early, soft upshifts

Low TV pressure reduces both line pressure and shift delay, causing early, mushy shifts that can lead to slipping.

In a transmission with a mechanical governor, governor pressure changes in direct relation to what?

Answer: Vehicle (output shaft) speed

The governor is driven by the output shaft, so its pressure rises as road speed increases.

After a valve body overhaul, the vehicle has erratic and harsh shifts. Which reassembly error is a common cause?

Answer: Missing or misplaced check ball

Check balls control flow direction and timing, so a missing or misplaced one changes apply rates and shift quality.

A pressure test shows low line pressure in every gear range. What is the most likely cause?

Answer: Clogged filter or worn pump

Low pressure in all ranges points to something common to all circuits, such as the pump supply or filter.