Question 1

Pascal's law states that if we place fluid in a confined space, pressure will:

Accepted Answer

Pascal's law states that in a confined fluid at rest, any change in pressure applied to the fluid is transmitted undiminished throughout the fluid in all directions.

Question 2

Tech A says that one benefit of using hydraulic pressure is that it is not affected by leaks in the system. Tech B says that hydraulic pressure is the same in all directions within a closed container. Who is correct?

Accepted Answer

Hydraulic pressure is indeed the same in all directions within a closed container, according to Pascal's Law. However, hydraulic systems can be affected by leaks, which contradicts Tech A's statement.

Question 3

The hydraulic system of an automatic transmission includes all of the following except:

Accepted Answer

A gasket is not a component of the hydraulic system; it is used to seal joints between parts to prevent leaks. The hydraulic system typically includes components like a sump, filter, and front pump.

Question 4

Depth filters may be made of:

Accepted Answer

Depth filters are often made of fibrous materials like felt, which can trap particles throughout the entire thickness of the filter.

Question 5

Tech A says that one type of front pump is a variable displacement pump. Tech B says that the front pump is turned by the torque converter hub. Who is correct?

Accepted Answer

Tech A is correct because some front pumps in automatic transmissions are variable displacement pumps. Tech B is correct because the front pump is typically driven by the torque converter hub.

Question 6

A pressure regulator valve ensures that:

Accepted Answer

A pressure regulator valve reduces pressures during cruise when less clutch and band holding power is needed, ensuring efficient operation and preventing excessive wear.

Question 7

Which of these is used to regulate line pressure on computerized transmissions?

Accepted Answer

The EPC (Electronic Pressure Control) solenoid is used to regulate line pressure in computerized transmissions by adjusting the hydraulic pressure based on the vehicle's operating conditions.

Question 8

Tech A says that a mechanical pressure regulator exhausts excess fluid back to the transmission pan. Tech B says that if the transmission pan is removed, the magnet must be replaced. Who is correct?

Accepted Answer

Tech A is correct because a mechanical pressure regulator exhausts excess fluid back to the transmission pan.

Question 9

When rebuilding a clutch pack, the piston needs to be carefully inspected for:

Accepted Answer

The piston should be inspected for cracks to ensure it functions properly and does not lead to clutch failure.

Question 10

Tech A says that multi-plate clutches must have a specified amount of clearance when they are installed. Tech B says that there should be no clearance when they are installed because the clutch would slip. Who is correct?

Accepted Answer

Multi-plate clutches require a specified amount of clearance to ensure proper engagement and disengagement. Without this clearance, the clutch may not function correctly.

Question 11

Tech A says that bands are a type of hydraulic valve. Tech B says that servos are devices used to allow free movement in one direction and lock up in the other direction. Who is correct?

Accepted Answer

Bands are not hydraulic valves; they are used in automatic transmissions to hold planetary gear sets. Servos are not devices that allow free movement in one direction and lock in the other; they are used to control the application of bands and clutches in automatic transmissions.

Question 12

Which of these valves is directly connected to the gearshift mechanism in the vehicle?

Accepted Answer

The manual valve is directly connected to the gearshift mechanism and is responsible for directing hydraulic fluid to the appropriate circuits in the transmission based on the driver's gear selection.

Question 13

Tech A says that spring tension against a spool valve regulates system pressure. Tech B says that a 50% pulse width modulation means the valve is closed 50% of the time. Who is correct?

Accepted Answer

Tech A is correct because spring tension against a spool valve can regulate system pressure by controlling the position of the valve. Tech B is also correct because a 50% pulse width modulation (PWM) means the valve is energized and closed 50% of the time, allowing for control over the flow or pressure in the system.

Question 14

Tech A says that park is obtained by mechanically locking one band and one clutch together. Tech B says that spool valves tend to be self-cleaning. Who is correct?

Accepted Answer

Spool valves tend to be self-cleaning due to their design, which allows fluid to flow around them, helping to remove debris. Park is not obtained by locking a band and clutch together; it is typically achieved by engaging a parking pawl in the transmission.

Question 15

Which of these is often used in conjunction with check balls and spool valves to restrict fluid flow for timing purposes?

Accepted Answer

An orifice is often used to restrict fluid flow, which can help in timing the operation of hydraulic systems by controlling the rate at which fluid passes through.

Question 16

Tech A says that transmission failures can be caused by failed lip seals preventing full pressure from being applied to the clutches. Tech B says that orifices are designed to speed up the movement of a valve. Who is correct?

Accepted Answer

Failed lip seals can indeed cause transmission failures by preventing full hydraulic pressure from being applied to the clutches, which is necessary for proper transmission operation.

Question 17

Accumulators are used to:

Accepted Answer

Accumulators are used to dampen the application of clutches and bands by absorbing some of the hydraulic pressure, which helps in smoothing the engagement process.

Question 18

Tech A says that accumulators are used to filter contaminates. Tech B says that accumulators are used to soften clutch engagement. Who is correct?

Accepted Answer

Accumulators are used to soften clutch engagement by absorbing hydraulic pressure surges, not to filter contaminants.

Question 19

A clutch and band application chart helps to:

Accepted Answer

A clutch and band application chart helps identify which components are engaged in each gear, aiding in diagnosing transmission issues before disassembly.

Question 20

Tech A says that band and clutch application charts can help to diagnose faults in a transmission. Tech B says that 100 psi (689 kPa) of pressure on a 2-square-inch piston results in 50 lb (23 kg) of force. Who is correct?

Accepted Answer

Band and clutch application charts are useful for diagnosing transmission faults. Tech B's calculation is incorrect; 100 psi on a 2-square-inch piston results in 200 lb of force, not 50 lb.

Quiz 8: Hydraulic Fundamentals