Question 1

Technician A says a pull to the right during braking could be caused by a defective metering valve.Technician B says a pull to the left could be caused by a defective proportioning valve. Which technician is correct?

Accepted Answer

A pull to the right or left during braking is typically caused by issues such as uneven brake pad wear, caliper problems, or uneven tire pressure, not by a defective metering or proportioning valve. Metering valves control the pressure to the front brakes to ensure the rear brakes engage first, and proportioning valves adjust the pressure between the front and rear brakes to prevent rear wheel lockup. Neither directly causes a pull to one side during braking.

Question 2

The rear brakes lock up during a regular brake application. Technician A says the metering valve could be the cause. Technician B says that stuck front disc brake calipers could be the cause. Which technician is correct?

Accepted Answer

B

Question 3

The rear wheels lock up during hard braking. Technician A says that a defective metering valve could be the cause. Technician B says that a defective proportioning valve could be the cause. Which technician is correct?

Accepted Answer

Technician B is correct because a defective proportioning valve, which is designed to adjust the pressure between the front and rear brakes, can cause the rear wheels to lock up during hard braking. A metering valve primarily affects the front brakes, not the rear.

Question 4

A combination valve could include ________.

Accepted Answer

Combination valves can vary widely depending on the vehicle's make and model, and they can include any combination of proportioning, metering, and pressure-differential valves.

Question 5

A residual check valve is used to ________.

Accepted Answer

A residual check valve is used to maintain a slight pressure in the hydraulic brake system to ensure that there is always a small amount of pressure in the system, which helps keep the brake system responsive and reduces the amount of pedal travel needed to engage the brakes.

Question 6

Technician a says that the red brake warning light can be turned on if a difference in pressure is detected by the pressure differential switch. Technician B says that the red brake warning light can be turned on if the brake fluid level sensor detected low brake fluid level. Which technician is correct?

Accepted Answer

Both technicians A and B are correct. The red brake warning light can be activated if a pressure differential switch detects a difference in pressure, indicating a possible leak or failure in the brake system. Additionally, the light can also be triggered if the brake fluid level sensor detects low brake fluid levels, signaling a potential issue with the brake fluid system.

Question 7

Which type of vehicles most often do not use metering valves?

Accepted Answer

Front-wheel drive vehicles often do not use metering valves because they typically have a simpler brake system that doesn't require the balancing of braking force between front and rear wheels, unlike other drive systems.

Question 8

Technician A says that some proportioning valves are one part and used to control both rear brakes.Technician B says that some proportioning valves are two parts; one for each rear wheel. Which technician is correct?

Accepted Answer

Proportioning valves can indeed be designed as a single unit to control both rear brakes, as mentioned by Technician A. Additionally, there are designs where the proportioning valve is split into two parts, with each part controlling one of the rear wheels, as stated by Technician B. Therefore, both technicians are correct in their statements.

Question 9

The button on the ________ valve should be held when pressure bleeding the brakes.

Accepted Answer

The metering valve is involved in brake systems to control the pressure to the front disc brakes, ensuring that the rear brakes engage before the front brakes. When pressure bleeding brakes, holding the button on the metering valve ensures that the system is properly bled by allowing brake fluid to bypass the valve and flow through the entire system.

Question 10

A typical brake light switch is electrically ________.

Accepted Answer

A typical brake light switch is electrically normally open and closes to complete the circuit when the brake pedal is pressed, turning on the brake lights.

Question 11

Two technicians are discussing the metering valve in a front-disc, rear-drum braking system. Technician A says that the metering valve delays application of the front brakes. Technician B says that the metering valve delays the application of the rear brakes. Which technician is correct?

Accepted Answer

The metering valve is designed to delay the application of the front brakes in a front-disc, rear-drum brake system, allowing the rear brakes to engage first. This helps in maintaining stability during braking. Technician A is correct.

Question 12

When the brakes are applied in a panic situation, the rear brakes have a tendency to skid. The most likely cause is ________.

Accepted Answer

The proportioning valve is responsible for balancing the braking pressure between the front and rear brakes to prevent the rear brakes from locking up during heavy braking. If it is faulty, it can cause the rear brakes to skid in a panic situation.

Question 13

A vehicle tends to lock up the front wheels when being driven on slippery road surfaces. Technician A says that the metering valve may be defective. Technician B says that the proportioning valve may be defective. Which technician is correct?

Accepted Answer

The metering valve controls the pressure to the front brakes and if defective, it can cause the front wheels to lock up on slippery surfaces.

Question 14

The residual check valve maintains between 20 and 60 psi in the brake lines.

Accepted Answer

The answer of The residual check valve maintains between 20...

Question 15

Residual check valves may be located in the combination valve.

Accepted Answer

The answer of Residual check valves may be located in...

Question 16

The metering valve delays front brake action.

Accepted Answer

The metering valve is used in some vehicles to delay the application of the front brakes to ensure that the rear brakes engage slightly before the front brakes, improving stability during braking.

Question 17

Dual braking systems sometimes use a fluid level switch in place of a pressure differential switch.

Accepted Answer

Dual braking systems can use a fluid level switch to monitor the brake fluid level in the reservoir, providing an alternative to the pressure differential switch which typically monitors the pressure difference between two circuits of a dual braking system.

Question 18

One type of fluid level switch uses a magnet and reed switch.

Accepted Answer

A magnet and reed switch type fluid level switch operates by moving a magnet in proximity to a reed switch within a stem, causing the reed switch to open or close when the fluid level changes.

Question 19

The metering valve blocks fluid flow to the front brakes when pressure reaches 75 to 125 psi.

Accepted Answer

The metering valve does not block fluid flow to the front brakes; instead, it delays the application of the front brakes to allow the rear brakes to engage first, ensuring balanced braking, especially in vehicles with front disc and rear drum brakes. The pressure values mentioned are not specifically related to blocking fluid flow to the front brakes.

Question 20

Residual check valves ________.

Accepted Answer

Residual check valves may be located under the tubing seat to maintain a small amount of pressure in the brake lines, which helps prevent air from entering the system and ensures proper brake function.

Quiz 95: Hydraulic Valves and Switches