Note: Your are not logged in. We can not keep your scores or track your progress unless you Register and Log In
5.2 – Dual Air Brake System
Most heavy-duty vehicles use dual air brake systems for safety. A dual air brake system has two separate air brake systems, which use a single set of brake controls. Each system has its own air tanks, hoses, lines, etc. One system typically operates the regular brakes on the rear axle or axles. The other system operates the regular brakes on the front axle (and possibly one rear axle). Both systems supply air to the trailer (if there is one). The first system is called the “primary” system. The other is called the “secondary” system. (See Figure 5.4.)
Before driving a vehicle with a dual air system, allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems. Watch the primary and secondary air pressure gauges (or needles, if the system has two needles in one gauge). Pay attention to the low air pressure warning light and buzzer. The warning light and buzzer should shut off when the air pressure in both systems rises to a value set by the manufacturer. This value must be greater than 60 psi.
The warning light and buzzer should come on before the air pressure drops below 60 psi in either system. If this happens while driving, you should stop right away and safely park the vehicle. If one air system is very low on pressure, either the front or the rear brakes will not be operating fully. This means it will take you longer to stop. Bring the vehicle to a safe stop and have the air brakes system fixed.
Multiple-Choice Questions:
The warning light and buzzer should shut off when the air pressure in both air brake systems rises to a value set by the manufacturer. This value must be:
- Less than 60 psi
- Greater than 60 psi
- Greater than 120 psi
- Greater than 100 psi
Before driving a vehicle with a dual air system, allow time for the air compressor to build up a minimum of:
- 60 psi pressure in both the primary and secondary systems.
- 100 psi pressure in both the primary and secondary systems.
- None of these are correct
- 100 psi in the primary system, 60 psi in the secondary system
What should you do if the air brake warning light and buzzer comes on while you're driving?
- Keep driving and watch the gauge. Do not lot it drop below 30 psi. If it does, park the vehicle.
- Stop right away and safely park the vehicle
- Push in the parking control knob immediately to preserve the air you have left in the system
- Continue driving normally, but use the trailer hand control valve to stop the vehicle.
In a dual air brake system, the warning light and buzzer should come on before the air pressure drops below what level in either system?
- 30 psi
- 90 psi
- 120 psi
- 60 psi
Which of the following describes a dual air brake system?
- The first system is called the “primary” system. The other is called the “secondary” system.
- One system typically operates the regular brakes on the rear axle or axles. The other system operates the regular brakes on the front axle (and possibly one rear axle). Both systems supply air to the trailer (if there is one).
- A dual air brake system has two separate air brake systems, which use a single set of brake controls. Each system has its own air tanks, hoses, lines, etc
- All these are correct
Complete!
You can Return To The Table Of Contents
Why Join Trucking Truth?
- The High Road Training Program
- The High Road Article Series
- The Friendliest Trucker's Forum Ever!
- Email Updates When New Articles Are Posted
Apply For Paid CDL Training Through TruckingTruth
Did you know you can fill out one quick form here on TruckingTruth and apply to several companies at once for paid CDL training? Seriously! The application only takes one minute. You will speak with recruiters today. There is no obligation whatsoever. Learn more and apply here:
TT On Facebook