Flashcards in 2010 KME Logbook Deck (69)
What kind of air barke system does this engine have?
Dual circuit air brake system
What are the two parts that make up the dual system?
- Primary: supplies air to the rear axle service circuit (Spring brake parking system)
- Secondary: supplies air to the front axle service circuit (auxiliary front axle parking brake system)
Normal air brake operating pressure
A warning buzzer and light will come on when air pressure drops...
...below approximately 65 psi
Warning buzzer and light will turn off when pressure reaches past...
What is recommended when applying the brakes?
Applying a firm constant pressure.
What is not recommended when applying the brakes and why?
Not recommended "pumping" the brake pedal, because doing so may deplete brake systems air reservoir supply.
The air brake system is designed with a quick build up feature which first fills the primary or secondary reservoir, and why?
Primary (rear) brake section first, to enable release of the parking brakes in case rapid movement of engine needs to occur due to an emergency.
At what psi should you use extreme caution when either of the reservoirs have this reading?
Is there an on/off switch for the antilock braking system (ABS)? Why?
There is no on/off switch for ABS because it is an integral (necessary) part of the air brake system.
How should braking be done by the operator as to make sure the ABS works as designed? How do ABS work?
Firm steady pressure on the brake foot pedal. The ABS works by automatically applying and releasing the brakes during low traction or panic brake applications to prevent wheel lock up, which improves both braking efficiency and steering control.
When the antilock brake system (ABS) applies what happens with Jacob's Engine Brake?
Spring brakes are applied and released by what on the dash?
Yellow parking brake valve
What is happening when you push yellow valve knob in?
Releasing the spring brakes due to air pressure
What happens when you pull out yellow valve knob?
Applying the spring brakes.
When should the parking brake circuit (yellow knob) NEVER be used, and why?
During normal driving, because parking brake intended to hold the vehicle in a parked position only.
What happens when air pressure is lost in the rear (primary) service brake section?
The secondary reservoir adjusts primary reservoir air pressure (giving air) which will allow a few brake applications before the spring brakes are automatically applied.
The spring brakes will automatically apply at what pressure?
When pressure is reduced to approximately 40 psi in BOTH systems.
According to Department policy, when should chock blocks be used?
When ONSCENE. Logbook suggest chocking wheels whether on level terrain or on a grade.
What are the primary purposes of the auxiliary front wheel locks?
To keep the front brakes applied and to help augment the rear spring parking brakes in the event the rear parking brakes cannot hold the apparatus on a steep incline.
Why is it a problem if there is an air leak and auxiliary front wheel locks are applied?
Because brakes for the auxiliary front are applied using air pressure.
When should the front auxiliary brake be used?
It should only be used when the engine is running (to help maintain proper pressure in case of leak).
Does the auxiliary front parking brake meet the Federal Motor Vehicle Safety Standards (FMVSS) parking brake criteria?
No. Therefore it is considered a SUPPLEMENTAL brake only and must be used in conjunction with the yellow parking brake valve when parking the vehicle.
When applying the auxiliary front wheel lock, what MUST be done first?
The spring brakes must be applied first by pulling the yellow knob out, then when the spring brakes are applied push in the black auxiliary brake knob.
To disengage the auxiliary front parking brake what needs to be done?
When the yellow spring knob is pushed in, the auxiliary brake knob with "pop" out and the auxiliary brakes will automatically release.
What is the Jacob's engine brake? And how does it work?
Jake brake is a device which uses engergy of the engine compression to provide vehicle retardation. The engine brake converts the engine to an energy absorbing device to reduce speed, accomplished by a hydraulic circuit that opens the exhaust valves near the end of the compression stroke.
What three components does Jake brake consist of?
- A three position selector switch
- An on/off switch to activate or deactivate the system.
- A throttle sensor
Diesel engines have _ retarding effect upon vehicles than do gasoline engines? Why?
substantially less. Due to the lack of restriction in the diesel intake manifold.
Jake Brake may be used for when?
Descending grades, driving in city traffic, or when approaching stop lights, and in general, whenever vehicle retarding is required.