Air Gauge 2 indicators? - 98 Monaco Dynasty

wny_pat wrote:

JetAonly wrote:
Pardon me for being dense, but Ivylog's link says rear is green.

And it can be white also. Mine are white. Green or White are both accepted as industry standard for the rear.

wny_pat wrote:
Answer: 1. The first gauge identifies the air pressure in the primary system (marked "primary" or "rear brakes" or displays a red needle). The air pressure in the primary system controls the rear brakes. With the heavy loads fire apparatus carry on the rear axles, the rear brakes can perform up to 80 percent of the braking.
The second gauge identifies the secondary system (marked "secondary" or "front" or displays a white or green needle). This gauge indicates the air pressure that controls the front (steering) brakes. Usually, most air-operated accessories (such as the air horn) will also operate from this tank and be registered by this gauge. The two gauges can be combined into one gauge with two needles, color coded as indicated above.

Uhhh, red green or white? Now I'm really confused.

JetAonly wrote:
Pardon me for being dense, but Ivylog's link says rear is green.

And it can be white also. Mine are white. Green or White are both accepted as industry standard for the rear.

JetAonly wrote:
FWIW, if I read the diagram correctly. it looks like either system below set point will trigger the spring brakes.

That is correct. And most importantly, you have to make sure you are looking at a schematic for a truck or motorhome, and not one for a road tractor. The road tractor is set up differently. I've always called them "Maxi brakes" but the proper name is spring brakes.

Pardon me for being dense, but Ivylog's link says rear is green.

FWIW, if I read the diagram correctly. it looks like either system below set point will trigger the spring brakes.

You have to make sure you look at the Bendex schematics for straight trucks and not road tractors, as they are set up differently. Following answers questions concerning straight trucks and motorhomes:

1. Most air brake systems have two dashboard air gauges. What do the two air gauges indicate?
Answer: 1. The first gauge identifies the air pressure in the primary system (marked "primary" or "rear brakes" or displays a red needle). The air pressure in the primary system controls the rear brakes. With the heavy loads fire apparatus carry on the rear axles, the rear brakes can perform up to 80 percent of the braking.
The second gauge identifies the secondary system (marked "secondary" or "front" or displays a white or green needle). This gauge indicates the air pressure that controls the front (steering) brakes. Usually, most air-operated accessories (such as the air horn) will also operate from this tank and be registered by this gauge. The two gauges can be combined into one gauge with two needles, color coded as indicated above.

2. For what two reasons does the driver-operator need to know how much pressure is in each system?
Answer: 2. Reason 1: By reading the gauges and knowing how much air is in each system, the driver-operator can estimate how much braking power the vehicle has.
Reason 2: During a failure in one or both brake systems, the driver-operator can make an informed decision as to whether he (a) needs to make an emergency stop, (b) can safely stop the vehicle without having to make an emergency stop, or (c) can safely and slowly return the vehicle to quarters.

3. On vehicles with multiair tanks, which tank is known as the "wet tank"?
Answer: 3. This tank is also known as the "main tank." It is the first tank to receive the hot compressed air from the compressor. As compressed air cools in the tank, water is condensed and stored in the main tank (wet tank). Since water is destructive to the air brake system, it is important that the water be expelled by proper operation of drains and air dryers. If excessive water or oil is found in the wet tank during the checks, this must be reported to maintenance; it might indicate a failure of the compressor or air dryer. The other tanks, one or more of which operate the primary system and one which operates the secondary system, should always be dry. If they are not dry, there is a problem. All tanks should always be checked daily for water.

4. How does the parking brake work?
Answer: 4. Parking brakes are installed on the rear axle(s) and use the rear air brake chambers. Springs apply the rear brakes and therefore are applied without the use of air pressure. To release the parking brake, air is sent to the chambers by the diamond-shaped parking brake knob and compresses the springs, which release the parking brakes. Experience and common sense tell you that if you lose air pressure, the parking brake will apply automatically.

5. What is the emergency brake?
Answer: 5. NO, it is not the parking brake! It is a system all its own. In case of total loss of pressure in either the primary or secondary tanks, the emergency brake system will use existing air so that when the brakes are applied, a controlled combination of parking and service brakes will activate so that the rear-controlled braking occurs under any circumstance. The existence of this braking system allows the release of the parking brake when air is at a minimum of 30 to 50 pounds in either the primary or secondary systems. This system should be checked by qualified technicians during every preventive maintenance. This is critical on apparatus that often operates with minimum air pressure, such as when leaving the fire station before the air pressure is properly built up.

You need to study up on how your air system works. This school bus diagram may help. When the red pressure drops below 60 psi you will stop in the middle of the road and will not be able to move.

Dual tanks, dual gauges, they work find in all the bigger trucks with air brakes over having two gauges. So common off the shelf parts really.

FormerBoater wrote:
Front and rear tanks....separate systems hence the 2 gauges.

What he says. Two needles in the same gauge is to save dash space. Which is which? I dunno, The manual doesn't say. If i was guessing I'd say the red is for the back tank, 'cause if its low the park brake will set.

(Edit) Se lower post for confusion


FWIW the rears brakes provide as much as 80% of braking.

Front and rear tanks....separate systems hence the 2 gauges.