Air Brakes Question, 3 pumps and warning light comes on?

Try it and see.

In the old days when DOT man is walking towards me from the coop house (Im usually parked at the very end of his row for that reason...) for a inspection that includes brake length, I would apply the service brake to the floor about 7 or so times. That would drain the air mostly and trigger the low air. And set the slack adjusters somewhat into adjustment if they were not. By the time he got to the truck the air is usually back to or close to normal and ready for the inspection.

So if it took you 3 or 4 times to the floor draining the necessary air to trigger the warning then you should be in pretty good shape. It is not something that is done normally. But I would say from your description that your rig is behaving exactly what I would expect a 18 wheeler to behave being treated like that.

 

Start with draining your air tanks.

Edit: Didn't have enough time to finish my post. If you've got lots of water in the air tanks, it takes away reservoir volume (less storage capacity). I've seen some trucks with several litres of water in the tanks before when lack of air system capacity was the complaint.

 

Then,check your brake adjustment.

 

Also depends on how hard you pump. (That’s what she said)

 

The behavior I described in my posts is with a full up working 18 wheeler with no water in the tanks and tanks themselves are drained by a air dryer that removed fluids before the supply air is sent to the dry tank to be held for use in braking.

Many truck tanks have drain valves on the ends where you can dive under there and open up. In a minute you will know very fast if that tank contains sludge. oil, water etc. If so, drain em overnight with engine off. Otherwise that sludge will try to get to your brake chambers and start eating the rubber divider between your service application chamber and the emergency (Parking) spring chamber creating for you a very dangerous brake leak every time you apply the service braking.

 

I can gaurantee if you had water in the tanks. You'd already know about it by now as you wouldn't be able to get the truck OR trailer aired up to release the brakes to move. If the temps are cold enough for water to freeze.

But it never hurts to check. No one does it and those things freeze up if you have the screw out types instead of the cable that pulls.



I just went through this 3 weeks ago. And it don't take much water. Maybe a spoonful to cause problems.

I don't know how many pumps it takes but it's more then 3 or 4. You've probably got a leak with the brakes applied if you can't hear anything without the brakes.

 

Had same problem but brakes were way out of adj should take ten or twelve pumps or more to drain air

 

If your sitting still not moving, it will take 3 or 4 full to the floor pumps and the light and buzzer will be on.