Air Brake Excess Moisture Release

[Xjaywalker]

I have a 2006 National TropiCal on a Frieghtliner Chassis, 350 Turbo CAT.

I was reading my manual one day (looking for information on my on board compressor) and saw a note "to release excess moisture by pulling these cords located under the chassis along side the front tires".

I have only had my coach 2 years but was never told this from anyone. I looked and sure enough there was a cable with a loop dangling from the bottom of the chassis.

Now before I go messing around with my brake system, I thought I would ask some more knowledgable people. I will also check with Frieghtliner.

Just wanted to see if anyone else was doing this and if its required. Brakes are kind of important in these big rolling house on wheels.

[JBDISCOVERY]

You should have two aux tanks in that there are two separate air brake systems on your coach. All air compressors will create water vapor which will accumulate in the aux tanks. It is standard procedure for over the road drivers to pull the halyards on each aux tank to blow out any moisture in the system.
Additionally it is important to change the HALEDEX air dryer filters on a regular basis. These keep the moisture in the air system within specs.
Water in the air brakes lines can cause reduced brake performance, and in freezing temps, the water vapor in the brake system can lock up the whole system
Check it out on GOOGLE AND YOUTUBE.
JimB

[FIRE UP]

Originally Posted by Xjaywalker

I have a 2006 National TropiCal on a Frieghtliner Chassis, 350 Turbo CAT.

I was reading my manual one day (looking for information on my on board compressor) and saw a note "to release excess moisture by pulling these cords located under the chassis along side the front tires".

I have only had my coach 2 years but was never told this from anyone. I looked and sure enough there was a cable with a loop dangling from the bottom of the chassis.

Now before I go messing around with my brake system, I thought I would ask some more knowledgable people. I will also check with Frieghtliner.

Just wanted to see if anyone else was doing this and if its required. Brakes are kind of important in these big rolling house on wheels.

XJwalker,
About 99.9% of the Freightliner chassis'd coaches, will have THREE lanyards to pull. Sometimes they are actually routed into and through the passenger side frame, just inside the right front wheel well. Sometimes they're not routed at all but, instead are coiled up and left in the middle, underside of the frame, near the tanks. It all depends on the coach mfgr. and how they handled it, at the factory.

But, in most circumstances, the air dryer will handle the removal of about 99.9999999% of the moisture that's injected into the system by the air compressor. Occasionally, if you're operating in a high humidity environment, such as some parts of Florida and some other states, the air dryer may not be able to keep up with drying all the air, passed through it. And, some will accumulate in the lines/tanks. In that case, "bleeding" the system should olleviate any trapped moisture.

As stated, the dryer get's the major majority of it. Most posters on here that have commented on this type of thread, have not seen ANY when they've pulled on the lanyards. Some have but, not all that many, based on who's reported here. I never have and, we've owned the coach now for 3.5 years and I've pulled on the occasionally.

The manufacturer, Freightliner, will advocate a time frequency at which to pull them and, when pulling, most will pull them for about 5 seconds or so. If no moisture is seen, then bleeding each tank all the way down is useless. Moisture will gather at the bottom of the tank where the valves are at.
Scott

[navigator336]

I pull them everything year or so (manual says to do it every six months). I have never seen any water even when I completely drained them prior to replacing the desiccant cartridge. I live in California with a generally dry climate. When I replaced the cartridge, it was completely dry and appeared oil free, although oil may get trapped inside and not be visible. You probably should replace the cartridge unless you know it's been done before. Most likely you have a Haldex Purest drier. The cartridges are about $95 on line. It would be a very easy job except for access to it. There are four bolts that hold the drier cover on. These are metric as I recall. An offset wrench and sockets with u-joints will help. If you do it, I suggest wiping down everything around the cover and then vacuuming any loose dirt anywhere near the cover before removing it. I got a little dirt inside the drier when I removed the cover. I used a small shop vac to vacuum out the inside before putting in the new cartridge. The cartridge comes with a new cover "O" ring, four new bolts and pretty clear instructions on how to do the replacement.

[Tony Lee]

but was never told this from anyone

All daily and routine maintenance is detailed in the owner-operators manual along with suggested driving techniques.
Recommended reading!

[Hooligan]

On the Freightliner site, they have a pub, "Knowing Your RV Chassis" that has a lot more detail and photos than in the manuals. It's used during the Camp Freightliner training course. Look in the panel on the right side...here:
Freightliner Motorhome Chassis ? RV Chassis

At the bottom of that panel you can also download the Maintenance Manual.

[Kiwi]

Pull the loops. No harm if no water. Air is cheap. NBD (no big deal)

[Pigman1]

Fire Up (Scott) has it right. 2 tanks but one has an internal baffle, so 3 air chambers, each with a valve. Some chassis manufacturers use one or more automatic valves, heated, and others do not but there will be a lanyard or valve to drain each. Just have to do a bit of reading and looking. The Air drier also has an automatic valve that you can release for changing the filter.

[Xjaywalker]

Originally Posted by navigator336

I pull them everything year or so (manual says to do it every six months). I have never seen any water even when I completely drained them prior to replacing the desiccant cartridge. I live in California with a generally dry climate. When I replaced the cartridge, it was completely dry and appeared oil free, although oil may get trapped inside and not be visible. You probably should replace the cartridge unless you know it's been done before. Most likely you have a Haldex Purest drier. The cartridges are about $95 on line. It would be a very easy job except for access to it. There are four bolts that hold the drier cover on. These are metric as I recall. An offset wrench and sockets with u-joints will help. If you do it, I suggest wiping down everything around the cover and then vacuuming any loose dirt anywhere near the cover before removing it. I got a little dirt inside the drier when I removed the cover. I used a small shop vac to vacuum out the inside before putting in the new cartridge. The cartridge comes with a new cover "O" ring, four new bolts and pretty clear instructions on how to do the replacement.

Good Information. I will review my last invoice from Freightliner, not sure if they did this as part of my service or not. Thanks

[brian-nicola]

I pull them every trip...sorry I am old school and it only takes 30 seconds

[bigdog]

I am a bit anal in my checks before any trip as I drive one of those big yellow buses that carry a whole bunch of screaming little kids to and from school. I am required to do a tap test,tire check and lug nuts, check all engine fluids and all lights every day on pre trip. When I bring it in in the PM,I am required to check all lights,visually check the engine compartment and open the air valves to drain any water.
When I am on the road in the MH,I'm not quite as bad,but I do check actual tire pressure,fluids,lights,tap test, etc before leaving home and every couple of days on the road. It is interesting as how many times I do the tap test that I almost always get someone that asks me why I do that. And they're out there on the freeway driving a vehicle that weighs between 25 and 55K#s not knowing how their brakes work. Yes,the tap test is to check your ebrake,but also to check your air system recovery time.