changing ad4 dessicant questions

[white-eagle]

anything difficult or hazardous about changing out  the dessicant cartridge on  my ad-4 air dryer, other than let the air pressure go to 0lbs?

i got the dessicant kit, not the full maintenance kit, becuase the air dryer seems to be working except i don't know when the dessicant was changed out, and i didn't know there was a full maintenance kit vs just the dessicant.

hints for ease of this chore also welcome.  i will be rtfm, but they don't always have all the easy experienced instructions.

[Sojourner]

Like the old tale "If all else fails, read the instructions"
Left click on the red letters to open pdf file and wait a few seconds.

Bendix AD-4 Service Data

Take Care.

Sojourn for Christ, Gerald

[TomC]

From having the AD-4 on my truck, I would highly suggest you get the full overhaul kit with O rings and the spitter valve.  While it seems to be working correctly now, it just doesn't cost much more to make sure it keeps working correctly-since it is a bit of a pain to work on.  Clue-take it completely off the bus and work on it on your work bench-much easier.  Good Luck, TomC

[white-eagle]

read the manual!  do i have to???

tomc, thanks, i was thinking that way when i did read the manual.  it did seem to indicate it would be easier to work on, i just wasn't sure what all might have to be undone to get it off.  if it's just a couple brackets, 3 air hoses and a couple wires, might be easier than undoing the nuts all the way around.

gerald, i had read the book pdf briefly, but the link makes it easy to do it again.  thanks.

i was looking for gotcha's, like watch it when you undo the heater becuase it's real easy to electrocute yourself or something    . 

[makemineatwostroke]

Manasst, nothing there to harm you, soak the nuts with parts blaster and watch your language       

have a great evening

[white-eagle]

i stopped by the parts store to find out what added parts kit i need in order to follow your suggestions to change it all out.  they suggested replacing the entire ad-4 with an AD-9.  $226 with the old ad-4 core back.   i know the dessicant kit was $85, so how much more could all the other stuff be and still not be new.

anything wrong with replacing an ad=4 with an ad-9, assuming there is enough room for the extra 2-3 inches in height?

[John316]

Not as far as I know, but then again, I'm not a pro. I think that the biggest advantage would be that parts are easier to come by (not that you want to be replacing parts on it all the time).

FWIW

God bless,

John

[VAN]

Take pics so's you will know what it looked like before ya took it out (just in case)

[makemineatwostroke]

Manasst, no need to change from the 4 to the 9 the AD-9 was a upgrade for disc brakes and the dessicant  is going to cost you more when you service it. Velvac makes a replacement dessicant for the 4 for less than 60 bucks new no exchange   have a great evening

[niles500]

If your not in a hurry always check Emart

http://shop.ebay.com/items/?_nkw=ad-4+bendix&_sacat=0&_fromfsb=&_trksid=m270.l1313&_odkw=ad-4&_osacat=0

[buswarrior]

The AD-9 is a product evolution. It is the next generation of air drier after the AD-4.

The air drier is not concerned with what components or style of brakes may be connected to the air system.

IMHO, the best air drier for a busnut is the one suitable for the duty cycle that is sourced cheap, and may be serviced cheap.

The evolution was AD-1, AD-2, AD-4, AD-9, and then the letter designations as the driers begin to be more application specific and integrate system valving into the drier. Sidenote: The relatively new AD-IS is one trick drier, arguably making your braking system safer by offering pressure protection individually for each circuit. Big job to retrofit, but really neat in a new application!

The improvement of the AD-9 over the AD-4 was that it withstood a longer compressor run time time, 60 seconds, versus 30 seconds, according to the literature. It was aimed at the same market segment.

How it works: An air drier gets "wet" as the compressor runs, and once it becomes saturated during the pumping cycle, it will begin to pass moisture to the tanks. The loud "sneeze" heard at compressor cut-out blows the accumulated moisture out of the desiccant, preparing it for the next pumping cycle.

The transit coach models of the air drier, (or an added purge tank) gives a "sneeze" of greater volume, in order to blow out the greater volume of moisture inherent in the larger air volumes, and quicker compressor cycling due to air use, of buses historically, over trucks.

Does the typical busnut put the same burden on the air drier? Well, the busnut does little mileage compared to the intended usage, but then, busnuts may tend to have leaky teakies, and compressor run time may be unusually high, from Bendix's viewpoint.

It's a draw?

For those with older models, be confident, you don't need to upgrade unless you want to to get one of those cartridge models for ease of maintenance - It may be argued that the original AD-1/AD-2 will dry the air in our applications just as sufficiently for our purposes as one of the later driers. An upgrade may not get you anything practical, performance wise.

happy coaching!
buswarrior

[makemineatwostroke]

Manasst, it is a simple rule the more air you use the more has to be dried we have have tandem  AD 9s on every truck we own because of the air need for brakes and your AD 4 was installed for your system, if more was needed you would have 2 (tandem) AD 4s have a great evening

[white-eagle]

thanks for the suggestions and explanations.

i think what i came away with so far is that if the extra parts to do complete proper maintanance on AD-4 cost more than $226, it's ok  and probably better to have a new one, if it easily fits.   if the extra parts total up to $200 or less, then just get the parts and the AD4 will be fine.

works for me! thanks again.

[VAN]

Does it come in chrome

[white-eagle]

an update:

called the parts store and told them about the ad-4, asked about the full base maintenance kit which includes purge valve and gave them bendix number.  they said they had it, $27.  cheaper to change dessicant and base maint kit than new AD-4, so i ordered them.  parts came in, so started getting AD-4 out per Tom C.  Bad idea.

never do air dryer maint when you are on a stone driveway by yourself and don't know what you're doing.  had to take that coach batteries out to get to the brackets, almost twisted a hose in half before i figured out i was turning the wrong nut, needed 3 arms and double jointed wrists to hold the bolt while i undid the nut on the bracket, then almost busted a nut trying to get the very highly torqued nuts off the rim of the AD-4.

got it apart, cleaned it up, grabbed the parts from the dealer.  Dessicant kit ok, baseplate kit which includes the purge valve kit, looked like a trailer left turnsignal.  Sure enough, right part number, wrong company's parts.  Found another company with the right part on sunday and put it all back together.  And it works!!!    .

i still have to get the bottom strap on the dryer.  haven't figured out how to push the band on which takes both hands, then use my foot to thread the nut back onto the bolt.  tomorrow's project i guess, along with figuring out how to get 3 afternoons of grease out of my fingernails.  if we get to florida this year, you may see a large amount of duct tape around my AD-4 while i beg for help getting the strap on.

mma2s and tom c, you guys made it sound tooo easy.  Eagle did not put it in an easy spot, so it's a 2 person job, i think.  however, as usual, thanks for the pointers from all of you.

no, it didn't come in chrome.