Constant air supply to tires

[lostagain]

http://ca.mg6.mail.yahoo.com/ya/download?mid=2_0_0_1_177564_AML0i2IAAA6kUNxqjQu%2FxhmM4LQ&pid=2&fid=Inbox&inline=1

On a recent trip to Puerto Vallarta, I noticed a lot of buses had this air supply to all tires. You don't see this on buses up here. Logging trucks here are using this system more in the last couple of years, but I think the purpose is to air down for bush roads, and air back up for the highway.

Advantages? Disadvantages?

I can see if you had a slow leak, you wouldn't know ?

Those hoses sticking out could get caught and ripped off ?

Anybody with experience with this kind of system?

JC

[John316]

Link did not work for me.

Sounds like an interesting idea and would love to hear more.

John

[Stormcloud]

Most of the ready-mix concrete trucks in our area have this rig on the drive axles. Also, most are using the tandem steering setup with wide-base tires, for flotation and to stay within road weight limits.

I haven't noticed the air supply setup on any other commercial rigs here.

Regards.

Mark

[bobofthenorth]

There was a program in SK for a while - may still be in place.  Federated Co-op had this system on their queen B's and they had some overweight privileges as a result.  They could run overweight on the axle or overweight based on tire width - I can't remember the details but the weights were somehow related to what tire pressure they were running.

I agree that it looks like one more thing to go wrong or get broke off and I don't understand how that rotating seal in the middle works.

(edit)
Just noticed the reference to Puerto Vallarta JC.  Perhaps I'm too cynical but I'd be afraid that in Mexico the main purpose would end up being to avoid having to fix slow leaks. 

[luvrbus]

It is a option on Volvo buses sold here in states the H1 Hummer has the setup except it goes through the wheel pretty neat setup on the Hummers

good luck

[lostagain]

Here is the picture:

[lostagain]

The one in the picture is on a late model Irizar. They were on late model Volvo and Mercedes buses as well that are used for airport transfers and sightseeing tours and excursions. I also saw them on a long distance 3 axle coach (I forget  the brand). They weren't on the city buses. So yea, they could mask a slow leak I suppose. What if you had a fast leak, that might not help very much. Unless there is a tire pressure monitoring system attached as well. I wish I would've asked more questions, although that would not have gone very far with my limited Spanish...

How about Dr Steve Mex-Busnut, are you reading this? What do you know?

JC

[belfert]

Since this is Mexico my guess is they will deflate the tires when going off road and then inflate them when getting back on pavement.  My understanding is sometimes when they repair roads they just route traffic out onto the dirt for a detour.

[Van]

Here's the Volvo we pulled up next to at Rail Road Pass Nv.

[buswarrior]

I have seen what appears to be that exact same system used on some of the B Train fuel tankers here in Southern Ontario.

All these things sort of arrived ahead of one another. The steady feed of air idea came along just ahead of decent tire pressure monitors. The cats eye units and related technologies all in there too.

The goal is proper tire inflation, since catastrophic tire failure primarily comes from running under-inflated.

I expect the in-cab displayed tire pressure monitors will win, the rest will become trivia answers, regulating tends to do that...

happy coaching!
buswarrior

[chessie4905]

  I remember several years ago seeing a setup in the trucking mags. A round puck that was free to rotate was mounted on the center of hub by a stubby shaft and a small hose attached to each of the tires on the duals and connected to the puck, keeping it from rotating. Inside the puck was a tiny air compressor that operated by rotation of hub. It had an adjustable air pressure regulator built in. It was to maintain proper air pressure, but wasn't designed to deal with moderate or significant leaks. Too lazy to look to see if they are still avail. If you are concerned about tires going low or flat, investing instead in a tire pressure sensor/ monitoring system could be an option.

[Van]

TIREBOSS, Will it get stuck?

[lostagain]

Thanks guys. I still don't see why you'd want that on a highway coach. Unless you're anticipating going off road, or driving in snow. When I drove the ski buses, and the hockey team's bus, there are times when lowering the pressure would've been nice, such as climbing mountain passes during a storm. Hey,you could still deflate manually, and air back up with a hose off coach air, or a portable compressor. That would take some time though...

JC

[Iceni John]

Next month I'll be in Mexico, taking buses between Toluca, Puebla, Cordoba, Veracruz and maybe elsewhere.   I'll try to ask the drivers there exactly why these air supplies are fitted to the new buses.   The city buses and the older buses don't have them.

John 

[lostagain]

Great John, that will be interesting.

JC