Air Tag Axle Oddity

[ThaddeusW]

So the air lift tag axle on my B has a bad lifting bag. I checked out the lift mechanism and I think its partially homemade as this setup cant be what comes from a respected suspension manufacturer (Neway)

Here you see one end of the lifting lever. there is no pivot point or attachment. When the lift bag inflates, the arms simply rest on top of the cross member. This does not look right to me.

If you look the plate the air bag is mounted to is bent and cracked on one side where it meets the rail. It simply isn't strong enough to deal with the forces necessary for lifting the axle. You still cant see any pivot point. the only thing preventing the arms from falling off is the air bag. From each arm, a chain runs down to an attachment point on the suspension so I believe it is a lift axle suspension that some bought incomplete and fabricated this mess. That or the original mechanism went bad and this was its replacement.

This is a problem because I cant lift the axle unless I remove this contraption and chain the axle in the up position. That or I simply leave the axle in the lowered position but I would prefer to get the setup working. I also noticed that next to the drivers seat is a an air valve looking thing that has a pressure gauge on it which has the Neway logo on the gauge. Three holes are next to the valve where hoses probably ran through them to the valve thing. Next to that valve are two air toggle switches that don't appear to do anything. The lift axle is now controlled by this control box to the left in the picture:

Here is that valve thing:

Any ideas on how I can fix this? Can I find a left mechanism or should I look at buying a used lift axle?

[41chevy]

IMO it has the look of a cobbled together set up. Granning used cables with the bags to lift the axle. I've never seen a lift with out pivot points for the lift arms.....ever. Probbly cheaper and safer in the long run to replace it with a new or good used one. Paul

[David]

Some early tag axles were made to always stay down. A previous owner probably didn't like that and added the current setup. You might want to test drive as is and see how the ratio works for your needs. If a change in ratio is necessary you could switch the entire setup for a camelback.

[Bollweevil]

So the air lift tag axle on my B has a bad lifting bag. I checked out the lift mechanism and I think its partially homemade as this setup cant be what comes from a respected suspension manufacturer (Neway)

Here you see one end of the lifting lever. there is no pivot point or attachment. When the lift bag inflates, the arms simply rest on top of the cross member. This does not look right to me.

If you look the plate the air bag is mounted to is bent and cracked on one side where it meets the rail. It simply isn't strong enough to deal with the forces necessary for lifting the axle. You still cant see any pivot point. the only thing preventing the arms from falling off is the air bag. From each arm, a chain runs down to an attachment point on the suspension so I believe it is a lift axle suspension that some bought incomplete and fabricated this mess. That or the original mechanism went bad and this was its replacement.

This is a problem because I cant lift the axle unless I remove this contraption and chain the axle in the up position. That or I simply leave the axle in the lowered position but I would prefer to get the setup working. I also noticed that next to the drivers seat is a an air valve looking thing that has a pressure gauge on it which has the Neway logo on the gauge. Three holes are next to the valve where hoses probably ran through them to the valve thing. Next to that valve are two air toggle switches that don't appear to do anything. The lift axle is now controlled by this control box to the left in the picture:

Here is that valve thing:

Any ideas on how I can fix this? Can I find a left mechanism or should I look at buying a used lift axle?

What sort of suspension does the tag axle have? The under dash valve is typical of an air tag set up. Flip the valve and screw the knob in or out to a predetermined pressure. Normally, just enough to equalize both axles when under a load. A neat thing about that set up was, back when the state highway scales could only weigh one axle pair at a time, they would set the scale platform for 32,000 plus allowance. If you were a little over gross you could crank the valve pressure up to shift weight to the steer, release the valve as the steer cleared the platform, and just keep rolling. Most of the tag axles that you saw were spring return. It doesn't take much to lift the axle at all. I don't see that what you have is poorly engineered at all. Figure out how it did work and fix it so that it will.

[ThaddeusW]

What sort of suspension does the tag axle have? The under dash valve is typical of an air tag set up. Flip the valve and screw the knob in or out to a predetermined pressure. Normally, just enough to equalize both axles when under a load. A neat thing about that set up was, back when the state highway scales could only weigh one axle pair at a time, they would set the scale platform for 32,000 plus allowance. If you were a little over gross you could crank the valve pressure up to shift weight to the steer, release the valve as the steer cleared the platform, and just keep rolling. Most of the tag axles that you saw were spring return. It doesn't take much to lift the axle at all. I don't see that what you have is poorly engineered at all. Figure out how it did work and fix it so that it will.

Here are two more pictures:

This is the part of the air bag support that is cracked clean off. Its also bent up pretty bad. Plus they welded it to the frame, something that should not be done, especially on the flange.

The suspension does have these chain mounts.

I figure I could remove the wheels if there is a problem. I am sure the ride quality will be affected if I inflate the air bags. If I don't inflate them the tag axle brakes will lock the wheels and it will drag along the road. Still on the fence here on what to do.

[Bollweevil]

Here are two more pictures:

This is the part of the air bag support that is cracked clean off. Its also bent up pretty bad. Plus they welded it to the frame, something that should not be done, especially on the flange.

The suspension does have these chain mounts.

I figure I could remove the wheels if there is a problem. I am sure the ridge quality will be affected if I inflate the air bags. If I don't inflate them the tag axle brakes will lock the wheels and it will drag along the road. Still on the fence here on what to do.

You might be able to jack the lift axle high enough to to chain it in place without removing the wheels. The worse case could be that with the wheels off, and the axle not chained up, it would hang low enough for the drums to drag. If your first goal is to move it around to get in position to work on it, I would first try to chain it up. When you get it to where it will move around fairly easy, step back and look at it for a while. You have been a long time getting this far. Someone was using it like it is, and You already have on hand most of the stuff that it will take to make it work again. If it would go up and down on demand, you could live with it for a while, until you figure out which direction you want to go. The worse thing you can do is to start taking things off with out a plan. In one respect a truck is like a race car, it absolutely will not nickle and dime you to death. They will take every penny you can scrape together.

[swjr]

i am extremely familiar with lift axles and this is not a design I have seen in the last  30 years. I am not sure what you want to do to proceed in terms of making the design right, replacing the parts that are affected or blow $3800 US on a new suspension + labour.

If your budget conscious, you can go to a steel mill and ask for a 1/2"section of AR 400 [145,000 psi yield] which will s set you back $75 USD and a machine shop will precisely duplicate the holes for a few hundred more, I suspect, perhaps less.

there are plenty of places that have used lift units for $500 or so, and even a grand is not too shabby.... Sometimes starting over is the way to fly, but be aware that many Mack dealers bill a half hour to drill each hole, so count your bolt holes you need drilled while in the shopping process..

If you have any question, just ask. I'm here to help.

good luck there driver.

edit: after further review of the photos, the cross member resembles  one that was from a peterbilt [but holes are different in pic] and the upright flanges are not likely machine made as these form the gusset and there are no flanges or box shaped webbing to connect the two. .... Hartley in Indiana might be a good try, if you wanna try the used replacement route...also, I suggest you consider making the two 2"box sections a single piece 48"x12"x1/2" flat section and install new mounting studs for length if needed. you can get these at Fastenal and they will custom make them if needed. -- I also recommend you extend the cross member flange the two box sections rest on and try beefing up the hinge with a poly urethane bushing, say from Euclid truck parts and fab a new hinge bracket from that AR 400 I mentioned if you can spare the change. Most of these steps can be done incrementally to lesson the blow to your time and budget...  you can also try metal supermarkets for the sections.

Edited September 25, 2011 by swjr

[theakerstwo]

Drive i have one just like that laying out here.

[swjr]

Drive i have one just like that laying out here.

perhaps. In fact you may own a 100 trucks with this thing super glued to the frame, however, I still do not recognise it and my goal is to help out on the forum. - I hope I have.

I hope that you will join me in finding concrete answers for these truckers and hobbyists that will get them a little closer to where they want to go both on the road and in life.

In the end, this fix is chump change and the materials are readily available anywhere there driver, I strongly recommend using google or similar to research the info Ive offered and this way, when you approach a supplier, you can approach him with knowledge and confidence.

You might even consider switching to a self steerable unit if your budget is in goodd shape or you could stand a nice end of year tax write off.

there are lots of good ones out there. Watson-Chalin is a good bet.

God bless and good luck.