Steerable Tag Axle

[Traps90]

Have coma across something a little interesting lately, have met 2 people who have bent one of the arms on there tow bars (one was a blue ox not sure of the other one) cause of turning to tight. Both of them had just recently moved up to a new coach with IFS and a larger wheel cut.
Both incidents are believed to have been caused by turning to tight. A problem both said never happened with there older solid axle coaches.

[Gordon Dewald]

Originally Posted by Dutch Star Don

If I recall, the tests were compared to a tag coach that lifted. It sounds weird, but it's not the dragging of the tag that increases the turning radius, but the steerable tag forcing the drive tires to turn sharper.

When it comes to Comfort Steer there is really no comparing it until you've driven one all day and see the difference. My Monaco handled well and there were days when I drove 600 - 700 miles. I wasn't worn out at the end of the day, but I was done. The Comfort Steer leaves me more relaxed than the Diplomat did. No matter what, non Comfort Steer coaches don't correct for road crown or wind push automatically. So at the end of the day, you've had to steer the Comfort Steer coach substantially fewer times.

Here is a quote from the Spartan website

The 7% reduction is comparing a passive steer tag axle to a standard non-lifting tag axle both fully loaded (14K at the ground).

This is from the FCCC website:

From the FCCC website. http://www.fcccrv.com/chassis/xc/tag...on/#ultrasteer

Increased Maneuverability

Up to 17% reduction in curb-to-curb turning radius as compared to a competitor's chassis on a fixed tag—that's a 140% improvement over the competition.

In both cases it appears they are comparing to a fully loaded tag. And for FCCC we really have no idea what they are comparing. SAD!

[Crasher]

Originally Posted by Cat320

The way I understand my tag it is not "liftable" all the system does is dump the air pressure from the tag.

On my system that "Dumps" the tag air, it does not completely release the air. Ours reduces whatever I have the inflated pressure set at down to 20 psi. I played with that setting and tried 10 psi, but had sliding tag tires when braking below 10 mph when the ABS is no longer active. I set it back to 20 psi and no more sliding unless on a slippery surface and braking hard. I doubt that American dumps it to zero either.

[Gordon Dewald]

Our tag slides when on loose surfaces in the dumped position. It is either going to skid when turning under some weight (on all surfaces) or slide with minimal weight (on loose surfaces) when braking. Either way there is going to be a bit of tag rubber sacrificed.

[Cat320]

Originally Posted by Crasher

On my system that "Dumps" the tag air, it does not completely release the air. Ours reduces whatever I have the inflated pressure set at down to 20 psi. I played with that setting and tried 10 psi, but had sliding tag tires when braking below 10 mph when the ABS is no longer active. I set it back to 20 psi and no more sliding unless on a slippery surface and braking hard. I doubt that American dumps it to zero either.

Interesting...I don't/can't control the air pressure in mine.

[Crasher]

Originally Posted by Cat320

Interesting...I don't/can't control the air pressure in mine.

I have had the proportioning valves replaced with manual regulator valves which allows me to adjust the tag bags to carry what ever I want. I have also had the control modules reprogrammed so that the directional signal dumps the tag when under 20 mph and the "Dump Tag" switch inflates the tag. After signalling a turn, if I need to brake hard, I'll inflate the tag momentarily just prior to stopping. Then hit the directional again for the turn. It also works great when switching lanes in slow bumper to bumper traffic when my speed will not get up to 20 mph for an auto inflate. After the lane switch, I can inflate the tag at will. A passive steering tag axle would eliminate the need for all of this, but I'm happy with what I have.

[Gordon Dewald]

Our tag dump needs to be initiated after the ignition is turned on. It will remain 'active' until the ignition is turned off or the switch is placed in the off position.

So the procedure is start the engine and dump the tag leaving the switch in the auto position. From then on the tag will dump below 8 mph and inflate above.

We have never had the tag slide on dry pavement when braking unless there is loose gravel or debris. It will slide under braking on gravel parking areas. I have noticed it mostly when backing up and a few times in forward when maneuvering into a parking site.

[Crasher]

Mine used to be set like that too, but at 5-8 mph. I often found that the tag would inflate before I had completed the turn due to speed above the dump point. I have led lights showing when the tag is dumped. I wanted more control especially when hooked to our trailer with 1500# tongue weight as we would often turn onto a desert road and not be able to get above 8 mph for a couple miles getting back to our camping site. When dumped, the drive axle was carrying 24,000 lbs. Now, I am in control for any situation.

[Daytonaman]

18 wheelers do not have or need steerable axels. They bend in the middle. Their turn radius is determined by the wheel cut. Monaco coaches have one of the tightest. Tag raise systems have been around for years and any truck shop can work on them. I can easily spin around a 45 with the tag up on a 4 lane.

[Gordon Dewald]

Originally Posted by Crasher

Mine used to be set like that too, but at 5-8 mph. I often found that the tag would inflate before I had completed the turn due to speed above the dump point. I have led lights showing when the tag is dumped. I wanted more control especially when hooked to our trailer with 1500# tongue weight as we would often turn onto a desert road and not be able to get above 8 mph for a couple miles getting back to our camping site. When dumped, the drive axle was carrying 24,000 lbs. Now, I am in control for any situation.

IMO the rationale is if you are going more than 8 mph you will not be making tight radius turns. I could see the possibility of raising that speed if one were inclined to.

We have a dash display and a tone sounds when the tag dumps. When dumped our drive axle carries around 27,000 lbs so driving longer distances with the tag dumped may not be the best for the drive axle.

[MarkofSJC]

Additional thoughts

Newell has offered the ZF rear steering tags for more than a decade. They've been just as bullet-proof as regular tag set ups, from everything I've heard.

For me, it's the tight maneuvering aspect in a very large coach that would make a huge difference. It's one thing to know how to get your coach parked by the side of your house (though that, too can be a challenge), but I think it really shines when a "surprise" occurs that would be really hard to overcome without A) reversing or B) doing a zillion-point turn (after dropping your trailer or toad). How many times have you thought "if I could have just turned a few inches tighter..." on a low speed maneuver?

And it's not just large coaches. You've seen long pickups and SUV attempt to park in simple parking lots? Not fun there either. Audi is now offering a much more sophisticated rear steering than what's being considered here...but interesting to see.

https://www.youtube.com/watch?v=I_1lErXtITI

[Mr_D]

Originally Posted by Cat320

The way I understand my tag it is not "liftable" all the system does is dump the air pressure from the tag.

Ours actually lifts the tires clear of the ground. And yes, I'm sure having seen it in action and the tires off the ground afterward.

[Mr_D]

Originally Posted by Traps90

Have coma across something a little interesting lately, have met 2 people who have bent one of the arms on there tow bars (one was a blue ox not sure of the other one) cause of turning to tight. Both of them had just recently moved up to a new coach with IFS and a larger wheel cut.
Both incidents are believed to have been caused by turning to tight. A problem both said never happened with there older solid axle coaches.

Our last two MH's have had IFS, been towing our Honda Odyssey with a RoadMaster Sterling bar since 2005. Have never bent a towbar yet and the steering turn angle is 55° for both units.

[Gordon Dewald]

Our IFS is 60 degrees. It works very well in tight places.