Tag Axle Loading

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Tag Axle Loading

October 05, 2018, 10:20:45 am

I just had my coach weighed and was surprised at the results.
Steer 15040
Drive 10620
Tag 16160
Total 41820
I've known that the tag axle supports allot of weight. I run 90 PSI in the tag and drive tires and the tag tires squat more that the drive tires. Also, on wet pavement its not hard to spin the drive tires on acceleration and slide the drive tires with the retarder (I know I'm not supposed to use the retarder on wet pavement). The tag tires come up to temperature quicker than any of the others. So here's the questions;
1. What should the ratio of load be between the tag and drive?
2. Are there published specs for that by Foretravel?
3. Are the controls for that electronic and adjustable and how besides going to Nac can I tell?
4. What the heck?

Anyone had experience with this?

Re: Tag Axle Loading

Reply #1 – October 05, 2018, 11:13:10 am

Quote from: Don Hays – October 05, 2018, 10:20:45 am

I just had my coach weighed and was surprised at the results.
Steer 15040
Drive 10620
Tag 16160
Total 41820
I've known that the tag axle supports allot of weight. I run 90 PSI in the tag and drive tires and the tag tires squat more that the drive tires. Also, on wet pavement its not hard to spin the drive tires on acceleration and slide the drive tires with the retarder (I know I'm not supposed to use the retarder on wet pavement). The tag tires come up to temperature quicker than any of the others. So here's the questions;
1. What should the ratio of load be between the tag and drive?
2. Are there published specs for that by Foretravel?
3. Are the controls for that electronic and adjustable and how besides going to Nac can I tell?
4. What the heck?

Anyone had experience with this?

Don, not sure on your coach, but my tag axle is only rated for 9000 lbs. 16000 is way overloaded. Should be about 18500 on drive and 8000 on tag. Look at plate by drivers seat. I run 90 psi drive axle and 75 tag axle just like Foretravel recommends. My tag is not adjustable and uses same HCV as drive axle.
Don't make my dumb mistake. Would put my tag on 3rd scale on Cat scale and it always read high. Adjusted pressures, still high? Had DW positioning my rear axles on scale one time and she said "Can we weigh the CRV" Guess what, toad was also sitting on last scale along with my tag. Lost 3600 lbs off tag and all was good.

Re: Tag Axle Loading

Reply #2 – October 05, 2018, 11:37:33 am

I have not worked on your year coach, so do not know if/how tag axle weight is adjusted. On many coaches, it as simple as changing air pressure to the tag axle bags.

You asked "ideal". Ideal is for each axle to be loaded to the same percent of its GAWR.

Re: Tag Axle Loading

Reply #3 – October 05, 2018, 12:24:33 pm

Quote from: wolfe10 – October 05, 2018, 11:37:33 am

I have not worked on your year coach, so do not know if/how tag axle weight is adjusted. On many coaches, it as simple as changing air pressure to the tag axle bags.

You asked "ideal". Ideal is for each axle to be loaded to the same percent of its GAWR.

Maybe different on Don's coach, but Aubrey at MOT [ex foretravel designer] told me coaches of my era [03] do not have the ability to change pressure on the tag axle bags. For leveling uses same pressure as drive axle, and for running down the road, uses same HCV as drive. Beamalarm does not have specs for the 09, but 07 max axle weights are 14800 steer, 22000 drive and 10000 tag. With 46800 overall. Excess weight on steer, would indicate tag overfilled and removing weight from drive, and transferring to steer. Would lower tire air pressure on tag and reweigh.

Re: Tag Axle Loading

Reply #4 – October 05, 2018, 12:27:35 pm

Quote from: Don Hays – October 05, 2018, 10:20:45 am

I just had my coach weighed and was surprised at the results.
Steer 15040
Drive 10620
Tag 16160
Total 41820
I've known that the tag axle supports allot of weight. I run 90 PSI in the tag and drive tires and the tag tires squat more that the drive tires. Also, on wet pavement its not hard to spin the drive tires on acceleration and slide the drive tires with the retarder (I know I'm not supposed to use the retarder on wet pavement). The tag tires come up to temperature quicker than any of the others. So here's the questions;
1. What should the ratio of load be between the tag and drive?
2. Are there published specs for that by Foretravel?
3. Are the controls for that electronic and adjustable and how besides going to Nac can I tell?
4. What the heck?

Anyone had experience with this?

Are you 100 percent sure the person weighing did not transpose weights per axle into the wrong axle location?

Re: Tag Axle Loading

Reply #5 – October 05, 2018, 12:32:18 pm

Our 2003 40' U320:
Actual axle weights as percent of GAWR (Per axle):
Front 87.7%
Drive 79.0%
Tag 81.1%

Weights:
Steer 12175
Drive 16600
Tag 7300

GAWR Steer 13,880, drive 21,000, tag 9,000

Re: Tag Axle Loading

Reply #6 – October 05, 2018, 12:39:59 pm

Mine are close to Dans. Tag [called trailer on cat scale readout] is too heavy because it is reading my 3600 toad as well.

Re: Tag Axle Loading

Reply #7 – October 05, 2018, 12:55:28 pm

Don,

I would assume your metal manufacturer plate next to driver seat would specify the GAWR for each axle, just like Dan's. Did you check it?

Re: Tag Axle Loading

Reply #8 – October 05, 2018, 01:30:09 pm

This was my first experience weighing any vehicle. It was a "cat" scale and I'm guessing that the report is computer generated by the cat system. There were 3 platforms and I split the drive and tag between the 2nd & 3rd. I'm not 100% sure of anything about this right now... the spec plate calls out tire pressure per axle, not sure about weight, I'll look. I'm going to call Tech Services at Foretravel and I'll post the results.

Re: Tag Axle Loading

Reply #9 – October 05, 2018, 01:35:03 pm

The plate should also give GAWR for each axle.

Re: Tag Axle Loading

Reply #10 – October 05, 2018, 01:49:01 pm

Quote from: Don Hays – October 05, 2018, 01:30:09 pm

This was my first experience weighing any vehicle. It was a "cat" scale and I'm guessing that the report is computer generated by the cat system. There were 3 platforms and I split the drive and tag between the 2nd & 3rd. I'm not 100% sure of anything about this right now... the spec plate calls out tire pressure per axle, not sure about weight, I'll look. I'm going to call Tech Services at Foretravel and I'll post the results.

So your spec plate calls for 90 psi drive and 90 psi tag?

Re: Tag Axle Loading

Reply #11 – October 05, 2018, 03:08:11 pm

Quote from: AC7880 – October 05, 2018, 12:27:35 pm

Are you 100 percent sure the person weighing did not transpose weights per axle into the wrong axle location?

Ya, looks that way to me as well-- More on tag than drive???

Said another way, the two tires on the tag are carrying more weight than the four on the drive axle???

Re: Tag Axle Loading

Reply #12 – October 05, 2018, 03:25:47 pm

They fact that he can spin the drive tires make me suspicious that his stated weights are correct. All the cat scales that I have used are computer generated to a printer, no people involved. Plus over 15000 on the steer when total coach weight is less than 42000 lbs?

Re: Tag Axle Loading

Reply #13 – October 05, 2018, 03:28:15 pm

Well, as we say in Texas: "that just ain't rite"!

Re: Tag Axle Loading

Reply #14 – October 05, 2018, 04:08:43 pm

Just spoke w/ James at Foretravel. He said that just ain't rite.
He sent me the weight ticket from the factory before sale and the values were;
Steer 13280
Drive 18480
Tag 9780
Total 41540
No choice but to re-weigh the coach. I'll git that done and report back.
Thanks for all of your comments.

Re: Tag Axle Loading

Reply #15 – October 05, 2018, 04:51:29 pm

Don, that

Quote from: Don Hays – October 05, 2018, 04:08:43 pm

Just spoke w/ James at Foretravel. He said that just ain't rite.
He sent me the weight ticket from the factory before sale and the values were;
Steer 13280
Drive 18480
Tag 9780
Total 41540
No choice but to re-weigh the coach. I'll git that done and report back.
Thanks for all of your comments.

Don, that looks better, try 95 in the drive and 75 in the tag before you weigh. If you are still towing your tracker, and it is on the 3rd scale platform, don't forget to subtract its weight from your tag weight.

Re: Tag Axle Loading

Reply #16 – October 05, 2018, 05:22:39 pm

NO, disconnect the toad before weighting. No point in potentially getting erroneous results if 5 minutes of "unhook/rehook" can fix it.

Re: Tag Axle Loading

Reply #17 – October 05, 2018, 05:35:07 pm

Quote from: wolfe10 – October 05, 2018, 05:22:39 pm

NO, disconnect the toad before weighting. No point in potentially getting erroneous results if 5 minutes of "unhook/rehook" can fix it.

Have tried it both ways, found tag weight the same by subtracting the toad weight as tag weight weighing without the toad. Weigh platform does not care where weight is on platform, it just records total weight. As I mentioned in reply #1, I had to find this out the hard way.

Re: Tag Axle Loading

Reply #18 – October 06, 2018, 10:16:21 am

Just re-weighed the coach this morning with very similar results to Thursday's.
today Spec Plate data GVWR
Steer 15060 14800 46800
Drive 10160 21000
Tag 16520 11000
Total 41740

No toad involved 1st or 2nd time. Near full fuel, 1/4 water, 0 sewer.

OK, here is what is different from factory weight
1. 12KW Generator was replaced just before I bought coach. Original Genset and inverter was a hybrid type, whatever that is...
2. I replaced tag air bags just after purchase. Originals were delaminating- very scary.
3. 4 months ago noticed evidence that both tag tires were in early stages of tread separation. Moved newer steer tires to tag axle installed 2 new tires on steer.

My fleet manager and I agree that we should push the tag tire pressure up to 110 or so due to the heavy loading until we find a solution. We speculate that this condition has existed since I bought the coach. Leaving Thursday for NE Tennessee then to KC Mo. If I can't find a solution, this will eat on me the whole trip.

The coach drives and handles just great. It has the HWH Active air system .So, what the heck is next?

Re: Tag Axle Loading

Reply #19 – October 06, 2018, 10:37:20 am

Call James Triana and find out how tag axle weight is adjusted on your coach.

May be adjustable air pressure, ride height valve, other? Again, have not worked on your model coach.

The tag axle is SEVERELY overloaded!

Re: Tag Axle Loading

Reply #20 – October 06, 2018, 10:55:26 am

I just learned something. The HWH Active air controller has a screen that shows air bag pressure. I started engine and set for travel and scrolled to that screen. After it reached equilibrium, it individually shows in round numbers;

Tags 125 PSI ave
Drive 31 PSI
Frt 78 PSI

System Pressure 128

I can't say that I have ever looked at this screen while in travel mode before now. The book says nothing about changing the settings/ pressures for each bag. My guess is that either a sensor has malfunctioned and is telling the system to add tag air or there is a programming disorder. Looks like a call to James or HWH is in order.

Re: Tag Axle Loading

Reply #21 – October 06, 2018, 11:00:01 am

Appears that the Active Air System actually sets the air pressure in all your airbags. If your tag bags are overinflated, they will put excess coach weight on the tag axle. and you adding more air to tires will just increase the load on that axle. I would read your Active Air Manual.
https://www.hwhcorp.com/ml47147.pdf

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