Gross vehicle weight rating (GVWR) considerations

[xrvr]

Most if them are clapped out work trucks now.

[PSchw]

Originally Posted by InterBlog

My husband said the same thing - they do exist. When I pull listings it's almost always with the 2500 stock photo (including on cars.com), so I wondered if it were a misprint. Edmunds doesn't list them at all. But if I do a Google image-search, I see a few T1N 3500s. I've never seen one in the wild, and I eyeball every T1N that I pass.

Yes they do exist I had a 2004 3500 with rear dully wheels. I used it for work it was the long and high version.
It run grade with the 5 cylinder diesel. I always was thinking about making it to a camper van but then things changed and In sold the company with the Sprinter and purchased the Airstream Interstate a few years later.

Peter

[jdthor]

"How would you carry the two generators......" I used to have the 3K, which is actually quieter than the 2k, but traded it for the two smaller models because of the weight. I just throw the two Honda2k units into the back. They are easy to move around, and the parallel kit is easy to connect. The other advantage is that you can leave one of them at home if you know you won't need the ac on your trip. The little Hondas are attractive theft targets, however.

[InterBlog]

Originally Posted by jdthor

...The little Hondas are attractive theft targets, however.

Ugh... what are these manufacturers THINKING?! First thing I notice when I look at the pic is that it would be ONE MORE challenge for me to lock up. It looks like I might could run a chain through the plastic handle, but that's about it in terms of easy and direct measures. Why can't they bury a friggin' big steel eye-bolt in it or something? Gosh...

[Protagonist]

Originally Posted by Mcrider

Protag, do you know if anyone has successfully replaced the Onan and permanently mounted a Honda unit?

Can't mount a Honda underneath the van. The Hondas are too tall and would reduce the Interstate's already low ground clearance. If you want to use a Honda in place of the Onan you'd have to carry it on a hitch-mounted tray, or if you have the propane conversion carry it inside.

[Sebtown]

Interblog, check out the Honda website as they make a few different "theft deterrent" devices for their generators. We've resigned ourselves to the Onan as I don't want to add a rear tray and a Honda can not be practically mounted below as Protagonist pointed out. We try and use our Onan exclusively to charge the battery when boondocking on days when we can be outside and away from the noise. We're fortunate to live close to the Pacific ocean where we rarely need to run the AC. My son has a Honda portable and I must say I admire how quiet it is.

[bchali]

I just wanted to say something about the CAT Scale portion of your post. A vehicle weigh-in is a great idea for ANY Airstream owner. I will go through the specifics on how to quickly accomplish this at any CAT or (really) any other scale house that is available to you. You do not need to set up an iPhone or other way of payment, when using the following instructions.

At the scale:

• Get in-line with the other vehicles waiting (on the ‘IN’ end)

o The sign over the scale will show which end is the ‘Exit’

• Drive squarely onto the scale, keeping all tires on the platform

o The inside portion of the scale framed with the steel edges

• Go forward until your window is close to the CAT Scale sign post

o There will be a speaker box or phone on this post

• At this point you should quickly look (using your mirrors) to see that:

o ALL the tow-vehicle tires are fully on the first and/or second platform; and,
o ALL your Airstream trailer axle tires are on the next platform.

• Push the button (or pick up the receiver) and it will start ‘ringing’
• When the person on the other end speaks they will say:

o ‘First Weigh or Reweigh’?

• Answer this question by saying ‘First Weigh’

o ‘Company’?

• Answer with your last name

o ‘Vehicle Number’ or ‘Trailer Number’?

• Answer this with ‘999’ or whatever you like.

This requested ‘number’ is used by enforcement agencies to ensure that the CAT scale ticket presented is for the same tractor-trailer equipment the trucker he has stopped is driving. This ‘number’ does not need to be accurately shown on your CAT ticket, because you are not a commercial vehicle (CMV) and therefore usually not subject to Federal Bridge axle-weight or roadway capacity carry limits. You will never be asked to produce a Certified Scale weigh ticket, as this is information only you will find useful. The Maximum weight found on the registration paperwork for the tow-vehicle and trailer, will be used if necessary, for all computations (if any are required) for enforcement purposes.

Having these three pieces of information, the person operates the scale taking the weights from each of the platforms (if you are not fully on the platform, the weight is not accurate). This all takes about 10 seconds and then they will say, over the speaker (or phone) that they have ‘your weight’ and come on in to the fuel-desk or scale masters desk (usually it is the fuel desk).

At the Fuel desk:

• Say you have ‘scale ticket’ for ‘your last name or whatever you said’

The desk person will sign and then present you the shown ‘yellow’ CAT scale ticket, charging you the ‘first weigh’ price. Your Cash or Credit is gratefully accepted (most likely with a smile).

A reweigh (hence the question ‘first or reweigh’, when you were on the scale) is available because large semi-trucks have to generally move the trailer-tandems (the trailer axles) to shift the weight of the vehicle (forward or back) to equalize the weight carried on each axle set. This balancing act may take several ‘attempts’ before this is correctly accomplished, hence the re-weigh provision. This re-weigh may be free for ‘x’ attempts, but it is (almost) always at a price lower than a ‘first weigh’. This re-weigh must be attempted within a specified time frame (usually 24 hours, after the first weight ticket is presented).

If this pass is a subsequent weigh attempt:
• To the Question (once you on the scale and on the speaker or phone), “First or Re-Weigh?”

o Answer: “Reweigh”

• They will ask for ‘Ticket Number’ or ‘Weigh Number?’

o Answer (on a CAT Scale Ticket) is the number found in the lower LEFT corner of the previous ticket you received.

Once they have that number, the scale system again fills in the blanks, weighs the equipment, and they will then say come on in and bring money.

The weight on any vehicle axle, side-to-side, is not considered for valid for legal or for ANY other enforcement compliance review, because of the following reasons. The concern I have is that there is NO reason to attempt to weigh the vehicle side-to-side. What you have described is just dangerous.

If you have ever visited any of the many Facebook pages devoted to commercial trucking (or just browsed YouTube) there are innumerable examples of professional drivers ‘missing the scales’ and destroying their equipment by rolling those vehicles and attached trailers over. I will just call your side weight scale ‘technique’ lucky (being generous). The ‘Sprinter’ frame shown in the on-line pictures of the Airstream Interstate 22 foot vehicle was designed by MB/Chrysler to equalize the weight of the vehicle across the footprint. No matter how the weight is distributed, that being front to back or side-to-side, the overall weight of the vehicle, trailer or the entire combination, it is always, the ‘total weight of the vehicle’.

The ‘name plate’ or ‘manual’ GVWR is calculated by ‘vehicles’ manufacturer (using their engineering calculations) in compliance and guided by Federal Regulations.

Federal safety standards are regulations written in terms of minimum safety performance requirements for motor vehicles or items of motor vehicle equipment. These requirements are specified in such a manner "that the public is protected against unreasonable risk of crashes occurring as a result of the design, construction, or performance of motor vehicles and is also protected against unreasonable risk of death or injury in the event crashes do occur." See: Title 49 CFR Part 571 Et al.

This total ‘vehicle’ gross weight rating (GVWR) is based on:

1) The maximum weight bearing capability of the vehicle frame;
2) The weight bearing capability of the springs and other suspension components, per axle set (meaning across the entire axle); and,
3) When using the recommended tire sizes and load ranges on the manufacturer’s supplied wheels (this includes the proper inflation pressure as shown on the side-wall by the tire manufacturer).

It is assumed (per Regulation) that the vehicle will not be excessively ‘side’ loaded, which would enhance the possibility of roll-over. The design of the suspension is to prevent such side-load conditions (to the extent possible) and equalize the total weight to be carried center-line (middle) of the entire axle set. To an extent this GVWR calculation also provides some (10% or so) ‘side-load’ safety margin in case of suspension component failure. This margin provides for the safe stopping of the vehicle before a roll-over moment develops and any subsequent events are avoided. This does not mean you can exceed the GVWR to any great extent, without damage to the vehicle and the associated suspension components. Do so and you are just asking for trouble (and it gets very expensive, quickly).

[InterBlog]

Originally Posted by bchali

[FONT="Arial"]...

...The concern I have is that there is NO reason to attempt to weigh the vehicle side-to-side. What you have described is just dangerous.
.....

Welcome to Air Forums. That was quite an elaborate inaugural post.


The Interstate's mass is so incredibly much lower than everything else that pulls onto those scales that we didn't worry about what you describe. Plus the scale was new and built robustly like [a vernacular term that the mods would not allow me to use on this Forum].

The reason we did this is that we're designing a swing-away arm for a hitch carrier. In contrast to most other devices on the market, this carrier will attach on the driver's side rather than at the hitch receiver which is in the middle of the vehicle. We are not talking about a boat-load of mass, but my husband was concerned about the possibility of unequal side loading. Shouldn't be a problem with a small added mass, but if we didn't confirm how the vehicle was balanced to begin with, there was the outside possibility that we could exacerbate an imbalance that was imparted by Airstream, if one had been imparted.

To my knowledge, this subject had never been discussed on Air Forums nor anywhere else, and so we were completely without knowledge. The T1N Interstate is already close to GVWR in its empty as-built config, so any weight that is added should be evaluated from all possible perspectives. And of course in being two feet taller than it is wide, it's got stability issues even at the best of times. My husband is a mechanical engineer, and any design element that CAN be reality-checked WILL be reality-checked, even if the possibility of problem is small.

Anyway, that's the reason why we did what we did. It did not cause any problems for the scale owner, and did not reveal any issues worth worrying about with respect to balance.

[bchali]

Thanks for the quick read and I did not mean to offend. If that happened, please forgive me. The last post and the following comes out from my years as an Operations Safety and Compliance Officer, in both the commercial freight and passenger tour company environments. I'm recommending that you just keep it down the middle unless you have a special reason to 'really miss the scale'. This is more cautionary for those attempting this with tow-vehicle/trailer sets.

I understand your specific engineering input needs in this instance, however, depending on which scale you are using, sometimes it is just dicy when getting lined up and placed properly on the 'pads'. On those scales, that are just tough to 'get onto', even the pros miss! All drivers occasionally kinda miss (not all the tires on the 'scale') and there are times you have to wonder to yourself (as a former OTR type) "How did devil did I get on that one properly?" Occasionally, you will see that rollover 'mishap' even with a 2-3 million mile driver sitting behind the wheel.

Generally, innovative modifications (such as you describe) require engineering testing 'special dispensation' to ensure you have the margins required. On CMV's this 'innovation' would require an actual written approval from the FHTSA, issued to the manufacturer, before public road operation would be legally sanctioned. If this approval was not obtained, prior to public operation, then the liability picture shifts entirely to the owner of that (as least legally defined) 'dangerous' CMV equipment. If the OEM manufacture does not provide some sort of engineering approval after review, or they actually fully sanction this modification, your intended design (although, your engineering says otherwise) might lead to that legal conclusion of 'dangerous' under the existing regulations, if events required that level of examination.

My experience is that a letter to the engineering department of the 'chassis' manufacturers' engineering division, usually produces the needed engineering 'envelope' recommendations. They designed it and have the needed specifics (including hidden design features/performance numbers, all discovered during initial testing and field evaluations) that might not be available during any 'external' modification engineering development. Basically they have already done the work, and, if you just give them the numbers they are very happy to 'run-m Dano' (and, there my 'engineering' degrees show up).

This is particularly true when you are talking about Mercedes, who is known for their engineering expertise. You have to understand that beyond just automobiles, they are the builders of the long used European 'Sprinter' designed van/chassis; the manufacturer of the 'SETRA' tourbus line [one of the best designed and safest passenger tour coaches on the planet]; and, still the primary owner of Freightliner Truck (which includes the Detroit Diesel division), acquired when they merged with Chrysler/Dodge.

It is no small guess as to why Airstream picked this particular 'base chassis' to build their great product on top of! I bought my Airstream because of their expertise in building a great 'place to call home, away from home.' :{)

[ROBERTSUNRUS]

Originally Posted by Protagonist

You can get a propane conversion kit for a Honda Eu2000i. There are several threads on the subject here on the Forums. Not only that, but you could get a Honda companion unit to run two in parallel for home hurricane kit use, that would provide a total 4kW in place of the Onan's 2.5kW, and still weigh 26% less (46# each vs. the Onan's 125#). Really, the only benefit of the Onan is its low height that allows permanent mount underneath a Sprinter. In every other respect it's an inferior product.

Hi, I think if you check the generator specs. you will find that the Onan will put out 2.5 KW and the Hondas will put out 1600 watts each. [3200 watts for two paralleled] Not 4 KW.

[Protagonist]

Originally Posted by ROBERTSUNRUS

Hi, I think if you check the generator specs. you will find that the Onan will put out 2.5 KW and the Hondas will put out 1600 watts each. [3200 watts for two paralleled] Not 4 KW.

I stand corrected. But the point is still valid.

[73shark]

Off the Honda website:

EU2000i

(EU2000iT1A1, EU2000I1A1, EU2000IKN, EU2000IKC )
Features

• 2000 watts, 120V
• Ideal for TV/DVD, satellite, fridge, coffee pot, and more
• Super quiet
• Easy to carry - less than 46 lbs!!
• Fuel efficient - up to 8.1 hrs on 1 gal of gas
• Inverter - stable power for computers and more

[LB_3]

The new CAT scales we've seen are flush with the parkinglot and have a reinforced concrete apron all the way around. This is much different from the scales I've used at dragstrips that are elevated a bit above the return lane and would be dangerous to miss with a pair of wheels.

[ROBERTSUNRUS]

Originally Posted by 73shark

Off the Honda website:

EU2000i

(EU2000iT1A1, EU2000I1A1, EU2000IKN, EU2000IKC )
Features

• 2000 watts, 120V
• Ideal for TV/DVD, satellite, fridge, coffee pot, and more
• Super quiet
• Easy to carry - less than 46 lbs!!
• Fuel efficient - up to 8.1 hrs on 1 gal of gas
• Inverter - stable power for computers and more

Hi, if you go back to that same Honda site and click on "Specs" you will see this:
"120V 2000W max (16.7A) 1600W rated (13.3A)"

[InterBlog]

Originally Posted by bchali

Thanks for the quick read and I did not mean to offend. If that happened, please forgive me. The last post and the following comes out from my years as an Operations Safety and Compliance Officer, in both the commercial freight and passenger tour company environments. ...

Generally, innovative modifications (such as you describe) require engineering testing 'special dispensation' to ensure you have the margins required. On CMV's this 'innovation' would require an actual written approval from the FHTSA, ....
...

This is particularly true when you are talking about Mercedes, who is known for their engineering expertise. ...

Oh, no offense taken! On the contrary, I was impressed that anyone read all that stuff I wrote. I didn't initially explain why we did a side measurement because I didn't figure anyone would care or even notice!


To re-state what my husband LB_3 said, the CAT scale was basically idiot-proof. It was very new and well-designed, flush with the concrete surround.

And yeah, there are formal ways to do what we are doing, but this is strictly DIY. Mercedes may be known for their engineering expertise, but based on what we've seen out of Airstream so far, we do not take anything for granted. They altered profoundly what Mercedes produced and pursuant to that, we don't want any more surprises than we've already had.

[73shark]

Originally Posted by ROBERTSUNRUS

Hi, if you go back to that same Honda site and click on "Specs" you will see this:
"120V 2000W max (16.7A) 1600W rated (13.3A)"

Should have known because most, if not all, gensets are usually advertised that way. However most list the max and rated together. Lesson learned.

[bchali]

An example of 'missing the scale' (posted by Twisted Truckers/Facebook)..
Even though this is a 'flat design' it still looks really expensive..