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    Default Single Rail verse Double Rail Frame

    Hey all. I need some help with a very critical issue we are facing. We are in the process of specing out a tanker to be purchased through the AFG program. It will have a 3000 gal tank, 750 pump and a crew cab. We were reduced in price to $250,000 and are having a terrible time finding a manufacturer able to supply such a unit in this price range. We do have one quote offering to complete this purchase for right around the grant amount. The problem is that the chassis does not have doubled frame rails. Will this unit still be safe without the double rails? Or would we be making a mistake by making this purchase? Thank you for your help.

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    Only one? Imagine that! Wonder why.

    I know of at least one chassis builder who absolutely will not supply a single rail chassis for that much water.

    Stay safe out there, everyone goes home!

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    That would be a huge mistake.
    Put it this way, when specing a Spartan you automatically get a double frame when you go above 1000 gallons.
    Stay away from anyone that tries to sell you a single frame 3000 gallon tanker. They are obviously more concerned with making the sale then anyones safety or the longevity of the rig.

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    Default Single Rail Vs Double Rail

    Listen to Vanisle EVT and other's DON'T even consider a Single Rail for this application and the difference should only be maybe about $1,000-1,500 for a Double Rail.

    Also depending on the body design have you thought of or would a Wetside Tanker work with the 3,000 G and 750 GPM Pump? Take a look at Danko Emergency Products, S&S Fire etc.

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    This manufacturer has to put out a chassis that passes the DOT standards, correct??? I am looking through the other specs that I have and for the most part, the inner frame is 1/4" rail. When I compare the ratings, they definitely increase, but only by about 25%

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    Quote Originally Posted by SAFETEK View Post
    the difference should only be maybe about $1,000-1,500 for a Double Rail.
    We are being told that the difference in cost could be as much as $18000 to $20,000

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    I'm working on spec/quotes for a similar firegrant project but 1500gpm rearmount CAFS pumper tanker w/3500gal tank. Sure looks to me like you should be able to do a fine job at $250k. Send me private email with whatever details you have. I'm still discussing final budget # with DHS. If they are going with $250k for 3000gal and small PTO pump that's good info.

    Check out www.jeffersonfire.com recent deliveries. Several similar trucks and THEY LIST SELLING PRICES. Nice info few provide. Might also check out www.hgacbuy.com they have contract prices on tankers.

    Chassis well equiped for fire service will run $90-100k. I'm looking at the spec for a IH 7600 (Workstar). Frame reinforcement after applying discount is $741.

    I have a .pdf for full spec from the HGAC IH vendor for an ext cab 7600 I'll email you if would like. Nice that they itemize every single option/item with it's price. Found that I can get similar/better price from local IH dealer (and haven't even started negotiations).

    a crewcab will run you around $8k. Might think about an extended cab. Cost on the 7600 is $1500. You can still get 2 or 3 FF on the rear seat (no SCBA). Do you really need the extra seats on a tanker? We finally decided just overkill for us and made a large truck even longer/less maneuverable.
    Last edited by neiowa; 08-19-2007 at 10:19 PM.

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    Quote Originally Posted by neiowa View Post
    I'm working on spec/quotes for a similar firegrant project but 1500gpm rearmount CAFS pumper tanker w/3500gal tank. Sure looks to me like you should be able to do a fine job at $250k. Send me private email with whatever details you have. I'm still discussing final budget # with DHS. If they are going with $250k for 3000gal and small PTO pump that's good info.

    Check out www.jeffersonfire.com recent deliveries. Several similar trucks and THEY LIST SELLING PRICES. Nice info few provide. Might also check out www.hgacbuy.com they have contract prices on tankers.

    Chassis well equiped for fire service will run $90-100k. I'm looking at the spec for a IH 7600 (Workstar). Frame reinforcement after applying discount is $741.

    I have a .pdf for full spec from the HGAC IH vendor for an ext cab 7600 I'll email you if would like. Nice that they itemize every single option/item with it's price. Found that I can get similar/better price from local IH dealer (and haven't even started negotiations).

    a crewcab will run you around $8k. Might think about an extended cab. Cost on the 7600 is $1500. You can still get 2 or 3 FF on the rear seat (no SCBA). Do you really need the extra seats on a tanker? We finally decided just overkill for us and made a large truck even longer/less maneuverable.
    Just keep in mind that some of these rigs on the Jefferson Fire site were delivered a year or two ago (or more), so the pricing will reflect that. Unfortunately, the inflation of anything fire service related seems to be more than the typical cost of rising materials, etc. I work for the company, so I wanted to make sure this wasn't a surprise...
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    Double rail all the way. Overwhelmingly I think that is the consensus here.

    I have something to put out there for the chassis Mfg’s reading this, or general opinions– a question really.

    Are there any plans in the near future to fully utilize hydro forming for Boxed frames? Obviously I am not a designer, but “boxed” & “hydro forming” seem to be the way the big three have gone for strength and 4 sides are stronger than three –

    Less material required for equal or better strength in principle, increased RBM, etc.

    It would seem that whomever offers this first would have a "practical" corner on the market (not a gimic), so what is everyone waiting for? TL
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    Is he buying a commerical or custom chassis. If custom and frame is designed for vocational use/heavy may not need extra "beef" tacked on. The commerical guys design for light weight then tack extra steel on as required for "heavy duty" applications.

    Takes a big press to form 12" truck frame rails of 3/8" steel compared to the puny little frames that Chevy makes for a pickup/Vette.

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    I understand the use of the press Iowa, but hydroforming is what I am getting at ( & not really a press).

    Because of the strength imparted by the shape and the forming process itself, the thickness of a given frame would be reduced. While car and truck frames are relatively thin compared to the chassis used in the FS, they aren't that thin.

    All of the big 3's frames used to be alot thicker before they started boxing and hydroforming and since boxing and hydroforming, GVRW's have done nothing but go up. Surely this could be done in the FS. my /02. TL
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    I think the problem with a hydroformed frame rail is that the crossmember location would have to be predetermined. The voids in the frame would need a support everywhere a fastener passes throught it or it would crush when tightened. With c-channel you just punch or drill it where ever you like. Much easier to make different wheelbases. Auto manufacturers only offer a handful of wheelbases, on trucks that is.

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    Quote Originally Posted by neiowa View Post
    Is he buying a commerical or custom chassis. If custom and frame is designed for vocational use/heavy may not need extra "beef" tacked on. The commerical guys design for light weight then tack extra steel on as required for "heavy duty" applications.

    Takes a big press to form 12" truck frame rails of 3/8" steel compared to the puny little frames that Chevy makes for a pickup/Vette.
    This is on a custom cab application with tandem axles. From the spec:

    "Each rail shall measure 11/32" material formed to a "C" channel shape with 3-1/2" flanges x 10-15/16" web. The section modulus shall be 16.92 cubic inches per rail and the RBM shall be 2,031,000 inch-pounds, per rail."

    They also offer a lifetime warranty against cracking or breaking. What are the possibilities with a unit with these rails?

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    Default Bounce

    Be very careful even on a custom cab with a single frame rail. The truck you have discribed is bigger than the 2 units in my area having bounce issues as we speak. On is a commercial 1000 gallon rescue pump and the other is a 100' custom cab aerial. Both trucks have an extreme and violent bounce while driving, it has become so bad they have had to take them out of service. These trucks both have single rails and they have both been told by the manufacture it is there problem because it was the way they spec'd it. The frame warrenty won't play into this until it breaks and my guess is when it does it will be your problem because you spec'd it wrong.

    We have double frame rails on all of the trucks I was involved the first didn't really need it but for $1400 it cost us it was cheap insurance on a 30 year truck.

    Good Luck! Congradualtions on the grant!

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    No box frames for me,thank you.Up here in sodium heaven, box frames last about half as long as their conventional counterpart.As far as a single frame,there are a lot of variables.Cross section,material,thickness of stock will all play into the finished rail.Like the others,I would be leary of a single with that much water although I have seen them in the past.I think you would be better served with a double and the price SHOULD NOT be significantly higher. T.C.

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    Quote Originally Posted by Tower47 View Post
    Be very careful even on a custom cab with a single frame rail. The truck you have discribed is bigger than the 2 units in my area having bounce issues as we speak. On is a commercial 1000 gallon rescue pump and the other is a 100' custom cab aerial. Both trucks have an extreme and violent bounce while driving, it has become so bad they have had to take them out of service. These trucks both have single rails and they have both been told by the manufacture it is there problem because it was the way they spec'd it. The frame warrenty won't play into this until it breaks and my guess is when it does it will be your problem because you spec'd it wrong.

    We have double frame rails on all of the trucks I was involved the first didn't really need it but for $1400 it cost us it was cheap insurance on a 30 year truck.

    Good Luck! Congradualtions on the grant!

    I contacted the dealer today to ask about this issue. He called me back after 2 hours of investigation and assured me that the engineers have looked into this and that the single rail frame will perform fine without placing the inner rail in the frame. He also informed me that the only double frame applications they have is with the aerials. I asked if we could have the double added to our spec and he informed me that it is not even offered as an option. On the units with the bounce problem, are they tandem axle units? Also, what manufacturer if you do not mind. If you do not want to post it, please email me direct. Thank you all for your insight.

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    Quote Originally Posted by Tower47 View Post
    Be very careful even on a custom cab with a single frame rail. The truck you have discribed is bigger than the 2 units in my area having bounce issues as we speak. On is a commercial 1000 gallon rescue pump and the other is a 100' custom cab aerial. Both trucks have an extreme and violent bounce while driving, it has become so bad they have had to take them out of service. These trucks both have single rails and they have both been told by the manufacture it is there problem because it was the way they spec'd it. The frame warrenty won't play into this until it breaks and my guess is when it does it will be your problem because you spec'd it wrong.

    We have double frame rails on all of the trucks I was involved the first didn't really need it but for $1400 it cost us it was cheap insurance on a 30 year truck.

    Good Luck! Congradualtions on the grant!
    Just looked at my chassis quoting software, and for the brand of chassis I sell, for a 2007 chassis, quite a bit under $2000 will get you double frame rails. What if I say between $1000 and $2000? Don't want to get any other dealers who sell the same chassis in a lather because I give away pricing...
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    Quote Originally Posted by imafireman View Post
    I contacted the dealer today to ask about this issue. He called me back after 2 hours of investigation and assured me that the engineers have looked into this and that the single rail frame will perform fine without placing the inner rail in the frame. He also informed me that the only double frame applications they have is with the aerials. I asked if we could have the double added to our spec and he informed me that it is not even offered as an option. On the units with the bounce problem, are they tandem axle units? Also, what manufacturer if you do not mind. If you do not want to post it, please email me direct. Thank you all for your insight.
    I dunno, I could be wrong, it's certainly happened enough times before, but I'm getting the feeling that this dealer or his factory has something to unload and is looking for a fish.

    Stay safe out there, everyone goes home!

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    Default No more double frames for us!

    I have little experience with fire trucks, but I have extensive experience with highway plow trucks. It is a different kind of abuse, but it's still abuse. The impact these trucks take on the framerails forward of the front axle and the side impact they take because of the rear mount for the side wings is incredible. The difference is the single frame is able to be cleaned and therefore lasts longer. Double frames hold the corrosives between them. By the time a problem is visible, it's too late.

    Sterling recognized the the problem and developed a single frame rail strong enough to meet most requirements. When we bought our last truck, Peterbuilt still had not addressed the issue. It all depends on the manufacturer of the frame, but double frames don't always exceed the specs of a well designed and manufactured single frame.

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    Quote Originally Posted by mongobob View Post
    I have little experience with fire trucks, but I have extensive experience with highway plow trucks. It is a different kind of abuse, but it's still abuse. The impact these trucks take on the framerails forward of the front axle and the side impact they take because of the rear mount for the side wings is incredible. The difference is the single frame is able to be cleaned and therefore lasts longer. Double frames hold the corrosives between them. By the time a problem is visible, it's too late.

    Sterling recognized the the problem and developed a single frame rail strong enough to meet most requirements. When we bought our last truck, Peterbuilt still had not addressed the issue. It all depends on the manufacturer of the frame, but double frames don't always exceed the specs of a well designed and manufactured single frame.
    Now, that corrosion issue on a double frame I've wondered about. Just looking at a doubleed frame it's easy to see where the salt/slush would settle and sit.....Forever. Can't get at it to wash the stuff out.

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    Quote Originally Posted by mongobob View Post
    The difference is the single frame is able to be cleaned and therefore lasts longer. Double frames hold the corrosives between them. By the time a problem is visible, it's too late.
    I have seen this too - on more than just firetrucks as bob says. I would also say that a box frame if designed and formed correctly could easily account for fasteners, cross members, and a ready ability to shorten the frame where required (the same as is currently done on c-channel frames in the FS). I also see no reason a boxed frame cannot be properly washed out to prevent corrosion - I have been doing it for years on more than one vehicle.

    ps. Iowa, on a previous posting (another subject) you were as correct in terminolgy as I was when you said "stiffness". It took a while to come to me but "Young's Modulus" is what you were getting at, my appologies, TL

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    Quote Originally Posted by SSIaerialmanTIM View Post
    ps. Iowa, on a previous posting (another subject) you were as correct in terminolgy as I was when you said "stiffness". It took a while to come to me but "Young's Modulus" is what you were getting at, my appologies, TL
    I did notice on the spec I have with the single frame that it talks about MODULUS and RBM I believe are the letters. What are these numbers representing and how do I apply that to our situation? Also, is it possible to have a frame that is to heavy? Once again, thank you all for your insight. It is very helpful.

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    Default Getting technical

    Quote Originally Posted by imafireman View Post
    I did notice on the spec I have with the single frame that it talks about MODULUS and RBM I believe are the letters. What are these numbers representing and how do I apply that to our situation? Also, is it possible to have a frame that is to heavy? Once again, thank you all for your insight. It is very helpful.
    When dealing with truck frames, modulus is usually referred to as SM or Section Modulus.

    Truck frame strength is the structure's ability to resist yielding, buckling, fracture, and fatigue.

    The section modulus (SM) is an engineering term that indicates the strength of a frame by the shape of its section. The SM in truck frames relates to vertical loads on the frame rail, and is expressed in in3. The SM of a typical frame section is calculated by this formula:

    SM=(BxH3)-(bxh3) 6H

    SM= section modulus B=outside flange length H=outside web length b=inside flange length h=inside web length

    RBM (resisting bending moment) is the product of the material yield strength and the section modulus of one sidemember. RBM is used as a means of comparing the relative strength of sidemembers with different geometry and fabricated from different materials. RBM equals SM multiplied by yield strength of material.

    These numbers mean very little by themselves. They become VERY helpful when comparing competitors if they are willing to supply them. It gives you an opportunity to compare the frames "apples to apples" because the numbers are based on the assembled frame, not just a side rail or a crossmember.

    My experience has been that any manufacturer willing to discuss these numbers with you isn't afraid of the long term durability of their product IF they understand the numbers themselves.

    Just to clarify, I'm not an expert. I have however found these numbers to be very helpful in determining a frames ability to hold up to impacts caused by underbody and wing plow mountings. Every frame gives a little. The important thing is, will it return back to it's original shape!

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    Quote Originally Posted by imafireman View Post
    I did notice on the spec I have with the single frame that it talks about MODULUS and RBM I believe are the letters. What are these numbers representing and how do I apply that to our situation? Also, is it possible to have a frame that is to heavy? Once again, thank you all for your insight. It is very helpful.
    What are the other mfg (custom cab) building for chassis that would meet your spec? Single frame (similar dimensions) or reinf frame (std or as option)? If similar trucks in similar price range are all single frame (with warrenty) that may reassure you.

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    Tim,I invite you up to my section of the woods where I can show you any number of 5-10 yr old box frames that are JUNK.Granted these are small imported pickups but you don't see this damage on C frames.Could they be washed out? Perhaps but you still have that residue sitting in the bottom of the section.I'm prejudiced,I'm NO fan of a box frame and that goes way back to reparing them in the 60's and 70's.I DAMN sure don't want one on my truck for these and other reasons including assembly.If you like 'em,you're welcome to my share.Double/triple frames are prone to the same damage but you can repair those even though it's a tedious job. T.C.

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