Front wheel drive car hauler
 

While surfing around the net today I came upon this page:

http://www.perftrlrs.com/Products_low_floor.html

It's an article from Performance Trailers about a new Marmon Herrington design for a low profile van body.

http://www.perftrlrs.com/images/FRONT004S.jpghttp://www.perftrlrs.com/images/REAR001S.jpg

This new design is mainly for delivery vans but could also be used as a car hauler. There are a couple of guys on the board who are contemplating doing something like this with their trucks and I thought they might be interested in seeing this truck and maybe doing a little more research to get more ideas for their projects.

As for the rest of us, how many of you are going to get one of these prebuilt trucks? They can't cost more than what, $40-40K for a bare chassis. They would make a great truck hauler. All you have to do is tell the little lady you are going to get one, nothing to it :-X02

There's a local guy that went the home made route using an Olds Toronado FWD set up. To me using FWD in something designed to haul a lot of weight is asking for trouble, unless of course, you've got the bullet proof engineering that M-H brings to the effort.

I'm guessing you couldn't pull a trailer very easily. Unless you hitched it to the truck you're hauling on the back. I'd be curious to see how badly the front tires wear out on that big guy. It is a tremendously unique approach to hauling. I've seen trailers built that way, but I've never been comfortable with type of axle that's used. Like Truckdog said, the M-H badge makes it much more comforting.

As per a recent previous thread, these M-H front wheel drive vehicles are very well made and when used in the proper application, do a terrific job. I have two of them in my fleet. One is a 1999 International 4000 series bus which has been in continuous service. It has an 8,000# capacity front drive axle and a variation of the "Dallas Smith" independent air-bagged rear suspension (GVW=19,000). It's suspension pieces all made of stainless steel, as is all of the coachwork. M-H took their truck axle's 12,000# knuckles and bearings and derated this axle to 8,000# as they thought it would be more abused as the only drive axle in the vehicle. It is also their first (in modern times) drive axle with the pinion located on the outside (passenger's side) of the ring, as you face forward from the transfer case. This now would make the vehicle go in reverse when the transmission driveshaft turns in its normal dirtection. So, they added a forth shaft to the tranfer case (more correctly called a "drop box" since it has no output to the rear axle). This now reverses the rotation to the front axle. The advantage of the outside mounted pinion, is that it moves the front axle "bowl" and the front prop shaft away from the engine and transmission oil pans, and allows the vehicle to sit lower that the typical all wheel drive heavy duty truck. I also have a 2005 Freightliner M2 low floor M-H FWD and it has a 16 foot van body on it and a 12,000# M-H front axle (GVW=26,000#). The bus floor is 14" above ground and the van floor is 18". Makes for easy transfer of passengers and/or goods as the case may be. Neither vehicle has demonstrated any unusual front tire wear, over that of a typical all wheel drive truck of the same type, and the rear tires seem to last forever (its similar to a semi-trailer's tires). Of course, we like M-H's as we have about 25 all wheel drive trucks that get used every day. By the way, the bare chassis' cost every bit of $45,000 and then you have to add about $18,000 for the FWD conversion.

Marmon, I'm confused by your description of the pinion being outside of the ring gear, and this moving the bowl away from the engine pan etc. The big part of the bowl would be where the ring gear is, so if the pinion is outboard of that, the bowl would be pushed towards the engine?

I don't see how the rear suspension on the new model shown gets any travel, either. The floor of the box area appears to be about flush with the top of the axle beams, or is that something else?

I've always wondered why they don't make school buses lower, they look like Conestoga wagons. Seems like they would be real prone to rollover. A design like this would help.

That just makes them REALLY fun to watch on a windy day. :-D

Stu, there's a guy locally that built a car hauler from a coe cab on a custom frame. He used a Toronado front clip mated to a rectangular tube frame, with air bags front & rear. He reminded me that the '70's GM front drive motor home used the same drive train sucessfully. Don't know what what rear axle it had, but with the air bags it could get very low for loading.

Sorry if I wasn't clear enough:
By on the "outside of the ring gear", I mean that the pinion is located on the right side of the ring gear (towards the street side of the vehicle when viewed from the driver's seat), instead of on the left side of the ring. Placing the pinion on the left of the ring, as is the case in virtually all front drive axles, provides forward motion of the vehicle when the front drive pinion (and of course, the front driveshaft) is turned counterclockwise (again, when facing front from the driver's seat), the same as would be the case for the rear driveshaft when driving forward. Now if the complete center differential section (ring, pinion, spider gears, etc.) of the axle (or "bowl") is placed on the left side of center, the typical left side location of the pinion places the propshaft further outboard of the vehicle's centerline. This is a good thing, as stated before, to keep it away from the engine/transmission oil pan. The problem comes from interference with steering gear and linkage being on that side in the same location, especially with medium and heavy duty trucks. So on this class truck, the bowl is almost always mounted on the right side of the vehicle, but the pinion would normally be located to the left of the ring gear and be so close that the suspension would have to be raised for the front driveshaft to clear the oil pan and the tranny. With M-H's design of having the bowl to the right side of the truck and putting the pinion on the outside (or right side) of the ring gear, the front driveshaft is moved as far as possible from the vehicle's longitudinal centerline. Now the rotation is wrong as far as matching the rear driveshaft, but that is covered by using a four shaft t-case or dropbox instead of the usual three shaft case (which wouldn't change rotation). Meritor came out with this a few years ago as well, but their t-case is a cast iron unit that weighs over 650# and their front axle is a one-size-fits-all (10,000# to 16,000# capacity) and it weighs about 1,850#. This is qiute a bit of dead weight to add to a truck/bus in the 20,000# to 30,000# GVW range. M-H uses a German made ZF brand t-case which is work of art from a design and construction standpoint and has a die-cast aluminum housing - weight is 250#. The M-H front 12,000# capacity axle only weighs about 1,000#, so there's over a half ton difference in the systems. Interestingly, both brand t-cases have the front output shaft in the exact same location, making it possible to mix and match, as I had to do a few years ago when we couldn't get the ZF t-case and I used the Meritor case with the M-H front axle.
The rear suspension on the low floor front drive vehicle's is fully independent, and there is no connecting beam between the left and right sides. That's how you can drop the load floor even lower. There's no rear driveshaft to begin with, and if you eliminate the axle beam you don't have to allow for it and room for it's suspunsion travel. The rear suspension has individual trailing arms with a Firestone air bag at each side, and the roll center is better (lower) than a typical beam axle with leaf springs. This combined with the lowewred center of gravity of weight that the truck/bus is carrying, combine to produce a more stable vehicle. The air in the rear suspension can also easily be exhausted when stopped in a loading mode, making the floor another 4" lower.
Hope I did better at explaining this time around.

Thanks, Marmon! I get the picture now.

Re: the Z-F dropbox; it may well be an engineering masterpiece, but if past experience is any guide, I'll bet it is a 6-to-9 week wait for the simplest seal and they'll need to know the full serial # so they can tell which shift it was made on, and which of 27 engineering revisions it incorporates, etc. Between them and Bosch I know I'll never own a European car!

I know the ZF t-case sounds like an aftermarket nightmare, but it really isn't bad because M-H stocks all of the parts stateside. Many of the M-H axles offered in the last twenty years have been made in Hungary (their center pinion planatery hub reduction units which have a GFAWR from 14,000# to 23,000#). In fact, we ran in-service field tests on one of the first prototype ZF t-cases and at the conclusion, M-H supplied us with a new, late production t-case and installed it. We've never had a problem with getting M-H parts, but we do have a long history, having purchased AWD Ford/M-H trucks almost every year since 1949. We do a lot of our own warranty work and get reimbursed from M-H.

My wife drives school bus and this year the bus company bought two bus to try out a new design and she drives one.

http://www.c2thefuture.com//_img/gallery/6.jpg

The bus is still rear wheel drive but the floor is lower than a regular bus and the ceiling is higher. The lower design is to help prevent children from going underneath the bus.

My wife's route is in a rural area and I wonder how this new design will work in a major snow fall. We haven't had one this year but in years past it has gotten pretty deep and I have a feeling this new design is going to get hung up in the deep snow or at the very least the lower panels will be damaged. She says the bus gets hung up on some driveway aprons.