Four Slide H-Series

[travelite]

Folks,

A friend of mine was poking around the new four slide H-Series shell at the Tampa RV Supershow. He snapped this quick shot of slide carrying structural enhancements made to the chassis. In the pic is a pair of 6" I-Beams, 0.25" thick, spaced approximately 6 feet apart. Very impressive:

http://lh3.ggpht.com/_gvgLrX-Wxk0/TTOVjY-uObI/AAAAAAAADsI/ggiao1C1KjA/s800/IMAG0034.jpg

[Jon Wehrenberg]

What Prevost has done is changed the structural part of the bus from a truss type beam running under the windows and on top of the axle structural assemblies (housings) to a "bridge" that runs from the top of the axle structural assemblies to the bottom of those assemblies (bottom of the bays) in between the axle structures.

Now cutting the sides of the shell to accomodate slides has little or no impact on the strength, but by shifting where the coaches get their longitudinal strength to the bays (which formally just hung under the truss) it has raised hell with the converters. Their job of housing all that goes in the bays is made much more difficult because of the corner gussets and the reduced space. It also impacts the owner who also has less usable bay space, something made more valuable by the loss of space due to the exhausts going out the roof.

But I would be very comfortable with the changes which were made by Prevost and would surmise them to be a better alternative to cutting through the truss and then adding back structural members to frame the slide opening.

[travelite]

(Pictures, compliments Wikipedia)

From a Pratt Truss above the axles:

http://lh4.ggpht.com/_gvgLrX-Wxk0/TTRwRVe2kYI/AAAAAAAADso/HzuXZbc9xjs/s800/Pratt_truss.jpg

To a Vierendeel Truss below the axles:

http://lh4.ggpht.com/_gvgLrX-Wxk0/TTRwVV6SucI/AAAAAAAADss/-xHdb0cqYoI/s800/Vierendeel%20Truss.jpg

[Jon Wehrenberg]

Exactly. Unlike motorhomes that use a pair of frame rails on a conventional chassis (including Newell) Prevost was never originally designed to accomodate slides. I suspect if Prevost could begin designing coaches today it would use that approach or something similar to what is now on trucks and most motorhomes.

Today's compromise allows the use of as many slides as desired, but the impact goes beyond the loss of space in bays. Today with multiple slides there is no provision for OTR and servicing anything located in the bays has gotten much more difficult. I suspect but don't know that with the longer wheelbase of the new motorhome shells (matching the entertainer shell) it is going to be extremely difficult for converters and owners to keep steer axle weights within limits so as motohomes evolve in the future I suspect owners of current vintages to resist trading up for new coaches because the product has not improved, it has just gotten newer. I'm not even bringing the impact of the new engines, urea, and roof exhausts into the equation, but that also is going to impact owner's decisions.

[jack14r]

David,I recently saw Millennium's 4 slide and you are right about the structure that has been added,my 2 slide has this structure on the slide side and I think that this started with the 2007 shells which have the slides that are referred to as no pin slides.Jon is right that this really created havoc for the converters in the bays,I know that Liberty had to redesign the generator cooling.This structure is much stronger than the previous coaches,I don't know if the converters that are adding their own slides are using this style coach,I do know that all Prevost installed slide coaches are engineered with real structural engineering considerations.

[travelite]

I agree John,

The development effort that Prevost has put into the multi-slide chassis clearly indicates their commitment to the market. It's clear that they've approached the multi-slide platform problem with their typical "multi-million mile" mindset. I for one am happy to see Prevost make the transition from bus to motorhome. Converters will adapt and we'll get through this engine mess!

[garyde]

Are those 6 inch I beams & corner gussets aluminum ? I can't tell but f they were they would probably reduce the shell weight from earlier coaches don't you think.

[Jon Wehrenberg]

They are steel or stainless steel. Since they appear to be unpainted I suspect they are stainless, not as strong as some of the steels available today, but in keeping with the stainless steel used in the "birdcage" frame.

[jack14r]

Mine are stainless and painted to match the rest of the interior of the bay.