Is the frame of the PD4106 steel or aluminum?

matzeinusa · June 07, 2021, 10:58:55 AM

Just wondering.
Thanks
Matt

richard5933 · June 07, 2021, 04:03:57 PM

There is no frame on a 4106, at least not in the traditional sense. Same for nearly all GM intercity coaches. They are true monocoque construction with the bulkheads, lower bay floor, and shell making a structural unibody construction similar to an airplane's fuselage. There are some steel panels involved, like around some of the windows, the front and rear caps, and a few other places. The remainder of the construction is aluminum but for some structural steel in the engine cradles and a few other supporting sub-structures.

Truly an engineering marvel that our GM buses roll down the road with no frame rails.

TwoFeathersRD · June 07, 2021, 04:13:58 PM

Here is a photo of the underside of a 4106 we just purchased

luvrbus · June 07, 2021, 04:16:06 PM

MCI's and Prevost have no frame either , GM has steel roof bows for roll over protection and engine mounts from the roof,GM's have enough steel to rust too

6805eagleguy · June 07, 2021, 04:58:57 PM

Can some one tell me if a mci dl3 has frame rails

luvrbus · June 07, 2021, 05:08:09 PM

Quote from: 6805eagleguy on June 07, 2021, 04:58:57 PM
Can some one tell me if a mci dl3 has frame rails

No frame on the MCi DL3

richard5933 · June 07, 2021, 05:34:43 PM

Don't MCI and Prevost buses have more of an exoskeleton than a GM bus though? If you pulled off the skins on one of those you would still have the outline of a bus made by the exoskeleton. On a GM, pull off the skins and not much is left.

Utahclaimjumper · June 07, 2021, 07:53:30 PM

What else does it really need.?? >>>Dan

freds · June 07, 2021, 11:48:05 PM

Quote from: richard5933 on June 07, 2021, 05:34:43 PM
Don't MCI and Prevost buses have more of an exoskeleton than a GM bus though? If you pulled off the skins on one of those you would still have the outline of a bus made by the exoskeleton. On a GM, pull off the skins and not much is left.

Yes Prevost's do have an exoskeleton. I found this diagram in the parts manual.

Plus when I was installing my solar panels, I first drilled through aluminum and then steel...

Dave5Cs · June 08, 2021, 12:41:18 PM

"On a GM, pull off the skins and not much is left."
And you think that is a good thing?

dtcerrato · June 08, 2021, 04:36:23 PM

Quote from: Dave5Cs on June 08, 2021, 12:41:18 PM
"On a GM, pull off the skins and not much is left."
And you think that is a good thing?

Yes, it's monocoupe and needs no exoskeleton, neither does our Grand Cherokee toad...

luvrbus · June 08, 2021, 04:45:45 PM

LOL GM sure have a ton of rivets holding the skins on to metal for a true monoscope

Nova Eona · June 08, 2021, 06:06:17 PM

Well back in the day they couldn't use computer models to determine exactly how many rivets a bus would need holding it together to last the designed service interval, so they just put an absolute crapload of them on. 60+ years later, here we are enjoying them still.

gg04 · June 08, 2021, 06:40:01 PM

Lol ....Exoskeleton = frame... aka birdcage Maserati...

Dave5Cs · June 08, 2021, 07:22:41 PM

MCI are similar and if you pull off the inside wall panels and the outside skin without supporting the rest it would collapse. The baggage bays are supported by the above Monocque Frame above but only as the panels support it. The front and the rear are supported with the Bulkhead front and rear and the engine is supported by a truss on either side of it that it sits on.

Found this on an engineering site;
Monocoque means "one shell" or "single skin". Almost nothing is a true monocoque -there's always some load condition that can't be sustained by a single shell. It's become a marketing term.