UNICAT Expedition Vehicle: Subframe e Chassis
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- Опубліковано 10 тра 2020
- The frame assembly is the foundation of your home on wheels.
Its function is to connect the body with the chassis, just like the foundation of a house serves to anchor it to the land it stands on.
If a house is situated on a slope, a sandy beach, rocky ground, or perhaps even in an earthquake zone, in each case the foundation is different, in each case it adapts to the particular conditions of the substratum.
It's the same in vehicle manufacture: the connection between body and chassis must be adapted to the selected chassis, the body size and weight, and the purpose.
As to purpose, there are two fundamentally different categories: on-road use and off-road use.
For pure over-the-road operation-and thus for 99.9 % of all trucks-the subframe recommended by truck chassis manufacturers is adequate; the body is rigidly bolted to the chassis via the subframe, which introduces the little torsion generated into the body. This is quite sufficient for a normal haulage body with no cut-outs in the side walls and no interior finish. But if the body is a container for transporting gases or liquids, then for this type of body, in which the torsion would cause cracks, the chassis manufacturers specify a more sophisticated subframe that makes limited use of the three-point mounting principle-even for pure over-the-road operation-in order to keep chassis torsion occurring in road operation safely away from the body.
For off-road use, a simple subframe is far from adequate; even a subframe with three-point mounting would be a bad compromise.
The body specifications of Mercedes-Benz accordingly stipulate the compulsory use of a torsion-free floor unit for the Unimog, whereas subframes are deemed adequate for trucks-with or without all-wheel drive.
The fact that the engineers of Mercedes-Benz Unimog have developed a special torsion-free floor unit specifically for their chassis, with its great cross-country capability, shows the need for a sophisticated technical solution and is in the best tradition of that company.
The question whether such a floor unit is necessary only for the Unimog, or also for trucks in off-road use, can be reduced to this: do other laws of physics apply to the Unimog? Therefore, from the outset UNICAT has used torsion-free frame assembly for all the vehicles it builds.
How does the torsion-free frame assembly of UNICAT function?
The chassis should be suitable for cross-country driving and afford good directional stability and road adhesion at high speed. The flexibility designed into it by the manufacturer must not be restricted. Frame distortion ensures that the vehicle retains ground contact with all four wheels even in extremely rugged terrain. Only then can it move safely off-road.
The shelter, on the other hand, is designed as a sturdy box and should permit only minimal distortion. Of course, this likewise applies to the permanently installed furnishings and technical equipment.
If you've ever loosened ice cubes from their tray, you know what the effect of deforming the tray is: the ice cubes separate from it.
What is desired in that case-to make the ice cubes fall out of the tray-should be avoided at all costs where body and furniture are concerned!
So, chassis and shelter should be connected in such a way that no torsional forces at all are transmitted from chassis to body.
The torsion-free frame assembly of UNICAT, like the frame assembly of the Unimog, therefore always consists of one fixed bearing and 1 or 2 self-aligning bearings.
The fixed bearing acts to locate and fix the body in the middle and transmits forces in all directions.
The self-aligning bearings in the forward and rear third transmit forces only in certain directions so that the vehicle frame beneath can twist freely.
When frame distortion occurs, it is no longer possible to introduce body weight pressure evenly into the now twisted frame. In the UNICAT frame assembly, the forces are thus introduced into defined areas of the frame. The principal forces are introduced exactly where the rear axle is attached to the frame so that the load on the frame is even reduced.
The intended freedom of movement between frame and body also must be taken into account, of course, when pipes and cables are laid and the tanks and other frame add-ons are fitted.
All in all, this is a problem of considerable complexity that only can be optimally solved if body and frame assembly originate under the same roof-as at UNICAT.
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Sir, I really love your engineering explainations and how humble you are. Be happy, healthy and blessed.
I've been searching for this information for a week now. This video answered all my questions. Only a German can explain engineering well. Thank you very much.
Thanks Thomas, it is quite impressive how much the frame and subframe are able to twist. Great explanation!
Thank you so much for share your knowledge with us. Greetings from Brazil!
Thank You Thomas for this Excellent video. Thanks UNICAT!!! Atte: Pedro LEON
A very good and informative video thank you!
Fantastic explanation, I see for truck offroader unicat seems to have the right expertise.
Thank you for dedicating this interesting moment to us
Thanks so much.
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very informative! thank you for sharing!
Thanks so much.
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I love this guy!!!
Thanks for that impresives videos! regards from Spain!
well explained, thank you!
Thank you very much for sharing your knowledge about these technologies involved in the manufacture of your trucks, which I am a great admirer and fan of! One day I hope to fulfill my dream of having such a truck, even a small one would be very happy! congratulations!
Thanks so much.
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You could use a chassis with highly articulated suspension, like a Tatra.
Great video.
very-very cool!!! UNICAT+MAN - Best from the best!
Thank you for sharing this video so interesting
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Would love to see an updated video with wheel lifts that are that 20 cm higher. that maximize cab to chassis twist.
Great video !! How many degrees can it withstand sideways before it overturns?
Hi Sir, I love your vehicles and wonder if you ever think to build them over a Tatra base?
some things i wonder about is would it be possible to make the cab and living space into a single unit with this subframe design? and would it be possible to have air bags to support it similar to how the cab is mounted to the frame? and what about stability with how the center of gravity shifts due to the box? also would having a independent suspension for the tires alleviate the need for frame twist, or would it be better paired together? im not sure what to think on these variables.. racking my brain constantly isnt proving effective for integral parts so id love to hear your ideas and reasoning behind how you do these things. oh and sorry to add context to my questions, ive had the dream for a long time to make a expedition vehicle and almost every time i get a second to think plans and designs riddle my brain and answers are far and few between on the internet so its just been left to speculation on my part.
WONDERFULL VIDEO
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Dear Unicat Team! First of all thank you for that video! I know that top hamper suppliers usually do not care about the chassis especially when it comes to frame torsion. It is often seen as given. However, even though all wheels are on the ground there is definitely a high risk that you introduce deformations into the chassis that induce plastic (=permanent) deformations in the crossmembers of the shown MAN TGM when you lift the chassis by 400mm diagonally. Even more, in the long run if you perform such maneuvers repeatedly then there is a risk of cracks or loose rivets and screws in the chassis! Did MAN approve the driving maneuver (400mm) you show in this video?
Before we started building expedition vehicles on truck chassis which is more than 20 years ago, we had asked for information about the chassis torsion but finally had to find out by ourselves. When you do the calculation, you will see that the twist of the chassis rails will not cause plastic deformation.
I agree that there is a risk of plastic deformation caused by creeping if you leave the chassis twisted for a long time.
But that is nothing you want to do and will do in reality. More than 90 % of all traveling typically happens on paved roads, 9% on tracks and there are always only few situations where you need the full offroad capability of your vehicle. So the time and number of load cycles is very limited.
At our UNICAT vehicles, we never had problems with loose rivets or bolts on crossmembers. But that certainly is also related to the fact that we oversize and stay away from the limits.
The 4x4 UNICAT TC59 which you have seen on the Video has a weight of appr. 12 tons but the chassis is a 18 ton chassis.
Thank you for your time and your extensive explanation!
you could use some custom made spring body mounts instead of a sub frame . . . the spring mounts will compensate for the flex (twist) in the chassis frame, regardless of the degree of flex . . .
Thanks guys, great explanation, best I have seen. As an aerospace engineer myself looking for a truck I find this very interesting. Can you explain a little the advantage of having the pivot at the front? Is it possible to do it the other way around or is this optimal? Many thanks, following with interest and hope to introduce a truck into my travel series one day. 👍
if you watch the Live streaming that we recorded on Monday 11.05.2020, there is a lot of information about it.
Pivot is at both front and rear, the solid mount is in the centre, where there is the least twist.
Nice explanation! I would like to ask you where did you buy the pneumatic lifts you are using in the video? Or at least what I have to look for? Thank you.
in the warehouses of products for truck mechanics, where they also sell lift trucks, but we bought them almost 30 years ago 😂😂
It is great job and brilliant idea Thomas and team, well done. My question is how do you control the unnecessary swing of the box, how do you dump this effect if the box is completely free to swing around the pivot, have you considered installing some sort of small lightweight shock absorbers or something similar under the two sides?
There is no dampener. I love the engineering and explanation given by Thomas and Unikat.
is a sub frame necessary to install a rear chassis frame mounted camper body unit???
Will constant twisting cause stress fractures in the chassis?
Now I know the purposed of those center pivots for. But speaking of longest travel of rear suspension setup. Unimog has more travel in their suspension set up in 6x6 configuration, because the Unimog 6x6 rear suspension design is like independent suspension. While comparing to Man or Mercedes 6x6 rear setups that are using big springs which are link to the two axles. Just for my opinion.
Many thanks for that impressive demonstration! Always better to actually see it then just to read about the theory.
Also thanks for pointing out to consider the twist on add-ons mounted on the chassis (e.g. tanks) and all the other parts.
Many try to figuere out the max. twist by lifting the wheels with a forklift etc. But this is only static. I think the twist in dynamic conditions while driving rough terrain would be much higher. As the manufactureres are not providing the details, how is your approach for actually getting the maximum chassis torsion?
Keep up that great source of information 😉
Viele Grüße, Florian
Thanks for your nice words.
Please use a wireless microphone for future videos. Thank you anyway for the knowledge sharing. Excellent.
Dear sir ,i was a year ago by a concurent and a engineering showed me a zetros and he didnt know that the beams where double i ask him why in Breda i mean with that one beam into an other . Is that wy the zetros is famos or is it unnessecary ? It still keeps in my mind, and again i will make the unicat team people a very great compliment in the thinking of the technical design of your own volvo pherhaps overdesignd but thats what we need in the force of the field where they are for designd, the technical knowhow is in the veins of you and your people and somethimes this a curse, but mostly a heaven to do , kind regards acgm Vermeulen.
Hallo Thomas,
in UNICAT are you working only with MAN or also with Mercedes Zytros?
Viele Grüße
Hi, we use any type of frame, depending on the customer's requests.
So...what does the gas mileage work out to?
有没有tatra的
👏👏👏👏🥂🥂
Thanks so much.
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need to increase the suspension travel on the rear wheels (especially the rear most wheel since it's a 6X6) . . .
We will talk about it in Live # 6, Monday 18.05.2020 at 18.00 German time
TATRA truck is superior in everything. I'm just waiting to be electric, to buy Three.
It possibility open the door...
Yes, of course, we thought when we were done, you're right.
It would have been a great video if I could hear anything....
I'm sorry, you don't hear anything, but there was wind and we made the mistake of not using a microphone. We will try to improve this too.
Use external microphone please.
We had bought one but it didn't work, we will improve this too.
Na ja, wenn Qualität von Unicat ist so gut wie die Aufnahme, dann danke schön.
Fortunately we are better at making Expedition Vehicles than videos.
Unfortunately cause Covid 19, we have to make arrangements internally to make videos, without video professionals, only Thomas and a Unicat employee.
We are trying to do something useful for everyone, since the Abenteuer-allrad exhibition was canceled this year.
If you don't like them or if you find them poor, you can always watch something else, UA-cam is full of videos!
Good day
UNICAT Expedition Vehicles - ich schaue gerne Unicat Fahrzeuge und bin zu 100% an Qualität gewohnt!!! Desto mehr hatte mich das dilettantisch aufgenommene Video geärgert! Alles Gute 👍
Sorry, aber das ist schon ein bisschen überheblich Herr Kowalski.
Seien wir doch dankbar und froh, dass ein solcher Hersteller sein Wissen an alle Kunden und Interessierten einfach so kostenlos weitergibt.
Klar, der Ton ist teilweise schlecht, aber wie ich gelesen habe ging das externe Mikro nicht. Kameraführung usw. ist doch alles ok...
Wer lieber eine im Studio gedrehte Seifenoper schauen will, bitte schön, das Netz quillt über davon. Wer jedoch fundierte Infos zu solch einem Spezialthema sucht, der kann wahrscheinlich sehr gut auch ohne Ü-Wagen, Kamerateam, Tontechniker, Beleuchter etc. produzierte Videos leben.
ChaosCamperCouple - tut mir leid aber das stimmt nicht ganz was du schreibst. Es gibt viele Beispiele von super Filmen, aufgenommen nur mit Handy und zusatz Mikrofon auf UA-cam. Man muss nicht beim Wind, Regen, oder anderen störenden Geräuschen aufnehmen.
Interesting and informative video👍 awful sound quality👎
Leider spricht Ihr nur Englisch und kein Deutsch.
Being able to build trucks for millions but also being to stupid to use wireless microphones and a wind protection.
And please do me a favour: Please speak in your nativ language and use subtitles. Combined with your creepy audio it is a pain in the ass to listen to you.
We had bought one but it didn't work, we will improve this too.
Wow, how greatful you are for getting some in depth information for free... Thomas is German but nevertheless makes an effort to speak in an international language which most of the people will understand.
They are not a professional TV company but still share their valuable knowledge with us, for free. If you are interested in the topic, you will manage to understand all of the video. Just as I and many others did.
But in cases like yours, I propose to switch the channel and watch some sit-com etc.
@@ChaosCamperCouple
I must admit, I was not particularly polite, but that was quite intentional.
It's strange that I have to be grateful for free knowledge.
It's more about paying attention to details, because as a potential client I realize that you can't manage to spend a few hours of work and maybe 100 - 200€ for better sound. If it doesn't work even with such small details, I wonder if the vehicle is of the same quality as the video.
Well meant is the opposite of well done.
@@goainge2
Well, for me it's strange not to be greatful for free information, especially when people put effort in providing this to us.
For example, when you look at other companies in this segment, they present some nice shots of their vehicles in some remote area but you don't get any real information like this.
OK, maybe it's also some advertiment for such a company, but I rather doubt that many of their customers will decide to by a Unicat based on such videos... But for those really interested in the details, they get some real good points to consider when checking the quality of builts of different brands.
Also I cannot understand how you could compare the quality of their work with their videos? And as they said, they will also improve quality in the future... ;-)
@@ChaosCamperCouple
I doubt that you understand me, and I do not have the time and energy to correct your misinterpretation.
BTW: Do you get percentages? ;-)
Thanks for that impresives videos! regards from Spain!