cost of production

[azz7772]

Apparently we are thinking along the same lines. I’m a hydraulics designer (started at Cat on that specialty) and Eaton is one of my major vendors and I spec out their stuff all the time. My first thought is that I wouldn’t use anything but hydraulic motors on each wheel. I know I could make one go 100mph and enough torque to pull a house off of the foundation.



I have never laid eyes or hands on that Hydrotraxx (I think that’s the hydraulic one) that I know of but I have to wonder why that design is not the unchallenged leader in performance. I could put multiple accessory loops on it and power just about anything from the same pump. I’ve searched the web for any type of technical info on those models and so far have not gotten much. If the project gets approved I imagine one of the team will buy one just to examine it. I cant say much more right now because I have not seen the motors and pumps along with their control circuit they are using. Just based on the comments on the thread devoted to them I wonder if that unit is not substantially under-engineered. Maybe they had to power it down because it might have more available power than the body and frame in their units could handle. I don’t know but I really intend to investigate the hydrostatic units on the market because that would be my first choice on speed, power, torque, overall weight and simplicity/reliability.

I like your thinking but at 2500 per drive motor that's 15000 for a 6x6 and 20000 for a 8x8 before anything else to be cost effective you need to only use one per side and also get rid of the chains everyone hates chains.

[mudNmallards]

I like your thinking but at 2500 per drive motor that's 15000 for a 6x6 and 20000 for a 8x8 before anything else to be cost effective you need to only use one per side and also get rid of the chains everyone hates chains.

I dont know where you got those figures but with Eaton their top end charlyn line motors come in at about $400-600 each and the pump is about 1,500 that would power all of them.

[kadookid]

another major cost is legal fees,to protect the company, one fatality and lawsuit is why cushman dropped the trackster. PS the nick name kaddookid actually came from the 70's when I terrorized the neiborhood with my kadoo most did'nt actually know my name I was known as that damn kid with the kadoo, and the name just kinda stuck. Mike.

[azz7772]

I dont know where you got those figures but with Eaton their top end charlyn line motors come in at about $400-600 each and the pump is about 1,500 that would power all of them.

what size motors you talking about and do you not need two pumps my predator has Eaton char-Lynn 4000 series hydraulic motors and Eaton manually controlled variable piston pumps I got my prices off the net if you can get them for that price that is awsome .......... I just relooked and they are around 700.00

[Outdoorsy74]

Hydrotraxx and Mud Ox have hydrostatic drives from what I've gathered.

When I first got my Max II I was thinking of using hydrostat motors (1 per side) to get the same turning/steering capabilities as my zero turn mower. Adding it in place of the jackshaft then chains or cog belts to the wheels. For suspension you could mount the motors inside backspaced wheels, run the hoses up inside with a protective loom, and the spindles would be mounted like trailer torsion axles into the frame.

As for the body- kevlar reinforced fiberglass or stamped steel, maybe even the high density hard plastic like a truck box material. The frame- dom tubing.

Just thinking out loud.

[Robinhood02]

so who's in on designing and building a new machine ?? i can design and build the fiberglass tub and top molds for a proto, and i have an idea for the suspension on an 8x8 but it won't work on 6x6

http://www.6x6world.com/forums/max-atvs/16721-dear-recreative-industries-my-wish-list-you.html

[azz7772]

so who's in on designing and building a new machine ?? i can design and build the fiberglass tub and top molds for a proto, and i have an idea for the suspension on an 8x8 but it won't work on 6x6

walking beam?

[Robinhood02]

yup

[azz7772]

yup

have you seen the wolverine before it is made in Saskatchewan but very pricey

[Robinhood02]

nope never seen it before, but it apears the walking beam works LOL, why do they allways have to make them so big and bulky ?? that thing looks huge for an aatv

[kadookid]

the walking beam (hendrickson) suspension would be ok for an 8x8 but a 6x6 would still have one rigid axel, it looks like it would ride smooth but if you ever drove a semi with a Hendrickson suspension I guarantee you'll feel every little crack in the road,if we all could sit down at a huge round table with a chalk board I'm positve with the caliber of open minds that we have we could reinvent the aatv.

[mudNmallards]

what size motors you talking about and do you not need two pumps my predator has Eaton char-Lynn 4000 series hydraulic motors and Eaton manually controlled variable piston pumps I got my prices off the net if you can get them for that price that is awsome .......... I just relooked and they are around 700.00

Just give me a little leeway because I’m conferencing this week and all I have is my personal laptop so I don’t have my applications information with me so I’m answering somewhat from memory so I cant answer you “exactly” right now but will do a follow up post in about a week with more precise detail if you want or a PM.

In most cases Hydraulic motors are spec’d out by RPM and torque rather than hp and that price was off my head from a set of hydraulic reciprocating screens for a mine in Oz. I used reversing gerolers to accommodate shock factor if memory serves because it had to shuttle but I’ll check the BOM when I get back there.

My price would probably be substantially different because I’m a tier III industrial purchaser ( tier II in some cases because I don’t buy much of a lot of things) so consider about a 20-60% discount and no tax on industrial MRO depending on a number of variables such as type, volume, extra features and whatnot. That’s important because any manufacturer is going to get that same rating even if they start out as a Tier I- they will work into it. Also, if you hug your distributor and offer them some advertising usage (should it work) and tell them you are prototyping a new design, they will often donate some stuff or “find” factory rebuilds or warranty returns somewhere in their system at substantially reduced prices and even free sometimes. Many of them also have tons of “secret” applications and usage data because chances are someone else has also already experimented on the application you are using and you may find the distributor “smile” and see some crumpled up paper on the floor by the chair when he leaves. Don’t thow that paper away without reading it first. LOL (remember- they WANT you to be successful and they WANT you to use their product but much of this stuff is IP or other customer data so you cant just ask for it openly but [especially Eaton] are VERY capable of helping you)

I have not even begun sizing motors yet because until you have a gross weight, wheel size, desired ground speed and desired torque along with any reversing/braking capabilities you really cannot even begin the typing (gearotor, gearoler, vane, piston etc) and selection of flow etc. Since I’m not the designer of the frame/body and our group has not even come close to deciding operating parameters I have to wait for that. I just already know there is one sitting on the shelf ready to go- I just have to figure out which one it is. Since these systems have to be designed from the motor back the type and number of motors (6 or 8) and “everything else” will determine the pump size/type, engine size requirement, accumulators, cooling and reservoir size. ( not to mention any additional accessory loops you may desire) That will also tell you whether you can direct couple to the axle or whether you have to use a belt or sprocket configuration to either increase/decrease the RPM and torque at the wheel.

Regarding the number of pumps- that’s the beauty of hydraulics. Your prime mover and control piping have an almost infinite number of combinations. You can do a series system and have a pump per side driving each side or a single pump and control each motor independently (or together or left/right drive sides). That decision is best made after you decide how you want the system to work.

[jpswift1]

I just wanted to put this out there, but you guys should also consider the heat that's produced by all those hydrostatic motors. The Mudd Ox 8x8 is hydrostatic drive, and it doesn't even have motors for each wheel, it has motors which drive chain to the axles (one or two per side I believe) and the machine is very prone to overheating. AATVs somewhat closed in drive compartments don't circulate much air and with all the heat produced from all the hydrostatic drive motors (one per wheel), even with electric puller fans running, I'm sure that the overheating would be an issue.

The Super Swamp Fox had a very limited run of hydrostatic drive systems, but they did away with them quickly because they were also very prone to overheating and they went back to the good old reliable T-20 transmission.

[mudNmallards]

the walking beam (hendrickson) suspension would be ok for an 8x8 but a 6x6 would still have one rigid axel, it looks like it would ride smooth but if you ever drove a semi with a Hendrickson suspension I guarantee you'll feel every little crack in the road,if we all could sit down at a huge round table with a chalk board I'm positve with the caliber of open minds that we have we could reinvent the aatv.

I am NOT the suspension guy ( closest thing to a suspension I do is a torque arm for a gearbox or vibration dampers on pads) but we have an automotive designer on the team and I work close with him because if we decide to do a suspension, his decisions will have a direct effect on my final drive and what I have to do. If anyone has any specific questions about suspensions let me know and I’ll forward them and try to get you an answer. His information made us go back and seriously reconsider whether a suspension is really the way to go because of the necessary requirements to put one on the unit that would function properly and last along with being affordable.

We got a good class (and education) the other week when we were discussing suspensions for an application such as this so I’ll share some of the take away points I was given.
Any suspension that actually accomplishes something due to the shock factors will mandate a substantial metal frame and probably body as well because if the forces are not absorbed in a large mass it can tear itself off the unit.

His suggestion was a spring over strut design because it would allow for modular installation, independent wheel control, simplicity and be lighter when compared to other beefier designs as well as the cheapest way to go.

Unless you want to sacrifice some of the performance characteristics over uneven terrain by using a solid axle tube driving L&R wheels or half shafts with a heavy support per wheel, you would almost have to use a zeppa type CV axle.

Any suspension will require substantial “X” axis support more than the “Y” because weight, inertia, torque and the terrain itself will want to force the wheels/axles to bend inward under load. (“X” being linear forces along the wheel side and “Y” being the up/down movement so you are facing a caster/camber type force) Look under a vehicle- there will be a strut with rubber bumpers or sway bar holding the wheels and keeping them from folding in should the vehicle hit something. This goes back to that “substantial” frame and the associated weight along with the cost.

Those were some of the key points we were given. Looking back on some of the parts manuals here after Ben’s class looking specifically at the frame/axle relationships- I think I’m beginning to see why the majority of these vehicles don’t have a suspension. I’m sure in my mind that every manufacturer has thought about a suspension and probably experimented with some designs and I would be willing to bet they encountered everything he pointed out and decided that unless they completely redesigned the frame/tub it was not financially feasible. It certainly can be done mechanically but the question is can it be done financially and light enough.

[mudNmallards]

I just wanted to put this out there, but you guys should also consider the heat that's produced by all those hydrostatic motors. The Mudd Ox 8x8 is hydrostatic drive, and it doesn't even have motors for each wheel, it has motors which drive chain to the axles (one or two per side I believe) and the machine is very prone to overheating. AATVs somewhat closed in drive compartments don't circulate much air and with all the heat produced from all the hydrostatic drive motors (one per wheel), even with electric puller fans running, I'm sure that the overheating would be an issue.

The Super Swamp Fox had a very limited run of hydrostatic drive systems, but they did away with them quickly because they were also very prone to overheating and they went back to the good old reliable T-20 transmission.

Oh yeah, heat is a hydraulic systems most deadly enemy and since all force is transmitted through the fluid it gets real hot real quick. If you don’t cool it- it will boil itself to death in short order. The good news is that because this is a mandatory requirement for almost every hydraulic system and there are all kinds of ways to cool it adequately.
You just need to figure out how many BTU’s the system is generating and size the cooling system accordingly. I’m nowhere near that point yet but my first thought would be dual exchangers (1 per side) with fans pulling engine heat also at the end of the circuit and maybe a kidney loop exchanger to filter and pre cool the reservoir before the fluid hits the pump.