Outer Limits 4x4 Board

I was wondering if anyone had experimented with hydraulic drive on this forum.

Anyone tried setting up such as system, or know anywhere for some good shots of someone who has?

I can see a lot of good reasons both for and against using such a system, particularly for the front wheels, and just wondering..........

I have never played with the idea but 1madengineer has often told me how it can work!

Each wheel has a separate hydrostatic drive and each wheel can have any speed in any direction (just like a bobcat).

The thing is it could only max out to about 20 kmh.!

Yes its good for Rock Crawling but go to the UROC site or watch some VIDS of the UROC, EROCC, and Calrocs and tell me how well it would go!

Not only is it going to be HEAVY, but crawling can only get you so far!

Waste of time and money, if you want ideas for ROCK DRIVING/CRAWLING this is what i think people need to aim for!

POS wrote:I have never played with the idea but 1madengineer has often told me how it can work!

Each wheel has a separate hydrostatic drive and each wheel can have any speed in any direction (just like a bobcat).

The thing is it could only max out to about 20 kmh.!

Not going to do it on my own Vitara - Im not THAT serious.


Just interested. The potential for effectively unlimited suspension travel (just need some way of rolling up the hoses when it's compressed) and individual control of wheel direction and motion could have some useful combinations - for instance turning like a bobcat as you said.

If you coupled it with hydraulic ram suspension then in theory you could make the 4wd raise or lower itself to whatever height needed to drive pretty much level over any obstacle, without concerns about driveshafts being too short for the obstacle or cv joint loading.

Of course, speed, weight and the potential for craking or leaking of hoses
are just some of the obvious downsides.

working for a company which builds hydraulic driven gearboxes, your idea isn't realy viable, the boxes are heavy, bulky and would be slow, hydaulic motors which we use most wont even pull 1000rpm, these are small motors which we then couple through plantaries to get the power required, this is unless you want to buy a wheel motor which = $$$$'s

I think that in-wheel electric motors have far more potential.
There are proto-types now that can provide 55kw of in-wheel power that weight 42kg (including gearing).
Think of one of these on each wheel...(and max torque available from 0rpm !).

Link to the proto-type (road) car...

http://www.popsci.com/popsci/auto/article/0,12543,463605,00.html

Battery weight looks to be the issue for quite a while however.

Sav

sav wrote:I think that in-wheel electric motors have far more potential.
There are proto-types now that can provide 55kw of in-wheel power that weight 42kg (including gearing).
Think of one of these on each wheel...(and max torque available from 0rpm !).

Link to the proto-type (road) car...

http://www.popsci.com/popsci/auto/article/0,12543,463605,00.html

Battery weight looks to be the issue for quite a while however.

Sav

I agree that the hydraulic drive would be too bulky. Electric would be the way to go for sure.

Potential for electric is enormous - instant torque on tap - nothing provides torque like an electric motor, no minimum engine speeds, no restrictions whatsoever for gearing, no issues about fuel delivery on slopes, about the cv angles or suspension travel limits etc. In fact this would be much easier than hydraulic.

Top speed should not be a problem - not with 220kw on tap.

The "engine" weight being on the suspended part of the body is a downside. As is the potential for electrical shorts in water, but there should be far less likelihood of any mechanical breakages of anything once the system is ironed out.

And of course they still have the ability to be driven independantly so that the bobcat/turning circle factor is still there.


I think the weight of the batteries is not gonna be an issue either since there is no need for an engine, gearbox, diffs, driveshafts or petrol tank. The weight could be pretty much placed whereever most suited (ie as low as possible, or centralised in the cabin.

Total running time is the main limit for electric cars, but for 20-30 minute stages this is a non issue (except maybe some of the night ones will need extra batteries) - the less time you need to run for the less battery weight you need.

A quick change set of battery packs shouldn't be too hard to organise, with a couple of sets in the support truck all charged up/being recharged.

Electric motors arnt that good. I dont think you are going to mount an electric motor on a wheel that has 10000ft-lb of torque that will operate down to 0 rpm on a wheel without a gearbox. you are still going to need a 100:1 gearbox to make it work.

And why bother around with hydraulic motors. The whole point of this 4wd thing is that it is all based on road going 4wd technology. If you are going to start using hydraulic motors (which have no use on a road going 4wd) then why not just use a helicopter or something. A helicopter would have to be the ultimate off road machine.

Sam

Strange Rover wrote:Electric motors arnt that good. I dont think you are going to mount an electric motor on a wheel that has 10000ft-lb of torque that will operate down to 0 rpm on a wheel without a gearbox. you are still going to need a 100:1 gearbox to make it work.

And why bother around with hydraulic motors. The whole point of this 4wd thing is that it is all based on road going 4wd technology. If you are going to start using hydraulic motors (which have no use on a road going 4wd) then why not just use a helicopter or something. A helicopter would have to be the ultimate off road machine.

Sam

Or tracks like a Bren gun carrier!

sav wrote:I think that in-wheel electric motors have far more potential.
There are proto-types now that can provide 55kw of in-wheel power that weight 42kg (including gearing).
Think of one of these on each wheel...(and max torque available from 0rpm !).

Link to the proto-type (road) car...

http://www.popsci.com/popsci/auto/article/0,12543,463605,00.html

Battery weight looks to be the issue for quite a while however.

Sav

You would need one hell of an extension lead.

The interesting thing about these in-wheel electric motors is that the required gearing is integrated into the 42kg wheel.
The car shown uses a 4.588 ratio (geared for a top speed of 190mph+ and a little high for a 4x4) but the principle is shown.
A 4x4 would have much more scope for gearing and electric motor capacity with the increased wheel size.

Who knows - if electric cars become common-place one day then this may be the future of our vehicles.

At the very least it would free up a whole boat load of design options !

It also doesn't have to be powered via a large bank of batteries.
A small 4cyl engine could provide a constant source of power generation to a smaller battery storage system.

Sav.

Battery powered vehicles (locos, shuttle cars unihaulers etc) have been around for about 40 years in the underground coal mining industry and are still common. A lot more reliable and safer than diesel power. One with two 10HP motors (Joy 8SC) can haul 8 tonne of coal. I know of one instance above ground when one towed a fully loaded semi coal truck that had blown a diff. Pulled it up a hill and off the road over a curb gutter as easy as. And their motors or wiring (flame proof) dont have many problems with water or anything else that I know of. Its all a matter of $$$.

sav wrote:The interesting thing about these in-wheel electric motors is that the required gearing is integrated into the 42kg wheel.
The car shown uses a 4.588 ratio (geared for a top speed of 190mph+ and a little high for a 4x4) but the principle is shown.
A 4x4 would have much more scope for gearing and electric motor capacity with the increased wheel size.

Who knows - if electric cars become common-place one day then this may be the future of our vehicles.

At the very least it would free up a whole boat load of design options !

It also doesn't have to be powered via a large bank of batteries.
A small 4cyl engine could provide a constant source of power generation to a smaller battery storage system.

Sav.

Pretty cool - good acceleration and 190+mph. Cut top speed down to 80-90 mph (or even 60mph) and imagine the grunt..... Or cut it down from 8 seats and 8 wheel drive to a 2 seater 4 wheel drive 1 tonner, keep the gearing and the acceleration the same even.

I wonder would we be allowed to compete in an a 8 wheel drive?

There's no reason why electric motors are not allowed on street registered vehicles so this is a relevant topic for this forum which a helicopter isn't - go look at Prius and tell me it's not street legal. Yeah we could use a hybrid system but for the time that the vehicle would be needed to run under it's own battery power I think it'd detract from the "pure engineering".


Maybe we should see about hovercraft too - but I suppose that might be taking the pi55......

Like it or not guys, this is our future in another 20 years or so anyway - whether it be hydrogen fuel cells or batteries makes no difference.

Imagine the potential suspension arrangements and weight distribution possibilities......... All your major weight (4x40 odd kilo) is at the lowest point on each of the 4 corners of the vehicle, and since there's no driveshafts or diffs your suspension options are incredible. Talk about low c of g.

I know I'd have the entire driveline out of my Vitara in a flash if someone was gonna offer me 4 of these for use.

Actually, since the car doesn't really need to be a 4wd since it doesn't need transfer case or any of that maybe I'd put it in a 120Y chassis for a laugh instead......

That might upset some of the Landcruiser boys!


Maybe Holden Australia could do that with their crappy Eco-mmodore instead so someone might get excited enough to buy one.....



You never know maybe a bored Holden executive might even find this thread while surfing the web....


In a sport where the potential for use of this type of engineering design seems to be quite well suited I'd think someone might be exploring some of these possiblities so I was just interested if anyone has given it a go yet, and whether they'd really come up with reasons it wasn't suitable.

Yeah I think that the limits of hydraulic are gonna be too much, but with the money being thrown at the development of electric and hybrid cars by the larger car manufacturers watch this space. 220kw actually at the wheels from 180kg is damn good going - you'd need something like 400kw at the crank on a 4wd to get that....

Now we are starting to talk around in circles - we got a petrol motor charging batteries to run the motors.

I carnt think of any reason to put a wheel motor on each wheel. The added unsprung weight would be huge. To get the reduction down to something like 100:1 so that you can get torques near 10000ftlb at each wheel is going to take some fairly serious steel.

The reasons why electric powered 4wds wont work is the same reasons why electric cars dont work and are the reasons why nobody that is serious is mucking around with these things.

Its going to take a massive leap forward in electric power technology for any of this to be worth considering. The stuff is just way too heavy.

Sam

I don't think we are talking in circles.
There are a number of hybrid electric/pertrol cars in production today - and good reasons for doing this way (although probably only an interim step).

Have a look at the following link which I found after the original link.

http://www.autointell-news.com/News-2003/August-2003/August-2003-2/August-13-03-p5.htm

Shows that some people beleive in the possibilities and are trying it in real world applications (if only in prototype).

Sav

Strange Rover wrote:Now we are starting to talk around in circles - we got a petrol motor charging batteries to run the motors.

I carnt think of any reason to put a wheel motor on each wheel. The added unsprung weight would be huge. To get the reduction down to something like 100:1 so that you can get torques near 10000ftlb at each wheel is going to take some fairly serious steel.

The reasons why electric powered 4wds wont work is the same reasons why electric cars dont work and are the reasons why nobody that is serious is mucking around with these things.

Its going to take a massive leap forward in electric power technology for any of this to be worth considering. The stuff is just way too heavy.

Sam

Some of the improvements are already there - an 8 seat limo normally weighs 3 tons anyway so weight isnt really the issue anymore, it's more user acceptance and take up.

There aren't many 8 seat limos that so 0-100 in 7 seconds either....

Think about it - full 220 kw drivertrain - diffs, axles, engine, gearbox, transfer case and driveshafts for 180kg?

Too heavy - not in my book. What does all this weigh on your car? Even a small iron block V8 weighs more than that without any of the driveline that supports it. Add a few diffs capable of dealing with 220kw (300 hp) at the wheels! (maybe some 9"s front and rear) and you have a weighty beast.

The problem is the fact that if you drive off the wheels then it's unsprung. Hey - that's an engineering choice - you don't have to - you can put it in the normal diff location and run driveshafts if you want. Whatever works best for your application. No one said it has to be there.......

Sure unsprung weight is a problem for normal suspension arrangements, but you havent got the same suspension design limitations now - so I'm sure the right people can think around these problems.

Remember part of what the suspension does is keep the tyre on the road, but part of it is to keep the driveline connected to the wheel. Half that job isnt a problem any longer.

What is the weight of stub axles and brake discs, plus the proportion od axle/driveshaft weight that each shock/spring supports? Probably about 10-15kg less than the electric engine being suggested.

Remember a smaller lower output engine (or a different gearing for the motor) would be lighter if you dont really need 300hp. After all a 1.3 Zook seems to do ok with only 40 or so at the wheels - so maybe 4 30hp motors at maybe 15-20 kg each might be more appropriate - after all that's about the same power at the wheels as a stock 3.8 Litre commodore engine (about 130hp).

The MAIN reason why electric cars are not being used on our roads is not to do with their ability to perform, it's about RANGE and refuel network. These aren't an issue in this application.

It seems that the US military is a few steps ahead.

Check out this 4x4 that they currently have in testing (using in-hub/wheel) electric motors).

http://www.spacedaily.com/news/unmanned-combat-03a.html

Sav

The only reason why anybody is working on this crap is because governments are forcing car companys to go down this path of zero emisions.

This technology is a long way off being or any use and is a lot longer being of any use in 4wd competition rigs. IMO these people shouldnt even bother trying to make electric cars until the storage and charging problem is solved.

In fact I dont think that any of these electric cars are better than some of the production diesel cars that you can buy now. I think they are getting less than 2L/100km. Thats 4 litres to do 200km which is the range of these electric cars. To put this into perspective a 2L/100km thats say 1000L/50000km or say $800 per 50 000km. Now spend $800 on a set of tyres and they will be lucky to last the same 50 000km. So whats the point trying to get the fuel enonomy down to impossible levels when the cost of the fuel is the cheep part.

And of course where is the electricity comming from??

I just dont see the point.

Sam

Hey i was just reading in another FORUM about this thing called a HOVERCRAFT, it sounds unreal!!! It can go over land and water and can really CRAWL along, it has no drive motor so its very light blah blah blah!!!

Guys wake up and smell the roses!!!

We are here to 4wd and advance on whats already been given to us, not to create a monstrosty that at the end of the day will be totally useless anyway! (Refer Chainlink, i doubt we will ever see that compete again)

Here's a challenge!!

If its so great and easy to do then build it, when you have built it give us a call and we can go out wheeling sometime.

I think the best part of that would be at night back at camp we should have plenty of power to run the lights!!!

Really doesn't matter what the US military are up to there motives to use this technology is a combat requirement and not a economic one.

Stealth, low signature and multi use are a couple of reasons why they might use this stuff. Payloads, reduce running gear weight for more counter recon kit. etc. The US rarely do stuff because it is either cheap or economic. They just like to win.

If you really want good Power to weight ratios why not run a small gas turbine. Low emissions and constant torque.

Missus could also do her hair with twenty others whilst chin wagging.

I never said it was better or worse - I said there was potential and that potential deserved investigating. I am not a mechanical engineer, nor a guy working in a workshop with enough time and access to develop these ideas.

The US army thinks there is sufficient potential for their needs, and have backed it with investment...

Whether or not the potential becomes "better" or "worse" depends on the engineer and the application - I doubt there's many applications out there that currently match the needs of the forum, so mods to existing engineering solutions would be required.....

Still it's good to see some discussion - and some people are more than happy to show their views one way or the other.

There is no right or wrong decision here, or correct or incorrect decisions either. People either believe there is a potential benefit in looking at the possibilities or don't.

However responses that don't give any justifcation other than "it's not as good as my diesel" don't cut it with me if you're serious about looking at the best engineering solution.

Given the money some of yuo have thrown at your rigs, or are considering throwing at your rigs, this may be worth investigation or may have been investiagted before.

Strange Rover wrote:The only reason why anybody is working on this crap is because governments are forcing car companys to go down this path of zero emisions.


And of course where is the electricity comming from??

I just dont see the point.

Sam

Because some people believe they have a right to use 3 mpg to get to point b from point a doesnt mean this is a good thing or sustainable. Even 30 mpg. There is a lot more than the use of fuel to deal with - the cost of infrastructure (eg roads maintainance and creation, parking spaces pollution control, health issues fue to pollution etc).

You have to understand the governments aren't just being mean and taxing car companies and forcing them to introduce Zero and LEV cars for no reason. There are damn good reasons for doing so, other than just the $$$$. Maybe 30 years ago we didnt understand that be we do now.

Additionally, Fossil fuels take a damn long time to manufacture, so oil is a limited resource, unless you're prepared to wait a few hundred million years for your next tank of juice.......

Of course, it the power station is coal fired this argument is pointless, although I can't really see coal fuel conversions being economically viable in the near future either.

I havent taken in to account petrol tank weight, fuel pump weight, carburettor/injector/injection computer or fuel line weight in calculations either.

Likewise I havent included battery weight, since I cannot accurately estimate the amount of time the vehicle will be running at or the average electical load. Hence I would have been relying on wild estimates at best.

Suzuki Viagra wrote:I never said it was better or worse - I said there was potential and that potential deserved investigating. I am not a mechanical engineer, nor a guy working in a workshop with enough time and access to develop these ideas.

The US army thinks there is sufficient potential for their needs, and have backed it with investment...

Whether or not the potential becomes "better" or "worse" depends on the engineer and the application - I doubt there's many applications out there that currently match the needs of the forum, so mods to existing engineering solutions would be required.....

Still it's good to see some discussion - and some people are more than happy to show their views one way or the other.

There is no right or wrong decision here, or correct or incorrect decisions either. People either believe there is a potential benefit in looking at the possibilities or don't.

However responses that don't give any justifcation other than "it's not as good as my diesel" don't cut it with me if you're serious about looking at the best engineering solution.

Given the money some of yuo have thrown at your rigs, or are considering throwing at your rigs, this may be worth investigation or may have been investiagted before.

Im the guy that said "its not as good as a diesel" AND I gave an explanation to as why it isnt and why considering electric powered cars at this point is a waste of time.

I didnt think I could make my case any clearer.

I dont have to go and spend $$s to find out if this idea is any good. I can very easily tell that to progress down this path at the moment is a waste of time.

The only people backing absolute zero emmisions are governments because they are trying to be seen as being "greener".

Sam