Why no Hydraulic Drive Systems on roadcars?

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mike
2
Joined: 10 Jan 2006, 13:55
Location: Australia, Melbourne

Re: Why no Hydraulic Drive Systems on roadcars?

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im gonna ignore the comments made by giblet
to The FOZ
The FOZ wrote: you can push a major sized hydraulic ram, or produce a ton of torque...with nil horsepower and/or dynamic range.

Engineering types, please feel free to correct me as needed.
torque can be translated to horsepower via a set up gear
like the gears in your car, at 1st gear your engine may be going 300hp but your axle and tires are only doing 100hp, only at 4th gear(1:1 gear) or above will your axle do make the same or more horsepower as your engine
in over 90% of your daily driving, your drivetrain rarely makes as much horspower as your engine.

so if you use hydraulics to transfer the power to your wheels there should be no issues compare to normal axles at daily driving, and there is also a torque multiplying ability with all hydraulic systems.

hydraulic systems does creat heat, but it is not necessary to get rid of,and will benefit form HERS, since providing heat to the system will actually creat pressure and hence power. hydraulic system also have the ability to acommadate KERS. Reading about the artemisip system i believe that hydraulic drive does carry an advantage, or else a normal axle with flybrid would have been chosen to do the job of double the mileage of the car.

and about the efficiency of the system read the thread about hydristor

and something for you to think about xpensive if you introduce a setup/down system it will only have greater pressure when you accelerate and since you do not operate at max power at 1:1 gear or over at the most of the times i do not think thats an issue, and if you have taken account the improvements that could be made in reducing pressure drop with in the pipes, hydraulic system could be viable.

xpensive
214
Joined: 22 Nov 2008, 18:06
Location: Somewhere in Scandinavia

Re: Why no Hydraulic Drive Systems on roadcars?

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Torque without rpm is useless propulsion-wise, an F1-engine is only some 280 Nm (200 ft-lb) anyway.

And as for engine- vs wheel-power, the difference there is only a few percent lost for a conventional transmission, but much more if you convey power hydraulically. Anyway you cut it I'm afraid.
"I spent most of my money on wine and women...I wasted the rest"

avatar
3
Joined: 13 Mar 2009, 22:01

Re: Why no Hydraulic Drive Systems on roadcars?

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mike wrote:i not an expert at hydraulics xpensive, but can you take a look at this for me
http://www.artemisip.com/index.htm
That's fantastic.

I had the same idea (albeit minus the regenerative breaking/hybrid aspect) about 10 years back as a way to solve the "continuously variable transmission" problem, having decided expanding belts and cog systems would break (after building some bad examples in lego :wtf: ).

Their design appears different to mine. I'd come up with a non-infinitely varying system using

I never built anything as I don't really have the expertise & no idea what the efficiency would be. I did consider giving it a go, but had no funds at the time (I'd just left school).

I'd considered switching the throttle to a leaver (to set/tune the power output), then using the accelerator peddle to control the "rate of expanse" of the gearing.

This arrangement would change the mode we drive in:
- set the throttle
- the drive system automatically varies the gearing
- the accelerator controls the revs & therefore the rate of acceleration

The final version would have required feedback to regulate the throttle as a TC system, as perfect gearing for optimal power delivery (by which, I mean highest output) could just spin up the wheels.


This form of drive also has huge implications for power distribution to each wheel, allowing a potentially infinitely tunable differential applied to each wheel independently!

Will

p.s. thanks to "n smikle" for pointing me to this thread from here:
viewtopic.php?f=4&t=6548&start=15

Conceptual
0
Joined: 15 Nov 2007, 03:33

Re: Why no Hydraulic Drive Systems on roadcars?

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Giblet wrote:My daily driver has a hydraulic drive. Slow as hell, but who would want to drive a vehicle quickly when you are operating it from 80 feet above?
Image

So you think you are a good driver?

Driving one of these you get to chuck everything away :)
JLG actually subcontracts many of their chassis parts to some of my local machine shops...:-)

Too bad that they are laying off heavily now :cry: :cry:

Anyways, I posted about that BMW Hybrid here (viewtopic.php?f=11&t=5845) many moons ago, and didn't get much interest here...

So, if I were driving a car with 15" tyres, how many RPM's do I need to spin it to go 100MPH? I think with hydraulics, you would need to determine your max speed requirements, and then work backwards.

I think that this tech for motor/pump might be great (http://www.radmaxtech.com/) but I am also interested in the 325CC Freedom Rotary engines that are turbocharged to 60HP running a pump.

The last conversation that I had with the Hydristor inventor was asking if I could operate a single 8" diaeter hydristor connected to an engine, and install 2" hydristors in place of the wheel bearings in the uprights, and he hasn't given me an answer either way yet...

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Ciro Pabón
106
Joined: 11 May 2005, 00:31

Re: Why no Hydraulic Drive Systems on roadcars?

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Some comments on fluid power:

[youtube]http://www.youtube.com/watch?v=ycAgr6tpRQg[/youtube]

Hydraulic car test drive (it's horrible! :D): funny how it reverses and goes forward without stopping the engine. Notice how the suspension is hydraulically controlled (check the variable camber). Remote controlled, it seems. Probably one of the most boring videos I've ever seen...

[youtube]http://www.youtube.com/watch?v=_IL4a12b ... re=related[/youtube]

Hydrostatic off-road vehicle: built in the 90's. It no longer exists. At the end it tries to climb a wall. Well, sort of.

[youtube]http://www.youtube.com/watch?v=kXuckwyW ... re=related[/youtube]

Diesel hydrostatic bike. This one is actually cool!

[youtube]http://www.youtube.com/watch?v=t6G_YrGu ... re=related[/youtube]

National Fluid Power Association (in US): http://www.nfpa.com/
Ciro

autogyro
53
Joined: 04 Oct 2009, 15:03

Re: Why no Hydraulic Drive Systems on roadcars?

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mike wrote:i not an expert at hydraulics xpensive, but can you take a look at this for me
http://www.artemisip.com/index.htm

[youtube]http://www.youtube.com/watch?v=CJw5AvvxBqg[/youtube]
Much easier to fit an eight speed gearbox and a hybrid system using a motor generator and batteries.
That way you can recharge it as well.
The figures quoted are not massive fuel savings.
Driving a car hard and braking hard is the only way to recover reasonable energy from deceleration.
The best economy driving is to coast without harvesting.
Typical government support of a grant laundering project, made possible by government ignorance.
A bit like all the current alternate energy schemes in general energy production.
The oil companies love it, maskes all the true potential out there.

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ds.raikkonen
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Joined: 04 Apr 2007, 08:11
Contact:

Re: Why no Hydraulic Drive Systems on roadcars?

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This is an article from "Design Engineering" magazine, November 1989 issue: Hydrostatic transmission for road vehicles
http://pigeonsnest.co.uk/stuff/trilink/trilink.html
Last edited by ds.raikkonen on 28 Jun 2012, 07:56, edited 3 times in total.
“Speed has never killed anyone. Suddenly becoming stationary...that’s what gets you.” - JC

mike
2
Joined: 10 Jan 2006, 13:55
Location: Australia, Melbourne

Re: Why no Hydraulic Drive Systems on roadcars?

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autogyro wrote:
mike wrote:i not an expert at hydraulics xpensive, but can you take a look at this for me
http://www.artemisip.com/index.htm

[youtube]http://www.youtube.com/watch?v=CJw5AvvxBqg[/youtube]
Much easier to fit an eight speed gearbox and a hybrid system using a motor generator and batteries.
That way you can recharge it as well.
The figures quoted are not massive fuel savings.
Driving a car hard and braking hard is the only way to recover reasonable energy from deceleration.
The best economy driving is to coast without harvesting.
Typical government support of a grant laundering project, made possible by government ignorance.
A bit like all the current alternate energy schemes in general energy production.
The oil companies love it, maskes all the true potential out there.
would you like to give us a quote as to the cost of these batteries? compared to 2 pumps and 2 tanks

Tommy Cookers
616
Joined: 17 Feb 2012, 16:55

Re: Why no Hydraulic Drive Systems on roadcars?

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Regenerative braking is fine when it involves mineral trains going up and down mountains, elsewhere it is a gimmick.
We shouldn't buy into the 'brainwash yourself' hybrid mystique, whereby anything with a whiff of Hybrid is exempt from rational or evidence-based consideration.

After 200 years of development batteries are not much use, they never will be, and they won't save the world.
In Hybrids etc they have an 8 year life only because they are run at one third capacity (so you need three times as many).
Their true cost will only be seen when the taxpayer subsidy is removed (inevitable before the takeup tipping point)

I am looking forward to the Hybrid takeover, though, to get away from that museum piece, the stick-and-clutch nonsense.


PS the people who wrongly thought they could make wave power work are now experts on what exactly ?

their stuff is yesterday's answer to the day before's problems
digital control of electrical motors/generators is economical and transformative to vehicle (and wind turbine) capability
power electroncs has advanced greatly (better late than never)

digital control could revitalise old concepts like differential input gearboxes with fluid coupled and mechanical torque paths


BTW whatever happened to the differentially supercharged diesel, with it trucks would only need 3 gears, not 12 ?

Greg Locock
230
Joined: 30 Jun 2012, 00:48

Re: Why no Hydraulic Drive Systems on roadcars?

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Conceptual wrote: The place I worked for when I got hurt had this smallish dump-cart. It weighed 2000lbs, and could take a 2500lb load. It was ran by a 50hp 2 cylinder diesel motor, and would easily hit 25mph when full. I always wodered why it couldnt run my wifes work car the same, since the car is actually lighter than the full cart...
The original Mini had 40 hp (on a good day) and would hit 80 mph. No hydraulics required.

Disadvantages of hydraulics - cost, noise, efficiency. Those aren't absolutes, there may be work arounds, but they do make it difficult to introduce a different technology.

autogyro
53
Joined: 04 Oct 2009, 15:03

Re: Why no Hydraulic Drive Systems on roadcars?

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mike wrote:
autogyro wrote:
mike wrote:i not an expert at hydraulics xpensive, but can you take a look at this for me
http://www.artemisip.com/index.htm

[youtube]http://www.youtube.com/watch?v=CJw5AvvxBqg[/youtube]
Much easier to fit an eight speed gearbox and a hybrid system using a motor generator and batteries.
That way you can recharge it as well.
The figures quoted are not massive fuel savings.
Driving a car hard and braking hard is the only way to recover reasonable energy from deceleration.
The best economy driving is to coast without harvesting.
Typical government support of a grant laundering project, made possible by government ignorance.
A bit like all the current alternate energy schemes in general energy production.
The oil companies love it, maskes all the true potential out there.
would you like to give us a quote as to the cost of these batteries? compared to 2 pumps and 2 tanks

2 pumps and two tanks? I see rather more than that.
Prices for batteries are fairly well known, it would be nice to have some costs for this system.
Conventional modification of the powertrain would easily see the fuel savings quoted.
If you are thinking of converting the car by this much for such little savings, I suggest you do as we have and get your own bio diesel production set up. Costs me 10 pence a litre.

riff_raff
132
Joined: 24 Dec 2004, 10:18

Re: Why no Hydraulic Drive Systems on roadcars?

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A hydraulic hybrid drivetrain is probably more efficient, lighter weight, lower cost and less complex than a battery electric system. The only real drawback with the hydraulic system is the durability and noise.

A hydraulic system outperforms a battery electric system in braking energy recovery. That's why they are now being used for some applications like delivery and trash trucks.

For automobiles, it looks like flywheels may work best.
"Q: How do you make a small fortune in racing?
A: Start with a large one!"

mike
2
Joined: 10 Jan 2006, 13:55
Location: Australia, Melbourne

Re: Why no Hydraulic Drive Systems on roadcars?

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autogyro wrote:Conventional modification of the powertrain would easily see the fuel savings quoted.
ICE works at best around 50% for diesels and 35% for petrol, to use any forms of alternative energy such as electric/hydrogen the energy requirement must be lowered by using KERS or regenerative things. 34MJ/l is pretty much unbeatable

batteries have too little power density to recover energy quickly enough for KERS, hydraulic systems does have this issue and for that it is advantageous for this application with the technology today "if all goes well i'm converting my car to cold fusion power plant that produce gold as a by product"

agent10w40
0
Joined: 04 Jan 2013, 10:06

Re: Why no Hydraulic Drive Systems on roadcars?

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On the subject of Hydrostatic drive units. The easiest, and most affective way to increase axle rpm is increasing the gear ratio at the drive side of the hydrostatic unit.The rpm of the hydrostatic unit is not what needs to increase. Hydrostatic units have the capacity of infinite hp, and load transfer. When you increase the gear ratio, you must take into consideration that your drive units power output will have to be affective enough to compensate for the increase, however I have achieved high speeds in excess of 90 mph on a converted hydrostatic drive unit that I re-designed. I wont spill the secret to the achievement here, but I can say the power source that I used, you can find in most garages. One more thing to consider is lash control, or compensation. Because the hydrostatic drive is immediate power at the drive line, you must install lash prevention in the drive train to compensate for the instant power, if no,t you will break axles, or u joints, not to mention, it would be a very uncomfortable acceleration. So the answer to your question is yes it is possible if you have the right component combination, and pressure flow regulation, and of coarse...power source.

superstewie
0
Joined: 01 Sep 2015, 04:58

Re: Why no Hydraulic Drive Systems on roadcars?

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I've been thinking about the same thing for a while. I don't think there would be much direct performance benefit if the traditional thinking of how a cars engine is governed and used doesn't change. We'll compare tractors and cars, tractors being the only thing that really uses hydrostatic transmissions.

Tractors are normally idled at a constant engine speed for a long time, but have to go through a very wide range of speed and torque requirements for that engine speed. Hydrostatic (John Deere calls them IVT) transmissions are very good at this because they offer a very wide range of wheel speeds for a given engine speed. On the other hand, cars go different speeds by staying in a gear, and changing the engine speed. In other words, to get different vehicle speeds with a hydraulic drive system you change the gear ratio, to go different speeds with a traditional transmission you select different engine speeds.

What I think would make hydraulic drive in a car really work is to turn the gas pedal into a speed selector pedal. Have an engine with a very very flat power curve, and a computer regulate swashplate angle and engine speed.