Hello and the hydraulic car project
 

Hello, my first post and hope I do it right. I have read alot of posts in the last few days about building contollers and EVs. Great site. I am interested in building a vehicle and am looking at all different types. I ran across an article in either Popular Science or Popular Mechanics (or some magazine) a long time ago, maybe circa 1976, that described a high mileage vehicle using hydraulic drive. The vehicle was a small car of its time, maybe a Pinto or something and was driven by a hydraulic motor that used a gas engine to drive a pump that drove the motor. The key to its efficiency, about 75mpg was that the gas engine, about 15HP, ran at the same speed all the time even at a stop. Running at its most efficient rpm all the time and keeping a hydraulic accumulator charged were the keys to its success. I find it an interesting concept and would like to reread the article if it can be found. Anyone else know of this article? If anyone knows of it or finds it let me know. Any thought on how this would compare to EV? Any hydraulic experts here? I dont know much about hydraulic drives and but will continue to research. Great to be here with like minded people.

regards

rese

I don't know much about hydraulic drives, but I know of someone who does. He is not a member, but he lives very near me and is (as far as I know) working to get his patented idea implemented in pretty much everything. All the buzz about his "Hydristor" seems to have come and gone, as several of his press references have been taken down. You may want to contact him, he is willing to talk to people who email him.

Hydristor - Home Page

Hydraulics are typically very inefficient means of power transfer. But your idea sounds interesting, don't give up because of some silly post (like this one) on the internet.

You might want to check these guys out, they've made 3 hydraulic motorbikes, including one with 2-wheel drive!
Welcome to Hydraulic Innovations

There has been quite a lot of work done with hydraulic hybrids, but the application area seems to be trucks that do a lot of stop & go driving - USP delivery vans, garbage trucks, and similar.

My impression from what I've read is that hydraulics are really efficient at storing braking energy & using it for the next start, but heavy and don't have a lot of storage capacity. That makes them a good fit for stop & go things, not so good for a typical car.

Thanks to all. Sure wish I could find the magazine article that I read so long ago. I will investigate the suggested links. Vinny, went to the forum at the link you posted and some guy was talking about building the same type of hydraulic car. Small world.

rese

The same concept with a compressed air drive may work just as well.

Being able to fill the tank from home using electricity would lower running costs too

Sounds like a winner for city driving - UPS would't be funnelling so much money into it otherwise. i believe I read an article recently saying that their test run worked wonderfully and they are moving on to a larger test.

How do you suppose you would work the braking regeneration system? Without it, i don't think that there is much point. It may be very simple, for all i know...

Available hydraulic components are designed for compact dimensions, not efficiency, although it could be the other way. The motors are generally quite reversible - using them for regenerative braking is just a matter of valving and tank pressure. Unfortunately, storing energy by compressing air in an accumulator tank can lead to huge losses from the heat of compression, and storing substantial amounts of energy that way is potentially very dangerous, since the "fuel" does not burn; it expands as readily as high explosive.

Bob - on a tangent here, what do you (or anyone else feel free to chime in) think about hydraulics in applications other than passenger cars such as elevators and heavy machinery where the regenerative capabilities of hydraulics are (as far as I know) seldom taken advantage of? This is discussed in one of the interviews with the inventor of the hydristor linked to in my previous post, but here's a direct link to the audio.