It doesn't need to boil, it can be stone cold. Water has a lower viscosity than brake fluid therefore requires better sealing/seals. The existing seals in car braking systems aren't good enough so the car would fail on the part of the test where the pedal is pumped then pressure constantly applied to it to see if it drops.
Idiots...
I suggest you do some research into braking systems that use water instead of hydraulic fluid.
Says the expert on spare tyres and MOTs...
John
Who gives a shit?
Have you ever actually tried this? I'd expect an otherwise perfect braking hydraulic system to continue working without leaks if the fluid was replaced with water - certainly for MOT purposes.
It's a bit academic, but there we go.
I'm just putting it up as indicitive of your knowledge in all things motoring. If I could be arsed I know I could find more.
John
Eh? I suggested seals in my message - you may observe it in the quoted text above.
Well, steam powered ones presumably existed. I don't know of any off hand - do you? Unfortunately you seem so desperate to prove yourself right that you're unlikely to provide a helpful answer to this question.
clive
Steam - no, not ideal for braking. Fundamental problems if the temparature drops below zero, for starters. Steam powed vacuum brakes very common though - virtually all steam trains used this system.
Mmm, yes. I wouldn't use it :-)
Corrosion too.
How did they generate the vacuum? A venturi, or something more mechanical?
cheers, clive
Most engines used a venturi system, simple and reliable. It was also fail-safe, in that you apply the vacuum to release the brake - that way, if the brake pipe was blocked or parted, the brakes would come on. Usual arrangement was to have two, a 'small injector' that ran continuously to maintain the vacuum when running, and a 'large injector' used to release the brakes quickly when moving off. If one failed, the other could be used to keep things running. On some later engines, the small injector was replaced by a pump driven by the engine - obviouly it only works when the engine is moving, so you also needed a venturi to release the brakes to move off.
Where the hell do you get all this crap from? Are you just making it up, or are you inventing it off the top of your head? if so, 10/10 for creativity!
Quite.
I suggest you do some research.
THe tolerances with the seals isn't sufficiently good enough.
I got it from the website of the University graduates who created a system using water instead of hydraulic fluid to overcome the problem of ride on grass cutters killing grass on golf courses.
Go on then, post the link.
I would be intrigued to know how exactly the hydraulic fluid was killing the grass, given that a hydraulic braking system is a sealed!
The hydraulics that would be leaking on a ride-on mower would probably be related to the steering, or raising/lowering the cutting gear. So we are talking about the sort of large machinery hydraulics, with exposed pistons and seals (think big yellow JCB.) These seals are probably of much lower tolerance than those of a hydraulic brake system, so they won't work with water - but they won't work with brake fluid either, so the argument is a bit spurious.
Bollocks, to put it mildly. They'll seal against air pressure - have you no practical experience?
You need to buy your bake parts from somewhere else then.
Exactly. I'm waiting for Conor to post the link, as I have a feeling that the system he refers to has nothing to do with hydraulic brakes, given that if the brakes were leaking enough fluid to kill the grass, they would soon fail anyway! I somehow don't think he will post it though.
Students put the hydro in hydraulics
By Steve Tally
Four Purdue undergraduates have built an industrial riding lawn mower that's a cut above the rest.
The students have created what is thought to be the first vehicle that uses water in all of its hydraulic systems, including power steering, power brakes and transmission.
Recent advances in water hydraulic systems have allowed them to perform as well as petroleum hydraulic systems. Because water offers several environmental and economic advantages over petroleum hydraulic fluid, the students teamed up to demonstrate that such a vehicle is now possible.
May graduates Jason Brown of Pendleton, Ind.; Dan Sellers of Bourbon, Ind.; and Dan Pitstick of Rensselaer, Ind., worked through their final semester at Purdue to build the machine. Nathan Schoonover, of Evansville, Ind., who graduated in December, also worked on the project.
Although the mower was redesigned to prove a point, it does have a practical purpose. Mowers leak some hydraulic fluid, and on golf courses that fluid can kill grass on greens that often cost tens of thousands of dollars to construct and maintain.
The Jacobsen Company donated the Greens King IV mower, a 31-horsepower, front-wheel-drive mower with three sets of gang mowers that are raised and lowered hydraulically.
Gary Krutz, professor of agricultural and biological engineering and the students' adviser, says water hydraulic systems only would be practical in vehicles that use high-pressure systems, such as heavy equipment used in construction, agriculture, forestry and mining. (Automobiles have hydraulic brake and steering systems, but these are not typically highly pressurized.)
Using water in hydraulic systems currently costs twice as much as using petroleum products, but that could change as more applications are found for water hydraulics.
"If all of the research and development were done, all of the major companies would be using water instead of hydraulic fluid," Krutz says. "Because the industry is in its infancy, mass production hasn't lowered the cost. But once you start mass producing the necessary parts from ceramic, fiber-reinforced plastic or stainless steel, the prices will drop."
The water used in the mower isn't straight from the tap; ordinary city water contains too many minerals and impurities and could cause build- up and corrosion. Instead, the system uses distilled water that has been de-ionized to remove any electrical charges that could cause corrosion.
Corrosion also is the reason parts for water hydraulic systems have to be made of stainless steel, plastic or ceramics. But the more expensive parts would be worth it because using water in hydraulic systems makes machinery more energy efficient, saving money.
The boost in energy efficiency is due to water's lower viscosity. Viscosity is the measure of how fast a liquid flows. Water flows up to
1,000 times faster than hydraulic fluid at normal air temperatures. Once the machine is warmed up, water is still 10 times less viscous.Reduced viscosity means less energy is required to push the hydraulic fluidthrough the system, making it more efficient. By using water instead of heavier petroleum fluid, Krutz estimates the efficiency could be boosted at least 10 percent.
Replacing hydraulic fluid with water won't be without problems, however. Because tighter fittings and higher quality parts are needed to prevent leaks and corrosion, water systems are more costly. Also, the reduced viscosity of water means that turbulence within the system could reduce efficiency if the parts aren't engineered properly.
Tell you what, try working a 65 hr week on nights every week, having only 6 hours sleep a day and not having any sleep at all between the time you get up on Friday and late Saturday night. See how much sense you'll make after you've been doing it for 9 months.
Car brakes don't generally use what is known as 'petroleum hydraulic fluid'
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