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Bash valve longevity?

Posted by ChuckW 
Bash valve longevity?
April 21, 2010 11:12AM
Hi All,
Does anyone know how many hours the White Cliffs solar engine bash valves could endure?
I've built a few bash valve engines (that seem to work really well) and I'm curious if there is any hope of the valves lasting any time worth pursuing. The valves are stainless ball bearings matched to hardened seats with hardened activating rods. I've only put a few hours on one engine in particular (compressed air only) and it doesn't show any wear.
Chuck
HLS
Re: Bash valve longevity?
April 21, 2010 12:49PM
Hi Chuck
The ball has to be harder than the seat other wise the seat will line the ball and it will leak in short time.
Steam is a whole new world. soft 304SS seat ,hard ball 440c SS 58r ball , ceramic ball, best. Anything will run on air. even DC
Harry
Re: Bash valve longevity?
April 21, 2010 02:15PM
Any idea how many hours you could expect from such a valve?
Chuck
HLS
Re: Bash valve longevity?
April 21, 2010 02:49PM
Hi Chuck
Depends on how many times it opens per hour, the preasure , the hole diameter in relation to the ball diameter, the temperature and the water quality ,they all add up . We did a lot of testing on valves it is a lot of work and time testing takes time.
Harrry
Re: Bash valve longevity?
April 21, 2010 03:15PM
ChuckW Wrote:
-------------------------------------------------------
> Does anyone know how many hours the White Cliffs
> solar engine bash valves could endure?
> I've built a few bash valve engines (that seem to
> work really well) and I'm curious if there is any
> hope of the valves lasting any time worth
> pursuing. The valves are stainless ball bearings
> matched to hardened seats with hardened activating
> rods. I've only put a few hours on one engine in
> particular (compressed air only) and it doesn't
> show any wear.

There's been a lot of documentation about the RJ Smith bash valve conversion of the Mercury outboard engine; also, Pete Barrett's experience with the Merc led to the development of his own engine (based on the VW) using bash valves. Pete went through many iterations before he felt comfortable with the valves

The valve (ball?) and seat seem to be pretty straightforward issues--but the pin (or rod) and its mounting on the piston seem to be a source of endless problems. The load concentrations in these components is obvious.

Personally, I think the Williams type of impulse valve is a superior solution to the ball and pin type.

FWIW

Bill
Re: Bash valve longevity?
April 21, 2010 03:44PM
Could you point me to some of the documentation you mention? (Williams impulse valve especially)
Does anyone know how long the White Cliff engine got on a set of valves?
Chuck



Edited 1 time(s). Last edit at 04/21/2010 04:32PM by ChuckW.
Re: Bash valve longevity?
April 21, 2010 04:41PM
ChuckW Wrote:
-------------------------------------------------------
> Could you point me to some of the documentation
> you mention? (Williams impulse valve especially)
> Does anyone know how long the White Cliff engine
> got on a set of valves?
> Chuck

Google for US patent 2,402,699
Re: Bash valve longevity?
April 21, 2010 05:55PM
I do not know about the White Cliffs' project, but the two best bash valve work was done by Jay Carter and the Mobile Steam Society. Jay showed me two handfuls of experiments that were bent and bruised. He ended up with a Chinese hat shaped thing that had light weight, sealing on a flat surface, self centering, and a lot of area around the edge so he only needed 50 thousandths lift. The MSS went with an upside down mushroom shaped thing so that the bash impact was nowhere near the seating area, that was part of a spherical shape. The trick is to not use a ball bearing or any spherical shape because then the bashing impact will flatten a part of it, unless it is ceramic. These days the smart money is using recompression pressure to lift the bash valve and so then there is no metal touching metal. Tom Kimmel
Re: Bash valve longevity?
April 21, 2010 06:06PM
tkimmel@locallink.net Wrote:
-------------------------------------------------------

> The trick is to not use a ball bearing or any
> spherical shape because then the bashing impact
> will flatten a part of it, unless it is ceramic.
> These days the smart money is using recompression
> pressure to lift the bash valve and so then there
> is no metal touching metal. Tom Kimmel

A ball bearing has 'WAY too much mass in relation to its seal and flow areas; the only thing it offers is simplicity IMO.

Recompression pressure can work even if it doesn't do all the lifting necessary; for us amateurs the variations in pressure created by throttling mean there's no single target for this effect. Even so, it can help at many operating points when correctly utilized; the max throttle setting would imply highest pressures at the valve and thus highest unseating forces. Luckily for us these occur mostly for brief periods in the real world of steam vehicles.

Bill
Re: Bash valve longevity?
April 22, 2010 08:01AM
Sounds so simple and smart (initial cost). Just finished a full hydraulic system with variable lift and timing that I feel necessary to fully disect this animal. Miniaturized the engine so I can afford to build it. Only 7 hp now. Will be turning metal next week.
Re: Bash valve longevity?
April 22, 2010 11:16AM
Yeah, simplicity is the only point here.
I built a variable stop for the ball and use the momentum to change the cut-off. No throttling, fully variable cut-off, two dollars worth of parts. Longevity is the only question. I'm not trying to build a car, just a battery charger.
I was hoping to find a number from the White Cliff project since the web page said it gave good service and deserved development. Guess I'll have to find out myselfsmiling smiley
Thanks for the information on the other bash valve projects. I'm a complete steam newbie but it seems like using bash valves for an automotive engine may be misguided. If you are going to go to that much work its probably better to use a proven valve... and perhaps the same applies to my little project too. We'll find out.
Chuck



Edited 1 time(s). Last edit at 04/22/2010 11:16AM by ChuckW.
Re: Bash valve longevity?
April 22, 2010 05:28PM
The people who like bash valves, meaning Jay Carter, do the following analysis: they get about 5% cutoff and thus a 25 - 1 expansion ratio. They get approximately the rpm and torque of a conventional gasoline engine and thus the usual drive train will work. There are some interesting benefits to high speed, and Jay was getting 5,000 rpm, which is difficult to get with any other valve system. The benefits had to do with time. When high temperature, high pressure steam is admitted, you want a very short dwell time for the temperature to convect and the pressure to leak. Therefore there are some very good benefits to having a high speed steam engine. Few other people have explored this aspect of steam. In other words, the bash valve is a proven system, it is just an emotional issue. Tom Kimmel
Re: Bash valve longevity?
April 22, 2010 06:02PM
Any idea how many hours Carter got from a set of valves?
Chuck
Re: Bash valve longevity?
April 22, 2010 08:09PM
Hopefully Graeme Vagg will log onto this topic, he was involved with White Cliffs.

Regards,

Ken
Re: Bash valve longevity?
April 23, 2010 09:49AM
ChuckW

At the '09 Berrine Springs meet, Jay reported that their test vehicle racked up 10,000 miles.

jerry
Re: Bash valve longevity?
April 23, 2010 11:27AM
Anywhere from 100 to 300 hours? Recognizing that there are a lot of variables involved, is anyone willing to venture a guess on how long you could get a bash valve to last? A range? What is possible...
Thanks for the info.
Chuck
Re: Bash valve longevity?
April 23, 2010 03:53PM
If you do something to cushion the blow a bit it should last quite long. Something like the hat idea. Use the bash feature on the piston to generate some pressure, enough to unseat the valve just about the time it would contact.
Re: Bash valve longevity?
April 24, 2010 08:08AM
ChuckW

For vehicles having a wheel diameter between 24 & 25 inches and fixed gear drive ratio between 2.0 and 2.5 to one (1), you can expect a state of the art bump valve to fail within 40 million cycles. However, if you get out of the "box" and incorporate some of the new ideas, you can expect that a failure may occur after 360 million cycles. This is my best guess based on observations combined with analysis.

jerry
Re: Bash valve longevity?
April 24, 2010 11:45PM
Thanks Jerry,
If I'm figuring correctly, 40 million cycles at 1800 rpm would occur in 370 hours. That's reason for optimism.
Are the 'out of the box' ideas materials or mechanism related?

I have been running the engine on steam the last few days. Quite a learning experience. Balancing heat and feed on a monotube is, as all the literature suggests, continuous. I had no idea you could get so much power from such a small displacement (31cc). I don't actually know how much it is... its just surprisingsmiling smiley

Any other takers on hard numbers for bash valve longevity?
Thanks,
Chuck
Re: Bash valve longevity?
April 26, 2010 07:52AM
The person who has the most experience with bash valves is Jay Carter. I have visited him several times in Wichita Falls and seen his shop and handfuls and coffee cans full of mis-shapen and broken clumps of metal, all tested experiments. Jay does not use the computer, he makes things. Therefore do not expect him to weigh in on this discussion as he is probably unaware of it and could not join if he wanted to. His final design, which Jerry Peoples says went 10,000 miles and I believe him, was a Chinese hat with 50 thousandths lift and a spring to push it down and prevent float. It worked up to 5,000 rpm because, first of all, there was a large, possibly close to one inch diameter, valve. The steam came in from the periphery and so there was a lot of area for the steam to move through. This is why a spherical ball is the wrong geometry; it is heavy and has a small cross-section and the square-cube rule starts to get you when you make it larger. Then, Jay used up to 2,000 psi steam. I have no idea how much wire drawing his system suffered from, but at least the steam got into the cylinder. A person might look at the cost, in energy, to make high pressure steam, and it is probably not much, just a little more power to drive the water pump, so one might as well start out with some high pressure steam. It is my opinion that Jay concluded that a bash valve was the only way to get a 25-1 expansion ratio and high rpm speed as any other valve train had too much inertia in it. One should always keep in mind when running a bash valve that clearance volume needs to be carefully considered. There needs to be some or there is no steam flow. Therefore all of the talk at the steam meets about small clearance volume and Jerry Peoples' calculations on the deleterious effects of high clearance volume do not apply to bash valves. Try to not get me started on all of the attempts to make a variable cut-off bash valve or about Bill Cartland's bash valve exhaust valve. Tom Kimmel
Re: Bash valve longevity?
April 26, 2010 11:37AM
ChuckW Wrote:
-------------------------------------------------------
> Yeah, simplicity is the only point here.

I'm currently doing some interesting experiments with a small 2-cycle engine salvaged from a weed whacker. Single cylinder.

I'm using compressed air for the first efforts.

Originally, I tried using a solenoid valve and parts of the original magneto to create a crank position sensor to trip the valve (feed through the spark plug hole). I wasn't happy with the results--the valve just isn't responsive enough for a high-speed motor. However, I made an interesting discovery when the valve was held open continuously by the defective reed switch used to activate it. The motor just took off, and started running smoothly at high speed with a lot of power. Since then I've redone the setup and the only work needed to duplicate this success is to convert a spark plug to accept a high pressure air feed.

I have a theory about why this works so well: The impedance in the relatively small port for the inflow of the high pressure air is offset by the massive flow area of the piston ports at BDC for the low pressure exhaust. Efficiency is somewhat compromised by the continuous inflow from the untimed, unvalved intake port--but even this is mitigated somewhat by the high operating speed. Think timing advance here.

I'll get an rpm number in the next day or so, and post a youtube link to a short clip showing how well it runs. You'll be amazed.

I'd be interested in comments about this from others.

Bill
Re: Bash valve longevity?
April 26, 2010 12:59PM
Bill, how did you test the power?

terry
Re: Bash valve longevity?
April 26, 2010 01:26PM
heavysteamer Wrote:
-------------------------------------------------------
> Bill, how did you test the power?

Sorry--just a qualitative observation at this point; no numbers (yet). It's turning a pretty heavy flywheel and still accelerates
rapidly. I also applied friction to the flywheel rim and was surprised at how little rpm drop there was.

I'm going to build a primitive prony brake to try and get some numbers.

The most interesting aspect right now is that it runs at all without any valving.

Bill
HLS
Re: Bash valve longevity?
April 26, 2010 01:36PM
Hi Bill
Our WHE engine will also run with out an intake valve however there is a large power loss as well as a very high water rate. There is still an area for expermenting on porting.
Harry
Re: Bash valve longevity?
April 27, 2010 02:45PM
Variable cutoff bump valve...
Other than just getting my feet wet in steam, part of this experiment was to try out a variable cut off bash valve idea. It is nothing more than a movable stop for the ball to hit after inertia sends it up its cage. When the ball can travel a long way (half an inch) before rebounding off the stop you have long cut off, opposite when short. Close it a little more and the engine quits. No throttling needed.
It works very well... I was just hoping someone could tell me how long to expect it to last (without burning the fuel to find out myself). Its a perfectly simple and usable system if all you have to replace is a little ball bearing and its seat every 500 hrs. If you have to do that every 100 hrs, its probably not worth it.

The steam moped and the White Cliffs engine are what I copied; thus the question about how long the White Cliffs valves lasted. Any idea where I might find the answer to that question?
Chuck
Re: Bash valve longevity?
April 27, 2010 04:15PM
If you follow the thread and the answers, you received, you can determine life expectancy to be between 5 and billions of cycles. Depends on the design you choose. You can design a non contacting basher if you try. I would do it for you but I'm swamped. Valve seat wear is another issue.
Re: Bash valve longevity?
April 27, 2010 05:16PM
I already have a design KDC2... I understand that it isn't the best, but others have used it with some success and I'm just hoping to find out how long they have gotten it to last.
I appreciate all the info and design tips, but they aren't the answer to my question. Just trying to be persistent, sorry if its annoying.
I'll go find the answer myself as Harry hintssmiling smiley
Chuck
Re: Bash valve longevity?
April 27, 2010 06:26PM
ChuckW Wrote:
-------------------------------------------------------
> Variable cutoff bump valve...
> Other than just getting my feet wet in steam, part
> of this experiment was to try out a variable cut
> off bash valve idea. It is nothing more than a
> movable stop for the ball to hit after inertia
> sends it up its cage. When the ball can travel a
> long way (half an inch) before rebounding off the
> stop you have long cut off, opposite when short.
> Close it a little more and the engine quits. No
> throttling needed.
> It works very well... I was just hoping someone
> could tell me how long to expect it to last
> (without burning the fuel to find out myself).

> Chuck

Hey Chuck:

I'll be interested to find out whether you discover (the hard way, BTW!!) a resonant frequency for the bash valve, its seat and the limiter. Each of these has elastic properties, and IF (that's a BIG "IF"winking smiley some or all of these achieve co-resonant frequencies you're going to have quite an experience. Stand back, dude!!

Please keep us in the loop with your ongoing experiences here.

Bill
Re: Bash valve longevity?
April 27, 2010 07:32PM
NOT annoying, but if you don't present thr design your using, nobody can answer your question.
Re: Bash valve longevity?
May 01, 2010 06:25PM
I found some relevant information in 'The Steam Automobile' archives.
In relation to Peter Barret and his work on the Project 77 car, here are some of his calculations and conclusions about the ball type bash valve.
-Sav26n3- pg 32 Peter Barret
"Conclusion: the ball valve does not have acceptable life and will have to be replaced with a different design."
-Sav26n4- pg 16 Peter Barret
"It is believed these calculations explain why the bash valves have destroyed themselves in 100 miles of operation.
I recommend abandoning the use of steam operated bash valve because it is very difficult to prevent the lift pin from running away from the valve. The use of a spring to keep the valve in contract with the liftpin is a logical next step."

Anyone know if the limiting spring fixed the problem on that engine? Seems to be running today... is it using the same valves?
Chuck
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