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throttles

Posted by Andy 
throttles
February 13, 2004 06:11PM
Hi Jim

I know you like the White throttle. And you have said the Doble is a good one also. Just how often does one have to maintain them to keep them in good working order. Any idea in driving hours or miles?

I think a good steam throttle should be as reliable and consistent in operation as the current breed of IC cars acceleratoir controls. And have about the same maintaince requirments. Which is about nill. Of course opening a butterfly valve on a carb is simple compared to errosive enviorment a steam throttle valve has to work in.

I think there is lots of room for improvement. Even on the best of thoes old throttle valve designs.

The pressure regulating steam throttle is a old idea. And was used on some of the most recient locomotives. A pressure regulating type valve has much less of a problem with surface errosion. It's basic steam valve is either open or closed. In service these require less maintaince then older flow restricting throttles.

The pressure regulating throttle has the ability to be used in conjection with the brake. Sense it regulates pressure you can hold the car with the break with out the build up of pressure you would have with a flow restricting throttle.

There are industrial variable pressure steam regulators that could possably be used. For someone like Peter, planing on producing steam cars, throttle operation and maintaince are vary important design ellements.

Andy
Peter Brow
Re: throttles
February 14, 2004 06:47AM
Hi Andy,

Thanks for starting a new thread. Please Andy, ixnay on the oductionpray alktay; I want to get the basic system designed, built, running, and debugged before really deciding about that, and that's more than plenty to think about for now. At present, "oductionpray" is officially "just a possibility", though it is being kept in mind with design decisions. The only thing I would add in that department is that for a small manufacturer, equipment cost/development time is at least as important as features. Big manufacturers can slap on gizmos right and left with barely a thought; a limited-production shop has a lot more cost and trouble producing and installing extra things. I think that this is part of the reason why the Stanley brothers were always counting the moving parts and trumpeting exactly how few there were in their cars. It was very important to them, though probably not as big a selling point to most of their customers as the Brothers might have thought.

The more I think about it, the less I think that any kind of throttle add-ons will be an issue. Even in close quarters, there will not be enough pressure on the engine to override the brakes if a sudden stop is needed. I might just forget about the brake-pedal cylinder venting, and link the cylinder vents to the parking brake.

For lining up your trailer hitch or working into a tight parallel parking place, give the engine a "puff" of steam with the (foot-operated in my case) throttle, as David Nergaard says, then control the motion with the footbrake just like a creepy automatic tranny. To reverse motion, just hold down the brake pedal and shift into "other direction", easing off of brake to creep back with the steam you already "puffed" in. Here is an advantage of piston valves over slide valves.

Also an advantage over my previous idea of having the brake pedal automatically vent the steam line & cylinders. If you're headed downhill, use gravity instead of a "puff". Then, when your trailer hitch is lined up, or the car is parked and it "absolutely positively has to stop", the parking brake is linked to the cylinder vents and releases all the steam pressure. This may be better than my previous footbrake-vent idea.

It sounds very intuitive, and new drivers should figure it out pretty quick with no instruction. If you want the car to creep a few inches, and you take your foot off the brake and it doesn't move, what do you automatically do? You give the throttle pedal a slight nudge. If you want to stop and it keeps creeping, what do you automatically do? You hit the brake pedal or pull the parking brake lever. People automatically compensate for & figure out slippery auto trannies and manual trannies this way all the time, without giving it a moment's thought. Also "creep thrust" varies from one automatic gas car to the next, and people automatically compensate without the manufacturer having to tell them "Warning: creep thrust is higher/lower than average on this vehicle".

To illustrate, about 15 years ago I had an office-moving temp gig which involved driving the boss's brand-new titsed-out auto-tranny Chevy Silverado pickup truck, with some Frankenstein factory V8 under the hood. The tires would spin on the slick concrete parking building roadway -- engine barely idling -- when I eased off on the (grabby overboosted) brake pedal! Absolutely nerve-wracking, what a lousy rig. Sorry Chevy guys, but "Like A Rock", my tailpipes! Chevy really blew it with that one. Yeah boss, it's got some torque all right. A stock 1908 Stanley Mountain Wagon engine with an old-fashioned plain throttle would have been a much better drivetrain for that vehicle.

The "plain ole throttle" may need a tiny bit more pedalwork than a creepy automatic gas car under some conditions, but it is still much less work than a manual-tranny gas car, of which plenty still sell each year (though only about 10% of the market at least in the US), and the difference in driver effort looks pretty negligible to me. Plus one less of already too many subsystems to design, build, debug, and tool up for. Most people will probably be too blown away by the car's performance to notice, let alone care. How many people gripe that their Italian exotic sports car doesn't have an automatic tranny? Everyone at the Millionaire's Club would roll their eyes at such poor taste. smiling smiley

But maybe the Andymatic™ Autothrottle will be ready to offer as standard equipment in model year 2010? smiling smiley

The only thing I will definitely add is an ultra-simple linkage between the brake pedal and the throttle, to guarantee that the throttle is positively shut by brake pedal in case of sticking. Even that safety backup feature may only come into play once in a blue moon.

On throttles in general, I like the idea of a simple Stanley-type throttle with a very gradual-opening port in the sleeve. Maybe a round drilled port with a wee triangular notch or thin slot parallel to axis of travel, at the edge that opens first. From what Jim said, if the poppet valve and its seat are faced with (or made of) Stellite, it will not leak for many decades of regular service. That's more than good enough.

Modern valve seat alloys, ceramics like titanium nitride, and some of the ceramic- and diamond-coating and other plasma-spray coating processes, are also possibilities, but a few ounces of plain ole Stellite reportedly does well enough -- making the throttle more durable & reliable than analogous parts in the latest gas cars -- that there doesn't seem to be any need to get more exotic or expensive than that.

Peter
Peter Brow
Re: throttles
February 14, 2004 08:26AM
Andy,

Another issue is hill-holding.

Do all gas cars have "hill-holder" features in their trannies now? I have seen both manuals and automatics that will roll backward from stops on a steep uphill grade without some fancy pedalwork, and don't know whether a hill-holder is now a universal feature, or outmoded, or still just an option. My daily driver ('69 VW with oddball "Automatic Stickshift" semi-automatic transmission) doesn't have a hill holder, but it is easy to hold her on a hill with a little gas for brief stops, esp in granny gear.

A hill-holder feature could be incorporated into a pressure-regulated throttle, but again, more development time & effort, and more equipment cost. Maybe just add an inclinometer input. Enough full-time minimum pressure to hold on the steepest hills could give excessive leakage & creep during level stops. But if the regulated-throttle car has a low pressure setting & needs throttle (or brake) pedal pressure to hold it on a steeper hill, then it has no convenience advantage over a plain throttle under those conditions.
And if the regulated-throttle car is set up to not only hold but give the same net forward creep on any hill, then it would actually be more hassle to drive than a car with a plain throttle, as the foot would have to be moved between brake and throttle, whereas the plain throttle car could be both held and moved with the throttle pedal alone.

A minor issue, but worth considering. Like many places, we have lots of hills & canyons around here, some very steep.

Peter
Jim Crank
Re: throttles
February 14, 2004 11:00AM
Andy,
The White throttle: Tapered length to do the throttling, a seat to do the shutoff, the tapered length is ahead of the final seating area.
Considering they were made in 1910, they were probably nothing more than case hardened steel of the day. Today, superior steel with Stellite on the final seating area.
Problems: The big bronze packing gland-threaded area casting often comes loose and you get a throttle that progressively doesn't want to shut off completely, due to creeping rotation. Very simple procedure in the owners manual, tells you to loosen the big nut, and rotate the throttle wheel to fully OFF, then rotate the bronze casting to close the throttle and then tighten the nut. This could be done today so very simply by a better assembly design; but still keeping the White concept.
The owners manual has a great cutaway drawing of the throttle.
Except for occasionally resetting the OFF position, in fifteen years of driving my White, I never had to touch the throttle.
If done again for a new car, lengthening the tapered area a bit would give even better and more delicate control at slow speeds; but as made by the White Co. it was a very good throttle and so very easily used. Easy to adapt for foot operation. A most superior throttle design.

The Doble foot throttle: A poppet valve for final shutoff with a sleeve with holes in it for actual throttling, exactly the same as the Stanley throttle.
A double cam box with the foot lever and pedal gave the mechanical advantage to get the unbalanced poppet off its seat, then all throttling was done by the sleeve. Modern improvement is to Stellite face the poppet valve and the seat in the main forging.
Barney Becker drove E-14 to work for decades, every day. In all the many years that I knew the Doble, the throttle was never touched at all. Now some fifty years later, and nothing is ever done with the throttle, not even the packing has been touched.
On E-23, the cams were badly worn after 365,000 miles and lack of lubrication in the cam box, and I made new ones that were hardened.
Once set up correctly the Doble throttle never needs attention. Setting the cams correctly is a very delicate job; but once done right, that is it. Then it is one hand to open the throttle against 1500 psi, or just the touch of the toe.
Jim
Re: throttles
February 15, 2004 11:50AM
Peter, Don't get carried away with hill holding. The throttle needs to be simple and trouble free. As Jim discribes the Doble and White they seem a lot more reliable then I ever suspected. I have heard about a lot of problems with throttles leaking. Knowing Jim's expertise I suspect that thoes problems were caused by wrong setup.

All though I have seen pictures of pitted, erroded throttle parts.

Jim, Do you think a White or Doble throttle could be damaged(in use) if set up wrong. Say by excesive erosion or ware.

Andy



Post Edited (02-15-04 11:54)
Peter Brow
Re: throttles
February 16, 2004 06:52AM
Hi Andy,

I've seen photos of pitted and corroded throttle parts too, and have also read lots of stories about "wandering" steam cars with leaky throttles. This is definitely worth some attention in the design department. Many steam car drivers have the valve chest drain cock set up for remote operation, and/or routinely open it when parking, in case of throttle leaks. This is where I got the idea of having the parking brake lever automatically open the cylinder warmup vents via a simple linkage. I wouldn't be surprised to learn that some steam car owners have already retrofitted their cars this way.

Driving around here, and also on road trips across the country, in both old and new cars, my own, borrowed and rented, I find I have to make uphill stops on a regular basis, and it can be annoying, and sometimes unnerving, to have a car roll backwards, even an inch or two, while my foot is travelling from brake to gas pedal. Especially with a careless driver stopped a few inches from my rear bumper, which is not a rare occurrence. Some people seem to think that tailgating is required by law. Also, on many occasions I have had the car ahead of me roll back downhill towards me after an uphill stop, so on uphill stops I always leave a few feet between my car and the guy ahead.

Agree that the throttle should be kept as simple and trouble-free as possible, like the rest of the steam car. As you know, simplicity is not easy to achieve, especially when designing to maximize convenience and automation for modern driving.

Peter
Jim Crank
Re: throttles
February 16, 2004 10:06AM
Andy, Peter,
Damage to throttles that I have seen, with something like twenty steam cars, is always pitting from water. This is because the old throttles were made from rather common steels in those days, nothing like what we have in the way of corrosion proof tool steels today. The cars have stood for years and water remains in the throttle causing the pitting and corrosion.
From an operational standpoint, the White will not shut off if the bronze housing starts rotating. This is super easy to prevent, as I described.
The Doble foot throttle can so easily be misadjusted, by amateurs that don't know how it is supposed to work. It is a matter of delicately adjusting the stem in relationship to the cam face. If it is wrong, you can't open the throttle with both feet on the pedal and both hands under the dash, pushing like mad! Correct corrosion proof steel and Stellite facing cures this completely.
I have never seen wire drawing on either throttle.

Peter, The Series E Doble has the cylinder-steam line drain connected to the hand brake. Pull on the brake and the valve is open.
Jim
Peter Brow
Re: throttles
February 17, 2004 07:00AM
Hi Jim,

Oops. Another "original idea" down the reinvention tube! smiling smiley

Peter
Re: throttles
January 10, 2009 07:09AM
In January 2009, 5 years after this thread was started, Jeremy Holmes posted a link to it, with commentary, in a different thread. Re-reading Jim Crank's very important and useful throttle comments here, and seeing how much my own steam car design ideas changed between 2004 and 2009, has been very interesting.

My engine piston valves were replaced with flat D-slide valves in May, 2008. I replaced the 2004 foot throttle with a classic hand throttle lever on the steering wheel column. The basically Stanley-type "M2009" throttle includes a 440C stainless ball on a high-performance IC engine exhaust valve seat for the poppet section, and a cast iron piston/sleeve valve inside a bronze bore for the throttling section. V-notched hole in sleeve valve (as mentioned above) for gradual opening. The valve stem will be Monel 400 alloy, with pure-graphite packing (Garlock 98/Palmetto) in its stuffing box.

The engine drain valve linked to the hand brake lever, which Jim Crank informed me was Doble's idea in this thread, remains. The hand brake lever handle is now located close to throttle lever for handy engine pressure release. The hand brake lever can be clicked back one notch to open valve for engine warmup draining, while car is moving, without engaging parking brake.

My steam car is approximately 90% blueprinted as of January 2009. In the process, many design features have been changed since 2004, too many to mention here. In 2004, this project was still in the "concept stage", with only a handful of small components & mockups blueprinted or built, and the basic powerplant parameters calculated.

It is interesting and important that corrosion, not wire-drawing-erosion of soft metals, was the cause of leakage in classic steam car throttles. I have upgraded both corrosion resistance and sealing-surface hardness in the poppet section of my current throttle valve design, relative to antique steam car throttles. I believe that this will a long-lived and trouble-free throttle, which Andy Patterson mentioned a need for at the beginning of this thread. As usual, "only building and testing will tell for sure".

There is negligible wire-drawing (~0.25 cubic inch of steam over a tiny fraction of a second) at initial throttle opening, but for all practical purposes there is "no wire drawing" in a Stanley/Doble style "staged poppet/sleeve" throttle, as Jim says above.

Thanks to Jim Crank for his comments here, and to Jeremy Holmes for posting a new link to this old thread. I think it is a good idea to occasionally update some of these old threads, and to "float them to the top" for review.

Peter

Re: throttles
January 10, 2009 09:21AM
Peter,

Definitely we have better corrosion and erosion protection with the metals we have available today. They just had to use what they had back then.

Let's not forget one other totally different way of controlling a steam engine.
Do you actually throttle the steam, or do you use the cutoff to throttle, as Harry does and then use some interlocked valve to just shut off the steam totally when you stop?
Personally, I never have seen any car that uses cutoff for throttling, only a beautiful couple of Skinner Unaflows in hospitals that ran big generators. Watching the valve lift change with varying loads was very educational.
I wonder how good cutoff throttling would actually be in a car? Or could it cause some very jerky movement when starting out?

In the Dobles, that "Wilson" valve just drained the steam line, it didn't act as a cylinder drain unfortunately. The very first Series E engine did have cylinder drains all built in. The most complicated casting possible, the core work was a nightmare for the foundry. Only one or two were built before they, as usual, changed the design and removed this feature.
One has to be extremely careful when first starting out and work the water out of the cylinders, or they can and have split in that very thin wall between the HP and LP cylinders. Many did split right there.

What I wondered about with the White throttle was erosion from high velocity steam going past that tapered part on the stem; but none was ever seen, so I guess it wasn't a problem in service. Anyhow, the White throttle is so very delicate in operation when in traffic, that I just think that basic design is the best.

Jim
Re: throttles
January 12, 2009 12:04AM
Hi Jim & Peter B.

Without a lot of cylinders wouldn't one have to use a throttle at long cutoff to get going smoothly? My design has totally variable cutoff from nothing to full but still would need a throttle to start.

At short cutoff for low power movement there wouldn't be enough overlap of the cylinder pressures for smooth movement. At very low cutoff no steam would enter the engine at certain crank positions then would be jerky if it did start to move. Long cutoff at low pressure looks nice and smooth.

Best regards, ---- Bill G.
Re: throttles
January 12, 2009 09:00AM
Bill,

From what I have learned, at least three double acting cylinders and six for a single acting. You would have to design the long cutoff to provide enough overlap for smooth startup.

What concerns me, is that if it is a throttle, then you better pay close attention to providing very smooth flow with the minimum of turbulence and no 90° bends in the steam flow path. That White throttle design again.

Jim
Re: throttles
January 12, 2009 12:49PM
Thanks Jim,

With my compound design I can cheat a bit on some things to get the overlap for a smooth start. I think we are only talking of less than 7 MPH to worry about but jerky movements here runs into the garage door and over the cat so it's gotta be really smooth.

The design is basically two high, two medium and two low pressure cylinders or six bangs/revolution but the power is unequal (for insurance reasons) It will require long cutoff and throttle for smooth starting.

Thanks for the info about the turbulence problem with a throttle. I can see how the onset of turbulence would produce flat spots in the torque of the engine or just instabilities in the flow that would feel wonky, kind of like an IC engine with carburetor problems. Another good reason for a ball valve not being good would then be the turbulence exiting through the ball problem.

Thanks,---- Bill G.
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