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Stanley D-Valve dimensions

Posted by Rick.H 
Stanley D-Valve dimensions
May 07, 2023 06:34PM
I'm hoping Rolly sees this post. However, all can see it and respond if one knows the answer.

A little background first. I was with Herb de la Porte a couple of weekends ago and who just overhauled his 20 HP Stanley engine. Note that I'm in the process of starting my 10 HP build along with interface to the rear end. Both Herb and my engine have valves that have one side slightly shorter than the other. I was told by Billy Barnes that one should put the shorter lap if I may say it that way to the top side in the block. Herb machined new valves provided by Billy. He did not have any drawings to go by, officially.

The big question is why do this?

At times like this I wish Pat Ferrell was still around. My theory is that you adjust the valve so it is line-to-line on both bottom and top piston locations. Note that you adjust the valve rod by screwing it in or out to center it. With the shorter end in play, the valve favors the top side of the cylinder for steam admittance. When in cutoff or hookup, the valve allows more steam to the top and starves the bottom. However, the bottom provides more compression that lightens the valve friction. This allows for more speed.

If someone else has the answer, please state it here and all to see.


Re: Stanley D-Valve dimensions
May 08, 2023 04:36AM
Yes Rick the small end goes toward the top cylinder head.
Also I see you have a bent rod
This Co can straighten it, Chrome and grind it.

Electronic Chrome and Grinding Co Inc
Santa FE Springs Cal 90670
562 946 6672

Re: Stanley D-Valve dimensions
May 08, 2023 09:04AM
Yes, very observant. However, if you look closely at the end of the bent rod, it is broken off. It is stuck in the piston 1/2 to the far left.

I made a jig for my lathe, 4 jaw chuck and will drill out the bent rod and drill/tap for a new one. I'll touch it with weld to hold in place.

Back to my question...what's the reason for the short side of the valve?

"When in cutoff or hookup, the valve allows more steam to the top and starves the bottom. However, the bottom provides more compression that lightens the valve friction. This allows for more speed." by Rick.H

Is this a plausible explanation?
Re: Stanley D-Valve dimensions
May 08, 2023 09:29AM
It’s Geometry, Do a valve diagram with eccentrics keeping both the bottom valve and top valve opening at the same percentage before top dead center and closing at the same angle. The valve faces will be different.

Re: Stanley D-Valve dimensions
May 08, 2023 11:46AM
This is related to a topic that comes up from time to time. There are a number of books on the topic of valve gears which can be downloaded for free from Google Books.

Ernest L. Ahrons

William N. Barnard

Cecil H. Peabody

Charles H. Fessenden



There is also an outstanding computer program that allows you to plug in all the dimensions for a number of different valve gears and then simulate their operation -- allowing you to fine tune the design:

Dockstader Valve Gear Simulator

Edited 1 time(s). Last edit at 05/08/2023 11:47AM by frustrated.
Re: Stanley D-Valve dimensions
November 07, 2023 05:27AM
There are two (2) schools of thought about steam engine valves. The Stanley D-valve is what I would call the classic valve design. The Stephenson and Walschaerts are 2 examples of the actuating system. Piston valves will fall into this category also. Then there is the Stumpf philosophy that introduces the uni-flow steam engine with a method to conserve water rate more than the classic and even more than a compound.

To compare the 2, classic is typically set up for ~50% cut-off. The reason for this (my deduction) is to use the steam expansion during the d-accelerating piston motion. Use the boiler pressure during the piston accelerating motion during the cyclic turning of the crank. Hook-up or the reduction of this cut-off is typically down to ~40%.

The uni-flow can be set up to go down to single digit cut-off. In essence this is to reduce that water rate to the point where it is better than a compound. The valve of choice for this might be the poppet valve and a cam/follower actuation system. Also, a bash valve will do nicely also. However, the bash valve has little flexibility to change its admission/cut-off. One missing piece of information is that the uni-flow will not have much ability to produce work at lower cut-off. The way that the engine can perform well in practice is to increase/allow its rpm higher to make up for the work compared to the classic valve design. Keep in mind that the uni-flow valve cut-off w/poppet/cam can vary valve timing to what ever one wants and up to the point where it can be 50% allowing for self starting. The rpm is roughly 85% greater compared to the classic to get the same work while maintaining a lower water rate.

Back to the classic steam engine, this engine can also be improved to lower it's water rate. There is so much torque in these engines that it can allow it to be geared up. This will give more work completed per rev. This is how the Stanley's achieved the land speed record. If this gearing were to be used in common practice, there would be a lower gear used for starting and accelerating. Then a high speed gear for cruising.
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