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A little Throttle-Valve for my STUART #1

Posted: Wed May 13, 2026 3:13 pm
by dampfspieler
Hi,

i have got a STUART #1 from a ebay UK. It was described as built at a high standard and should run well with compressed air. I have it checked and was like the Queen - "not amused". So i have it comprehensively overhauled.

I wanted a separate throttle-valve on the engine, and the design was inspired by the NAVY K because I find that absolutely fascinating.

It is a slide valve made from semi-finished products. During its construction, I chose some new solutions that I believe might be of interest to others as well.

Rendering
Rendering
Fahrventil_20260512_001_links.16.jpg (129.05 KiB) Viewed 19248 times
The connections are as follows:
- Top: Steam from the boiler
- Bottom right: Steam to the engine (steam chest)
- Bottom left: Connection port for the cylinder lubrication oil trap

Dimensions
Dimensions
Fahrventil-2D-Uebersicht.JPG (54.15 KiB) Viewed 19248 times
Section through the assembly
Section through the assembly
Reglerarmatur_kplt-Schnitt_20260513.png (109.51 KiB) Viewed 19242 times

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Dietrich

Re: A little Throttle-Valve for my STUART #1

Posted: Sun May 17, 2026 1:54 pm
by Kelly Anderson
Well done!

Re: A little Throttle-Valve for my STUART #1

Posted: Sun May 31, 2026 2:58 pm
by dampfspieler
Hi Kelly,

i'm glad you like it. I hope that applies to the now-finished valve as well.

This is what the valve face looks like. Thanks to the pointed shape, the steam can be metered more precisely at small valve openings, allowing for better control over the engine's operation.

the valve face with its special port before lapping
the valve face with its special port before lapping
FahrVentS01_042kl.jpg (109.81 KiB) Viewed 17380 times

The valve is mounted slightly differently than in the design, as it must be operated from the column side due to the engine's primary direction of rotation.

FahrVentS01_094kl.jpg
FahrVentS01_094kl.jpg (48.1 KiB) Viewed 17380 times

A view of the engine's control side. The valve lever is in the closed position. The reversing lever is in the reverse position. For improved operability, it is now angled—a departure from the original design.

FahrVentS01_095kl.jpg
FahrVentS01_095kl.jpg (48.19 KiB) Viewed 17380 times

Both levers can be locked in the desired position by means of a clamping mechanism.
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Dietrich

Re: A little Throttle-Valve for my STUART #1

Posted: Sat Jun 20, 2026 12:51 am
by TahoeSteam
Gorgeous work, as always Dietrich. Thank you for sharing with us!

Yesterday in the garden

Posted: Mon Jun 22, 2026 6:47 am
by dampfspieler
Hi Wesley,

thank you.

Yesterday, I tested the newly built whistle valve under steam and checked that the steam whistle setup was correct. That was successful.
And since the boiler was already up and running, I also tested the throttle valve with steam. That worked very well, too.
FahrVentS01_104kl.jpg
FahrVentS01_104kl.jpg (92.4 KiB) Viewed 15697 times
However, the test came to a premature end when the pressure piece of one of the safety valves unscrewed itself due to the vibrations caused by the escaping steam and flew off.


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Dietrich