Marshall (Hackworth) Valve Gear Design?

[Curtis_F]

Good day,

I know almost nothing about Marshall (or Hackworth) Valve gear, and now want to use it on a personal project, so I need to do some research!

Paul Pickard remembers an article in Model Engineer from the 70s that talked about it, can someone tell me which issue?

Are there any books or other technical articles written about Marshall and/or Hackworth that someone can point me towards?


I've been "messing" about with a design in SolidWorks and checking it in Docksteader's program, but I'm concerned that I'm missing something obvious that will bite me in the butt later.


Any help will be appreciated,

Curtis F.

[marshall5]

Several published designs in the U.K. feature Hackworth valve gear, all narrow gauge, the most popular being the 5"g 'Sweet Pea' and 7 1/4"g 'Sweet William'. There is a construction manual (I got one on Amazon a few months ago) to accompany the drawings for this loco. Another is Ken Swan's 'Wren' in 7 1/4 and 7 1/2"g for which excellent drawings are available. I'm no expert on Hackworth gear but understand that it's main advantage is its simplicity whilst its main disadvantage is that spring deflection affects the valve events. Hope this helps. Ray.

[Fred_V]

I've built 2 engines with Marshal and one with Hackworth. The big complaint with Hackworth is the sliding block that wears out over time. I liked the Marshal design and it worked well but was a bit tricky to get it all centered initially. I could see no issues with spring deflection with the Marshal and the Hackworth engine had the drive axle fixed. since it was a smaller engine. I think the Marshal gear is easier to design and build.

[Curtis_F]

Several published designs in the U.K. feature Hackworth valve gear, all narrow gauge, the most popular being the 5"g 'Sweet Pea' and 7 1/4"g 'Sweet William'. There is a construction manual (I got one on Amazon a few months ago) to accompany the drawings for this loco. Another is Ken Swan's 'Wren' in 7 1/4 and 7 1/2"g for which excellent drawings are available.

Ray,

Every little bit helps. Having specific design names helps track down articles written about them.

...whilst its main disadvantage is that spring deflection affects the valve events. Hope this helps. Ray.

Actually this is not a concern for me. A designer for the Baldwin Locomotive Works found a way to get around that problem. I'll be posting drawings of this solution when I get the design ironed out for this engine I'm working on.

---------------

I've built 2 engines with Marshal and one with Hackworth.

Fred,

Before staring this thread I was doing searches of the forums for Hackworth and Marshall, many of your posts came up with gems of wisdom in them about setup and timing. I'm beginning to think I've been over thinking this valve gear. I'm used to Walschaerts and Stephenson where they have all sorts of hidden tweaks and pit falls. Marshall really may be as simple as it seems to be.

Thank you for the help, even if you were actually answering someone else's questions.

Cheers,

Curtis F.

[JJG Koopmans]

Regarding the books you asked for:
Model Locomotive valve gears by Martin Evans. My 1962 version has 2 1/2 pages on H & M gears with drawings.
Another one is Valve and Valve gears for Steam Locomotives by Lake & Reidinger, 3 pages with text and drawings in my 1981 reprint.
Both are available at Camden.
I must have Yoder and Wharren lying somewhere around, but cannot locate that book.
Kind regards
Jos Koopmans

[Sandiapaul]

Curtis,

Check this, lots of articles the 2006 articles by Pope look like they might be good:

http://www.itech.net.au/modelengineer/ME_Response.aspx

Paul

[david griner]

Once you spend a bit of time with this program it becomes a significant tool for valve gear work. Have used it for my engine where I designed the gear, then tested it on the program and finally, tuning it during construction.


http://www.billp.org/Dockstader/ValveGear.html

Dave Griner