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 Post subject: New rod oil covers for HHGB 4
PostPosted: Sun Jul 24, 2022 7:19 am 

Joined: Thu Apr 14, 2005 9:34 pm
Posts: 2836
Location: Copenhagen, Denmark
Helsingør Hornbæk Gilleleje Bane number 4 is a 4-6-0 from Henschel, 1907. HHGB was an early convert to diesel, and number 4 was in storage by 1923. It was sold to a neighboring railway and saw heavy wartime service due to oil shortages. After the war, it was a "reserve" locomotive, which in reality saw use only a few times a year.

It is very obvious that number 4 never saw good maintenance, I theorize because everyone believed it was shortly to be scrapped. We have been rebuilding it for service, and everywhere we look, we keep finding parts that are worn past repair.

An example I have been working on is the drive rod oil covers. How something that has no moving parts would be so worn is a mystery to me. The covers have a spring loaded "plug" for filling. The rotation of the rod splashes oil up and down the oil hole. My best guest for the plug wear is the violent rotation causes the plug to move against the spring, and thus the "nonmoving" part moves. But there is no excuse for the severe wear of the cover mounting holes. Many of them are so elongated that the mounting screws almost pass through.

Making new replacements is a lot of fiddly work. The plug especially does not have any good holding points when it is finished. One has to be careful to hold the matching taper correct. The originals were brass castings, but we are just cutting them from solid.

Oh, and of course the parts do not match the drawing 100%. You would think with a production shop they would make a template to keep all the dimensions uniform? No. The screw holes in the rods appear to have been laid out by hand, and they are just a little out of square. The covers have to be custom drilled to match the rods, and even then some filing of the holes is required. The covers only fit in one orientation. In some of the covers, the oil plug is not centered on the cover. The threads are theoretically standard, but the fit standard is just a little different, so our new CNC turned screws sometimes do not fit the existing holes.


Attachments:
File comment: New parts compared to old parts
Old and new comparison.JPG
Old and new comparison.JPG [ 50.33 KiB | Viewed 1794 times ]
File comment: Cover and plug test fitted, no spring
cover installed small.JPG
cover installed small.JPG [ 46.03 KiB | Viewed 1794 times ]
File comment: New machined cover and plug
Eccentric rod cover and plug 4H.JPG
Eccentric rod cover and plug 4H.JPG [ 85.05 KiB | Viewed 1794 times ]
File comment: The plug
Plug drawing.jpg
Plug drawing.jpg [ 44.39 KiB | Viewed 1794 times ]
File comment: Original Henschel drawing of the cover
cover drawing.jpg
cover drawing.jpg [ 52.49 KiB | Viewed 1794 times ]

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Steven Harrod
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Danmarks Tekniske Universitet
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 Post subject: Re: New rod oil covers for HHGB 4
PostPosted: Sun Jul 24, 2022 8:57 am 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 6464
Location: southeastern USA
Having worked primarily on older industrial and shortline steam, the concept of "standard" didn't last too long in service, and standards as such were pretty wide on the erecting floors at the time. I found that the most practical way to deal with keeping them running was in doing what the industries and shortlines did - make what's there work and fit all new parts to what is real, not what is drawn. Use some stamps to mark each as to its location and orientation and save future mechanics a lot of headscratching and debate as to your probable ancestery.

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