MoW: Undercutters

Matt Wayand commented in Facebook

As a comment to the track welder Facebook posting, Matt Weyand provided a picture of a switch undercutter attachment on an excavator that is another example of using an excavator attachment that uses a secondary hydraulic power source. (Previous examples are a brush cutter and snow blower.)

A Google search quickly reveals that several manufactures make an attachment for undercutting. It is basically a chain on a bar that is powered by a hydraulic motor. This video has the lowest ratio of "fancy" graphics to information of the ones I watched.

NMC Railway Systems

When the ballast becomes filled with dirt (below), it can no longer do its job of draining water away from the track.

20150720 3500
Illinois Railway in
Yorkville, IL

The undercutter is used to remove the dirty ballast. Then new ballast will be dumped on the track and the track will be surfaced.

Undercutter attachments are used for small jobs and in places where the big machines can't operate such as under turnouts. Speaking of the big machines. They undercut, pick up the ballast, run it over sifters (see 2:18 in video), and drop the cleaned ballast back on the track (2:27). The dirt and broken rocks that fall through the sifters are deposited to the side (2:57). A video of a longer ballast cleaner uses separate machines in one long unit for cleaning the side ballast vs. the ballast under the ties, but it doesn't seem to go much faster than the compact machine in the first video.

Update: now I need to figure out what "sledding" is because that would be what the machine with the big "wings" is doing in Facebook. BTW, the pictures are not in order because the DYNA-CAT is a tamper that levels the track after the ballast cleaning equipment has disturbed the track.

Update: video. Comment by Matt Weyand on Facebook: "Ballast Tools Equipment 15 Foot Undercutter Bar with spoil removal wheel. This is how we like to Undercut!!!"

A UP video of a train that lifts the track for the undercutter chain, cleans the ballast, then replaces the ballast. I wish they had added some overview shots of the train. I see UP is using concrete ties. BNSF is still replacing wood ties on their mainline into Chicago.

The first part of this video is an undercutter being transported to another work site. At -0:18 is a high production tamper.
(source)
Dennis DeBruler At the end is a ballast distributor. It looks like it can do in one pass what a normal ballast regulator has to do with several passes back and forth over the same area using different attachments.
http://www.plasseramerican.com/.../ballast-distributing...
Dennis DeBruler Between the ballast undercutter and the distributor is a continuous action tamper, http://www.plasseramerican.com/.../tamping-09-3x-cw...