Railroad tie extractors/inserters, like most maintenance equipment used
in the industry, have little symmetry to them and all of the working
parts are exposed and on display for all to see (which do make them
interesting to watch as an observer). Using hydraulics to accomplish
the heavy lifting and pulling a single-operated tie extractor today can
remove as many as seven ties a minute. Compare this to the days when railroad maintenance
required armies of men to remove spent ties using tongs and shovels,
and everything was done by hand. To remove a used today today, typical
railroad tie extractor, even a small model, will apply nearly 40,000
pounds of force to the rail (lifting it so the machine can free the tie
as well as nearly 20,000 pounds to the tie itself to pull it free. If
the job is small the same machine will replace the tie but if a large
section of main line is being overhauled the tie relaying machine will
According to Brian Solomon's Railway Maintenance: "In order to remove a tie, the machine clamps on to the rails, and lifts the track slightly with hydraulic jacks. A hydraulically controlled telescoping boom then grips the tie from the end and pulls it out. Since ties can become angled, the boom is able to rotate right or left 10 to 20 degrees off axis from a hypothetical perpendicular in order to grab any wayward ties. The boom must be able to lift as high as 25 degrees above the track plane, and drop up to 15 degrees below the track plane to extract the tie from below the rails." Additionally, when at work these machines are designed to disrupt the right-of-way as little as possible since the line is expected to be ready for service again after the work is completed.
Of course, before the days of tie extractors and inserters, or any type of mechanized equipment at all for that matter, railroads were forced to rely on the brute strength of sectionmen to pull and replace ties using standard hand tools such as track jacks, rods, crowbars, and tie tongs. This meant pulling spikes by hand to release the tie, lifting the rail up with hand jacks, digging out all of the ballast (stone) by hand, and finally pulling out the tie itself with the aforementioned tongs. Needless to say this required an incredible amount of time and forced railroads for many years to employ thousands and thousands of employees working as track gangs to keep up with maintenance. Today, there are several different manufacturers of extractors/inserters although one of the leading companies is Harsco Rail, which builds a wide variety of MOW equipment.
Lastly, for more reading about tie extractors you may want to consider the book Railway Maintenance Equipment: The Men and Machines That Keep the Railroads Running
from noted author Brian Solomon. Throughout the book's 128 pages
Solomon covers all types of maintenance equipment from tampers and
undercutters to Jordan Spreaders and rotary snow plows. I own this book myself and have used it as reference material for this site many times. It's a great read on
an often little understood area of railroading. If you're interested
in perhaps purchasing this book please visit the link below which will
take you to ordering information through Amazon.com.