Rail grinders work by using a circular grinding stone, that are situated underneath the equipment right above the rails.
These stones wear out extremely quickly and usually only last a few
hours before needing replaced. As you might have guessed because of
this a grinder will go through dozens and dozens of these stones
(sometimes into the hundreds) in a single day. There is however,
usually a method to the madness. Rail grinders will typically use a coarser stone to work out all of the dips and wear found along the rail head and a finer stone to finish the work and return the rail to a nice, polished finish.
A typical rail grinder doing work along a heavy, freight main line in the United States is not a singular unit but an entire train staffed with several workers. It includes the lead locomotive, which pulls the grinding equipment and crew quarters. A typical grinder is stocked with enough tools, equipment, and amenities for the crew to be out on the open main line for days at a time. For freight railroads in this country almost all rail grinding work is contracted out to a company which specializes in the field such as Loram, Speno, Pandrol Jackson, and Harsco Track Technologies. However, some railroads have purchased small grinding units to do light work to save the costs involved in contracting and most light-rail/commuter lines which do not see freight traffic always use these singular units as their rails simply don't take the heavy beating like freight lines do.
According to Brian Solomon's book Railway Maintenance more than twenty years ago the estimated cost of grinding operations cost railroads between $15,000 to $30,000 per day. As such, you can imagine that this price tag has jumped considerably higher today liking costing an additional 50% or more. As mentioned above Loram generally receives the bulk of the contracts concerning heavy grinding and their unique maintenance trains have become a common sight on Class I main lines not to mention a favorite photography subject for those interested in railroads and their operations. However, Loram also specializes in other areas of MOW work such as undercutting, ballast cleaning, and general ditching. To learn more about their services please check out the company's website.
Lastly, for more reading about rail grinders 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.