YARD FRICTION MODIFIERS SOLVE MANY PROBLEMS
In spite of considerable modernization and automation, yards continue to face serious problems in the areas of safety, lost productivity, loss and damage, increased track maintenance, and environmental concerns.
Problems in Yard Operations:
Yard Safety Issues:
Railroad yards continue to face the hazards of car collisions and derailments. In addition to being safety concerns, these events can cost thousands of dollars in damage and lost productivity. Some of the problems associated with car derailments are tipped rail, crossed couplers, short stops, worn-out rail and switch points, and damaged and misaligned track.
Car collisions are not uncommon in a yard. They are caused mainly by rollout, insufficient speed control, inefficient skates due to excessive grease on the rails, and worn, out of maintenance retarders.
Loss and Damage: The number of derailments and collisions that take place in a yard is a significant portion of the total derailments or collisions that occur in a railroad. Some of these are due to human error, but a significantly large percentage are due to insufficient control of car speeds. When collisions or derailments take place, there is significant damage to the car and the freight inside, as well as the track, which in turn increases the track maintenance cost.
Loss of Productivity: Collisions, derailments, and cars stalled before their destination cause a loss of productivity in a yard because classification is suspended while these problems are remedied. In theory, 10 or more cars can be humped every minute and one or more cars can be kicked in a flat yard in the same time. In reality, however, output is considerably less, about one-tenth of the maximum. One of the factors that contribute to this is stalled cars that have to be trimmed by locomotives.
Main Problem: At present it is not possible to achieve consistent rolling speeds in hump yards or flat yards. In hump yards, computer-controlled retarders cannot be set once for everchanging friction conditions. In flat yards, engineers have to make intelligent guesses on prevailing friction conditions and then estimate kicking speed. Both scenarios often result in either car collisions or short stops. Sharply curved track sometimes produces such high lateral forces that it tips the rail and causes derailments. High lateral forces combined with crosscoupler impact at high speeds are a recipe for derailments. \
Wayside Greasers: Until recently, many yards used wayside greasers to reduce the rolling resistance of cars on curves. Greasers are not generally effective in solving the problem and in some cases make things worse. In order to make rolling easier, it is a common practice to set greasers at high rates of grease application. Excessive grease makes the surroundings messy by forming grease pools under the applicator.
A coating of grease also forms between the rails for a stretch of track beyond the application site, making the area a safety hazard. Thus, the effective overall cost of these greasers is quite high considering the large amounts of grease used and the manpower required to maintain them and clean up excess grease.
The New Yard Friction Modifiers:
The newly developed yard friction modifiers solve many of the problems stated above. Many yard personnel use the abbreviated form ‘‘modifiers’’ to describe these units. This system sprays a clean, environmentally safe friction modifier fluid on the wheels of a car as it enters its classification track. The application is in the form of microburst lubricant jets, which hit both wheels of the lead axle of an approaching truck of a car. Figure 25.12 shows how the modifier works. It is located just before the main switch of a group of tracks into which the classification is intended.
Friction Modifier Fluid:
Friction modifier fluid is a thin, synthetic polymer liquid, and not a grease. It is safe to handle and biodegradable. It contains no solids such as graphite or molybdenum disulphide and dissipates as trains pass over it, leaving little or no buildup on rails or wheels. It is effective for a wide range of temperatures, from 20F to 150F, ensuring smooth delivery flow throughout the year. In the United States, it is currently produced for Tranergy Corporation by Shell Oil Co.
How Many Modifier Units Does a Yard Need?
The number of units needed by a yard is determined by the groups of tracks present in the yard. the layout of a hump yard equipped with modifiers. It has five
groups of tracks, five corresponding retarders, and one primary or master retarder.