Wayside rail lubrication has been used in the railroad industry primarily to reduce the wear of wheel and rail on curves.  The most common devices used for such lubrication are wayside rail lubricator strips.  These strips are parallel to the rail and dispense grease before and during the passage of a wheel allowing the wheel flange to pick up the grease and lubricate the gage side of one or both rails.  Most of these lubricators are designed to avoid lubricating the top of the rail so that the wheel treads are not affected by the lubricant applied by the wayside lubricator.  The situation is slightly different in railroad hump yards.  In these yards, it is currently common practice to apply grease to the top of the rail either manually or using a greasing system that dispenses grease through a hole in the rail so that the rolling resistance of the cars is reduced and the rollability is improved.  There are several problems with both the wayside grease lubricators and the grease plugs used in the yards.  These include the mess created by the black grease which coats the rails, the ties, ballast and the area where the wayside lubricator or the grease plugs are installed.  Often the grease spreads, and coats such a large area that it is a slipping hazard to ground personnel.  Wayside rail lubricators are difficult to maintain and adversely affected by temperature and weather changes.  In yards, the grease plug lubricators do not consistently improve the rollability of cars.  The hole in the rail often results in a broken rail which has to be replaced with a similar rail with a hole.  Many cars do not clear the curves in the yard as they are supposed toxe2x80x94they have to be pushed into position (trimmed) by a locomotive.  The skids, used to stop the rollout of the cars beyond safe points, fail to stop the cars because of excessive grease on the rails.  The skids themselves slide for long distances creating situations where the car rollout can result in impact with another car.  At times, the grease has contaminated the retarders which are supposed to slow down the cars to a defined speed.  Such contamination can result in a loss of control for the retarders. 
Lubrication with grease has traditionally been used on the wayside of rail curves as well as on curves in the different yards.  As mentioned earlier, the current practice is to use wayside grease lubricators which consist of long grease application bars through which the grease is pumped in a certain quantity so that when the train approaches and crosses the curve, this grease is picked up by the flanges of all wheels including the locomotives and cars.  In the railroad marshaling and hump yards, the lubrication of the rail is done either manually or through a device commonly called a xe2x80x98grease plugxe2x80x99.  These are through holes in the head of the rail through which grease is squeezed under pressure when a wheel passes over it.  Both the wayside lubricators and the yard grease plug lubricators have serious problems.  The new method proposed in this invention overcomes the problems encountered to date and improves both wayside lubrication and yard rail lubrication.  The problems of wayside lubricators are discussed first. 
The grease bars laid parallel to the rail traditionally apply large quantities of grease which are picked up by the wheels and flung all over the track.  The grease spreads all over the rails, track, ties, ballast etc.  developing a hazardous coating which makes it difficult and dangerous to service these lubricators.  Over the years, these lubricators have been found difficult to maintain.  Temperature and weather seriously affect their functioning.  In order to make sure that some grease is applied to the rail gage corner, the common practice is to increase the quantity of grease in the lubrication bars.  This is so large in many cases that it spreads all over the rail head as well.  When the train approaches the curve with the grease spread over the rail head, the locomotive wheels slip.  As a result, sand is automatically injected.  This results in the development of a sand-grease grinding paste which defeats the purpose of rail lubrication and contaminates the ballast, ties, etc. 
Looking at the railroad yards, the current practice of lubrication uses wayside lubrication devices such as grease plugs through a hole in the rail head.  These also do not function well.  Although a large quantity of grease is applied via this through hole in the rail head, it does not adequately lubricate the wheel-rail contact on sharp curves.  Since the quantity of grease put through this hole is quite large, it spreads in a coating on the rail throughout the yard as well as builds up on the sides when spills take place.  The coating on the rail head is enough to coat the skids placed on the rails to stop the cars from sliding on the rails.  Thus, the skids do not stop the car and let it go into a rollout sometimes resulting in collision damage.  In spite of such greasing, the rolling friction between all the wheel and rail contacts is not reduced enough and many cars do not go beyond the sharp curves and have to be pushed by a locomotive which has difficulty itself pushing because of locomotive wheel slip. 
This invention solves the problems indicated above by applying a spray of clean, smoothly-flowing lubricant directly on the approaching car wheel.  For revenue service trains, appropriate sensors detect the passage of the locomotive wheels and do not apply any lubricant.  After the locomotive wheels have passed, the lubricant is sprayed by a nozzle on the wheels of the trailing cars.  Such an application may be made to both wheels of a wheel-set or a single wheel.  The wheel to which the lubricant is applied becomes a carrier and spreads it on the rail at the points of wheel-rail contact to benefit the trailing cars.  For the railroad yards, the situation is simpler in that for all approaching cars, the wayside wheel lubricator puts out a spray to lubricate one or more wheels. 
This system requires a number of sensors by the wayside which detect the approach and passage of the car or the train.  It also requires a lubricant supply and a pressurizing system which develops pressure to move the lubricant from its reservoir to a spray nozzle.  In addition, it requires that the spray nozzle can be turned on for a defined duration of time so that the quantity of the lubricant is kept under control.  The number and frequency of applications can be calculated for the train or the cars in the yard.  By avoiding application of the lubricant to the wheels of the locomotive, this invention reduces the friction between the wheel tread and rail on curves for the trailing cars only and thus reduces the friction and the force that is experienced by the wheel flanges on curves.  This method is superior to the current wayside lubricator approach a in that it does not degrade the traction of the locomotive wheels and it reduces the friction as well as the lateral force produced by the car wheels on the rail.  In other words, the force exerted by the wheel flanges on the rail is reduced.  Current wayside lubricators are designed to reduce only the flange friction with the rail.  Furthermore, it applies an accurate amount of lubricant in small quantities directly on the wheels so that the cleanliness of the rail bed is maintained.  By using this approach, the rollability of cars in yards can be improved significantly (50% or more).  A similar reduction in rail forces and rail-wheel wear on curves in revenue service is expected by using this method of wheel lubrication. 
For good lubrication, it is necessary to lubricate much of the wheel tread and the flange that comes in contact with the rail head.  The new method of the present invention achieves the needed characteristics and accomplishes the following:
it reduces the friction between the car wheel tread and flange with the rail for all positions that the wheel can have on the rail in a curve including an xe2x80x9cSxe2x80x9d curve;
it reduces the lateral force developed by the wheel on the rail;
it is beneficial to reduce rail and wheel wear and also reduce the cost of maintenance of curves; and
it does not negatively affect the adhesion of locomotive wheels on curves.