This invention relates, in general, to a new and improved apparatus for forming a continuous rail and, in particular, to a new and improved welding apparatus for welding rail sections together to form a continuous rail. 
Welding apparatus for welding together rail sections and other similar materials are generally well-known in the art.  Various welding apparatus of this type is disclosed, for example, in U.S. Pat.  Nos.  2,781,026; 2,787,698 and 3,134,012.  Furthermore, in U.S. Pat.  No.  3,030,494, there is disclosed a method and apparatus for forming a continuous rail, using a welding apparatus of the type disclosed in the above-mentioned U.S. Pat.  No.  2,781,026. 
While the welding apparatus disclosed in these prior patents have been used to weld many rail sections together successfully, they also have been found to be unsatisfactory in that they result in the production of a number of unsatisfactory welds which must be corrected by severing the joint and making a new weld.  Obviously, the production of improper welds increases both the time required and the cost of production of the rail. 
In addition, in many of these prior welding apparatus, the hydraulic cylinders thereof are closely located to or in the flash-zone.  As a result, the flash accumulates on these hydraulic cylinders and ultimately impairs their operation, unless the flash is periodically removed.  In many others, the arrangement of the hydraulic cylinders is such that substantial shearing and/or bending stresses are exerted on their piston rods.  These stresses likewise tend to impair and, in extreme cases, prevent the operation of the hydraulic cylinders.  In still others of them, the action point of the aligning forces are removed from the welding plane, making it difficult if not impossible to satisfactorily weld deformed rails.  Also, in many cases, the electrodes are not easily accessible for cleaning, or exchange. 
The welding apparatus of the present invention overcomes these above-mentioned shortcomings of the prior welding apparatus and, in addition, provides various other improvements and features.  For example, the construction of the welding apparatus is such that it is movable plus or minus approximately two feet to compensate for the position of the continuous rail, i.e., the already welded together rail sections, as the latter is removed from the welding apparatus.  Accordingly, the entire length of the continuous rail need not be moved to properly position it with respect to the welding apparatus to form or make a subsequent weld. 
The welding apparatus also is provided with a vertical clamping and aligning system and a horizontal clamping and aligning system, each of which contain pairs of hydraulic cylinders, one of which is larger than the other, with the larger cylinder in each case being operable to a set position with respect to the rail line of the apparatus, to position the rail.  The smaller cylinder then operates to effectively clamp the rail against an arm operated by the larger cylinder.  Both of the pairs of cylinders are fed from the same source of hydraulic power.  With this arrangement, the rails can be more accurately and quickly aligned, as described more fully below.  In addition, for still greater accuracy, the cylinders are connected in a parallelogram-type arrangement, with the entire arrangement being adjustable by means of still another hydraulic cylinder, for a final alignment adjustment. 
Another feature of the welding apparatus is that the lever arms which support the electrodes to vertically clamp the rail are very rigid in the vertical plane in clamping the rail, but are flexible to some degree in a horizontal plane.  This flexibility permits the level arms to be laterally adjustable during the horizontal clamping and aligning process, so that the horizontal and vertical aligning systems are not effectively opposing one another, as in the case of many of the welding apparatus in the prior art. 
The above described arrangement also eliminates scratching of the rail which may cause the rail to deteriorate. 
Still another feature of the welding apparatus is the fact that the deburring or shearing apparatus thereof for shearing off the upset metal surrounding the welded joint can be operated to do so, without removing most of the clamps which support the rail.  With prior welding apparatus, all of the clamps had to be removed, before the shearing apparatus could be operated.  Since the shearing of the upset metal usually is done while the metal and the welded joint both are still in a semi-molten state, releasing the clamps would permit a deformed rail to move out of alignment and a defective or unsatisfactory joint would result. 
Still another important feature of the welding apparatus is the provision of a sensing apparatus for sensing the aligned positions of the rails at the joint and for automatically operating the horizontal and vertical clamping and aligning apparatus to align the rails prior to welding the joint. 
Accordingly, it is an object of the present invention to provide improved apparatus for forming a continuous rail. 
More particularly, it is an object to provide an improved welding apparatus for welding rail sections together to form a continuous rail.