Mobile apparatus for welding studs to rail base plates

Mobile apparatus for, on site, welding of rail retaining clip studs to existing railroad rail plates which includes a railway car assembly having wheel and axle assemblies and propulsion means to move the railway car assembly along the railway tracks. The railway car assembly further includes two carriage assemblies each of which carries two welding gun assemblies which project downwardly upon each side of the rail plate. The carriage assembly includes carriage actuator means for moving the carriage assembly both longitudinally and transversely of the rail plate to position the welding gun assemblies. A position and sensing control means is provided which includes a rail plate sensor which first senses the position of a rail plate to stop the railway car assembly and properly position the welding gun assembies with respect to the rail plate longitudinally thereof. The position sensing and control means further includes a rail web sensor which senses and positions the welding gun assemblies transversely of the rail in proper position.

BACKGROUND OF INVENTION 
The present invention applies to methods and apparatus for welding studs to 
railroad rail plates to which spring clip devices are attached to hold the 
rails in place and, more particularly, to such apparatus which is mobile 
and operates on the rails when in place to provide a retrofit for existing 
rails. 
Railways have, for years, conventionally utilized wooden cross ties upon 
which are positioned rail plates under the railroad ties. The rail plates 
are anchored to the railroad ties by means of the conventional railway 
spikes. Additionally, the railway rail is secured to the railway plate by 
means of conventional railroad spikes. 
The continual and repeated side loads upon the rails by the cars passing 
over the rails as well as other factors such as ice buildup under the rail 
flange ultimately cause the railway spikes to work upwardly from the rail 
tie. As this occurs, movement is permitted between the railway rail and 
the rail plate. This movement has the obvious disadvantage of permitting 
the rail to upset causing derailments. Additionally, the loose railroad 
spikes cannot control rail creep--i.e. longitudinal movement of the rail 
with respect to the rail plates. 
In the past, various different forms of securing the rail to the rail plate 
have been tried such as threaded anchor bolts screwed into the railway tie 
and cooperating with spring clip members bearing against the rail flange. 
Additionally, other devices have been tried such as concrete ties into 
which there are cast anchor or securing devices which likewise cooperate 
with spring members to maintain the rail flange in engagement with the 
rail plate. In this latter case, replacement of the entire ties under an 
existing railway is expensive and thus, impractical. 
The assignee of the present patent application, the KSM Division of Omark 
Industries, Inc., 301 New Albany Road, Moorestown, N.J. 08057, has 
developed a new spring clip rail retaining system. In the Omark system, a 
headed stud is welded to the rail plate on each side of the railroad rail. 
A spring retaining clip is engaged with the headed stud with a portion of 
the retaining clip bearing upon the flange or heal of the railroad rail. 
The stud-spring clip assembly provides flexure of the spring clip or a 
resiliency between the rail and the rail plate to overcome the foregoing 
described difficulties of railroad spikes. 
One of the very significant advantages of the Omark system is that the 
studs and retaining clips can be a retrofit system to existing railways. 
The configuration of the studs is such that they can be welded between 
existing railway spikes on a given rail plate without the necessity of 
removing the railway spikes or replacing the rail plates and ties. 
Apparatus for welding large headed studs to metallic base members such as 
railway plates has been known for considerable time. However, such 
apparatus is either a stationary machine located in a plant or a portable 
hand held welding gun. In the environment of welding studs to a railway 
rail plate, certain environmental difficulties are encountered. First, 
there must be four such studs welded to each of two rail plates for a 
given railway tie. The virtual number of studs which thus must be welded 
for a given section of railway track is enormous and the need for some 
apparatus to carry the studs and to automatically weld them becomes 
evident. Additionally, the supporting apparatus such as the welding 
generator and controllers must be capable of being moved along the rail 
conveniently. 
A first consideration would be to mount the stud welding apparatus upon a 
railway car and move along the rails and weld two studs each side of each 
rail for a given railway tie simultaneously or substantially 
simultaneously and thus, move to the next rail and so on. However, there 
are many practical difficulties encountered in such an approach by reason 
of the physical variations in the railway system. 
One significant variation is that the railroad ties are very often not 
absolutely perpendicular to the railroad rails. Thus, to align the welding 
guns to weld one set of headed studs for one railway plate will not 
necessarily align the other pair of welding gun assemblies in proper 
longitudinal relationship to the railway plate under the opposite rail. 
Likewise, variations in gage created by wear and displacement of the 
railway plates will create variations in the positioning of the railway 
assemblies for transverse welding position to the rail plate on a tie by 
tie basis. 
A further yet difficulty encountered is obstructions which occur along the 
railway. One form of obstruction which may create interference conditions 
with the welding gun assemblies is the utilization of angle bars or 
couplings applied to the joints of the rails. Other forms of obstructions 
which give difficulties are railway spikes which have worked upwardly out 
of the tie to such a height as to cause an intereference. 
A further yet variation which can create difficulty in an on site welding 
situation is the vertical distance between a given railway car and a rail 
as the railway car moves along the track. Deflection of the railroad rails 
upon loose ties, wear of the rail and the like will create a vertically 
varying distance betwen a welding gun and the rail which must be 
compensated for. 
OBJECTS AND SUMMARY OF INVENTION 
It is an object of the present invention to provide mobile apparatus for 
welding studs to rail plates for use with rail retaining clips which will 
automatically weld the studs to the rail plates on a sequential tie by tie 
basis. 
It is a further object of the present invention to provide automatic 
positioning of the welding gun assemblies to compensate for variation in 
longitudinal positioning and gage positioning of the rail plates. 
It is also a further object of the present invention to provide means for 
sensing obstructions incurred along the railway to protect the welding 
equipment. 
In accordance with the present invention, a railway car assembly is 
provided which includes axle means and propulsion means for mounting the 
car assembly upon the railway and for moving along the railway at a 
predetermined and controlled speed. Two carriage assemblies are provided, 
one for each rail of the railway system. The carriage assemblies each 
support two welding gun assemblies which extend from the carriage assembly 
upon an angle down to the railway plate upon which the headed studs are to 
be welded. 
Each carriage assembly includes carriage actuator means which will permit 
the carriage assembly and its associated welding gun assemblies to be 
moved in both the direction longitudinally of the rail plate as well as 
transversely thereof to position the welding gun assemblies properly with 
respect to the rail plate. 
Each carriage assembly further carries a position sensing and control 
assembly which, connected through sensor support arms, carries a rail 
plate sensor positioned on one side of the rail and a rail web sensor on 
the opposite side. As the railway car assembly moves from one cross tie to 
the next, one of the rail plate sensors chosen as a master sensor senses 
the appearance of the next rail plate and stops the railway car in the 
proper position of the welding gun assembly with the rail plate. 
Thereafter, the other rail plate sensor then operates through a welding 
gun assembly control means to move the opposite carriage longitudinally in 
a direction to bring the welding guns carried by that assembly into proper 
longitudinal welding position for the opposite rail plate. Following this, 
both rail web sensors then operate through the welding gun assembly 
control means to transversely position the welding guns with respect to 
the two rail plates. 
Following sensing and positioning of the welding guns with respect to the 
two rail plates, the sensors are moved out of position and the welding gun 
assembly moved into position whereupon the studs are welded to the rail 
plate. Thereafter, the welding gun assemblies are retracted and the 
process repeated. 
An obstruction sensor is positioned beneath the railway car assembly 
adjacent the inside web of both rails to sense obstructions. The 
obstruction sensor is in advance of the welding gun assemblies and the 
position sensing and control assemblies. Upon the encountering of an 
obstruction, the obstruction sensor operates through control means to stop 
the railway car assembly before damage can occur to the welding gun 
assemblies and the position sensing and control assemblies. 
Other objects and advantages of the present invention will become apparent 
to those skilled in the art from the detailed description thereof which 
follows taken in conjunction with the drawings.

DETAILED DESCRIPTION OF INVENTION 
In accordance with the present invention and as shown in FIG. 1 of the 
drawings, a railway car assembly 10 is provided. The railway car assembly 
includes axle assemblies 11 (one shown) which support the railway car 
assembly 10 upon the rails 12 of the railroad. 
The railway car assembly includes propulsion means (not shown) for driving 
the railway car assembly along the railway at predetermined speeds. The 
propulsion means includes two speeds, a first which is capable of moving 
the railway car assembly along the rail at a high speed of approximately 
17 miles per hour. The propulsion means also includes a low speed mode of 
approximately 2 feet per minute which is utilized during the welding 
operation to be described hereinafter. 
The railway car assembly also includes supporting apparatus which is shown 
in phantom such as a welding generator, hydraulic pumps, standard 110 
generating means and other related control modules and propulsion systems 
all of which are necessary to the welding operation but do not form a part 
of the invention. 
The railway car assembly includes two carriage assemblies 13 carried upon a 
rear portion of the railway car assembly 10. The operation of the carriage 
assembly 13 will be described in more detail hereinafter. 
Two welding gun assemblies 14 are carried by each of the carriage 
assemblies 13 and are adapted to extend downwardly into welding position 
with the rail plates 15 positioned upon cross ties 16 as partially 
illustrated in FIG. 6. 
Returning to FIG. 1, each carriage assembly 13 further includes a position 
and sensing control assembly 17 which extends downwardly from the carriage 
assembly 13 into the region of the rail plate 15 and web of the rail 12 to 
properly position the welding gun assemblies as hereinafter described. 
The railway car assembly further includes a control console 18 and an 
operator's seat 19 from which the railway car assembly and welding gun 
assemblies can be operated as well as the studs and arc shields loaded 
into the welding gun assemblies. 
Still referring to FIG. 1, an obstruction sensor 20 is positioned on the 
inside web of each rail and extends downwardly from and is supported by 
the railway car assembly in advance of the welding gun assemblies and 
position sensing and control assemblies. The obstruction sensor provides a 
determination of the presence of an obstruction and is in a position to 
stop the railway car assembly before damage occurs to the welding gun 
assemblies or position sensing and control assemblies. 
The details of the carriage assembly 13 of the present invention are shown 
in FIG. 2 of the drawings. The carriage assembly includes a box frame 21 
to which the two welding head assemblies 14 are attached. The box frame 21 
is adapted to operate through a hydraulic ram (not shown) so as to move 
transversely upon two guide bars 22. 
The entire box frame 21 and head assemblies mounted thereto are movable in 
dovetail guide blocks 23 mounted on side rails 24 at each side of the box 
frame 21. A carriage actuator means 25 which may be a hydraulic ram 
cylinder is attached to the box frame 21 and, upon command, moves the box 
frame 21 and associated stud welding assemblies in a longitudinal 
direction with respect to the rail and rail plate. 
By reason of the foregoing construction, the carriage assembly 13 has the 
capability of moving the welding gun assemblies both transversely and 
longitudinally of the rail plate upon the application of the appropriate 
control pressure to the various hydraulic cylinders involved. 
A position sensing and control assembly 17 is secured to each carriage 
assembly and extends downwardly into the area of the rail plate and web of 
the rail as shown in FIGS. 2, 3 and 5. Referring to FIG. 3, the position 
sensing and control assembly 17 includes two sensor support arms 26. The 
sensor support arms are interconnected through a scissors assembly 27 to a 
hydraulic ram 28. The scissors assembly 27 operating through the hydraulic 
ram 28 permits the sensor support arms to be swung upwardly out of the way 
or downwardly into sensing position as shown in FIG. 5. 
The sensor support arms 26 include a rail plate sensor 29 on one arm and a 
rail web sensor 30 on the opposite arm. The rail plate sensor and rail web 
sensor are electromagnetic devices which sense the proximity of the rail 
plate to the rail plate sensor and operate as will be hereinafter 
described. 
A welding gun assembly 14, in accordance with the present invention, is 
shown in FIG. 4 of the drawings. The welding gun assembly includes a first 
ram assembly including a hydraulic cylinder 31 and associated piston rod 
32. The first ram assembly also includes a guide rod 34 and associated 
guides 35 all of which terminate at a supporting block 36 which is moved 
upwardly and downwardly in accordance with the actuation of the first ram 
assembly. 
A second ram assembly 33 is secured to the supporting block 36. The second 
ram assembly is designed such that it has a center position between the 
extremes of its travel to which the ram assembly normally assumes its 
beginning position. The piston travel upwardly from this datum plane and 
downwardly throughout the stroke of the piston within the ram assembly is 
set at predetermined limits of travel in the raised and lowered positions 
to control the lift and plunge of the stud to be welded as hereinafter 
described. 
A stud chuck 37 is also provided at the lower extremity of the second ram 
assembly as shown in FIG. 4 of the drawings. Additionally, an arc shield 
retainer (not shown) is also provided at the lower extremity of the second 
ram and positioned in respect to the stud chuck by means of spring bias 
means such that the arc shield retainer may move relative to the second 
ram assembly and stud chuck so as the stud within the chuck can be exposed 
and permitted to contact the rail to which it is to be welded during the 
welding process for the purpose to be hereinafter discussed. 
Turning now to FIG. 7 of the drawings, the obstruction sensor 20 is shown. 
The obstruction sensor 20 is supported upon a long supporting rod 38 which 
is secured to the railway car assembly and may also be elevated upwardly 
manually to remove the obstruction sensor from the proximity of the 
railroad rail. However, in normal operating position, the supporting rod 
38 is positioned such that the obstruction sensor 20 is adjacent the inner 
web of the rail. 
The obstruction sensor includes a contact paddle 39 which operates through 
an arm 40 interconnected to the obstruction sensor 20. Upon the 
obstruction being contacted by the contact paddle 39, such as a railway 
spike projecting upwardly from the rail plate or the connecting bolts for 
an angle bar 41, the obstruction sensor will be switched to an activated 
position to deliver a signal indicating the occurrence of an obstruction. 
This signal, as described hereinafter, is utilized to stop the railway car 
assembly until the welding gun assemblies and position sensing and control 
assemblies can be manually retracted and moved to pass the obstruction. 
In operation, the railway car assembly and associated equipment and 
hardware is propelled down the railway tracks at a high speed to the point 
where the welding operation is to begin. At that time, the operator of the 
device controls the railway car assembly from the console 18 seated at 
seat 19. The railway car assembly is then placed in low speed operation 
and moves along the rails at approximately two feet per minute. 
At this time, the obstruction center 20 is lowered into its sensing 
position as shown in FIG. 7. At this time, the welding gun assemblies are 
in their retracted position as shown in FIG. 1 of the drawings and also 
the position sensing and control assembly is in retracted position as 
shown in FIG. 5 of the drawings. 
As the first rail plate upon which studs are to be welded is approached, 
the position sensing and control assembly moves the rail plate sensor 29 
and rail web sensor 30 into sensing position as shown in FIG. 5 of the 
drawings. The welding gun assembly control is programmed such that the 
carriage assemblies 13 will have the box frame 21 shifted to their 
furthest rightmost position at which the plate sensor 29 would be closest 
the rail web of the rail. This assures that the plate sensor 29 will pass 
above the leading edge of the rail plate. Additionally, this beginning 
configuration also maintains the rail web sensor 30 furthest from the rail 
web at the beginning of the sensing cycle. 
One of the two carriage assemblies 13 and its associated position sensing 
and control assembly 17 is chosen as the master. For the purpose of 
discussion, assume that the master is the left-hand carriage assembly 13. 
The master carriage assembly is positioned midway of its longitudinal 
movement and locked in that position. The other carriage assembly is then 
programmed to have its box frame 21 moved to a rearward position by an 
approximate 6 inches. This predetermined backset is calculated to be the 
worst case condition for a railroad tie being out of perpendicular 
alignment with the rails and rail plates. Accordingly, the rail plate 
sensor 29 for the right-hand carriage assembly will always be trailing 
behind the left-hand sensor by an amount calculated to be the greatest 
displacement of the tie in a rearwardly direction. 
As the railway car assembly moves forward, the rail plate sensor 29 of the 
left-hand carriage assembly 13 will sense the leading edge of the rail 
plate. As this occurs, a microprocessor controller 41, shown in FIG. 1, 
controlling the operation is programmed to stop the railway car assembly 
whereupon the welding gun assemblies of the left-hand carriage assembly 
are positioned midway of the rail plate. Such a condition is shown in FIG. 
1 of the drawings. 
At this time, the microprocessor then senses the condition of the rail 
plate sensor 29 of the right-hand carriage assembly. Under the preset 
conditions, the right-hand rail plate sensor will not have yet sensed the 
leading edge of the rail plate. The microprocessor then, operating through 
the welding gun control assembly, moves the carriage assembly 13 along a 
longitudinal direction to move the welding guns toward the rail plate 
until the rail plate sensor 29 senses the occurrence of the rail plate. 
When this occurs, the microprocessor further advances the carriage 
assembly longitudinally a predetermined distance to properly center the 
welding gun assemblies longitudinally with respect to the rail plate. 
As previously stated, the worst case condition encountered in railroad ties 
is that of being approximately 4 inches forward or back of being 
perpendicular to the rails. Since the backset was 6 inches, the worst case 
condition of a railroad tie being off in a rearwardly direction is taken 
care of. The carriage assembly has at least an 8 inch travel in the 
longitudinal direction. Thus, the worst case forward situation of 4 inches 
may be compensated for by the carriage assembly moving through a 
perpendicular position to a 4 inches forward out of perpendicular 
alignment condition. 
The next step in the sensing process is that both carriage assemblies, 
under control of the microprocessor, are moved to the left to bring the 
rail web sensor 30 toward the rail web as shown in FIG. 5. As each rail 
web sensor 30 reaches the proximity of the rail web, a signal is generated 
which, under the control of the microprocessor, stops that carriage 
assembly from any further movement to the left. At that point, the welding 
gun chucks and studs are properly positioned both longitudinally and 
transversely of the rail for proper welding. 
Once the proper position has been achieved both longitudinally and 
transversely, the position sensing and control assembly 17 and its 
associated sensor support arms and sensors are swung upwardly out of the 
way as shown in FIG. 5. Thereupon, the welding gun assemblies operating 
through the first ram move the second ram and associated welding chuck and 
studs downwardly into contact with the rail plate as shown in FIG. 6. The 
spring loaded arc shield retainer permits the stud to move fully into 
contact with the rail plate. 
Each welding gun assembly is energized until a predetermined pressure is 
generated in the welding gun's hydraulic cylinder. This pressure is sensed 
independently for each welding gun and, when achieved, the first ram 
assembly is locked into place to create a first datum plane. In this 
manner, variations in elevation of the rail plate from tie to tie is 
compensated for. 
The microprocessor then controls the welding gun actuator to initiate 
welding current to each of the welding gun assemblies. This may be done 
simultaneously or sequentially depending upon the welding power supply. 
Upon a predetermined time relationship to the initiation of the welding 
gun current, the second ram assembly is actuated to raise the ram and its 
associated welding chuck and stud upwardly a predetermined position from 
the second datum plane established by the normal piston positioning of the 
second ram assembly discussed previously. As this occurs, an arc is drawn 
which produces melting in the heretofore normally known arc welding 
process. 
After a predetermined time during the welding cycle, each second ram 
assembly is then energized in the opposite direction to move the piston 
therein to a predetermined position below the second datum plane to 
achieve plunge of the stud into the molten pool created during the welding 
process. At a predetermined time in the plunge, the welding current is 
turned off and the stud thus permitted to plunge into the molten pool and 
solidify completing the welding process. 
At this point in the process, the welding gun assemblies are retracted 
clear of the rail plates and the studs welded thereon. Thereafter, the 
railway car assembly, under the control of the microprocessor, begins its 
slow travel toward the next railroad tie. During this interval, the 
operator then manually loads arc shields and studs to the welding gun 
assemblies. 
The microprocessor controlling the system, after a predetermined time, then 
lowers the position sensing and control assembly support arms and sensors 
at a point midway between the cross ties and at a point where the position 
sensing and control assembly is free of the studs which have just been 
welded. Thereafter, the railway car assembly continues its travel toward 
the next rail plate at which the process is repeated upon sensing the 
leading edge of the left-hand rail plate. 
At any time the obstruction sensor 20 senses an obstruction along the rail, 
the automatic process is interrupted and the railway car assembly stopped. 
At this time, the operator is able to visually observe the nature of the 
obstruction and to manually control the advancement of the railway car 
past the assembly and, if necessary, retract the position sensing and 
control assembly as necessary to clear the obstruction. The operation may 
then be returned to the automatic mode. 
The foregoing invention has been described in respect to particular 
embodiments thereof as shown in the drawings and as generally described in 
the specification. It is to be understood that other variations and 
modifications of the invention will become apparent to those skilled in 
the art by reason of the foregoing disclosure thereof and, accordingly, no 
limitation was intended on the scope of the invention by the description 
thereof in reference to particular embodiments but the scope of invention 
is to be interpreted in view of the appended claims.