Mobile rail welding machine

A mobile rail welding machine comprises a frame, a hydraulically driven flash butt welding device, a "Thermit" welding unit and preferably an electric arc welding device mounted on the frame for selectively flash butt welding, "Thermit" welding or arc welding abutting rail section ends of a track rail, and a weld burr removal device adjustably mounted on the frame for selectively removing weld burrs at either rail.

The present invention relates to improvements in a mobile rail welding 
machine mounted on a track for mobility in an operating direction, the 
track being comprised of rails consisting of rail sections having abutting 
ends and ties supporting the rail sections. 
Known rail welding machines for welding the abutting rail sections ends of 
a selected one of the rails comprise a frame, a hydraulically driven flash 
butt welding device and a weld burr removal device adjustably mounted on 
the frame for selectively removing weld burrs at either one of the rails 
immediately after welding. These weld burrs, also called weld flashes, are 
formed during the flash butt welding operation and they are removed by the 
device by cutting, milling or grinding, and the like. Self-propelled rail 
welding machines have been developed which carry a flash butt welding 
device mounted on a boom projecting from the front end of the machine and 
adjustable to enable the welding device to operate on the right or left 
rail. The machine carries all power sources and controls necessary for the 
welding and weld flash removal operations, and has proved to be highly 
efficient, easy to operate and capable of producing high-quality welded 
rail joints. Since the chassis of the machine is built along the lines of 
a regular railroad car and has couplings at the respective ends thereof, 
it can be transported as part of a train or rapidly move on its own power. 
At the welding site, it can be quickly put into operation and thus is 
particularly effective to shorten the required down-time of the track 
during which trains cannot pass. 
German Auslegeschrift No. 1,271,740, published July 4, 1968, discloses a 
"Thermit" rail welding machine comprising a carriage mounted on small 
rollers for running on the tracks rails to facilitate the transport of the 
machine from working site to working site. The machine does not have its 
own drive nor does it provide coupling means enabling the carriage to be 
connected to railroad cars so that it requires a special transport vehicle 
for bringing the machine to the operating station and to remove it 
therefrom. The carriage has a "Thermit" welding unit and a hydraulically 
driven weld burr removal device mounted thereon for removing weld burrs. 
As used throughout the specification and claims, "Thermit" welding refers 
to the well known welding process using a mixture of aluminum powder and 
powdered iron oxide that, when caused to react by strong heating, evolves 
a greater deal of heat and yields alumina and a white-hot molten mass of 
metallic iron used in welding. In the apparatus disclosed in the German 
publication mentioned hereinabove, this welding mixture must be carried 
along on a separate auxiliary car. Particularly, since "Thermit" welding 
is much slower than flash butt welding, this machinery produces rather 
slow progress, particularly when extended lengths of track rails are to be 
welded at numerous joints. 
Practical considerations often require different welding processes to be 
used at rail joints along an extended track section, including butt 
welding as well as various other types of welds. In such instances, it has 
been the practice to use one type of welding unit adapted to effectuate 
the selected process in a first operating stage and to produce the other 
type or types of welds in a successive stage or successive stages. This 
involves several down-times for the affected track section and a great 
number of operators to man each working pass. Furthermore, the required 
apparatus for different types of welding processes is rarely available at 
the working site and must be brought there from long distances. Since such 
considerations are of considerable importance in choosing the welding 
process to be used, important economic and technical reasons for selecting 
a specific welding method are pushed into the background. 
U.S. Pat. No. 3,726,232, dated Apr. 10, 1973, discloses a mobile rail 
welding machine wherein a boom assembly supporting oxyacetylene welding 
torches and rail gripping mechanisms is mounted on a rail-bound vehicle. 
U.S. Pat. No. 3,355,991, dated Dec. 5, 1967, deals with a machine for 
conditioning welded rail joints, wherein a support frame is wheeled along 
a track and supports a weld flash removal machine. 
It is the primary object of this invention to provide a mobile rail welding 
machine of the first-described type and which is adapted to perform the 
most important and frequently encountered welding processes on track rails 
with optimal economic and technical efficiency, preferably in a single 
pass. 
The above and other objects are accomplished in accordance with the 
invention with a mobile rail welding machine which comprises the 
combination of a frame, a hyraulically driven flash butt welding device 
for welding the abutting rail section ends of a selected one of the rails 
mounted on the frame, a "Thermit" welding unit for welding the abutting 
rail section ends of a selected one of the rail mounted on the frame 
whereby the abutting rail section ends may by selectively flash butt 
welded or "Thermit" welded, and a weld burr removal device adjustably 
mounted on the frame for selectively removing weld burrs at either one of 
the rails. 
This combination for the first time provides a universally adaptable mobile 
rail welding machine which, without increasing the power and personnel 
requirements of a single-purpose machine makes it possible to use the 
special welding technique best suited for the specific purpose. Its 
structure is simple and rational, making easy operation without danger to 
the operating personnel possible. Since the different welding processes 
are effected in continuous succession in a single pass and the machine is 
self-propelled to move from welding site to welding site, the work 
proceeds rapidly and the downtime of the track is reduced to a minimum. 
In their planning of track maintenance machinery, railroad administrations 
need to acquire and use only a single machine for all types of welding 
techniques and, in addition, since the machine is self-propelled, it is 
capable of carrying along all the materials required in "Thermit" welding, 
either on its own chassis or in a car coupled to the self-propelled 
machine, thus alleviating the transport problems encountered in the 
above-described "Thermit" rail welding machine. 
While the machine is adapted for different welding processes, its structure 
is quite simple. Thus, the same weld burr removal device may be used for 
removing the weld flashes produced by butt welding and the weld beads 
resulting from the excess welding material in "Thermit" welding, this 
device being adjustable for use with either rail. It would be possible to 
use a similarly adjustable "Thermit" welding unit for selective use at 
either rail by transversely moving the unit or two such units may be 
provided, each unit being associated with a respective rail. 
If an electric arc welding device is additionally mounted on the frame, the 
usage of the machine will be further enhanced, enabling the machine to be 
used also for work requiring arc welding operations, including welding 
rail contacts to the rails and the like, such welding operations being 
advantageously effected, if desired, during the preparation of other 
welding operations and during such welding operations. This will save 
additional time. Since more than one welding device will be in operation 
simultaneously only in such special cases, the power plant for the entire 
machine need not be essentially larger than one used only for butt 
welding. Suitable safety switches may be installed to be tripped in case 
of overloads on the power plant when more than one welding unit is used at 
a time.

Referring now to the drawing. there is shown a mobile welding machine 1 
comprising frame 2 and two undercarriages 3, 3 spaced from each other 
along track 6 and supporting the frame thereon. The track is comprised of 
rails 4 and 5 consisting of rail sections having abutting ends (see rail 
joints 45) and ties 22 supporting the rail sections. The rail welding 
machine is mounted on track 6 for mobility in an operating direction 
indicated by arrow 9 and, in the illustrated embodiment, front and rear 
undercarriages 3 are double-axle trucks each including drive 7 for driving 
wheels 23, thus making machine 1 self-propelled. 
The closed machine housing or chassis 10 is constructed more or less like 
that of a regular railroad car and is mounted on frame 2 which has 
couplings 8, 8 at both ends to enable the machine to be incorporated into 
a train, if desired, the machine chassis including operator's cabs 11 at 
its respective ends. The machine frame has a recessed portion 24 
intermediate the undercarriages and somewhat closer to the front than to 
the rear end of machine 1, protected space 25 defined by intermediate 
frame portion 24 serving to house the operating devices of the welding 
machine. Power plant 13 and drive motor 12 of the machine, which is 
connected to drives 7, 7 are housed in the rear and longer portion of 
chassis 10, the power plant including at least one electrical current 
generator for supplying power to any selected welding device as well as 
the required pressure fluid source or sources for hydraulically and 
possibly pneumatically operated devices used in the machine. 
A self-propelled rail welding machine of a construction of this general 
type is disclosed in U.S. patent application Ser. No. 957,402, filed Nov. 
3, 1978 by Josef Theurer and owned by a common assignee, whose disclosure 
is incorporated herein by way of reference. 
As has also been disclosed and is claimed in the commonly owned copending 
application, a hydraulic jack 14 is mounted on machine frame 2 at each 
side of front undercarriage 3 and above each track rail for pivoting about 
a pivot extending transversely of the machine and the track. The free end 
of piston rod 15 of jack 14 carries a hook 16 for holding one end of a 
cable 51 whose other end may be affixed to the respective rail for a 
purpose and in a manner to be explained hereinafter. Furthermore, support 
means 18 for the machine frame is arranged in the region of the front end, 
the illustrated support means being constituted by a hydraulic jack means 
mounted adjacent and rearwardly of the front undercarriage and 
substantially centered between track rails 4 and 5, as shown in FIG. 2. 
This hydraulic means comprises centered hydraulic cylinder 19 projecting 
downwardly from frame 2 and shoe 21 attached to the free end of piston rod 
20 extending from the hydraulic cylinder. When hydraulic fluid is supplied 
to cylinder 19 to lower shoe 21 into engagement with an underlying tie 22 
to lift wheels 23 of the front undercarriage off the rails, the rails are 
relieved of the machine weight in the forward range of the machine where 
the welding operations take place. This, as has been pointed out in the 
copending application, is of particular importance in welding techniques 
wherein the rail sections to be welded are moved relative to each other to 
effectuate the weld, for example if flash butt welding. With the weight of 
the machine no longer pressing against the forward rail section, it may be 
readily moved in a longitudinal direction towards joint 45 after the rail 
fastening elements attaching the rail section to the ties have been 
loosened or dismantled. 
A rail pre-heating means 17 is associated with each of the rails and is 
arranged on frame 2 at each side of support 18 between front undercarriage 
3 and a foremost one of the welding devices to be described hereinafter. 
Recessed frame portion 24 of machine frame 2 defines protected operating 
space 25 of the machine, which is accessible from the interior of chassis 
10 through door 28. Vertically movable working platform or operating stage 
26 forms the floor of the operating space and is vertically adjusted by 
hydraulic jacks 27 relative to the frame. This operating stage in the 
region of the operating tools of the machine make the operation and 
servicing of these tools very easy since all these tools are readily 
accessible from the interior of the chassis and the operating stage can be 
readily adjusted to positions attuned to the selected operation. 
In accordance with the present invention, the various operating tools or 
devices for a variety of welding operations as well as for the removal of 
weld flashes or burrs are mounted on the machine frame in operating space 
25. This includes electric arc welding device 29 rearwardly of which, with 
reference to the operating direction, is mounted "Thermit" welding unit 32 
and rearwardly of which is mounted flash butt welding device 42. Finally, 
weld burr removal device 46 is adjustably mounted on machine frame 2 
rearwardly of the flash butt welding device for selectively removing weld 
burrs at either one of the track rails. 
With this preferred arrangement, the entire weight of the machine is 
substantially uniformly distributed over both undercarriages, which is 
important because of the allowable weight limitations particularly on side 
tracks and also makes the structure of the machine frame simple while both 
undercarriages may be of the same type. At the same time, all tools are 
readily accessible to, and controllable by, the operators who are 
protected against all weather conditions and from trains passing on a 
parallel track, thus assuring excellent working conditions. The 
specifically described and illustrated series arrangement of the operating 
devices takes into account the working requirements for most of the 
operations encountered in rail welding, thus further enhancing the 
efficiency of the machine. With the provision of the rail pre-heating 
means ahead of the welding devices, the machine is adapted to welding 
operations which require a narrow range of rail temperature, making it 
possible to use the machine even when the ambient temperature is too low 
for keeping the rails in the required temperature range. Thus, no special 
machines and crew are needed to precede the welding machine to bring the 
rails to the desired welding temperature, thus further improving the work 
speed and reducing personnel. 
The specifically illustrated arc welding device 29 is mounted for vertical 
adjustment on guide post 31 affixed to front wall 30 of operating space 
25. This device can be used for special welds, such as welding rail 
contacts to the rail and producing welds on the surface of the rail head. 
While only one electric arc welding device 29 has been shown in the 
drawing for the sake of clarity, it may be useful to mount a respective 
arc welding device associated with each rail or, alternatively, to mount 
one such device for transverse movement on the frame so that it may be 
associated with a selective track rail. 
Rearwardly of the electric arc welding device or devices are mounted 
"Thermit" welding units 32 associated with each of the rails for welding 
abutting rail section ends of a selected rail. Such "Thermit" welding 
units are conventional and, in essence, are comprised of a two-part mold 
33 adapted to encompass the rail, as shown in FIG. 2, a crucible 35 
holding the welding mixture and a bracket 34 interconnecting the mold and 
crucible and forming a welding assembly. Bracket 34 is vertically 
adjustably mounted on slide 36 which, in turn, is horizontally adjustably 
mounted on guide bar 38 affixed to bracket 37 on machine frame 2. 
Hydraulic jack 39 is operable to move the slide and thus the welding 
assembly 33, 34, 35 horizontally while its vertical movement is effected 
adjusting bracket 34 in slide 36. Again, for the sake of clarity of 
illustration, FIG. 2 shows only a single unit 32 although one such unit is 
preferably associated with each rail. 
Rail grinding machine 40 (shown for the sake of clarity only in FIG. 1) is 
mounted substantially centrally in operating space 25 and is suspended for 
free pendulum movement from machine frame 2 by hydraulic jack 41. In case 
the rail joint to be welded would fall in the range of a tie 22, where 
welding is not possible, one or the other of the abutting rail section 
ends can be ground down with machine 40 sufficiently to displace the rail 
joint into the range of the adjacent crib. 
As in the machine described in the above-identified patent application, 
hydraulically driven flash butt welding device 42 for welding the abutting 
rail section ends of a selected rail is mounted rearwardly of grinding 
machine 40. The flash butt welding device comprises a pair of welding jaws 
52 containing the required welding apparatus and is suspended for free 
pendulum movement from the free end of the piston rod of hydraulic jack 44 
to enable the welding device to be raised and lowered. The jack is affixed 
to a guide sleeve journaled on transverse guide bar 43 for moving the 
welding device from one rail to the other. When operated, the flash butt 
welding device will produce weld flash or burr 45 at the abutting rail 
section ends, which must be removed to produce a smooth-surfaced rail. 
Any excess welding material produced by "Thermit" welding at joint 50 
and/or weld flash 45 produced by butt welding is removed by burr removal 
device 46 which is hydraulically driven by a pair of guides constituted by 
hydraulic jacks 47 extending in a longitudinal direction of the machine 
and linked to slide 48 which is guided for transverse reciprocation from 
one rail to the other on guide bar 49 of dove-tailed cross section. The 
adjustability of the weld burr removal device relative to the machine 
frame in a plane parallel to the plane of the track considerably 
simplifies and accelerates operations. Since this and all other operating 
tools are adjustable on the machine, they may be readily coordinated 
without correcting the position of the heavy welding machine frame itself, 
thus preserving the machine drive and brakes from excess use and further 
relieving the machine operator to enable him to concentrate on other 
control operations. 
The operation of the welding machine will be obvious from the above 
description of the structure, in conjunction with the following 
explanation: 
While support 18 and all the operating tools are raised, machine 1 is 
driven in the direction of arrow 9 to the working site and drives 7 are 
disengaged and the machine is stopped as soon as the abutting rail section 
ends to be welded together are at least approximately beneath welding unit 
32 when this unit is to be used for the selected joint. If the rail 
temperature is below the required welding temperature range, heating means 
17 is actuated to raise the temperature of the rail to the required range. 
If "Thermit" welding unit 32 is used, two-part casting mold 33 is opened, 
the unit is lowered from its position shown in FIG. 2, jack 39 is operated 
to bring the casting mold into alignment with joint 50, i.e. it would have 
to be moved forwardly from the position shown in FIG. 1, the mold is 
closed about the rail, and the welding mixture is reacted in crucible 35 
until the white-hot molten mass flows into the mold to form the weld about 
the abutting rail section ends at joint 50. After the weld has been 
formed, the mold is opened again, unit 32 is raised to its rest position 
and machine 1 is rapidly advanced in the direction of arrow 9 to bring the 
welded joint into the range of weld burr removal device 46. Hydraulic 
jacks 47 are then actuated to drive the cutting head of device 46 over the 
joint and thus to remove all excess welding material therefrom, thus 
conditioning the rail to provide a smooth surface in a single pass of 
device 46. 
When flash butt welding device 42 is to be used, the machine is stopped 
before the front undercarriage has reached the joint to be welded and the 
operation proceeds in a manner described in the above-identified 
application. Wire rope 51 is attached to hook 16 of jack 14 associated 
with a respective rail comprising the two rail sections whose abutting 
ends are to be welded together, and the other end of the wire rope is 
suitably clamped to a forward portion of the rail section ahead of the 
front undercarriage. The rail fastening elements are previously loosened 
or removed so that this rail section rests freely on ties 22 and jack 14 
is actuated to pull the rail section to within about 5 to 11 mm of the 
abutting end of the adjoining rail section on which machine 1 stands. The 
machine is then driven in operating direction 9 until the rail joint comes 
to lie within the range below flash butt welding device 42. Jack 19 is now 
actuated to lower support shoe 21 and lift machine 1 sufficiently to 
disengage wheels 23 of the front undercarriage from the rails. Jack 44 is 
then actuated to lower device 42 until the rail joint is disposed between 
the pair of welding jaws 52. After welding is completed, the welding jaws 
are opened and the welding device is immediately raised, the removal of 
weld flash 45 then proceeding in the same manner as has been described 
hereinabove with respect to joint 50.