US3566546A - Apparatus for grinding welded rail - Google Patents

Abstract

APPARATUS FOR GRINDING WELDS FORMED BY WELDING RAIL SECTIONS IN END TO END RELATION TO FORM A CONTINUOUS RAIL. A PAIR OF BELT TYPE GRINDING HEADS SIMULTANEOUSLY GRIND THE RAIL HEAD RUNNING SURFACE AND THE RAIL BASE WITH ONLY MINIMAL AREAS ADJACENT THE UPSET OR WELD AREAS BEING ENGAGED BY THE BELTS. THE RAIL IS HELD IN STATIONARY POSITION DURING THE GRINDING AND ONE OF THE HEADS IS TURNED AROUND THE RAIL HEAD TO EFFECT CURVILINEAR OR ARCUATE GRINDING WHILE THE OTHER HEAD GRINDS THE UNDERSIDE OF THE RAIL BASE. THE HEADS ARE MOVED LONGITUDINALLY ACROSS THE WELD AND ARE SIMULTANEOUSLY MOVED TRANSVERSELY INTO AND OUT OF GRINDING ENGAGEMENT WITH THE WELD DURING EACH LONGITUDINAL PASS SO THAT EACH BELT FOLLOWS A CURVED PATH LYING TANGENT TO THE RAIL AT THE UPSET, WHEREBY MAXIMUM GRINDING OCCURS AT THE UPSET AND DEPTH OF THE GRIND FEATHERS OUT AS EACH HEAD MOVES BEYOND THE UPSET.

Description

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United States Patent Oilice 3,566,546 Patented Mar. 2, 1971 3,566,546 APPARATUS FOR GRINDING WELDED RAIL Karl L. Lindmark, Rockford, Ill., assignor to Chemetron Corporation, Chicago, Ill.

Original application Nov. 21, 1966, Ser. No. 595,738, now Patent No. 3,509,667, dated May 5, 1970. Divided and this application Apr. 24, 1969, Ser. No. 852,128

Int. Cl. B24b 21/16, 23/06 U.S. Cl. 51-140 31 Claims ABSTRACT F THE DISCLOSURE Apparatus for grinding welds formed by welding rail sections in end to end relation to form a continuous rail. A pair of belt type grinding heads simultaneously grind the rail head running surface and the rail base with only minimal areas adjacent the upset or weld areas being engaged by the belts. The rail is held in stationary position during the grinding and one of the heads is turned around the rail head to effect curvilinear or arcuate grinding while the other head grinds the underside of the rail base. The heads are moved longitudinally across the weld and are simultaneously moved transversely into and out of grinding engagement with the weld during each longitudinal pass so that each 'belt follows a curved path lying tangent to the rail at the upset, whereby maximum grinding occurs at the upset and depth of the grind feathers out as each head moves beyond the upset.

The present application is a division of Ser. No. 595,- 738, led Nov. 2l, 1966, now United States Patent No. 3,509,667, issued May 5, 1970.

The present invention relates generally to a new and improved apparatus for use in forming continuous rails wherein individual rail sections are welded together in end to end relationship and, more particularly, relates to a new and improved apparatus for grinding the upset surrounding the welded joint between the rail sections after the welding operation has been completed.

The present invention is an improvement on the apparatus for grinding welded rails disclosed and claimed in the United States Patent No. 3,090,170, which patent is assigned to the same assignee as the present invention. The apparatus of the present invention may be used in conjunction with the rail storage and transfer equipment and the welding and welded shearing apparatus shown in the United States Patent No. 3,030,494, which patent is also assigned to the same assignee as the present invention.

For a number of years it has been evident that the use of railroad tracks in the form of rail sections welded together to form a continuous strip is particularly desirable because such a construction not only increases the riding comfort of railroad passengers and reduces the shock and vibration to which rail freight is subjected but, at the same time, is substantially trouble free and, hence, requires considerably less maintenance than tracks of the type employing individual rail sections bolted or otherwise secured together. Despite the knowledge of these advantages, however, the use of welded rails has not been widespread due partly to their excessive cost and also to the inordinate amount of time usually required to form the welded joint for the rail sections. More specifically, in order to form an efficient welded joint, it is necessary not only to weld the rail sections together but also to shear off the upset or excess weld metal and then grind the remainder of the upset in the area of the weld in order to form smooth surfaces for the rail base and for the running surface which is adapted to accommodate the wheels of the railroad cars. In many prior art arrangements, all of these operations have been very time consuming and, hence, both the time required to form the continuous rail and the production costs have been excessive. In particular, the grinding apparatus heretofore employed has been relatively complex in that it is formed of a large number of expensive parts. Thus, this equipment has been expensive and is also subject to maintenance and repair problems.

An object of the present invention is to provide a new and improved apparatus for grinding welds produced by welding rail sections in end to end relationship to form a continuous rail.

Another object of the invention is to provide apparatus for grinding the weld area as rapidly as possible following the formation of the weld so that the metal to be ground can be easily removed because it is still hot and soft.

A further object of the invention is to provide a new and improved rail grinding apparatus which is so arranged that the abrasive grinding surfaces are not required to grind large areas of the rail adjacent the weld, -thus increasing the effective life of the abrasive surfaces.

A further object of the invention is to provide grinding equipment employing a plurality of grinding heads each including abrasive grinding means acting upon the welded rail with the different abrasive means being so arranged that each acts upon only a relatively small area of the rail surface with the result that the weld grind can be made very quickly and without undue wear on any of the abrasive means.

Another object of the present invention is the provision of a new and improved apparatus for grinding welds of the character described wherein the grinding head includes a moving abrasive surface which is movable longi- 'F tudinally along the rail and over the weld and is also movable transversely of the rail during this longitudinal movement.

Still another object of the invention is the provision of a new and improved apparatus of the type described wherein the grinding pressure between the abrasive surface of the grinding head and the weld is greatest when the upset is being ground but is decreased as the abrasive surface moves longitudinally of the rail beyond the upset, thereby to provide a feathering effect.

Still another object of the invention is the provision of a new and improved apparatus for grinding welds of the type described wherein the grinding head and its moving abrasive grinding surface is orbited or turned about an axis extending longitudinally of the rail to grind the running surface of the rail head.

Still another object of the present invention is the provision of a new and improved rail grinding apparatus having new and improved means for securing the rail in a grinding position to prevent movement during the grinding operation.

Yet another object of the present invention is the provision of a new and improved rail grinding apparatus employing a plurality of grinding heads operable to grind simultaneously opposite surfaces of the welded rail.

Still another object of the present invention is the provision of a new and improved rail grinding apparatus employing means for compensating for the wear on the grinding apparatus, thereby effecting uniform grinding of successive welds between rail sections and resulting in a longer useful life for the apparatus without requiring maintenance or adjustment.

A still further object of the present invention is to provide a new and improved rail grinding apparatus of the type described employing a new and improved grinding head which is movable in a controlled manner whereby only the weld and small portions of the rail sections 3 adjacent thereto are subject to grinding action, thereby increasing the speed of the grinding and reducing the wear on the abrasive surfaces of the grinding apparatus.

Still another object of the present invention is the provision of a new and improved rail grinding apparatus including means for automatically and adjustably controlling the movement of the abrasive surface into and out of grinding engagement with the weld.

Yet another object of the invention is the provision of a new and improved rail grinding apparatus employing new and improved means for selectively adjusting and controlling the grinding head whereby the grinding head can be rapidly moved away from the weld being ground to an inoperative position.

Still another object of the present invention is the provision of a new and improved rail grinding apparatus employing a grinding head which is relatively simple in construction and operation, easily controlled, and wherein the abrasive means thereof can be easily and rapidly replaced when worn or damaged.

The foregoing and other objects are realized, in accordance with the present invention, by providing grinding equipment for location at the exit end of the welding apparatus in order to grind the welded areas or upset regions of a continuous rail. The grinding equipment includes two grinding heads respectively acting upon the underside of the base and the rail head and each includes a moving abrasive grinding surface in the form of a belt extending longitudinally of the rail. The belts are so arranged that each acts upon only a very small section of the rail surface and each belt is urged into engagement with the rail surface to be ground lby means of a Huid pressure operated means. The grinding pressure exerted by each belt upon the rail is controlled by one or more guide rollers movable longitudinally along the rail surface to guide the heads and their belts into and out of grinding engagement. The guiding apparatus is adjustable to handle rail sections of different cross-sectional dimensions and different lengths. The moving belt of each head, is movable longitudinally of the rail and across the weld is also movable transversely into and out of grinding engagement with the weld during said longitudinal movement whereby only the weld and the immediately adjacent surfaces of the rail sections are ground. Means are provided for accurately controlling and prepositiouing the grinding head during the transverse movement to effect the desired grinding action. The grinding head acting upon the head of the rail is also orbited or turned about a pivot axis extending longitudinally of the rail to follow the curved or crowned surface of the rail head. The described orbiting occurs simultaneously with the longitudinal and transverse movement of the grinding head. Means are provided for rapidly moving both grinding heads out of grinding engagement with the rail when desired.

In a normal operating cycle of the apparatus, the rail is moved into a grinding position with the upset disposed adjacent both grinding heads whereupon the rail is tightly clamped against further movement. The grinding heads are then moved into controlled grinding e11- gagement with the rail and the grinding operation is performed. After the grinding has been completed, the rail is unclamped and released for longitudinal travel until the next succeeding weld upset is centered in the grinding apparatus whereupon the cycle is repeated.

The invention, both as to its organization and manner of operation, together with further objects and advantages thereof, will best be understod by reference to the specification, taken in conjunction with the accompanying drawings wherein: i

FIG. 1 is a side elevational view of a new and improved rail grinding apparatus characterized by the features of the present invention;

FIG. 2 is an enlarged, fragmentary end view of the 4 grinding apparatus looking in the direction of the arrows 2 2 in FIG. 1;

FIG. 3 is a fragmentary, sectional view taken along a line substantially corresponding to the line 3 3 in FIG. 2 and shows particularly the construction of the rail clamping means of the present invention;

FIG. 4 is an enlarged, fragmentary, sectional view taken along a line substantially corresponding to the line 4 4 of FIG. 1 and also shows particularly the rail clamping means;

FIG. 5 is a fragmentary, sectional view taken along a line substantially corresponding to line 5 5 of FIG. 4;

FIG. 6 is an enlarged, fragmentary, sectional view taken along a line substantially corresponding to the line 6 6 in FIG. 1 and illustrating means in accordance with the invention for supporting and orbiting the upper grinding head;

FIG. 7 is a fragmentary, sectional view taken along a line substantially corresponding to the line 7 7 in FIG. 6 and shows one side of the lower grinding head for grinding the bottom surface of the continuous rail;

FIG. 8 is an enlarged, fragmentary, sectional view of the lower grinding head taken substantially along the line 8-8 of FIG. 7;

FIG. 9 is a fragmentary, sectional view taken along a line substantially corresponding to the line 9 9 in FIG. 7;

FIG. lO is a fragmentary, sectional view taken along a line substantially corresponding to the line 10-10 in FIG. 8;

FIG. l1 is a sectional view taken along a line substan- 'tially corresponding to the line 11 11 of FIG. 8;

FIG. l2 is a fragmentary, sectional view taken along a line substantially corresponding to the line 12-12 of FIG. 9;

FIG. 13 is an enlarged, fragmentary, sectional view taken along a line substantially corresponding to the line 13 13 of FIG. 9 and illustrates the mechanism for prepositioning the lower grinding head with respect to the rail to compensate for wear occurring during operation of the apparatus;

FIG. 14 is a fragmentary, sectional view taken along a line substantially conforming to line 14-14 of FIG. 8 and illustrating the means for effecting longitudinal and transverse movement of the grinding belt relative to the rail;

FIG. 15 is a fragmentary, sectional view taken along a line substantially conforming to the line 15-15 of FIG. 14;

FIG. 16 is a view similar to FIG. 14 but illustrates the longitudinal movement of the belt along the rail to produce the feathering effect;

FIG. 17 is a view somewhat similar to FIG. 16 but shows graphically in exaggeration the transverse movement of the belt during its longitudinal movement;

FIG. 18 is a fragmentary, sectional view taken along a line substantially conforming to line 18-18 of FIG. 6 and shows the side of the upper grinding head for grinding the rail head; and

FIG. 19 is a fragmentary, sectional view taken along a line substantially conforming to line 19 19 of FIG. 18.

Referring now to the drawings, and, more particularly, to FIG. 1, there is shown a new and improved rail grinding apparatus in accordance with the present invention and referred to generally by the reference numeral 20. The rail grinding apparatus 20 is especially adapted for grinding upset areas 22 produced by welding conventional rail sections 24 in end to end relationship to form a continuous rail. The rail sections 24 may be welded together in accordance with the method and apparatus described in the aforementioned Baer et al. Patent No. 3,070,494 and, after the welding has been completed, the excess metal or upset produced during the welding may be sheared in the manner described in the patent before the continuous rail is delivered to the grinding apparatus 20 of the present invention for grinding.

The grinding apparatus may be mounted on the floor 26 of a railway car and includes a boxlike rectangular frame 28 having a base 30 that is supported by a plurality of anged wheels 32. The wheels 32 are mounted for movement along longitudinal tracks 34 secured to the floor 26 of the car. The grinding apparatus includes an electric motor 36 which is connected by a drive chain 38 to drive at least one of the flanged wheels 32 so that the entire grinding apparatus 20 may be power driven to move longitudinally along the tracks to adjust the position of the grinder relative to the welding apparatus which is also mounted on the car oor 26, thereby to accommodate different lengths of rails that may be used and, hence, to permit the welded area or upset 22 between the rail sections to be centered `with respect to the grinding apparatus. After the apparatus has been positioned on the floor 26 for a particular length of rail section 24, it is 4maintained in the selected position until the length of rail sections being welded is altered.

In addition to the base 30, the frame 28 includes a pairy of upright end panels or structures 40 supported at opposite ends of the base, and top plate 42 are provided to join the upper ends of the spaced apart end panels. Each end panel 40 includes a relatively thick, vertical end plate 44 strengthened by a pair of vertical columns or channels 46 extending along opposite edges of the plate. Each end plate 44 provides support for a rail guiding and clamping assembly 48 mounted on the outer surface thereof and, in addition, provides support for upper and lower grinding assemblies 50 and 52 mounted between the end plates and respectively acting upon the rail head and the underside of the rail base.

In order to permit the welded rail sections to pass through frame 28 so that subsequent welds may be ground by the heads 50 and 52, the end plates are formed with aligned openings 44a which are large enough to accommodate the largest size of rail sections that will be utilized. The lower grinding head 52 is supported from the end plates 44 by a pair of support blocks 44h (FIGS. 6, 7 and 9) which are mounted on the inside surfaces of the end plates beneath the openings 44a. To support the upper grinding head 50 for pivotal movement about the longitudinal axis of the rail, the end plates are provided with aligned inwardly extending, annular hubs 44C (FIGS. 6 and 19) secured to the inside surface of the end plates and arranged in concentric relation around the openings 44a.

The welded rail sections 24 are moved longitudinally through the opening 44a in one of the end plates 44 by suitable puller or pusher mechanism (not shown) until the weld area or upset 22 is centered between the end plate as illustrated in FIG. l. The rail guiding and clamping assemblies 48 are then operated to align and hold the rail sections 24 securely in place against both longitudinal and transverse movement, while the grinding heads 50 and 52 are operated to grind the weld area. After the grinding operation has been completed, the clamping means are released whereupon the rail is moved longitudinally until the next weld area or upset 22 to be ground is centered between the end plates. The cycle is then repeated and in this manner grinding of weld areas is continued until the desired length of continuous rail has been formed.

Referring more specifically to the two rail guiding and clamping assemblies 48, as illustrated in detail in FIGS. l, 2, 3, 4 and 5, each such assembly includes a base 54 formed in the shape of a cross with upper and lower vertical legs 56a. and 56b and left and right horizontally extending legs 58a and SSb. Each base is mounted on the outer surface of an end plate 44 and is formed with a central opening 59 adjacent the junction of the legs and concentrically arranged with respect to the circular opening 44a in the end plate to accommodate the rail sections 24 as they are moved longitudinally through the grinding apparatus. Each assembly 48 includes a lower clamping pad 60 engageable with the underside of the rail base, an upper clamping pad 62 engageable with the upper running surface of the rail head, a lower supporting roller 64, and a pair of lateral guiding rollers 66 and 68 engageable with opposite side surfaces of the rail head.

The lower support roller 64 is mounted on an axle 70 supported for rotation by a pair of pillow blocks 72 which are mounted on a horizontally extending shelf 74 of a lower bracket structure 76. The bracket structure 76 includes a pair of triangular shaped gussets 78 and a vertical plate 80 which is attached to the lower leg 56b of the cross-shaped base by a plurality of bolts 82. Preferably, the outer face of the leg 56b is provided with a plurality of vertical slots (not shown) to accommodate the bolts 82 and thereby permit the lower bracket structure 76 to be raised or lowered, as required, to accommodate various different sizes of rail sections 24. The upper rail clamping pad 62 is supported from an upper bracket structure 84 which is similar to the lower bracket structure 76 and includes a horizontal shelf 86, a pair of triangular gussets 88, and a vertical plate which is bolted to the outer face of the upper leg 56a of the cross-shaped base. The bracket structure 84 may also be adjustable vertically on the upper leg of the cross-shaped base in a manner similar to the lower bracket structure 76.

The upper and lower clamping pads 62 and 60 are movable toward and away from each other between a rail clamping position (FIG. 4) and a released position out of engagement with the rail. Each clamping pad is seated or mounted in a horizontal transversely extending recess or keyway 94a (best shown in FIG. 1) formed in a horizontally extending portion or base 94b of a pad backing member 94, and the pads can be easily removed from the keyways for replacement in the event of excessive wear or damage. The upper and lower clamping pad backing members 94 are identical with the exception that the upper one is somewhat smaller in size to accommodate the smaller pad 62 which engages the running surface on the rail head.

Each backing member 94 includes a vertically extending tang 94C and the tangs are mounted for pivotal movement about pins 96 adjacent the inner end portions of transversely extending, upper and lower actuating levers 98 and 100, respectively. The upper lever 9S is mounted for pivotal movement about a horizontal pin 102 and sleeve 104 intermediate its ends, and the pin is generally parallel with the rail sections 24 and is supported at its opposite ends by a pair of spaced apart plates 106 extending transversely of the rail section and secured to the underside of the shelf 86. The plates 106 are stiffened by pairs of spaced apart gussets 108 and 110 which are also secured to the underside of the shelf 86. The free end of the upper level 98 is pivotally connected to the outer end of a piston rod 112a operated by a fluid cylinder 112, the connection being formed by bolt 114l and clevis 116 and the fluid cylinder extends vertically upward through an opening or cut out 155 in a support member holding the lateral guide rollers 68. The free end of the lower lever is pivotally connected to the opposite end of the cylinder 112 by a bolt 118 and a pair of brackets 120. The lower lever 100 is pivotally mounted upon a pin 122 and sleeve 124. The pin 122 extends parallel to the pin 102 and is supported at its opposite ends by a pair of spaced apart plates 126 extending transversely of the rail section and secured to the upper surface of the shelf 74. When pressurized uid, either air or hydraulic fluid, is introduced into the lower end of the tiuid cylinder 112, the outer ends of the clamping levers 98 and 100 are moved apart and, accordingly, the clamping pads 60 and 62 move toward one another to tightly clamp and hold the rail. When fluid is introduced into the upper cnd of the cylinder 112, the clamping pads and 62 are moved away from each other to release the rail.

In order to permit vertical adjustment of the upper clamping pad 62 to achieve tight clamping engagement with the rail head running surface, an adjustable stop assembly 128 is mounted on and is movable with the inner end of the upper camping lever 98 directly above the tang 94e of the upper pad backing member 94. The adjustable stop assembly 128 includes a tubular housing 130 of rectangular or square cross section and having a vertically extending internal slideway or bore, as is best shown in FIG. 5. The housing, which is formed by a channel-shaped member 132 and a separate closure plate 134, protrudes upwardly through an opening 86a. formed in the shelf 86, as is shown in FIG. 4. The lower end of the housing 130 is open but the upper end is closed by an integral end plate 136 having a central threaded bore therein to accommodate a threaded stop rod 138. The lower end of the stop rod is connected to the upper end of a stop block which is slidable vertically within the bore or slideway of the housing 130. When the stop rod is turned and is then locked in position by tightening the lock nuts 142, the vertical position of the stop lock in the housing can be selected. The lower end of the stop block is recessed as indicated at 140a to receive the upper end of the tang 94e which is connected thereto by the pin 96.

The rail is clamped in place by delivering fluid to the lower end of the cylinder 112 whereupon the lower clamping pad 60 is moved upwardly to engage firmly the base of the rail section and the upper clamping pad 62 is moved downward to engage the top of the rail head running surface. The weight of the rail is supported by the lower rollers 64 and the clamping pads prevent vertical movement of the rail sections as well as lateral and longitudinal movement during the grinding operation. If the upper clamping pad 62 becomes worn, the stop rod 138 may be adjusted to compensate for the wear and, more importantly, if the radius or crown on the upper running surface of the rail head is changed when a different size rail is being ground, the stop block 140 can be raised or lowered and the lower support bracket 76 carrying the rollers 64 can be raised or lowered as desired to achieve the desired radius of grinding for the rail head. As will be described in detail hereinafter the upper grinding head S0 is mounted for pivotal or orbital movement about an axis which extends longitudinally of the rail and which is centered with respect to the apertures 44a in the end plates. By clamping the rail at different vertical positions within the apertures 44a, the grinding path along the rail head running surface can be altered. The uid cylinder 112 can be actuated rapidly to clamp or release the rail, and the iluid pressure supplied to the cylinder can be selected to obtain the clamping pressures or forces necessary to restrain the rail against movement during the grinding operation.

The lower clamping lever 100` is normally biased upwardly by a biasing assembly 144 (FIG. 2) which includes a short bracket 146 affixed to the shelf 74 and underlying the outer end portion of the lever. The bracket 146 is formed with an opening therein to accommodate an upwardly extending pin 148 having a rounded upper end engageable with the lower surface of the outer end portion of the clamping lever 100. The pin 148 is biased upwardly of the bracket 146 by a coil spring 150 seated against a pair of adjustable stop nuts 152 at the upper end of the pin. The nuts 152 may be adjusted to change the biasing force exerted by the spring. Upward travel of the pin 148 in relation to the bracket 146 is limited by a cotter key 153 at the lower end of the pin below the bracket. The stop nuts 152 are normally adjusted so that the spring is effective to insure that the lower clamping pad 60 is just below the upper surface of the support rollers 64 when the fluid cylinder 112 is in a re tracted condition to release the lower clamping pads y60 from engagement with the base of the rail sections. From the foregoing discussion, it is to be understood that the lower biasing assembly 144 and the upper stop block 140 are preferably adjusted so that the clamping pads 62 and 60 barely clear the surfaces of the rail sections when the cylinder 112 is in a retracted condition and, consequently, minimal movement is required to effect a rapid clamping engagement of the clamping pads with the rail when the cylinder is operated to actuate the clamps.

The lateral guide rollers 66 and 68 rmly engage opposite sides of the rail head in order to center the rail laterally with respect to the circular openings 44a. Each of the lateral guide rollers is supported on a support bracket assembly 154, and the support bracket assemblies are mounted on the outer faces of the respective horizontal legs 58a and `58b of the cross-shaped base structure 54. Each support bracket assembly 154 includes a vertical base plate 156 welded or otherwise secured to the face of the legs 58a and 58b, a horizontal stilfening web 158, a vertical outwardly extending guide plate 159 parallel to the web of the rail, and a laterally extending vertical plate 161 lying parallel to and spaced outwardly from the base plate 156. An adjustable roller supporting assembly 163 is mounted on each plate 161. Each roller supporting assembly includes a base plate 165 secured to the plate 161 and a pair of triangular-shaped, spacedapart, horizontal brackets 167 which provide support for a vertical pivot pin 169 mounted adjacent the outer ends of the horizontal brackets.

Each lateral guide roller 66 and 68 is supported on anaxle 171 mounted for rotation on a .pair of pillow blocks 173 and each pair of pillow blocks is mounted on a pivot plate 175 supported for pivotal movement about the vertical pivot pin 169 by a pair of small brackets i177. The pivot plates 175 are pivotal about the vertical pins 169 and are movable laterally toward and away from opposite side surfaces on the rail head. Means are provided for adjusting the pivotal position of the pi-vot plates to provide the desired lateral contact pressure of the lateral guide rollers 66 and 68 against the opposite sides of the rail head. As is best illustrated in FIG. 3, the right-hand pivot plate 1-75 after adjustment may be xed in a selected position relative to the central axis of the rail. To this end an adjusting screw 179 is connected at one end to the outer or back face of the pivot plate '175 by a pin 181 and bracket 183 and the outer end of the adjusting screw 179 extends through an opening in a fixed, vertical stop bar secured to the base plate 165. Adjustable stop nuts 187 are mounted on the screw on opposite sides of the stop bar to hold the guide roller |68 after it has been positioned properly. If the rollers 68 wear or if rail sections 24 of different lateral dimensions are being used, the screw 179 may be adjusted to compensate therefor, thereby to maintain the webs of the rail sections in a constant, laterally centered position relative to the apertures 44a.

The screw 179 for adjusting the left hand pivot plate 175 is biased laterally inwardly to force the rail head tightly against the opposite lateral roller 68. To provide this biasing, a coil spring 189 surrounds the screw 179 and seats at one end against an externally threaded sleeve 191. The sleeve 191 is threaded into an opening and can be moved laterally in the stop bar 185 or outwardly relative to this stop bar in order to regulate the compression of the spring 189, thereby to control the biasing force urging the lateral roller 66 against the rail head. Stop nuts 187 are provided to limit the inward movement of the adjusting screw 179 and, hence, to prevent the roller 66 from moving too far toward the opposite roller 68 when there is no rail 24 present in the apparatus.

Referring now to the construction of the grinding heads 50 and 52, the lower grinding head 52 is illustrated in detail in FIGS. 6 through 16 and is identical with the upper head 50 except for the supporting means for mounting the grinding head between the end plates 44. Accordingly, similar components of the two grinding heads have been assigned common reference numbers to avoid repetition in the description. Each grinding head includes an endless abrasive belt 160 urged against the rail by a backing roller assembly 162. The belt 160 extends over a Xed idler roller 164 and a movable idler roller 166; the latter two idler rollers being spaced vertically away from the rail and being disposed on opposite sides longitudinally with respect to the backing roller and the weld area 22 to be ground. The backing roller assembly 162 is rotated at high speed by means of an electric motor 168 mounted on the grinding head and drivingly interconnected with the backing roller by means of a driving pulley 170, a plurality of endless belts 172, and a driven pulley 174 which is carried on the shaft of the backing roller.

Each grinding head includes a belt supporting base unit 251 comprising a pair of spaced-apart, parallel, vertically extending, generally triangularly shaped inner and outer side plates 176 and 178 for supporting the backing roller assembly 162, and the two idler rollers 164 and 166 adjacent the respective points or corners of the triangular side plates. The spaced-apart side plates 176 and 178 are joined together to form the integral base structure 251 Iby a plurality of spacing blocks or webs 180 (FIGS. 7 and 8) provided at locations along and adjacent the peripheral edges of the side plates. Each drive motor 168 includes a mounting and support flange 16811 at its forward or shaft end which flange is pivotally mounted upon the inner side plate 176 by a pivot pin 182 so that the tension on the belts 172 can be adjusted by bodily moving the motor unit. In order to secure the motor unit in place on the inner side plate 176 after the proper belt tension has been achieved, the inner side plate includes an arcuate slot 176a concentric with the pivot pin 182 and a suitable cap screw (not shown) eX- tends through the slot and is threaded into the motor mounting ange 168a to lock the ange in position. The inner side plate 176 also includes an aperture 17617 somewhat larger in diameter than the motor shaft to permit movement of the motor unit during adjustment of the belt tension. The outer side plate 178 includes a large open-r.

ing or cutout 178a for accommodating the body or casing of the motor 168 which protrudes laterally outwardly from the inner side plate through the opening. The opening is somewhat larger than the motor and its supporting flange to permit the aforementioned adjustment of the motor unit to tension the drive belts 172.

Each backing roller assembly 162 includes a drive spindle or axle 184 keyed or splined to the driven pulley 174. The axle 184 is supported on the side plates 176 and 178 by a pair of bearing assemblies 186 which are preferably of the high speed roller type. A steel roller 188 including a cylindrical roll or sleeve 188a having a pair of annular end plates 188b (FIG. 16) at opposite ends is keyed to the axle 184 by keys 190 so that the roller 188 rotates with the driven axle. A resilient sleeve or cushion 192 is tted onto the roller 188 and drivingly engages the inner or non-abrasive surface of the belt 160. The fixed idler roller 164 is similar in construction to the roller 188 and is mounted on an axle 194 which is supported by bearing blocks 196 secured to the side plates 176 and 178. The roller 164 is rotatable with the axle 194 and rotates freely to guide the belt as it is driven by the backing roller assembly 162. The movable, belt tensioning, idler roller 166 is similar in construction to the xed idler roller 164 and is mounted on a movable axle 198 which is carried between a pair of outwardly projecting legs 200a of a fork assembly 200, as is best shown in FIG. ll. The axle 198 is flatted at opposite end portions and is slidable horizontally within slots 201 formed in the outer end portions of the legs 20011. One end of the shaft 198 is secured to the adjacent fork leg 200a by a vertical pivot pin 202 while the opposite end of the shaft is movable horizontally within the slot 201 in the opposite leg 200a by an adjusting pin 204, best shown in FIGS. 7 and 11. The movable belt tensioning idler roller 166 may be adjusted on the fork assembly 200 so that the belt will track as it is driven around the three rollers. The fork assembly 200 also includes a web structure 20011 extending between the inner ends of the legs 20011 which web structure 20019 is secured to the outer end of a push rod 206 by a pair of cap screws 208 (FIG. 1l). The push rod 206 is slidable horizontally within a tubular sleeve 210 having an open outer end mounted in one of the spacer webs 180 extending between the side plates 176 and 178. An annular flange 212 is provided adjacent the outer end of the tubular sleeve 210 to tightly seal the rod 206 within -the sleeve and prevent abrasive dust from e11- tering the sleeve to gouge or score the rod. The inner end of the sleeve 210 is provided with an annular ange 21041 for supporting the forward end of a belt tensioning pneumatic cylinder 214. The cylinder 214 includes an internal piston slidable horizontally therein for driving a piston rod 214a having its outer end connected to the inner end of the push rod 206. Pressurized air is normally maintained in the closed end of the cylinder 214 at a controlled pressure, whereby the roller 166 is biased outwardly to maintain the desired tension on the belt 160. The pressure of the uid supplied to the cylinder is regulated so that a constant belt tension is maintained at all times during travel of the belt around its three rollers. When it is desired to change the belt and replace it with a new one, or to perform other maintenance pressurized fluid is introduced into the opposite end of the cylinder to retract the push rod 206 and roller supporting fork 200 inwardly lwhereupon the tension on the belt is relaxed so that it may be easily removed from the rollers. This described tensioning assembly thus provides a simple and easy means for achieving a constant belt tension and also permits the rapid replacement of the belts if they become worn or torn.

Because each of the belts 160 travel in a generally triangular path around the associated rollers, only one corner of which path is adjacent the weld area, only a small portion of the outer abrasive surface of the belt is in grinding engagement with the rail at any time during the grinding operation. Thus, wear on the abrasive belt is relatively small and the grinding action is confined to a minimal area including the weld or upset 22 and those immediately adjacent areas at the extreme ends of the abutting rail sections 24.

In accordance with the present invention, the belt supporting base structure 251 of each of the grinding heads 50 and 52 is movable longitudinally with respect to the rail string and, in addition, is movable in a vertical direction toward and away from the surface to be ground. The backing roller assembly 162 on each base structure is adapted to move from a position adjacent one rail section 24 longitudinally of the rail string across the weld to a. position adjacent the other rail section. The described movement of the backing roller is effective to cause a corresponding movement of the belt which is moved transversely in a vertical direction to force abrasive surface into grinding engagement with the weld area 22. As is best shown in FIG. 18 each base structure 251 includes a pair of spaced-apart, vertically extending tubular sleeves 220 which are aixed to the inner side plates 176 of the grinding head base structure by pairs of support blocks 222 at the upper and lower ends of each sleeve. The sleeve supporting blocks are removably secured to the inner side plate 176 by a plurality of countersunk cap screws 224 (-FIGS. 7 and 18). Each of the vertical sleeves 220 is mounted for vertical sliding movement on a mating vertically extending rod member 226 which is supported at its upper and lower ends by support blocks 228. The latter rod support blocks are removably secured to a horizontally movable carriage 232 by a plurality of cap screws 230. The carriage plate 232 is supported for sliding horizontal movement upon a pair of horizontally extending, vertically spaced apart, parallel support rods 234. As is best shown in FIGS. l1 and 19, the carriage plate is supported on the rods 234 by a plurality of support blocks 236 which are removably secured to the carriage plate by a plurality of cap screws 238. The support blocks 236 are positioned at the respective corners of the carriage plate and each is formed with a horizontal bore 236a to slidably accommodate the rods 234. Bearing sleeves 240 are inserted into the bores of the blocks and the sleeves are held in place by lock washers 242 at opposite ends of the bore.

The horizontal rods 234 which support the grinding heads l50 and 52 are supported at opposite ends by pairs of vertical, spaced apart, parallel end plates 244 and 246 best shown in FIGS. 6 and 1-8. Each pair of grinding head supporting end plates 244 and 246 extend parallel with the inside faces of the end plates 44 of the main support frame 28. The spacing between each pair of end plates 244 and 246 is maintained by anges 234a on the outer ends of the rods which flanges seat against the outer surface of the respective end plates (FIG. 6). A pair of upper and lower horizontally extending channel members 248 (FIG. 8) and a large, horizontally extending center channel member 250 extend between each pair of end plates 244 and 246. The upper and lower channel members 248 include a vertical web 248a secured by bolts 254 to spacing blocks 252 mounted adjacent the ends of the rods 234. Preferably each of the spacing blocks 252 is square in cross section and includes a central bore through which the rod 234 extends. Each of the spacing blocks 252 is secured to a flange 250a of' the large center channel 250 by machine screws 258, as is best shown in FIG. 8. The belt support base 251 of each grinding head 50 and 52 is thus supported for horizontal movement upon the parallel rods 234 while each of these base structures 251 is further supported for vertical movement upon the vertical rods 226.

In accordance with the present invention the grinding heads are movable to accurately control the position of the moving surface of the belt 160 and backing roller assembly 162 relative to the weld area 22. Movement of the belt supporting base structures 251 of each grinding head vertically toward and away from grinding engagement with the Weld area 22 is accomplished by a pair of vertically disposed fluid cylinders 260 mounted on the carriage plate 232. As is best shown in IFIGS. 7, 8, 11 and 18, each of the fluid cylinders 260 is secured to the carriage plate 232 by a pair of brackets 262 and associated screws 264. Each of the vertical cylinders 260 includes a piston Vand rod 260a connected at its outer end to the inner side plate 176 of the base 251 via a connecting block 2616. When fluid pressure is introduced into the rod end of the cylinders 260, the piston rods 260a are retracted to move the base '251 and its backing roller assembly 162 away from grinding engagement with the rail and its weld area 22. Conversely, when fluid is introduced into the opposite ends of the cylinders 260, the base 251 is advanced towards grinding engagement with the weld area. If the grinding belt 160 breaks or if an obstruction is encountered on the rail, the base 251 can be rapidly moved out of grinding engagement with the rail sections to prevent damage to the equipment by operating a push button (not shown) to direct the fluid into the cylinders 260 to retract the piston rods 260a. The uid pressure in the cylinders 260 resiliently biases the grinding heads toward the rail so that if extreme pressures are encountered during a grinding operation the grinding heads can move against the fluid pressure.

From the foregoing description, it will be apparent that the abrasive belt 160 and backing roller assembly 162 are movable transversely of the rail axis towards and away from the weld or upset area 22. In addition, in accordance with an important feature of the present invention, each of the grinding head sub-assemblies mounted on the carriage plate 232 is reciprocated longitudinally with respect to the rail and across the weld area 22 along the supporting rods 234 by means of a pneumatic cylinder 268 is best shown in FIG. 10. The cylinder 268v extends horizontally and is secured at its closed end to the end plate 244 by means of a bracket 270 which is attached by bolts 272 to a bearing block 274 welded to the end plate 244. The rod end of the horizontal cylinder 268 is secured to the web 250b of the large center channel section 250 by a similar bracket 270 and bolts 272. The cylinder 268 includes a piston and a piston rod 268a having its outer end connected to the horizontally movable carriage plate 232 via a block 276 which is secured to the carriage plate by bolts 278. Reciprocating movement of the carriage plate 232 and the grinding head structure supported thereon is accomplished by periodically delivering uid at a predetermined rate first to one end and then to the other end of the cylinder 268. In order to limit the horizontal travel of the carriage plate 232 in both directions from a neutral or longitudinally centered position stop blocks 280 (FIG. 9) having apertures therein to accommodate the rods 234 are mounted on the webs of the upper and lower channels 248 in longitudinally centered positions. 'Referring specifically to FIGS. 9 and 10, when fluid is introduced into the left-hand or closed end of the cylinder 268, the horizontal carriage plate 232 is moved towards the right until the left-hand support bock 236 reaches the stop block 280 in the middle of the structure. Fluid is then directed into the right-hand or rod end of the horizontal cylinder 268 whereupon the carriage plate 232 is moved in the opposite direction or to the left, until the right-hand support block 236 engages the stop block 280. The 'web portion 250b of the large horizontal center channel 250 is provided with a centrally located, horizontally extending slot 253 in order to permit reciprocal sliding movement of the block 276 which connects the piston rod 26-8 with the carriage plate 232. Compressed air supplied to the horizontal cylinder 268 is pressure regulated to control the rate of reciprocation of the carriage plates 232. In order to control the period of each cycle, an automatic fluid controlling device 290, best shown in FIGS. 8, 12 and 19, is provided for each grinding head. The fiuid controlling deivce includes a base structure formed by a pair of downwardly depending bars 292 secured to a base plate 294 which is, in turn, welded or otherwise secured to the outer edges of the anges on one of the channel members 248. The bars 292 are attached to the base plate 294 by bolts 296 and protrude vertically beyond the edge of the channel 248 in order to accommodate a mechanically actuated fiuid control valve 300, which is held in place by bolts 298. The fluid control valve 300 includes a pivotally mounted actuating arm 300a having a roller 300b at its outer end engaging a sloping channel 302. The channel 302 is mounted on a plate 304 attached to the underfaces of the support blocks 236 by means of angle brackets 306 and removable bolts 308, best shown in FIGS. 8 and 19. As the carriage plate 232 of each grinding head is reciprocated longitudinally on the supporting rods 234 the channel 302 is reciprocated horizontally to pivot the actuating arm of the fluid control valve 300 in order to reverse control of the fluid flow into the horizontal cylinder 268 at the end of each stroke.

In order to accurately control the grinding pressure exerted by each abrasive belt 160 upon the upset 22 and upon the adjacent surfaces of the rail as the carriage 232 is reciprocated in such manner that the maximum grinding pressure is exerted upon the upset with a feathering effect or reduced grinding pressure exerted as the belt moves away from -the upset, each of the grinding heads 50 and 52 includes a guide roller assembly 310 comprising a movable base 312 mounted between the inner and outer side plates 176 and 178. The base `312 includes a pair of parallel, yspaced apart, V-shaped side members 314 which are structurally connected by a lateral spacer lblock 315 disposed between the plates. The V-shaped side members of the base 312 include diverging leg portions 316 disposed on opposite sides of the backing roller assembly 162 and a guide roller 318 is mounted adjacent the outer end of each diverging leg. The guide rollers 318 include a tubular metal roller 320 mounted for free rotation on an axle 322 and a sleeve bearing 324 is provided in the bore of each roller to facilitate rotation. Opposite ends of the axles 322 are supported on adjustable bearing block assemblies 326 which are attached to the outer ends of the legs 316 of the V-shaped side members 314. The outer bearing block assemblies 326 permit horizontal adjustment of the axles 322 to eiect accurate tracking of the rollers 318 against the adjacent rail surface, and the inner bearing block assemblies permit pivotal movement of the axle about vertical pivot pins 326a (best shown in FIG. 9) to prevent lateral movement of the axles. Each of the rollers includes a replaceable outer sleeve 330i adapted to directly engage the surface of the rail. Each guide roller base 312 is mounted for pivotal movement about a lateral, horizontal axis extending between the triangular side plates 176 and 178 to effect the aforementioned feathering action. To this end, as is best shown in FIG. 15, each guide roller base is supported on a horizontally extending tubular sleeve 340 which, in turn, is journaled on an eccentric spindle axle 342 extending through bearing assemblies 344 carried within openings in the side plates 176 and 178. The guide roller base 312 is freely rotatable about the supporting sleeve 340 and7 to this end, each of the V-shaped side members 314 includes a shouldered opening 314a which accommodates a bearing ring 346. The two bearing rings 346 are respectively seated within annular recesses 340a formed adjacent opposite ends of the sleeve 340. The sleeve 340 includes a longitudinal bore 340b eccentric with respect to the recesses 340a and a central eccentric portion 342a of the spindle 342 extends through the bore. The spindle 342 includes a pair of annular stubs 342b at opposite ends which are eccentric with respect to the central portion 34261. The bearing assemblies 344 support the stubs 342b so that the spindle 342 may rotate with respect to the side plates 176 and 178. As is best shown in FIGS. 16 and 17 of the drawings, the sleeve 340 turns or oscillates on the spindle 342 as the carriage plate 232 reciprocates horizontally on the supporting rods 234. Oscillation of the sleeve 340 is accomplished by a radially extending lever arm 348 secured to the outer surface of the sleeve which arm is bolted to an extension 350 by a pair of spaced apart bolts 352. The free or outer end of the extension 350 is pivotally connected to one end of a link 354 by a pin and sleeve connection 356 (best shown in FIGS. 15 and 16). The opposite end of the link 354 is lixed against longitudinal movement as the carriage 232 reciprocates and is pivotally connected to a lixed block 358 mounted on one of the end plates 244 and 246 by a pivot pin and sleeve assembly 360 (FIG. 7). As the carriage plates 232 reciprocate longitudinally between the xed end plates 44, the link 354 and the arm 348 are moved to rotate the sleeve 340 about the spindle 342.

Referring specifically to FIGS. 16 and 17, when the backing roller assembly 162 is to the left of the weld area 22 or is in the position represented by the dotted lines designated L, the guide roller base 312 is so positioned that the backing roller assembly 162 does not guite force the belt against the rail surface. The guide rollers are maintained in constant engagement with the rail surface by the cylinders 260 and, accordingly, the abrasive belt 160 and its associated backing roller assembly 162 are positioned a slight distance away from the rail surface and out of grinding engagement therewith. When the carriage 232 begins to move toward the right to the center position designated C the sleeve 340 is rotated in a clockwise direction about the spindle 342 and, consequently, the backing roller assembly 162 moves vertically with respect to the guide roller until the abrasive belt moves into grinding engagement with the rail or, more specifically, with the weld or upset area 22. As the carriage 232 continues its horizontal movement from the center position to the right the backing roller 162 passes longitudinally beyond the center of the weld or upset area 22 and the sleeve 340 continues to rotate in a clockwise direction about the spindle 342. Because of the eccentric relation between the spindle 342 and sleeve 340, the backing roller assembly 162 moves vertically relative to the guide rollers and the abrasive belt moves out of grinding engagement with the rail.

Considering only, the lower guiding head 52, during movement of the carriage plate 232 from left to right, the guide rollers 318 are maintained in engagement with the under side of the rail. However, because of the relative vertical movement between the guide roller base 312 and the base structure 251 of the grinding head, the abrasive belt is moved from an initial position out of engagement with the under surface of the rail upwardly to a center position in rm engagement with the upset as the backing roller assembly 162 passes longitudinally over the area 22. Continued travel of the carriage plate 232 from left to right moves the backing roller assembly beyond the weld area and also moves the abrasive belt 160 downwardly and out of engagement with the undersurface of the rail. When the carriage 232 then reverses direction to move from right to left the abrasive belt is moved upwardly into grinding engagement with rail as the backing roller assembly approaches the weld or upset area and then moves downwardly and out of grinding engagement as the backing roller assembly 162 passes beyond the weld area. Transverse, vertical movement of the abrasive belt 160 and backing roller assembly 162 relative to the rail engaging guide rollers 318 is thus accomplished by turning the sleeve 340 upon the eccentric axle 342.

A similar action occurs in the upper grinding head 50 as its carriage plate is reciprocated. By adjusting the relative rotational positions of the sleeve 340 and the spindle 342 of each head with respect to one another, the degree of feathering or, more specifically, the extent of movement of the backing roller assembly and abrasive belt in a transverse vertical direction during each longitudinal movement of the carriage plate can be accurately controlled, thereby controlling the grinding pressure between the abrasive belt and the weld area as well as the longitudinal extent of the area being ground.

Referring to FIG. 17, which shows the path traversed by the backing roller assembly 162 and the abrasive grinding belt 160 of the lower grinding head `S2 during a longitudinal stroke of the carriage 232, in either direction, it will be observed that the latter path is curvilinear or somewhat arcuate and lies tangent to the underside of the rail being ground at the center of the weld or upset 22. On either side of the weld the path begins to diverge slightly from the surface of the rail and accordingly the grinding action is restricted to a limited area including the upset 22 and every small surface portion of the rail lying on opposite sides of and immediately adjacent to the upset. The grinding pressure between the abrasive belt 160 and the rail is greatest at the center of the upset and then decreases as the backing roller assembly 162 moves in either direction from the center of the upset. The eccentric portions of the sleeve 340 and the spindle 342 are so shaped that the desired grinding path is achieved. The grinding action is thus feathered as the backing roller assembly 162 moves longitudinally away from the upset 22 to produce a very smooth grind.

Because the backing roller assembly 162 is lixed against transverse movement with respect to the base structure 251 while the guide rollers 318 are movable relative thereto, the depth of the grind on the rail section may be accurately controlled to cover only a minimal area of the surface adjacent the upset 22.

After usage of the grinding heads 50 and 52, the guide roller sleeves 330 may become thin from wear and, in addition, the backing roller assembly 162 or the resilient backing sleeve 192 may become worn. In order to compensate for such wear and still maintain accurate grinding depth on subsequent Welds, means are provided for adjusting the relative positions of the backing roller assembly 162 and guide rollers 318. The adjusting means is best shown in FIGS. 13 and 15 where it is designated generally by the reference numeral 370. As illustrated in FIG. 15, the eccentric spindle 342 includes an outwardly extending shaft portion 342C disposed concentrically with the stubs 342b. A gear 372 is mounted on the shaft portion 342C and is locked thereto by a key 374. The gear is held on the shaft portion 342C by a limit plate 376 and a nut 378 threaded onto the end of the spindle 342. The gear 372 meshes with a worm gear 380 (FIG. 13) to provide a reduction gearing for a small electric gear motor 382. When the motor 382 is energized the worm gear 380y turns to rotate the gear 372 very slowly in either a clockwise or counterclockwise direction, thereby rotating the spindle 342 in the bearing blocks 344 so that the eccentric axle 342:1 changes the vertical position of the sleeve 340 relative to the side plates 176 and 178 of the grinder base structure 251. Accordingly, the gear motor 382 may be selectively energized to adjust the backing roller assembly 162 until it reaches a desired predetermined position to effect proper grinding pressure and depth of grind. In order to limit the rotation of the spindle 342, a pair of stops 376a and 376b are mounted on the plate 376 for engagement with a limit switch 384, which is operable to break the electrical circuit to the gear motor when the switch arm is operated by one of the stops. The operator may easily readjust both grinding heads for proper grinding action merely by energizing the respective motors 382 of these heads to move the backing rollers into proper position. The assembly 370 is housed in a removable cover member 386 to prevent dust, ground particles or the like from contaminating the equipment.

Turning now to the means for supporting the lower grinding head 52 and referring particularly to FIGS. 6, 7 and 9, the end plates 244 are provided with horizontally aligned, relatively large pivot pins 390 extending outwardly through openings therein and each including a short shank portion 390a which rests in a support block 44h on one of the grinder frame end plates 44. As is shown in FIG. 6, the pins 390 rest within semi-cylindrical bearing recesses 391 formed in the support blocks 44b, whereby the entire lower grinding head structure 52 is rotatable about a horizontal axis coinciding with the axes of the aligned pins 390 extending parallel with and below the rail. Each of the end plates 244 has an elongated, arcuate slot 24411 (FIG. 8) therein for receiving a positioning bolt 392 to guide the end plates 244 when the position of the lower grinding head is adjusted to bring its abrasive belt 160 into engagement with the underside of the rail. After the lower grinding head 52 has been properly adjusted and leveled the bolts 392 are tightened to lock the lower head in position.

As contrasted with the lower grinding head 52, the upper grinding head 50 is mounted for movement in an orbital path around the axis of the rail so that the abrasive belt moves over the top running surface on the head of the rail along a curved path. To this end, the supporting end plates 246 of the upper grinding head 52 are somewhat different in shape than the end plates 244 of the lower grinding head, as is best shown in FIG. 6. Specifically, the upper grinding head end plates 246 are supported for rotation about the tubular sleeves or hubs 44e which project inwardly from the opposite end plates 44. A split ring 396 is mounted for rotation on each of the hubs 44e and the lower ends of the end plates 246 are xedly secured to a split ring 396 by a plurality of bolts 398. To effect the aforementioned rotation or orbiting of the upper grinding head 50 about the longitudinal axis of the rail an adjustably controlled gear motor assembly 400 (FIG. l) is drivingly interconnected with the end plates 246 by means of a pair of endless chain assemblies 418. The gear motor assembly 400 is mounted on a base 404 which extends outwardly from one end of the grinding apparatus frame 28 (FIG. l). The motor assembly includes an output shaft 402 connected by -a coupling 408 to a longitudinal shaft 406 extending across the top of the frame 28 and the latter shaft 406 is, in turn, connected to a short shaft 410 via a similar coupling also identified by the numeral 408. The shafts 406 and 410 are respectively supported from the top member 42 of the grinding frame structure by pairs of pillow blocks 414 and 412. A drive gear 416 meshing with the chain 418 is mounted on each of the shafts 406 and 410 between the associated pair of pillow blocks. When the gear motor 400 is energized, both of the gears 416 rotate to drive the two endless chain assemblies 418. The speed of rotation of the gears may be selectively controlled by adjustment of the gear motor to orbit the upper grinding head at a predetermined rate. The endless chain of each assembly 418, is trained over a plurality of spaced apart idler gears 420 each of which is mounted for rotation upon a short shaft 422 supported from one of the end plates 44, as is best shown in FIG. 6. The lowermost idler gear and shaft 420a of each assembly (FIG. 6) is adjustable by means of a chain tensioning assembly 424 so that the proper tension on the chain may be maintained. Each chain tensioning assembly includes a spring 426 and an adjustable stop rod 428 which can be adjusted to increase or decrease the tension of the spring by pivoting a support block `429 for the shaft 422a about a xed pivot pin 430, thereby to slacken or tighten the associated chain 418. Each of the chains 418 is positively connected to an upwardly extending portion or arm on one of the end plates 246 by a bracket 432 so that as the chains are driven the end plates 246 are turned on the supporting hubs 44C. When the upper grinding head is turned past the center position, for example, in a clockwise direction as viewed in FIG. 6 it reaches a position where a limit switch (not shown) is engaged. Actuation of the latter switch reverses the direction of drive of the motor 400 in a well known manner, thereby to reverse the direction of movement of the two chains 418. The grinding head 50 is thus pivoted or turned in a counterclockwise direction (FIG. 6) from its extreme right position through the center position shown to its extreme left position whereupon a second limit switch (also not shown) is operated to again reverse the drive of the motor 400, thereby to again change the direction of movement of the chains 418. The upper grinding head thus oscillates or orbits between the two described extreme positions until the entire grinding operation has been completed. This lateral oscillating movement of the upper head 50 permits the abrasive belt to grind the running surface of the rail head along a curved or arcuate path. The lateral oscillating movement described occurs simultaneously with the vertical feathering movement of the abrasive belt 160 as previously described.

Considering now the operation of the grinding apparatus 20 described above, the grinding apparatus frame structure 28 is first moved to the proper position along the floor tracks 34 by manually operating a switch to energize the gear motor 36 so that the weld area or upset 22 is centered between the end plates 44 (FIG. 1). The lower supporting brackets 76 of the rail guiding and clamping structures 48 are adjusted vertically on the lower legs 56b of the cross-shaped base structure 54 to accommodate the type of rail section that is being utilized and the welded rail is moved longitudinally through the openings 44a in the end plate. During this movement the rail is supported on the lower support rollers 64 and is confined against lateral movement by the lateral guide rollers 66 and 68. When the weld area 22 is in proper position for grinding, the operator actuates a manually operated control to supply uid to the clamping cylinders 112 to bring the upper and lower rail clamping pads 62 and 60 into clamping engagement with the top and bottom of the

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