Title:
Railway ballast excavator having inclined portion
Kind Code:
A1


Abstract:
A railway ballast excavating apparatus comprising a guide frame having an endless excavating chain mounted thereon, the guide frame having a first portion for insertion beneath the railway tracks and a second portion parallel and inclined with respect to the first portion, the first portion for excavating ballast and the second portion for elevating the excavated ballast in order to deposit the excavated ballast in a pile adjacent the railway tracks. The apparatus is powered by a rubber-wheeled motive vehicle and can be advantageously lifted from the railway tracks in the event of an oncoming train.



Inventors:
Hall, Ronald (Woodstock, CA)
Application Number:
11/261709
Publication Date:
05/11/2006
Filing Date:
10/31/2005
Assignee:
RWF Bron
Primary Class:
International Classes:
E02F5/22
View Patent Images:
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Primary Examiner:
BUCK, MATTHEW R
Attorney, Agent or Firm:
BRUNET & CO. LTD. (Toronto, ON, CA)
Claims:
1. An excavating apparatus for excavating ballast material from beneath a railway track and for elevating the excavated ballast material, the apparatus comprising: a) a frame having a set of railway wheels thereunder; and, b) an excavating unit laterally adjacent the frame, the excavating unit comprising an endless excavating chain mounted on a guide frame having a first portion and a second portion parallel to and inclined from the first portion, the second portion having an inclination angle relative to the first portion, the second portion for elevating and depositing excavated ballast in a pile adjacent the railway track.

2. The apparatus according to claim 1, wherein the frame comprises a horizontal slide oriented transversely to the railway track and wherein the excavating unit is mounted to the horizontal slide.

3. The apparatus according to claim 1, wherein the excavating unit comprises a vertical slide permitting vertical movement of the guide frame.

4. The apparatus according to claim 1, wherein the excavating unit comprises a knuckle comprising a vertical pivot axis, the knuckle operable to pivot the guide frame about the vertical pivot axis.

5. The apparatus according to claim 1, wherein the guide frame comprises a plurality of debris clearing holes for reducing debris accumulation within the guide frame.

6. The apparatus according to claim 1, wherein the frame further comprises a connection means for releasable connection with a motive vehicle.

7. The apparatus according to claim 6, wherein the connection means comprises a cradle for receiving an articulated arm of the motive vehicle

8. The apparatus according to claim 7, wherein the cradle engages with an excavating bucket attached to the articulated arm and causes longitudinal movement of the apparatus along the track in response to movement of the motive vehicle along the track.

9. The apparatus according to claim 1, wherein the frame further comprises a connection means for releasable connection with a motive vehicle and wherein the excavating unit comprises a hydraulic motor for driving the excavating chain, the hydraulic motor releasably connected to a source of fluid power on the motive vehicle, the excavating unit powered solely using the source of fluid power on the motive vehicle.

10. The apparatus according to claim 1, wherein the apparatus has a total weight less than or equal to 11,000 lbs.

11. The apparatus according to claim 1, wherein the second portion of the guide frame is inclined with respect to the first portion of the guide frame by an inclination angle of from 10 to 45 degrees.

12. The apparatus according to claim 1, wherein the second portion of the guide frame is inclined with respect to the first portion of the guide frame by an inclination angle of from 15 to 30 degrees.

13. The apparatus according to claim 1, wherein the second portion of the guide frame is inclined with respect to the first portion of the guide frame by an inclination angle of from 20 to 23 degrees.

14. The apparatus according to claim 1, wherein the second portion of the guide frame is inclined with respect to the first portion of the guide frame by an inclination angle of about 22 degrees.

15. The apparatus according to claim 1, wherein the excavating chain comprises a plurality of excavating links, each excavating link having a first and second pair of vertically spaced apart horizontal joining plates, each pair of spaced apart joining plates comprising concentrically aligned through-holes, the excavating chain further comprising a joining link interspersed between each excavating link, each joining link comprising a spherical bearing at each end thereof located between the spaced apart joining plates, each spherical bearing having an aperture concentrically aligned with the through-holes for receiving a pin connecting the excavating link with the joining link, each pin having a vertical axis about which the excavating link is permitted to rotate relative to the joining link, each spherical bearing permitting angular deflection of the vertical axis in response to movement of the bearing from the first portion of the guide frame to the second portion of the guide frame.

16. The apparatus according to claim 1, wherein the excavating chain comprises a plurality of excavating links, each excavating link having an outwardly projecting excavating lug having an inclined row of vertically and horizontally spaded apart excavating teeth, each inclined row having a row angle with respect to the direction of movement of the excavating chain.

17. The apparatus according to claim 16, wherein the row angle is from 10 to 45 degrees.

18. A system for excavating ballast material from beneath a railway track comprising: a) a motive vehicle comprising a rubber-wheeled excavator having a set of selectively deployable railway wheels and an articulated arm; b) an excavating apparatus comprising a frame having a set of railway wheels thereunder and comprising a connection means for releasable connection with the articulated arm of the motive vehicle, the excavating apparatus further comprising an excavating unit laterally adjacent the frame, the excavating unit comprising an endless excavating chain mounted on a guide frame having a first portion and a second portion parallel to and inclined from the first portion, the second portion having an inclination angle relative to the first portion, the second portion for elevating and depositing excavated ballast in a pile adjacent the railway track; and, c) wherein the motive vehicle is operable to move the excavating apparatus longitudinally along the track, to lift the excavating apparatus from the track and deposit the excavating apparatus adjacent the track, and to drive off of the track by selectively raising the railway wheels.

19. A method of excavating ballast material from beneath a railway track comprising: a) providing an excavating apparatus comprising a laterally adjustable excavating unit comprising an endless excavating chain mounted on a guide frame having a first portion and a second portion parallel to and inclined from the first portion, the second portion having an inclination angle relative to the first portion; b) transversely positioning the first portion of the excavating unit at a first operative position beneath the track; and, c) operating the excavating unit to remove ballast material from beneath the track using the first portion, to elevate the ballast material using the second portion, and to deposit the ballast material in a first pile adjacent the railway track.

20. The method according to claim 19, wherein the method further comprises transversely positioning the first portion of the excavating unit at a second operative position beneath the track then operating the excavating unit both to remove remaining ballast material from beneath the track and to deposit the remaining ballast material in a second pile adjacent the first pile.

Description:

FIELD OF THE INVENTION

The invention relates to the excavation of ballast from beneath railway tracks and the simultaneous elevation and piling of excavated ballast alongside the railway track. More particularly, the invention relates to an apparatus and method of excavating railway ballast for the purpose of repairing small sections of track using a mobile endless-chain type excavator having a horizontal portion for excavating the ballast and an inclined portion for elevating the excavated ballast.

BACKGROUND OF THE INVENTION

Railway lines generally comprise a set of spaced apart rails mounted on a plurality of transversely placed railway ties that are located upon a bed of compacted ballast material. The rails, ties and ballast must be routinely replaced and machines for removing, cleaning and replacing ballast, such as described in U.S. Pat. No. 5,090,484, are known in the art. However, these machines are large and not particularly well suited to removing ballast from relatively small sections of track or for repairing a portion of a track.

U.S. Pat. No. 6,862,822, issued on Mar. 8, 2005, discloses a mobile railway track repair apparatus having an endless-chain excavator mounted on the end of an articulated arm of a conventional excavating vehicle. The endless chain conveyor may be positioned at any desired angle or orientation beneath the track and may be readily replaced by a conventional excavating bucket. This apparatus is limited in that ballast material can only be excavated from the immediate vicinity of the excavating vehicle and, since these vehicles are quite heavy, this can cause track instability resulting in misalignment and the need for extensive repair. Moreover, when the excavator is fully inserted beneath the tracks, excavated ballast material accumulates immediately behind the excavator and must be dislodged in order to remove the excavator. This spreads the material around in the vicinity of the tracks, making it difficult to collect and remove at a later time. Although the apparatus is suited for small track repairs, the apparatus cannot be operated continuously along a small section of track, such as a siding.

U.S. Pat. No. 3,967,395, issued on Jul. 6, 1976, discloses an endless chain excavator mounted to the front of a forklift vehicle. The excavator can move vertically along a vertical slide and can be rotated about a vertical axis. The vehicle must be driven toward the tracks from the side thereof in order to insert the excavator beneath the tracks and must be re-positioned when the ballast material has been removed. The excavated material accumulates behind the apparatus; the material must therefore be dislodged as the apparatus is removed, with the disadvantages described above, and driven over by the forklift vehicle as the apparatus is advanced beneath the track. The apparatus is not suitable to continuous operation along a small section of track.

U.S. Pat. No. 3,436,848, issued Apr. 8, 1969, discloses an endless chain excavator apparatus mounted on a railway vehicle for continuously removing ballast along a small section of track. The excavator may be moved transversely to the track using a horizontal screw mechanism and may be pivoted about a vertical axis to move from an orientation parallel to the tracks to an orientation perpendicular to the tracks. The apparatus is vertically moveable using a parallelogram linkage. The chain excavator extends under the full width of the tracks and can be used to excavate ballast from beneath an adjacent set of tracks, such as a siding. However, the apparatus suffers in that accumulated material is deposited immediately adjacent the end of the chain excavator and hampers excavation of additional material. The excavated material must therefore be manually dislodged or accumulated simultaneously with excavation using a separate apparatus adapted for that purpose. This is operationally cumbersome and requires additional labour and equipment. Moreover, the apparatus is vehicle mounted and neither the apparatus nor the vehicle can be readily removed from the railway tracks. This can pose a problem in the event of an oncoming train, even if the train is on an adjacent set of tracks.

U.S. Pat. No. 6,698,115, issued on Mar. 2, 2004, discloses a mobile track maintenance machine having a clearing chain for excavating bulk material that has a universal joint between each link of the chain. The chain has an ejection end positioned above a receiving end of a conveyor belt for transporting the excavated ballast and is guided to the ejection end in a curved guide track. The ejection end is oriented rearwardly of the excavating section of the chain and does not discharge material alongside the railway track in a direction parallel with the excavating section. The ballast material is not deposited in a pile but instead is simultaneously transported with the conveyor belt to a bulk material loading wagon coupled to the machine. This requires periodic emptying of the bulk material loading wagon and is operationally cumbersome as compared with simply depositing the material in a pile. Also, the excavating chain apparatus is mounted to a railway vehicle and neither the apparatus nor the vehicle can be readily removed from the track in the event of an oncoming train.

It would be desirable to provide an apparatus for excavating railway ballast from beneath a set of railway tracks that may be moved along a railway track for continuous excavation of a small section of track and that is readily disconnected from the motive vehicle in order to permit both the apparatus and the vehicle to be removed from the set of tracks in the event of an oncoming train. It would be further desirable to provide a railway ballast excavating apparatus that also elevates the excavated material to facilitate pile formation alongside the track to alleviate the need for simultaneous removal of excavated ballast while permitting the ballast to be readily removed at a later time. However, no such apparatus is currently available and the need currently exists for an improved railway ballast excavating apparatus having some or all of the foregoing features.

SUMMARY OF THE INVENTION

According to the present invention, there is provided an excavating apparatus for excavating ballast material from beneath a railway track and for elevating the excavated ballast material, the apparatus comprising: a frame having a set of railway wheels thereunder; and, an excavating unit laterally adjacent the frame, the excavating unit comprising an endless excavating chain mounted on a guide frame having a first portion and a second portion parallel to and inclined from the first portion, the second portion having an inclination angle relative to the first portion, the second portion for elevating and depositing excavated ballast in a pile adjacent the railway track.

According to the present invention, there is further provided a system for excavating ballast material from beneath a railway track comprising: a motive vehicle comprising a rubber-wheeled excavator having a set of selectively deployable railway wheels and an articulated arm; an excavating apparatus comprising a frame having a set of railway wheels thereunder and comprising a connection means for releasable connection with the articulated arm of the motive vehicle, the excavating apparatus further comprising an excavating unit laterally adjacent the frame, the excavating unit comprising an endless excavating chain mounted on a guide frame having a first portion and a second portion parallel to and inclined from the first portion, the second portion having an inclination angle relative to the first portion, the second portion for elevating and depositing excavated ballast in a pile adjacent the railway track; and, wherein the motive vehicle is operable to move the excavating apparatus longitudinally along the track, to lift the excavating apparatus from the track and deposit the excavating apparatus adjacent the track, and to drive off of the track by selectively raising the railway wheels.

According to the present invention, there is yet further provided a method of excavating ballast material from beneath a railway track comprising: providing an excavating apparatus comprising a laterally adjustable excavating unit comprising an endless excavating chain mounted on a guide frame having a first portion and a second portion parallel to and inclined from the first portion, the second portion having an inclination angle relative to the first portion; transversely positioning the first portion of the excavating unit at a first operative position beneath the track; and, operating the excavating unit to remove ballast material from beneath the track using the first portion, to elevate the ballast material using the second portion, and to deposit the ballast material in a first pile adjacent the railway track.

The frame may comprise a vertical slide for positioning the excavating unit at a desired height. The frame may comprise a knuckle having a vertical pivot axis therethrough that may be operable using, for example, hydraulic cylinders to open and close, thereby pivoting the guide frame of the excavating unit about the vertical pivot axis. This allows the guide frame to be moved from a transport position parallel to the tracks to a working position transverse of the tracks. The frame may further comprise a horizontal slide oriented transversely to the railway track and the excavating unit may be mounted to the frame to permit the excavating unit to be placed at any desired transverse position relative to the railway track. The frame may further comprise a tilt mechanism that permits the guide frame to adopt any desired angular orientation relative to horizontal. This permits the guide frame to be inserted beneath the tracks in one orientation, then allows the orientation to be adjusted in response to excavating conditions, obstacles, etc. The frame may include any of the foregoing features alone or in combination and permits the excavating unit to be adjusted in height, horizontal position, parallel or transverse relationship with the tracks, and/or angular orientation relative to the tracks.

The apparatus lacks its own source of motive power and is moved along the railway tracks using a motive vehicle. The motive vehicle is preferably a rubber-wheeled excavator having a set of selectively deployable railway wheels. The motive vehicle may be connected to the apparatus using one or more of a variety of different means, such as a tow bar, push bar, etc. Preferably, the motive vehicle is releasably connected to the apparatus using a connection means that is adapted for receiving an articulated arm of the motive vehicle. The connection means may comprise a cradle for receiving an excavating bucket attached to the end of the articulated arm. The cradle may comprise fore and aft transverse frame members that engage with the excavating bucket when the motive vehicle is moved along the tracks to cause a corresponding movement of the apparatus. The cradle may include clamping means for securing the bucket within the cradle or the bucket may be unsecured and maintained within the cradle through downward pressure applied using hydraulic cylinder mechanisms of the articulated arm.

The apparatus may be powered using a hydraulic motor or motors that may be releasably connected to a source of fluid power on the motive vehicle using suitable fluid conduits. The releasable connection between the articulated arm and the frame and between the source of fluid power and the hydraulic motor(s) permits the motive vehicle to be readily de-coupled from the apparatus. In the event of an oncoming train, it is often desirable to remove the apparatus from the tracks to prevent potential damage to either the train, the apparatus, or the motive vehicle. In the prior art, it has been necessary to move the apparatus along the track until a siding has been reached that permits the apparatus and motive vehicle to be moved off-line. In the present invention, the releasable connections permit the apparatus to be readily lifted from the track using the articulated arm of the motive vehicle and set alongside the tracks. The railway wheels may then be raised, permitting the rubber-wheeled excavator to be moved off of the tracks alongside the apparatus. When the train has passed, the apparatus may be again positioned on the tracks using the excavator and work may be resumed. This saves a tremendous amount of wasted time as compared with prior art ballast excavating machines.

To facilitate removal of the apparatus from the track, the apparatus may be equipped with a central lifting lug that provides a central connection point for the articulated arm. The apparatus may be equipped with ballast weights on the opposite side of the frame from the excavating unit to provide stability during cutting operations. These weights may be removed prior to lifting the apparatus from the tracks to reduce the overall weight being lifted. The allowable maximum weight of the apparatus depends upon the lifting capabilities of the motive vehicle; however, it has been found that for most excavating vehicles of the size utilized in railway ballast excavating operations a maximum total weight of 11,000 lbs is desirable. It is desirable that the apparatus be somewhat balanced while lifting and the frame may be devised in such a manner as to balance the weight vis-à-vis the position of the central lifting lug so that the apparatus does not tip during lifting.

During ballast excavation, debris may have a tendency to accumulate within the guide frame behind the excavating chain. The apparatus may desirably be equipped with debris clearing holes in the guide frame to permit the debris to naturally fall out of the guide frame and to permit debris to be readily cleared from the guide frame using a high-pressure water spray or jet of compressed air. The accumulation of debris can significantly affect the overall weight and balance of the apparatus and the removal of debris is desirable in facilitating the removal of the apparatus from the railway tracks.

In operation, the excavating unit is first moved to a desired location with the guide frame of the excavating unit oriented parallel to the railway track. The horizontal slide is then operated to move the excavating unit transversely away from the track. The excavating unit can then be lowered to a desired height relative to the track and the excavating chain can begin to operate. The angular orientation of the guide frame may optionally be adjusted if desired. The knuckle is then used to pivot the excavating unit about a vertical pivot axis, bringing the guide frame from an orientation parallel with the tracks to an orientation transverse to the tracks. As the excavating unit engages the ballast during pivoting movement, ballast is removed using the excavating chain and the guide frame is permitted to be inserted beneath the tracks. The motive vehicle is then operated in reverse to move the apparatus slowly along the railway tracks with the excavating chain continuously removing ballast material as the apparatus travels.

In the prior art, excavated material quickly accumulates in the vicinity of the outward end of the guide frame, which interferes with the rate of excavation, increases the likelihood for damage to the apparatus, and limits the amount of material that can be removed in each transit of the apparatus along the tracks. To overcome these disadvantages, the present invention is equipped with a first portion and a second portion that is parallel to the first portion but inclined thereto. This second portion serves to elevate the excavated material and deposits the excavated material in a pile alongside the railway track. The angle of inclination in some part depends upon the amount of material desired to be removed in a single transit of the apparatus along the tracks. If the full width of the tracks is to be excavated in a single transit (which normally results in a first portion length in excess of 13 feet), then a greater angle may be required as compared with an excavating unit having a shorter first portion. However, larger inclination angles have the disadvantage of losing more of the excavated material while elevating, causing the pile to be spread out alongside the tracks and generally reducing the efficacy of the second portion. It has surprisingly been found that only a small angle is required for proper pile formation, even during full-width cutting operations. The second portion may be inclined with respect to the first portion at an angle of from 10 to 45 degrees, preferably from 15 to 30 degrees, more preferably from 20 to 23 degrees, yet more preferably about 22 degrees.

A further benefit of using the smallest allowable inclination angle is found in the excavating chain. Since the excavating chain is required to deflect upwardly as it travels from the first portion to the second portion, the excavating chain may be provided with one or more universal joints between each link. The universal joints may comprise a semi-spherical eye within a complementary bearing race that permits the normally vertical pivot axis between each link to deflect to an angular orientation as the joint passes from the first portion to the second portion. As the inclination angle of the second portion increases, so too does the required deflection of the universal joint. In order to keep the chain as robust as possible, it is therefore desirable to utilize the smallest allowable inclination angle in order to reduce the required deflection of the universal joint. The use of a joining link having two universal joints between each excavating link is desirable in that it allows the deflection angle of each individual universal joint to be further reduced.

Each excavating link of the excavating chain may comprise an outwardly projecting excavating lug having a row of horizontally and vertically spaced apart excavating teeth. The individual teeth may be angled with respect to one another. The row of teeth may form an inclined row angle relative to the direction of movement of the excavating chain. The row angle may correspond to the inclination angle of the second portion so that when the excavating link is on the second portion, the row is substantially horizontal. This facilitates elevation of excavated material using the second portion, thereby reducing the tendency toward pile spreading and further reducing the allowable inclination angle. The row angle may be from 10 to 45 degrees, preferably from 15 to 30 degrees, more preferably from 20 to 23 degrees, yet more preferably about 22 degrees.

In the present invention, it is desirable that the second portion is substantially aligned with the first portion. This causes the second portion to eject material transversely of the railway track during operation of the excavating unit. If the second portion were not parallel with the first portion, the excavated material would have a tendency to be ejected from the first portion and not elevated using the second portion. Prior art devices have utilized a curved guide shield to prevent this ejection of material; however, a guide shield simply causes the excavated material to accumulate at the curve, reducing the throughput of the excavating apparatus and increasing the likelihood for excavated material to become lodged, resulting in mechanical failure. By keeping the second portion substantially parallel with the first portion, the need for any guide shield is reduced and desirably eliminated.

Further features of the invention will be described or will become apparent in the course of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more clearly understood, embodiments thereof will now be described in detail by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a side view of an embodiment of a system according to the present invention in operation on a railway track;

FIG. 2 is a top view of an embodiment of an apparatus according to the present invention showing the excavating unit in the transport and operating positions;

FIG. 3 is a side view of the apparatus showing the excavating unit in the raised and lowered positions;

FIG. 4 is a front view of the apparatus showing the excavating unit in the transport position;

FIG. 5 is a front view of the apparatus showing the excavating unit in the operating position while forming a pile of excavated material alongside the railway track;

FIG. 6 is a side cut-away view of an embodiment of an excavating chain for use with an apparatus according to the present invention;

FIG. 7a is a top view of the apparatus in operation at a first position beneath the railway track while forming a first pile of excavated material; and,

FIG. 7b is a top view of the apparatus in operation at a second position beneath the railway track while forming a second pile of excavated material.

DESCRIPTION OF PREFERRED EMBODIMENTS

Throughout the drawings, like indicia will be used to refer to like features of the drawings. All indicia present on a given drawing need not necessarily be described with reference to that particular drawing.

Referring to FIG. 1, an apparatus according to the present invention comprises a frame 1 having a set of railway wheels 2 thereunder for engagement with rails 3 supported by railway ties 4. An excavator 5 has a set of rubber ground wheels 6, a set of selectively deployable railway wheels 7 and an articulated arm 8 with an excavating bucket 9 at one end thereof that is releasably engaged within a cradle 10 of the frame 1. The cradle 10 comprises fore and aft frame transverse frame members so that when the excavator 5 travels along the tracks, engagement of the bucket 9 against the frame members causes corresponding movement of the apparatus. The excavator 5 is supplementary connected to the frame by means of a tow bar 11. The apparatus lacks its own source of motive power and relies upon the excavator 5 for movement along the tracks.

The frame 1 further comprises a central lifting lug 12. In the event of an oncoming train, the bucket 9 is disengaged from the cradle 10 and the articulated arm 8 is connected to the lifting lug 12 using chains or other suitable means in order to lift and remove the apparatus from the tracks. The railway wheels 7 are then selectively raised and the rubber wheels 6 are used to maneuver the excavator 5 alongside the tracks. In order to reduce the overall weight of the apparatus, frame cutaways 13 are provided and strategically positioned on the frame in order to balance the weight of the apparatus about the lifting lug 12. In the embodiment shown, the weight of the apparatus is less than or equal to 11,000 lbs.

Referring now to FIG. 2, the apparatus is shown in top view. An excavating unit, show generally at 14, comprises a guide frame 15 over which an endless excavating chain 16 passes. The excavating chain 16 is equipped with excavating lugs 17, only some of which are shown, that extend outwardly from the excavating chain. The excavating unit 14 is mounted to the frame 1 by way of a knuckle 18 having a vertical pivot axis passing through pivot pin 19. The knuckle 18 is mounted to a horizontal slide 20 that moves within a slide sleeve 21. The combination of the knuckle 18 and the slide 20 permit the excavating unit to adopt a transport position (denoted as A) close to the frame 1, an extended position (denoted as B) wherein the excavating unit 14 is transversely spaced apart from the frame, and an operating position (denoted as C) wherein the excavating unit 14 is pivoted about the pivot pin 19 using the knuckle 18 to move into a transverse orientation for excavating ballast material from beneath the railway tracks.

Iron ballast weights 22 are provided on the side of the frame 1 opposite the excavating unit 14 to stabilize the unit during operation; the ballast weights may increase the overall weight of the apparatus past 11,000 lbs and are normally removed prior to lifting the apparatus from the tracks. A hydraulic motor 23 is provided as part of the excavating unit 14 for powering the excavating chain 16 in its passage about the guide frame 15. The hydraulic motor 23 is releasably connected to a source of fluid power (eg: hydraulic fluid pump) on the motive vehicle (not shown) and is disconnected prior to lifting the apparatus from the tracks. The cradle 10 is present on both the front and rear of the apparatus; this permits the excavating unit to be positioned on either side of the railway track and permits the apparatus to be towed in either direction.

Referring to FIG. 3, the excavating unit 14 is shown mounted to a vertical slide 24. This permits the excavating unit to be moved from a raised transport position (denoted as A) to a lowered position (denoted as D) that is either extended or un-extended. The horizontal slide 20 moves within sleeve 21 to cause extension or retraction of the excavating unit 14. The knuckle 18 comprises a hydraulic knuckle cylinder 25 that is extended or retracted to cause pivoting movement of the excavating unit 14 about the vertical axis of the pivot pin 19. The guide frame 15 comprises a first portion 26 and a second portion 27 that is upwardly inclined with respect to the first portion with an inclination angle of about 22 degrees. When the first portion 26 is inserted transversely beneath the railway tracks and the hydraulic motor 23 is used to drive the endless excavating chain about the guide frame 15, ballast material excavated using the first portion is elevated using the second portion and ejected at the exit end 28 of the second portion 27 to ultimately be deposited in a pile adjacent the railway track (not shown). The angular orientation of the excavating unit 14 is adjusted by extension or retraction of angle cylinder 31. This causes the excavating unit 14 to pivot about a horizontal pivot axis passing through horizontal pivot 32. The angular orientation of the excavating unit can be adjusted by up to +/−15 degrees from horizontal in order to accommodate excavation around railway switches, upon steep embankments, or in other locations where it is difficult to obtain direct horizontal access.

Referring to FIGS. 4 and 5, the excavating unit 14 is shown in the transport position (FIG. 4) parallel to the railway tracks 3 and is also shown in the operating position (FIG. 5) transverse to the railway tracks 3 and inserted beneath the railway ties 4 in order to remove ballast material thereunder. The second portion 27 of the guide frame 15 is inclined with respect to the first portion 26 by an angle of about 22 degrees. This advantageously provides sufficient elevation of the excavated material to permit pile formation without undue loss of material from the excavating chain that could occur with overly steep inclination. The second portion 27 is parallel to the first portion 26 when seen in top view and inclined with respect to the first portion 26 when seen in front or side views. This co-alignment of the two portions reduces the likelihood of excavated material being expelled at the inflection between the two portions and obviates the need for guides and shields for keeping material on the excavating chain during elevation. Of course, guides and shields may be provided for operator safety purposes, however these guides are not normally of the robust nature needed in maintaining excavated material on the chain during elevation. Substantially all of the excavated material leaves the excavating unit after being elevated to the exit end 28 of the second portion 27 and is deposited in a pile alongside the railway track. The formation of a pile is advantageous in that it allows for subsequent retrieval and/or replacement of the excavated material and spaces the excavated material apart from the track to permit repairs or other work to be more easily conducted. Bumpers 29 are provided on the frame 1 above the railway wheels 2 to mitigate damage to the frame or motive vehicle upon inadvertent impact. The forward frame member 30 of the cradle 10 engages with the bucket of the motive vehicle (not shown in FIG. 4) to cause movement of the apparatus along the tracks in response to travel of the motive vehicle.

Referring to FIG. 6, an excavating chain comprises a plurality of excavating links 33 interspersed with joining links 34. Each excavating link 33 comprises an outwardly extending excavating lug 41 to which a plurality of excavating teeth 42 are mounted. The excavating teeth 42 are horizontally and vertically spaced apart and form an inclined row having a row angle that is opposite in direction to the inclination angle of the second portion 27 relative to the first portion 26. The row angle is generally from 10 to 45 degrees. The excavating teeth 42 are splayed apart relative to one another as an aid both in excavating and elevating ballast material.

Each excavating link 33 further comprises a pair of vertically spaced apart plates 35 having a pair of vertically aligned concentric holes 36. Each joining link 34 has a universal joint (generally indicated at 40) at each end comprising a semi-spherical swivel bearing 38 received within a ball race 39 and having an aperture concentrically aligned with the holes 36 for receiving a link pin 37 inserted therethrough. The link pin 37 permits the excavating link 33 to rotate relative to the joining link 34 about a vertical axis passing through the link pin as the excavating chain 16 travels endlessly about the guide frame 15. As the universal joint 40 passes from the first portion 26 to the second portion 27, the swivel bearing 38 moves within the ball race 39, permitting the joining link 34 to angularly deflect relative to the excavating link 33. The vertical spacing of the plates 35 corresponds to the inclination angle of the second portion 27 relative to the first portion 26 in order to permit sufficient deflection. The permissible deflection of each end of the joining link 34 is normally equally to at least half of the total inclination angle. As the excavating link 33 moves onto the second portion 27, the link pin 37 and the vertical pivot axis passing therethrough adopt the inclination angle of the second portion and the bearing 38 again moves within the ball race 39 to restore a substantially parallel relationship between the plates 35 and the joining link 34.

Referring to FIGS. 7a and 7b, the excavating unit 14 is shown in a first operating position (FIG. 7a) and a second operating position (FIG. 7b). In the first operating position, the excavating unit 14 is inserted approximately half-way beneath the railway tracks 3 and deposits excavated material in a first pile 43 at a first spaced apart location from the railway tracks. After the excavating unit 14 is operated along the section of tracks to form the first pile, the apparatus is returned to the beginning of the section of tracks being worked on and re-inserted to a second operating position across the full-width of the railway tracks 3. As the apparatus is operated in the second position, a second pile 44 is formed inwardly adjacent the first pile 43. This method of operation of the apparatus is particularly advantageous in situations where a large quantity of material is being removed from beneath the tracks, as the height of the pile might exceed the height of the exit end 29. By creating two piles 43 and 44, an excavating unit 14 having a relatively small inclination angle can still be used to remove a large quantity of material from beneath the tracks.

Other advantages which are inherent to the structure are obvious to one skilled in the art. The embodiments are described herein illustratively and are not meant to limit the scope of the invention as claimed. Variations of the foregoing embodiments will be evident to a person of ordinary skill and are intended by the inventor to be encompassed by the following claims.