US2976816A - Mobile railway ballast tamping machine - Google Patents

Description

March 28, 1961 F. PLASSER ETAL MOBILE RAILWAY BALLAST TAMPING MACHINE 3 Sheets-Sheet 1 Original Filed June 11, 1956 m H 25 6 ss e 0 e T wmwS r NP H IL/w M 07 l ssp BY 1? 6417 March 28, 1961 F. PLASSER mm.

MOBILE RAILWAY BALLAST TAMPING MACHINE Original Filed June 11, 1956 3 Sheets-Sheet 2 March 28, 1961 F. PLASSER ETAL MOBILE RAILWAY BALLAST TAMPING MACHINE Original Filed June 11, 1956 3 Sheets-Sheet 5 F z ffqssee 5WD Jo INVENMRJ BY QM M MOBILE RAILWAY BALLAST TAMPING MACHINE Franz Plasser and Josef Theurer, both of Johannesgasse 3, Vienna I, Austria, and Gerhard Schramm, Frankfurt am Main, Germany; said Schramm assiguor to said Plasser and Theater Continuation of application Ser. No. 666,728, June 19,

1957, and Ser. No. 590,769, June 11, 1956. This application July 7, 1958, Ser. No. 746,980

Claims priority, application Austria .lune 26, 1956 9 Claims. (Cl. 104-12) The present invention relates to ballast tamping machines mounted on cars adapted to travel along a railroad track whose rails are arranged on spaced ties.

This application is a continuation of applications Ser. No. 590,769, filed June 11, 1956, and Ser. No. 666,728, filed June 19, 1957, both abandoned.

Highly efficient and largely automatic machines of this type have been developed in recent years to effect ballast tamping under and about the individual ties relatively quickly and dependably, the quality of the tamping operation being independent of the skill, or lack thereof, of the operating crew. One such machine, with various modifications, has been described and claimed, for instance, in our US. patent application Serial No. 462,086, filed October 13, 1954, now Patent No. 2,876,709, granted March 10, 1959, and its divisional application Serial No. 741,984, filed June 11, 1958. However, the present invention is in no way limited to this or any other specific tamping apparatus.

While recent automatic ballast tamping machines have worked quite efliciently, their rate of production was still not fully satisfactory. For instance, particularly with machines having vertically adjustable tamping tool carriers which are raised after each tamping operation and lowered again for tamping the next succeeding tie, difiiculties have been encountered in that an operator must control the intermittent advance of the machine from one tie to the next. Accurate positioning of the tamping tools in relation to the tie to be tamped was often missed by the operator because of poor visibility and a certain inertia of the control means. It then became necessary to correct the position, which involved loss of time. In addition, of course, this constant supervision and control of the machine forward movement by the operator required his full attention and detracted him from other necessary control activities, causing undue fatigue.

It is the primary object of the present invention to overcome these disadvantages and to increase the productivity of mobile railway ballast tamping machines, particularly such machines with vertically adjustable tamping tool carriers.

It is a more specific object of this invention to provide an automatic control of the clutch and brake means of such a mobile tamping machine to eifect its intermittent stoppage on the track in a ballast tamping position.

It is a more specific object of the invention to provide automatic clutch and brake control means which will operate rapidly and dependably regardless of the type of tie to be tamped.

More particularly, it is an object of the invention to control the intermittent forward movement of the machine independently of the width of the tie to be tamped so that the track can be tamped in a continuous operation without any loss of time due to watching whether a single or a double tie is to be tamped, whether it is a Patented Mar. 28, 1961 wood, steel or cement tie or whether ties of irregular width are involved.

It is another object of the invention to provide accurate control means for stopping the machine exactly above the tie to be tamped so as to avoid time-consuming correcting movements of the machine to bring the tamping tools into the proper tamping position.

It is a concomitant object to actuate the clutch before actuation of the brake so that the brake may be controlled very accurately and effectively.

' It is also an object of the invention to provide an improved control of the forward movement of the machine in dependence of the upward movement of the vertically movable tamping tool carrier.

In accordance with the broad concept of this invention, the intermittent stoppage of the forwardly moving machine at each tie is automatically controlled by tieprobing means mounted on the machine and responsive to contact with each tie or tie element in the same vertical plane as the tie.

Preferably, the stoppage control means is operatively connected to means for actuating a brake as well as a clutch in the chassis, the clutch being arranged between the drive means and the wheels of the chassis.

In accordance with a preferred embodiment of the invention, the tie-probing means is mounted on the chassis centrally between the pairs of tamping tools and comprises a mechanism for probing or contacting the upper sides of the ties, which tactile means is arranged to control the brake actuating means.

The tactile means may be pivotal feeler elements, rollers, gliding plungers or the like. Preferably, the tactile elements have a tactile or tie-probing surface which is downwardly convexly curved. They may be supported on vertically glidable rods.

We prefer to assure the very accurate control of the brake actuation exactly when the tie to be tamped is centered between the pairs of opposing tamping tools by linking two such tactile elements to the ends of a scalebeam which is mounted longitudinally on the chassis in the direction of travel of the machine, the pivotal axis of the scalebeam being preferably vertically movable.

In a further preferred embodiment of the tactile means, an additional tactile element is mounted independently and centrally of the two tactile elements linked to the scalebeam, the additional tactile element being mounted in a vertical bearing and being biased downwardly, a stop being provided to limit the downward movement of the additional tactile element. The tieprobing means is arranged to actuate a switch which controls a circuit for the electrical control of the brake actuation means.

It is also possible to control the intermittent stoppage of the tamping machine by a lever element pivoted at its upper end on the chassis and having its lower end reach within the range of the ties so that it will engage the tie, or a part connected therewith, when the lever pivot is above the tie. This abutment for the pivotal lever may be, for instance, the head of the bolts serving to mount the rail on the ties.

The length of the brake path, i.e. the time lag between application of the brakes and standstill of the tamping machine truck, depends not only on the speed of the vehicle but also on the grade of the path. It is, therefore, preferred to mount the pivot of the control lever on a slide which is longitudinally adjustably arranged in the chassis so that the distance between the pivotal lever and the central axis of the tamping machine may be adjusted. This distance may be empirically changed without difiiculty so that, in each instance, the tamping machine truck will stop in such a position that the tamp- 3 ing tools will be accurately aligned with the tie to be tamped.

Mechanical transmission means may be provided to transmit the pivoting movement of the control lever to linkage means which actuates the clutch and the. brakes in the chassis, the engagement of the lower end of the lever with a tie, or part thereof, causing its back movement about its pivot and subsequent actuation of the brake and disengagement of the clutch.

After tamping of the tie and raising of the tamping tool carrier, the tamping machine truck must be moved forwardly to the next tie for another tamp-ing operation. This movement may be effected by an operator. However, in accordance with another preferred embodiment of this invention, the forward movement of the truck is also effected automatically. For this purpose, we have provided a device on the machine frame which automatically engages the clutch and disengages the brakes upon raising of the tamping tool carrier.

In accordance with one embodiment of the invention, the brake and clutch actuation is eifected by pressure fluid means and the fluid supply is controlled by an electromaguetically operated valve.

According to another preferred embodiment, all forward movement control elements of the machine, including the control element responsive to the upward movement of the tamping tool carrier, the tactile or tie-probing elements and the actuating means for the brake and clutch are connected to a common electrical circuit and thus cooperate without any mechanical connecting means.

The above and other objects, advantages and features of this invention will be more fully understood by reference to the following detailed description of two specific embodiments of an automatic intermittent stoppage control, taken in conjunction with the drawing wherein Fig. 1 is a side view of a tamping machine of conventional type, the essential details of the drive controls of the machine according to the invention being schematically shown;

Fig. 2 illustrates the drive control means in detail, together with the control circuit;

Fig. 3 is a side view, partly in section, of the tieprobing or tactile elements;

"Fig. 4 is a transverse section of the tie-probing or tactile elements;

Fig. 5 is a schematic side view of a tamping machine embodying another drive control; and

Figs. 6 and 7 are side views of the bell crank lever device of Fig. 5 for automatically moving the truck forwardly upon raising of the tamping tool carrier.

In the drawing, like reference numerals refer to like parts in all figures. As shown, the chassis of the machine comprises frame 1 which is freely suspended above the track portion to be tamped, motor 2 being mounted at the rear end of the truck to form a counterweight. This machine is of the type wherein each of a pair of tamping tool carriers 3 and 3 is vertically adjustably mounted above respective ones of the pair of rails on two columns or support posts 23, the tamping tools 26 being linked to the ends of arms which are vibrated by eccentric shaft 24. Tamping tool carrier 3' is invisibiy behind carrier 3 in the side view of Fig. l but is schematically indicated in Fig. 2. The tamping tools are connected at pivots 27 to means (not shown) for moving the tools relatively to each other. All this structure is well known and forms no part of the pres-v ent invention, one such ballast tamping machine being fully described and claimed, for instance, in above-mentioned Patent No. 2,876,709. It should be clearly understood, however, that the present invention is not concerned with the details of the tamping machine per se and is applicable to many of the automatic ballast tamping machines recently developed.

The shaft of motor 2 is connected by shaft 4 with gear drive 5 which is connected with the drive wheels 22 by means of universally mounted shaft 6. Clutch 7 is mounted between the gear drive 5 and Wheels 22, being actuatable by means of lever 7 Forward wheels 22' are provided with brake 8 of conventional type, which is actuatable by lever 8;

As schematically shown in Fig. 1 and as will be explained in detail in connection with Figs. 2-4, the tactile or tie-probing elements of the invention form an aggregate 9 mounted on frame 1 between the pairs of tamping tools 26. If desired, this aggregate may be vertically adjustable in the frame to enable the machine to be used with dilferent track heights and also to adjust the tactile element position in dependence of the distance of the upper side of ties 19 from the lower edge of the machine frame.

Fig. 1 also shows the stop 10 on the vertically adjustable tamping tool carrier 3, which cooperates with the two-armed lever 1?. on frame 1 in a manner described hereinafter.

A compressor 12 delivers compressed air through conduits 13 and 14 to electromagnetically controlled valves 15 and 16, respectively, which regulate the fluid supply to cylinders 17 and 18, respectively. Pistons 17' and 18', respectively, move in cylinders 17 and 18, being biased by return springs 17", 18". Piston 17' has its piston rod 7 linked to lever '7' to actuate clutch 7 while brake 8 is actuated by lever 8 linked to piston rod 8" of piston 18'.

The tamping machine moves on tracks 20 mounted on ties 19.

Referring now to Fig. 2, there is shown the cooperation of the diiferent control means in response to the movement of the tamping tool carriers 3, 3, on the one hand, and the position of the tie-probing elements in relation to tie 19, on the other hand.

In the conventional ballast tamping machines of the illustrated type, a separate vertically adjustable ta-rnping tool carrier 3, 3' is provided for each rail of the tracks 20, each tamping tool carrier supporting at least two and often four pairs of cooperating tamping tools 26. For the sake of clarity, Fig. 2 shows the separate tamping tool carriers 3 and 3 adjacent one another while the side view of Fig. 1 shows, of course, only one of the carriers.

A's also shown in Fig. 1, tamping tool carrier 3 (farther left in Fig. 2. than carrier 3), has mounted thereon the stop 10 which is arranged to cooperate with lever 11 of the drive control element which is fixedly mounted on the machine frame. Stop 10 can engage lever 11 only during the upward movement of tamping tool carrier 3. This is accomplished by mounting the stop member pivotally so that it may be swung back against the pressure of spring leaf 36 during the downward movement of the carrier.

Two-armed lever 11 is biased by return spring 28 whose lower end is fixed to lug 29. The opposite end of the lever is linked to piston rod 30 of piston 32. Rod 30 constitutes a sliding or slip contact member between the two illustrated terminals and has an insulated spot 31 which interrupts the current between the two terminals as soon as the piston has reached its uppermost position.

Piston 32 glides in cylinder 33 and divides it into two chambers which communicate with each other by means of conduits 34 and 35'. A check or back-pressure valve 34 of known type is mounted in conduit 34' while an adjustable throttle or butterfly valve 35 is mounted in conduit 35'. When piston 32 is pressed downwardly against the pressure of spring 28 by the upwardly moving stop 10 which engages lever 11, the pressure fluid wili open check valve 34 and fluid will flow through conduit 34' from the lower to the upper chamber of cylinder 33. The contact between the two electrical terminals is established by rod 30 and the circuit is closed. The spring 28 is biased to return the piston 32 into its upper starting position by exerting a pull on lever 11. However, as soon as pressure fluid flows in the opposite direction, the

back-pressure valve 34 closes automatically and the pressure fluid must flow back from the upper to the lower cylinder chamber through butterfly valve 35 and conduit 35. adjustment of the throttle valve 35. In the uppermost position of rod 30, the circuit is interrupted because the insulated area 31 of rod 38 will be located between the terminals.

As will be clear from the above description, this control element constitutes a pressure fluid operated timing switch. Obviously, any other suitable timing switch may be used in the arrangement with equivalent results.

A snap or quick-action switch 37 conventionally actuated by a tactile element, such as roller 39, is associated with the other tamping tool carrier 3 (extreme right of Fig. 2). Obviously, any equivalent switching means may be used instead of the illustrated switch 37. As shown, the switch comprises a gliding member 38 biased by pressure spring 38 and having linked thereto two contact springs 30 which are held by spring 40" in contact-making or contact-interrupting position, depending on the position of gliding member 38.

The current source for the electrical control circuit, for instance a storage battery, is shown at 41. The current source is connected to electromagnet 42 of valve 15 which is mounted in pressure fluid conduit 13 which leads to cylinder 17 of the clutch actuating means. When electromagnet 42 is deenergized, piston 15' of valve 15 is biased by tension spring 44 which pulls the piston to the right, as seen in Fig. 2, to establish communication between conduit 13 and cylinder 17 while closing ofi conduit 13'. When current is supplied to the coil of electromagnet 42, piston 15 is pulled into the position illustrated in the drawing, i.e. it closes conduit 13 which is connected to compressor 12 and connects the interior of cylinder 17 to conduit 13' which leads from cylinder 15 to the atmosphere. The pressure in cylinder 17 being thus relieved, compression spring 17" will press piston 17 and lever 7 into illustrated position I where the clutch is in operative position.

The control of the brake actuation means is identical with the above-described clutch actuation. The electromagnet 43 of valve 16 is also connected to the current source 41, the valve being mounted in pressure fluid conduit 14 which leads to cylinder 18 of the brake actuating means. When electromagnet 43 is deenergized, piston 16' of valve 16 is biased by tension spring 45 which pulls the piston to the right, as seen in Fig. 2, and establishes communication between conduit 14 and cylinder 18 while closing off conduit 14'. When current is supplied to the coil of electromagnet 43, piston 16' of valve 16 is pulled into the position illustrated in the drawing, i.e. it closes conduit 14, which is connected to compressor 12 and connects the interior of cylinder 18 to conduit 14' which leads from cylinder 16 to the atmosphere. The pressure in cylinder 18 being thus relieved, compression spring 18" will press piston 18' and lever 8 into illustrated position I where the brake 8 is inoperative.

An electromagnetic switch 46 is provided in one of the current conductors for electromagnet 43 of brake valve 16. The switch 46 is controlled by electromagnet 47 which is biased by tension spring 48 tending to keep the switch 'open. 47 is actuated.

Switch 49, which is generally similar to switch 37, is provided in another current conducting line for electromagnet 43 of brake valve 16. This switch comprises a gliding member 50 and contact springs 51. The tactile element 52 of switch 49 is actuated by the tactile element 55 which probes the upper side of tie 19 and moves vertically in bearing 56.

Either in a parallel current conductor (shown in broken lines) or in the same conductor (shown in full lines) leading to electromagnet 43, which controls brake valve 16, there is mounted another switch actuated by tie- The switch is closed when electromagnet The time required therefor may be regulated by 6 probing elements 60, 60. The switch comprises an atom ate contact bar 59 and a brush or wiper 57. The pivotal wiper 57 is fixedly mounted in the fulcrum of scalebeam 58. Support rods carrying tie-probing elements 60, 60 are vertically glidably mounted in bearings 61, 61', being linked to the ends of the scale beam at 58', 58''. The fulcrum of the scalebeam is mounted on a vertically movable rod which is journaled in bearing 66. The free end of the wiper 57 cooperates with contact bar 59 which is interrupted in the middle. Thus, the switch, which consists of the wiper and the bar and which is actuated by the swinging movement of scalebeam 58, interrupts the circuit when the scalebeam is in horizontal position while it closes the circuit to the brake actuating means in any position of the scalebeam deviating from the horizontal.

Figs. 3 and 4 illustrate the details of the tie-probing elements. The tactile elements 60, 60 are shown to have downwardly convexly curved tie contact surfaces and are mounted on rods journaled in vertical bearings 61, 61' with considerable play. The play with which the rods are mounted in the bearings must be suflicient to permit the scalebeam 58 to oscillate about its fulcrum. Alternatively or additionally, the pivots 58 and '58" may be constituted by longitudinal slots to permit the swinging movement of the scalebeam. Tie-probing element 55 is mounted centrally of elements 60, 60. The central tactile element 55 is independent of scalebeam 58 and is carried by a rod which is journaled in vertical bearing 56.

The fulcrum 62 of beam 58 is carried by rod 65 which is journaled in vertical bearing 66. Compression spring 63 is biased to press fulcrum 62 downwardly, the downward movement being limited by stop 67 mounted at the outer end of rod 65. The position of pivotal beam 58 is also determined by springs 64 which tend to hold the beam in its horizontal position. Obviously, any suitable means could be used instead of springs 64 to maintain the beam in its horizontal position, for instance a torsion spring in the fulcrum 62.

The mounting of the central tie-probing element 55 is similar to the above-described mounting of the beam fulcrum. Element '55 is depressed by spring 69 which is mounted between shoulder 68 of rod 53 and bearing 54. The downward movement of rod 53 is also limited by a stop mounted at the outer end of rod 53 similarly to stop 67. This stop is arranged to engage tactile element 52 of switch 49, as hereinabove described in connection with Fig. 2.

As appears from Fig. 4, the tie-probing elements 60, 60 are positioned in the center of the tracks one behind the other while the tie-probing element 55 is laterally offset. All tie-probing elements are relatively narrow in the direction transverse to the tracks.

As already mentioned in the description of Fig. 1, the entire aggregate 9 of tie-probing elements is mounted in the frame 1 of the ballast tamping machine for vertical adjustment. In the proper vertical position of the tieprobing elements, the tie contacting surfaces thereof make contact only with the upper side of the ties. Therefore, the height or thickness of the tie-probing plates themselves must not be too large to avoid disturbing contacts with the ballast between ties. On the other hand, the plates must not be too thin so that the swinging movements of the pivotal beam 58 may be properly used for the drive control of the machine.

To enable the control mechanism to be used for tamping ties of maximal and minimal width, for instance single ties and double ties, the distance from center to center of tie-probing elements 60, 60', as measured in the direction of the track, must correspond to the maximal width of ties to be tamped while the clearance between the probing surfaces of the tactile elements (also measured in the direction of the track) must be at least equal to the minimum width of the ties. In practice, therefore, the distance from center to center will be about 52 cm.

7 while the clearance will be about 12 cm. between elements 60, 60.

It will be obvious to the skilled in the art that the tieprobing elements need not be constructed in accordance with the illustrated embodiment. Rather, pivotal arms, gliding rollers and similar tactile means could be used with equivalent results.

The drive control mechanism of this embodiment operates as follows: 7

Fig. 2 illustrates the stage of operations when tamping of a tie 19 has been completed and the tamping tool carriers 3, 3 associated with each rail of track 20 have been lifted to withdraw the tamping tools 26 from the ballast (as shown in Fig. 1), the machine being about to be driven on to the next tie to be tamped.

In this position, the stop on tamping tool carrier '3 has just pivoted lever 11 against the force of spring 28 and thus, as the carrier 3 moved upwardly, piston 32 with piston rod 30 were depressed and the contact between the electrical terminals was closed by rod 30, thus closing the control circuit at this point.

As tamping tool carrier 3 moved upwardly simultaneously, it actuated switch 37 and thus also closed the circuit at that point. The essential point in this arrangement is the fact that the circuit is not closed as long as even one tarnping tool carrier is still in its operating position, which prevents the machine from moving while any tamping tools remain submerged in the ballast.

As soon as the control circuit is closed by the upward movement of the tamping' tool carriers, current flows from source 41 to the coils of ,electromagnets 42 and 47. The piston is moved against the bias of spring 44 and closes the pressure fluid conduit 13, cutting off pressure fluid supply to cylinder 17 whose piston rod 7 controls the clutch. Simultaneously, the switch 46 is moved against the bias of spring 48 to close the circuit to electromagnet 43 of brake valve 16. Under the pressure of compression spring 17", the piston 17 is moved downwardly in cylinder 17 which has been relieved of pressure fluid through fluid escape conduit 13', thus moving links 7" and 7 to actuate the clutch and connect drive wheels 22 with gear drive 5.

The simultaneous closing of switch 46 provides current to electromagnet 43. This will actuate valve 16 to cut off pressure fluid supply from conduit 14 to cylinder 18, the compression spring 18" will depress piston 18' and the brake 8 will become inoperative through movement of links 8 and 8'. With the clutch connected and the brake inoperative, the machine will move forwardly on the track.

Meanwhile, the piston 32 of the time switch operated by tamping tool carrier 3 is automatically moved back to its starting position under the influence of spring 28. After the preset time interval has elapsed and the piston has been returned toits original position, the control circuit is interrupted because the insulated area 31 of piston rod 39 has moved into the range of the current collectors. The coils of electromagnets 42 and 47 are cut off from further current supply, thus causing the clutch 7 to be disconnected and switch 46 to be opened under the bias of spring 48.

Due to inertia, however, the machine will continue to roll forwardly because the coil of electromagnet 43 will continue to be supplied with current,'thus maintaining the brake 8 in inoperative position. The current will be supplied through the circuit line established by the closed switches 49 and 57, 59 which have been actuated, respectively, by the tie-probing element 55 which glided off the tamped tie 19 and the pivotal beam 58 which has been swung out of its horizontal position established by contact of tie-probing elements 60, 60 with the tie (see Fig. 3).

Only after all tie-probing elements have made contact with the next tie to be tamped, ie when tactile element 55 is moved upwardly, tactile elements 60, 60' are on the same level and beam 58 is horizontal, switches 49 and 57, 59 are opened, the circuit is interrupted, current is cut :off from electromagnet 43 and piston 18 is moved by pressure fluid coming from compressor 12 against the bias of spring 18" to move links 8" and 8, thus applying rake 8. The machine is accordingly halted at the exact position in which the tamping tools are in operative position above the tie to be tamped.

' The tamping tool carriers 3 and 3' may now be lowered in a manner known per se (and which forms no part of the present invention) and the tamping operation may be completed about the tie. As previously mentioned, the stop iii is so constructed that it has no eifect on lever 11 during the downward movement of the tamping tool carrier. Switch 37 associated with the other tamping tool carrier also is temporarily open. Current for the control circuit connecting the clutch and disconnecting the brake can flow only when both tamping tool carriers have been lifted, as hereinabove explained. Therefore, the machine will remain stationary in the tamping position as long as the tamping tool carriers remained lowered.

When the current supply fails, the clutch automatically remains disconnected and the brake applied because none of the electromagnetic coils receives current. While the invention has been described and illustrated in connection with a now preferred embodiment, it will be obvious to the skilled in the art that many modifications and variations may be effected without departing from the spirit and scope thereof, as defined in the appended claims. Thus for instance, the actuation of the independent central tie-probing element could be used to initiate a pro-braking of the machine movement to assure instantaneous braking of the machine when the brake actuating means is operated by the two tie-probing elements balanced on the scalebeam.

As shown in Fig. 5, the tie-probing means may also be a pivotal control lever 79 mounted at the forward end of the chassis 011 slide 70 which is adjustably mounted in bracket 71. Screw 72 permits the slide to be longitudinally moved in the bracket. Lever 79 engages piston 74 which is slidably arranged in hydraulic cylinder 73. Hydraulic conduit 76 leads from cylinder 73 to cylinder 86. A flexible tubing 75 forms part of conduit 76-to allow for the longitudinal adjustment of slide 70 which also carries cylinder 73.

A similar hydraulic cylinder 77 with slidable piston 78 is fixedly mounted directly on the frame and forms part of the brake release mechanism which is actuated by raising the tarnping tool carrier. This mechanism is more clearly shown in Figs. 6 and 7 and comprises bell crank lever 79 pivoted on the frame. One end of the lever is actuated by piston 78, being limited in its movement by stop 80. The other end of the lever 79 is engageable by wedge-shaped stop 81 which is pivotably mounted on the vertically adjustable tamping tool carrier in lug 83. Pivotal stop 81 is biased by spring 82 against abutment 84.

Hydraulic conduit 85 leads from cylinder 77 to common hydraulic cylinder 86 which carries slidable piston 8'7. Piston 87 forms the final link of linkage system 88, 89, 90, 92 which actuates brake 8 and clutch 7. brake is actuated by schematically illustrated lever 8' and the clutch is actuated by link portion 92 and lever 7.

The intermittent forward movement of the mobile ballast tamping machine operates as follows:

Beginning with position II, II, and II" of the control elements, the chassis advances to the next succeeding tamping position. As it advances, the lower end of control lever 79 hits head 84 of the bolt used for fixing the rail on the tie next succeeding to the tie to be tamped. Further advance of the chassis will automatically pivot the lever backwardly, thus moving piston 74 to position I. The hydraulic pressure fluid in conduits 75, 76 will transmit this movement to piston The 9 87 in cylinder 86, forcing the piston forwardly. The forward movement of piston 87 will actuate linkage systom 88, 89, 90, 92 so that levers 8 and 7' will be brought into positions I and 1'', respectively. Position I of lever 8' will engage the brake while clutch 7 will be disengaged in position I of lever 7'. Thus, after the truck has moved distance s, it will quickly stop. As mentioned hereinabove, the distance between control lever 79 and the central axis of tamping tool carrier 3 must be so adjusted (by movement of slide 70) that the tamping tools are accurately aligned with the tie to be tamped after the machine has been fully stopped.

After the chassis is stopped, the tamping tool carrier is lowered in the usual manner and the tamping operation is effected. After conclusion of the tamping, carrier 3 is raised, which causes wedge-shaped stop 31 to engage and pivot bell crank lever 79 so that piston 78 is moved forwardly in cylinder 77. The hydraulic fiuid in conduit 85 will transmit this movement to piston 87 in cylinder 86, forcing both pistons back into position II. This movement will disengage brake 8 and engage clutch 7, thus causing forward movement of the truck until control lever 79 strikes the next tie, at which time the braking operation is repeated.

When the tamping tool carrier is lowered for the next tamping operation, wedge-shaped stop 81 remains ineffective in respect of lever 79 because the stop is pivotally mounted in lug 83 and, therefore, resiliently yields under the action of spring 82 as it slides by lever 79.

It is understood that the present invention is not limited to the illustrated embodiments thereof but that many changes and modifications may occur to the skilled in the art without departing from the spirit and scope of the invention. Thus,-the control lever 79 may be exchangeable so that any desired shape of lever may be used for engagement with any portion or part of the tie or rail fixing means. When the mobile ballast tamping machine is moved over the rails to the tamping location, the lever is, of course, disconnected or removed entirely. It may be advantageous to mount a brush or like means ahead of the control lever to remove foreign bodies from the track, which may cause premature actuation of the lever.

As soon as the control lever has passed over the abutment on the tie, the left chamber of cylinder 87 would be without pressure. It may be necessary, therefore, to provide safety devices in the linkage system or other suitable location to prevent premature reverse movement of the links. Such safety devices may include stops, pneumatic control means and the like. In addition to the automatic controls of the present invention, it may be desirable to retain the usual foot controls to enable the operator to stop the truck in case of emergency.

What we claim is:

l. A ballast tamping machine mounted on a chassis with wheels for mobility on a railroad track which is mounted on spaced ties, comprising means for driving at least some of said wheels, said driving means being mounted on the chassis, connecting means mounted between the driving means and the latter or driven wheels for operating said wheels, clutch means mounted in said connecting means for selectively disconnecting the driving means from the driven wheels, brake means mounted for stopping the wheels, mobility control means for effecting intermittent stopping of the wheels by operating the brake means to stop the wheels and disconnecting the driving means from the driven wheels by operating the clutch means, and stop control means supported on the chassis for operative contact with said ties and operatively connected to the mobility control means for operating the mobility control means to operate the brake and clutch operating means to stop the tamping machine in a ballast tamping position upon operation of said stop control means, the stop control means including tieprobing means mounted on the machine and responsive 10 to contact with said ties and any tie element in the same vertical plane as the tie for the operation of said stop control means.

2. The ballast tamping machine of claim 1, wherein said tie-probing means is a normally vertical lever having an upper end and a lower end, the upper end being pivotally mounted on the machine and the lower end being adapted to establish said contact in the vertical position of the lever, the mobility control means comprising a linkage system, and further comprising operating means for actuating the linkage system, said operating means being connected between the lever and a link of the linkage system, and being responsive to a pivoting movement of the lever, and another link of the linkage system operating the brake and clutch means when the lever pivots backwardly upon establishing said contact to stop the machine.

3. The ballast tamping machine of claim 1, wherein said stop control means includes anelectrical control circuit connected to the mobility control means to operate the brake and clutch operating means, and switch means for opening and closing the circuit, the tie-probing means being mounted to actuate the switch means upon contact with said ties and any tie element in the same vertical plane as the tie.

4. The mobile ballast tamping machine of claim 3, wherein the tie-probing means comprises a beam mounted on the machine in longitudinal direction in relation to the track for pivotal movement about its center, two tactile elements linked to the ends of the pivotal beam, support means for the pivot of the beams, vertical bearing means mounting the beam support means for vertical movement, and resilient means for maintaining the beam in horizontal position, and the switch means comprises a switch consisting of a contact having one free end and another end fixedly mounted in the beam pivot, and an arcuate contact bar interrupted at its center to accommodate the free end of the contact, the circuit being open when the beam is in horizontal position and the free end of the contact is spaced from the contact bar and the circuit being closed in any other position of the beam when.

for driving at least some of said wheels, said driving means being mounted on the chassis, connecting means mounted between the driving means and the latter or driven wheels for operating said wheels, clutch means mounted in said connecting means for selectively disconnecting the driving means from the driven wheels, brake means mounted for stopping the wheels, mobility control means for effecting intermittent stopping of the wheels by operating the brake means to stop the wheels and disconnecting the driving means from the driven wheels by operating the clutch means, stop control means supported on the chassis for operative contact with said ties and operatively connected to the mobility control means for operating the mobility control means to operate the brake and clutch operating means to stop the tamping machine in a ballast tamping position upon operation of said stop control means, the stop control means including tie-prob -ing means mounted on the machine and responsive to contact with said ties and any tie element in the same vertical plane as the tie for the operation of said stop control means, forward movement control means for intermittently moving the tamping machine from one tamping position to the next tamping position, said latter control means being mounted on the frame adjacent the tamping tool carrier and actuated when the carrier is raised on the support posts suificiently to lift the tamping tools above the ties, and said latter control means being connected between the stop control means and the mobility control means for transmitting the forward movement control means actuation to operate the brake and clutch operating means to release the brake from said wheels and to connect the driving means to said wheels whereby the machines moves forwardly under the control of the upward movement of the tamping tool carrier.

6. The ballast tamping machine of claim 5, wherein the forward movement control means comprises a bell crank lever pivotally mounted on the frame and an abutment mounted on the vertically adjustable tamping tool carrier, one arm of the bell crank lever being operatively connected to the mobility control means and the other arm of the lever being engageable by the abutment when the tamping tool carrier is raised sufiiciently to lift the tamping tools above the ties, engagement of the abutment with the other lever arm actuating the forward movement control means to release the brake means from said wheels and to connect the driving means to said wheels. a

7. A mobile ballast tamping machine comprising dn'ving means, wheels adapted to travel along a railroad track which is mounted on spaced ties, means operatively connecting the driving means with the wheels, clutch means mounted in said connecting means for selectively disconnecting the driving means from the wheels, brake means mounted for stopping the wheels, mobility control means for eliecting intermittent stopping of the wheels by operating the brake means to stop the wheels and disconnecting the driving means from the driven wheels by operating the clutch means, a vertically movable carrier mounted on said machine and supporting at least one pair of cooperating tamping tools, and control means supported on said machine for operative contact with said ties and operatively connected to the mobility control means for operating the mobility control means to operate the brake and clutch operating means to stop the tamping machine in a ballast tamping position upon operation of said control means, said control means including an electric control circuit, tie-probing means mounted on the machine within the range of the tamping tools for making contact with the upper side of the ties for the operation of said control means, a

switch means in said circuit and actuatable 'by the tieprobing means, another switch means in said circuit, means for actuating the other switch means and means actuated by the upwardly moving tamping, tool carrier for actuating the switch actuating means when the carrier has been raised sufliciently to lift the tamping tools above the ties to release the brake means from said wheels and to connect the driving means to said wheels.

8. The mobile ballast tamping machine of claim 7, wherein said other switch means includes a time switch pre-settable to open a predetermined time lag after closing.

9. The mobile ballast tamping machine of claim 7, wherein the other switch means includes a switch comprising a pressure fluid operated piston, an electrically conductive piston rod connected to the piston and making gliding contact with terminal means in said circuit, a lever linked to the piston rod for movement thereof, a lever actuating element mounted on the vertically movable tamping tool carrier and arranged to move the lever upon upward movement of the carrier, spring means arranged and biased to move the piston in a direction opposite to the direction it is moved by the lever upon npwardmovement of the carrier, conduit means for conducting the pressure fluid from one side of the piston to the other side thereof, and an adjustablethrottle valve in said conduit means.

References Cited in the file of this patent UNITED STATES PATENTS 878,797 Harding et al Feb. 11, 1908 1,297,680 Hanak Mar. 18, 1919 1,328,635 Lichtenberg Jan. 20, 1920 1,415,194 Robinson May 9, 1922 2,052,943 Scheuchzer Sept. 1, 1936 2,208,016 Cowles July 16, 1940 2,233,994 Cook Mar. 4, 1941 2,259,810 Freeman Oct. 21, 1941 2,433,443 Edge Dec. 30, 1947 2,561,169 Bickelhaupt July 17, 1951 2,766,056 Hudson Oct. 9, 1956 2,804,185 Segrist Aug. 27, 1957

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