EP0153772B1

EP0153772B1 - Improved work unit for platelayer waggon

Info

Publication number: EP0153772B1
Application number: EP85200105A
Authority: EP
Inventors: Ivo Cicin-Sain
Original assignee: ITI/CLM IMPIANTI TECNICI INDUSTRIALI SpA; Danieli and C Officine Meccaniche SpA
Current assignee: ITI/CLM IMPIANTI TECNICI INDUSTRIALI SpA; Danieli and C Officine Meccaniche SpA
Priority date: 1984-02-24
Filing date: 1985-02-01
Publication date: 1988-12-28
Also published as: ZA85744B; CZ120985A3; DK81285A; EP0153772A1; IT1221161B; DE3567043D1; DK81285D0; ATE39512T1; IT8483326A0

Abstract

The work unit (19) has the task of placing and fastening nuts (36) on bolts (44) already positioned (13) together with clips and washers on rails (12), and comprises two wrench means (20-21) positioned in series, of which the first (20) performs at least the prescrewing of the nut (36) onto the bolt (44), whereas the other (21) carries out the final tightening of the nut (36). The invention also concerns a platelayer waggon (10) for rails which employs such improved work unit (19).

Description

The present invention concerns an improved work unit for a platelayer waggon, and also a platelayer waggon which employs such work unit.

This platelayer waggon is of a type to bolt the rails of railway lines onto the sleepers, as described in the Italian patent application _'No. 83487 A/83 (corresponding to EP-A-143477) in the name of the present applicants, said European patent application constituting state of the art according to Article 54(3) of the EPC.
The above patent application should be consulted with regard to the general structure and fundamental method of working of such platelayer waggon.
Some embodiments are known in the art which are concerned with the depositing or fixture of components to connect rails to sleepers.
FR-A-2.118.600 (Plasser) concerns essentially the construction of a hydraulic screwing head which incorporates a striker means and is equipped with means able to absorb vibrations and to prevent them from being transmitted to the motor means. Such head can be fitted to a machine performing maintenance of rails and is installed on a movable trolley so as to be able to carry out screwing work while the machine itself is moving.
FR-A-2.072.850 (Plasser) discloses a self-propelled machine equipped with several wheeled devices to remove, or possibly deposit, the various components such as clips, bolts, etc. The devices are positioned one after another in the direction of movement of the machine. The work can be controlled visually by the machine driver.
US-A-3,628,461 (Plasser) discloses a movable trolley located below a special railway waggon, such trolley bearing a tool such as a screwing head. The trolley comprises wheels for alignment on the rails and can be lifted besides being able to move lengthwise to the machine. The work takes place under the direct control of the driver, who is positioned in a cab hung below the frame. This invention dwells particularly on the trolley bearing the screwing head and on the relative movement and alignment on the rail.
The improvements of the present invention concern the work unit which performs the positioning, screwing and eventual fastening of nuts to bolts already positioned in correspondence with their respective plates; a clip and a washer have already been placed in succession on such bolts.
The work unit of the invention has been developed so as to perform the following purposes.
Afirst purpose consists in providing a controlled extraction of the nuts, one by one, from a guide for nuts which delivers the nuts themselves to the position where they are deposited onto the rail. Another purpose of the invention is to make it possible for the nuts thus extracted from their guide, one by one, to be taken reliably by a first wrench head.
Thisfirstwrench head has the task of obtaining a speedy screwing of the nut onto its bolt.
This speedy screwing action is made necessary by the need for high processing speeds of the waggon corresponding with the necessary requirements.
In fact, it can be observed that, to enable bolting to be carried out at a high speed or hourly rate, it is necessary to proceed with a quick screwing of the nut onto the bolt and thereafter with a final tightening of the nut with the torque pre-established.
The present invention envisages that the wrench heads performing the two functions of speedy screwing and final tightening respectively are separated.
In fact, the head performing the final tightening has to be able to apply a high tightening torque as laid down in the regulations.
This is not suited to the requirements of a high screwing speed before the final tightening, and this invention therefore envisages that such two functions are separated.
The invention therefore visualises, below the platelayer waggon and at each of its sides, a positioner device which comprises two screwing units, called "wrenches" in the following text, positioned in series. Each of these wrenches has a frame, which will be called a "stationary frame" hereinafter.
This name is justified by the fact that the "stationary" frame, although attached to the platelayer waggon in an articulated manner and although adaptable to the curvature and gauge of the railway line, is solidlyfixed to the waggon itself in a lengthwise direction.
The "stationary" frame of each wrench cooperates with a trolley, hereinafter called a "movable trolley", which can run lengthwise to the "stationary" frame and can be fixed momentarily to the rail.
The work unit, including the two wrenches, is hinged at its front, with two degrees of freedom (vertical and horizontal), to another trolley positioned upstream, which bears the means which deposit bolts, clips and washers. These means do not form part of this invention and we shall therefore not dwell on them further.
The provision of an articulated joint between the work unit which positions the nuts and comprises the wrenches of the invention, and the front trolley which bears the other positioner means, has the effect that the above unit that positions the nuts is readily adapted to the curvature of the tract of rail involved and also to any differences between neighbouring lengths of rail.
Such differences may occur because the lengths of rail on which the platelayer waggon moves forward have still not been anchored and may therefore be at different levels.
The whole positioner device, including the work unit of the invention and the other means located on the front trolley, can be lifted by means of suitable cables or like means driven by a jack or other equivalent means, as described in the cited patent application.
This is so because the various operating means have to be raised from the rails when the platelayer waggon is moving from one position to another.
When the positioner device has been placed on the rail, the unit to position the nuts according to the invention can perform its own working function.
The wrenches are fastened together with a hinge provided between the respective stationary frames. Such fixture by a hinge enables the wrenches to follow the rail in its curved tracts.
The movable trolleys of the wrenches and therefore the stationary frames too are self-aligning on the rail by means of wheels having the shape of truncated cones, as has already been described in the cited patent application of the present applicant.
The movable carriage of the first wrench can be fixed firmly to the rail during the forward movement of the waggon so as to carry out the pre-screwing operation.
Such movable trolley then performs a forwards recovery travel so as to reach the next station for fixture of a bolt.
Likewise the second movable trolley supported in the stationary frame of the second wrench can move in relation to that frame in the same way as the first movable trolley and is also fixed firmly to the rail momentarily for the definitive fastening of the nut.
On each side of the rail the first movable trolley bears a high speed wrench head which has the purpose of screwing the nut quickly and partially onto the bolt.
This movable trolley also bears a bolt- alignment device which has the task of correcting any lack of vertical positioning of the bolts themselves by means of a feeler or aligner means. An aligner means is provided on each side of the rail.
The movable trolley also bears a brake device, which clamps the movable trolley firmly to the rail in coincidence with the bolting station.
In this way, while the waggon is moving, the movable trolley stays fixed to the rail at its working position and is brought forward only at the end of such operation by an appropriate actuator means.
Likewise the second movable trolley is equipped with a fastener head able to apply the torque laid down in the regulations for the final anchorage of the nut.
This trolley too is secured momentarily to the rail by a brake device like that of the first movable trolley.
This second movable trolley too is brought up to its previous relative position by an appropriate actuator so as to be repositioned at the next working station.
The invention envisages that the bolt-fixture sequence is automated according to the positions of the various operating means and, in particular, according to the extreme positions of the wrench heads and of the respective movable trolleys which bear the same. Such positions are monitored by suitable limit switches.
The invention also envisages safety switches which detect anomalous working conditions such as bad positioning of some parts, or working steps out of phase such as a position of a movable trolley too far behind the position of the platelayer waggon, for instance.
Such switches arrange to halt the waggon according to methods which will be described better hereinafter.
The present invention is therefore embodied with a work unit for a platelayer waggon for rails according to the features of Claim 1. Preferred embodiments of the invention are indicated in claims 2 to 11.
We shall describe hereinafter, as a non-restrictive example, a preferred embodiment of the invention with the help of the attached figures, in which:-

Fig. 1 shows a platelayer waggon which employs a work unit according to the invention;
Figs. 2 and 3 give a side view and plan view respectively of the work unit of the invention;
Fig. 4 gives a side view of a detail of a device that withdraws nuts from their relative guide and also of the engagement of a nut by a wrench head;
Fig. 5 shows a plan view of a detail of a platform that loads the nut;
Fig. 6 shows a plan view of means that align bolts and of the brake means that secure a movable trolley to the rail;
Fig. 7 is a partly cutaway side view of the first wrench head;
Fig. 8 is also a cutaway view of the second wrench head that performs the final fastening;
Fig. 9 is a view from below of the end of the first wrench head;
Fig. 10 lastly shows the reciprocal arrangement of the various limit switches which control the working of the whole unit.

In Fig. 1 a platelayer waggon 10 has a positioner device 11 in its lower portion. This positioner device 11 can be raised in a known manner when the waggon 10 is not operating; that is to say, when it is moving from one work station to another.
When working, the positioner device 11 is lowered onto a rail 12, with which it cooperates by means of wheels 23.
As can be seen in Fig. 1, the positioner device 11 consists of a first trolley 13, which is hinged at 22 to a second trolley, or work unit, 19 having the task of positioning, screwing and tightening nuts.
A station 15 to deposit bolts, a station 16 to deposit clips and a station 17 to deposit washers can be seen in correspondence with the first trolley 13 but do not form part of this invention.
The trolleys 13 and 19 cannot be displaced lengthwise in relation to the waggon 10 but always keep the same position in relation to the waggon 10.
Instead, the trolleys 13-19 can be adapted sideways to the gauge of the railway line and to the curvature of the rails, since the wheels 23 of these trolleys 13-19 are self-aligning as they have the shape of a double cone.
To be more exact, such wheels 23 are arranged on "movable" trolleys 26 and 27 (see Figs. 2 and 3) as will be seen later.
Fig. 2 shows in greater detail the work unit 19, which is secured with a hinge 22 to the front trolley 13, of which the rear portion can be seen.
The work unit 19 includes two wrench means 20-21, each of which comprises a frame 126 and 127 respectively having a substantially quadrangular shape.
These frames 126-127 will be called "stationary frames" hereinafter, as we said earlier in the foreword of this description.
Such frames 126-127 are joined together with a hinge 24. This connection with a hinge 24 enables the two wrench means 20-21 to follow the curvature of the rails easily.
The plan view of Fig. 3 shows the stationary frames 126-127 and their connection 24 better.
Fig. 2 shows a curved end portion 118 of a guide 18 for nuts; this end portion 118 is pivoted at 25 so that it can rotate and move towards the front of the waggon 10 so as to release one nut at a time from its lower end, as will become clear later.
The frame 126 of the wrench means 20 bears a movable trolley 26 in such a way that it can run; this movable trolley 26 is equipped with wheels or rollers 14 that cooperate with guides provided in the side structural sections of the frame 126. In this way the movable trolley 26 can run lengthwise along the stationary frame 126.
Likewise the frame 127 bears a movable trolley 27 in such a way that it can run.
The trolleys 26-27 are provided with actuators 28 and 29 respectively, which in this example are jacks.
These jacks 28-29 serve only to return the trolleys 26-27 respectively towards the left of the figure; in fact, the jacks 28-29 are free of load during the travel of the trolleys 26-27 towards the rear of the waggon 10.
For the sake of convenience in explaining the various movements, we prefer to refer to a solidly fixed relationship with the platelayer waggon 10 although in actual fact the so-called "movable" trolleys 26-27 are fixed solidly during working, as we shall see, to the portion of rail 12 on which the waggon 10 is working.
It is only after the screwing operation has been completed that the trolleys 26-27 are brought forwards again so as to reach the next bolt-fixture position.
The plan view of Fig. 3 has omitted all the devices forming part of the movable trolleys 26-27 and also the two actuators 28-29, the purpose being to show the arrangement of the frames 126-127 and movable trolleys 26-27.
Fig. 2 shows in the movable trolley 26 of the first wrench means 20 a wrench head 30 which has the task of obtaining a first speedy screwing of a nut.
The final screwing or tightening with the pre-set torque, on the other hand, is obtained by a wrench head 31 located on the trolley 27 of the second wrench means 21.
The wrench head 30 is moved vertically by an actuator 32, whereas the final wrench head 31 is moved likewise by an actuator 33; these actuators 32-33 consist of hydraulic jacks in the figure.
A device 34 to align bolts is located on the trolley 26 in correspondence with the wrench head 30. This device 34 will be shown better hereinafter with specific reference to Fig. 6.
A brake device 35 is positioned immediately downstream from the bolt-aligner device 34 and serves to keep the movable trolley 26 momentarily firmly anchored to the rail 12.
In this way, after the brake device 35 has been actuated and while the waggon 10 moves forward, the trolley 26 stays anchored to the rail 12 in correspondence with the screwing station; thus the trolley 26 becomes displaced backwards in relation to the waggon 10.
When the screwing operation has been completed by the wrench head 30, the trolley 26 is brought forward by the actuator 28 after the brake device 35 has been released.
The trolley 26 can be brought thus so as to coincide with the next screwing station for work on a new nut.
The trolley 27 in its turn is equipped with a brake device 135 fully analogous to the device 35 we have just described. In this way the trolley 27 too is momentarily anchored firmly to the rail 12.
In relation to the waggon 10, therefore, the trolley 27 is located rearwards until the wrench head 31 has completed the work of tightening the nut; then, when the head 31 has been withdrawn from the nut, the trolley 27 is brought up to its new position by the actuator 29.
While the trolleys 26-27 are left in the rear, the actuators 28-29 are free of load and have no effect at all on the positioning of the trolleys 26-27.
According to Fig. 4 the depositing of a nut 36 in correspondence with the outlet of the end portion 118 of the guide 18 takes place as follows.
The trolley 26 which bears the wrench head 30 moves towards the front of the waggon 10 under the action of the recovery actuator 28 (see Fig. 2) and therefore moves towards the left of Fig. 4 This trolley 26 meets a roller 37 solidly fixed to the end portion 118 of the guide 18.
The action of the trolley 26 on this roller 37 causes the whole portion 118, which is pivoted at 25 (see Fig. 2), to move to the left in the figure (to the position shown with dots and dashes in Fig. 4).
At the same time a roller 38 located on the movable trolley 26 acts on a cam 139 on a positioner arm 39; this positioner arm 39 in its turn bears at its end a pin 40 to withdraw nuts 36.
The action of the roller 38 on the cam 139 takes place slightly before the roller 37 is engaged by the trolley 26; in this way the pin 40 to withdraw nuts 36 is lowered and inserted into the threaded bore of the nut 36 present at the outlet of the end portion 118 of the guide 18 slightly before the portion 118 itself is retracted.
The engaged nut 36 stays held on the pin 40 withdrawing nuts and is supported by a platform 41.
Next, the trolley 26 leaves the position shown in the figure and is brought towards the right; this takes place when the trolley 26 itself is anchored firmly to the rail 12 by the brake device 35.
In this way, when the waggon 10 moves forward, the trolley 26 is left behind in relation to the waggon 10 and frees the guide 18 and also the positioner pin 40.
The positioner arm 39, being pivoted at 239, returns to its position of rest through the force of gravity as it has been embodied so as to be unbalanced in relation to the pivot 239.
The wrench head 30 carries out a downward movement first of all when it corresponds with the nut 36, so as to take the nut 36 itself from the platform 41 which supports the nut; it is then raised just enough to pass over a ridge-wise end portion 141 of the platform 41 (see Fig. 5).
Fig. 5 shows resilient foils 241 which withhold the nut 36 withdrawn from the end portion 118 of the guide 18.
A resilient blade 341 (Fig. 4) supports these foils 241 and is lowered with them under the thrust of the wrench head 30, thus freeing the nut 36.
Fig. 6 shows the brake device 35; this figure shows a portion of the trolley 26 which supports an actuator 42, a jack in this example.
This actuator 42 acts on two arms 43, one on each side of the rail 12, which in turn support two brake shoes 143 that act directly on the side portion of the head of the rail 12.
A spring 243 can also be seen which joins together the two arms 43 providing the braking action.
In fact, in the example shown the jack 42 acts in the direction of the opening of the arms 43, which are pivoted at 343 on the frame of the trolley 26.
As we said earlier, the brake device 35 serves to keep the trolley 26 firmly anchored to the rail 12 at the bolt-fixture station.
An alignment wheel 23 having the shape of a double cone can be seen below.
As is known (see the cited patent application IT 83487 A/83), this wheel 23 has the task of aligning the trolley 26, and therefore the stationary frame 126 solidly fixed crosswise to the trolley 26, on the rail 12.
Fig. 6 also shows the alignment device 34, which comprises two movable arms 134 bearing forks 234 at their ends.
These forks 234 can hold bolts 44 so as to correct any inaccurate vertical positioning of such bolts 44.
The arms 134 are connected to each other by means of a connecting rod 334. An actuator or jack 434 acts directly on one of the arms 134, namely the one shown below in Fig. 6 in this case.
Motion is transmitted through the connecting rod 334 to the other arm 134 too, and the two arms 134 move in this way symmetrically in relation to the axis of the rail 12.
Fig. 7 shows, in a view lengthwise in relation to the platelayer waggon 10, the first wrench head 30 able to slide vertically along guides 45; the end portion of the stem of the actuator 32 can be seen, the actuator 32 consisting of a jack (see Fig. 2) which serves to displace the head 30 vertically.
A motor, here an electric motor, 46 causes the rotation of a shaft 130 of the wrench head 30 through a belt or chain reduction transmission 47.
A slidable rod 48 is included within the shaft 130, which is envisaged as being hollow, and has the task of monitoring with its lower end the level of the point of the bolt onto which the nut 36 shown in the figure is screwed.
In this way, as the screwing proceeds, the rod 48 rises, resting on the point of the bolt, until its upper end meets a limit switch contact F7.
Resilient foils 50 to hold the nut 36 can be seen in the lower part of the wrench head 30 intended to cooperate with the nut 36. These resilient foils 50 are particularly evident in the view of Fig. 9 from below the end of the head 30 itself.
Within the nut 36 can be seen the end of a positioner shaft 49, this end being three-lobed in this figure. This shaft 49 has the task of engaging the inner bore of the nut 36 without spoiling its screw-thread, so as to obtain proper vertical alignment and support of the nut 36, which is thus held between the positioner shaft 49 and the resilient foils 50.
Fig. 7 also shows a flange 51 to discharge nuts 36. This flange 51 is usually kept in position by a spring 251 and serves to discharge nuts 36 which are faulty or which have not been screwed onto a bolt for any reason (for instance, defective threads or other causes).
Discharge of a faulty nut, after the nut itself has been engaged, takes place as follows; the nut 36 is held by the resilient foils 50 and is raised by an extent enough to take it out from the support platform 41 which can be seen in the figure.
Such raising of the head 30, however, is not enough to bring the flange 51 into contact with a stationary abutment 151 solidly fixed to the frame of the movable trolley 26. In this way the flange 51 keeps its vertical position.
The figure shows a position 30B for engagement of the nut 36, which is thus engaged with the head 30 and is raised and removed from the support platform 41 and is taken so as to correspond with a bolt, which cannot be seen in this figure.
The head 30 is then lowered and pre-screwing is carried out until the rod 48, thrust by the point of the bolt, engages the limit switch F7.
The screwing operation now ends and the head 30 can be raised again; if the screwing is not successful, the limit switch F7 does not detect movement of the nut 36 along the bolt and a timer causes the head 30 to be raised by the actuator 32 to position 30A.
In this way, during its ascending travel, the flange 51 engages the abutment 151, which prevents the flange 51 from being raised farther.
Instead, the head 30 is raised farther and causes the spring 251 to be compressed; the flange 51 thus acts directly on the nut 36, which is pushed downwards and therefore discharged.
In this way a nut which is not screwed onto a bolt is rejected automatically.
Fig. 8 gives a side view of the second wrench head, or tightener head, 31. In this case the head 31 is operated by a hydraulic motor 146 able to apply the fastening torque laid down in the regulations.
The head 31 can slide in vertical guides 145 made in the movable trolley 27, a part of the frame of which can be seen.
The wrench head 31 bears at its end an articulated hexagonal key 131. This key 131 has an inner hole 231 to lodge the point of the bolt, thus enabling the key 131 to be lowered until the nut 36 has been fully tightened (position 31 B of Fig. 8).
When tightening has been completed, the head 31 is then raised again to its normal position 31A and is moved away owing to the whole trolley 27 being moved forward by the actuator 29 (Fig. 2).
Fig. 8 does not show the actuator 33 which moves the head 31 vertically, such actuator 33 being shown instead in Fig. 2.
The key 131 comprises an articulated joint 52, which gives the key 131 a certain freedom on two axes.
In this way the nut 36 pre-positioned on the bolt by the head 30 can be readily engaged by the key 131, which is adapted thus automatically to small misalignments of the head 31 in relation to the nut 36.
The flaring of the mouth of the key 131 facilitates engagement of the nut 36.
Lastly, with reference to Fig. 10, we shall now describe the method of working of the pre-screwing and tightening station with regard to the nut 36.
Fig. 10 shows the positioner device or unit 19, in which the various limit switches with which the device 19 is equipped are marked in black.
For greater clarity, Fig. 10 gives only the references of the limit switches and various actuators, the references for the other means being shown in the preceding figures.
The method of working is as follows.
a) Pre-screwing step.
The movable trolley 26 is in its fully forward position in correspondence with the position to screw the nut onto the bolt.
The limit switches F1 and F2 are connected up by direct action of the trolley 26 and cause descent of the head 30 (actuator 32).
The head 30 takes a nut 36 from the support - platform 41. F3 causes re-ascent of the actuator 32 up to F4.
This re-ascent enables the head 30 to be disengaged from the platform 41 vertically.
F4 blocks the actuator 32 at the position it has reached, and releases the actuator 28 from load, the trolley 26 thus being free to _'move lengthwise.
As the waggon 10 advances, F5 detects the presence of the clip (and therefore the arrival of the trolley 26 at the required position) and operates the actuator 42 of the brake device 35.
The rail 12 is thus gripped (Fig. 6) and the trolley 26 is anchored firmly to the rail 12.
The trolley 26 is thus positioned to the rear in relation to the waggon 10 and therefore to the device 19.
F5 also operates the actuator 434 of the device 34 which aligns bolts. In this way the bolts 44 are aligned by means of the forks 234 (Fig. 6).
F6 indicates that the trolley 26 has reached a position where the platform 41 no longer lies on the path of the head 30, and causes descent of the head 30 (actuator 33). It also actuates a first timer.
The head 30 rotates first of all anticlockwise so as to align the nut 36 on the bolt 44.
The above timer reverses the direction of rotation (which now becomes clockwise) and causes the opening of the forks 234 by means of the actuator 434.
The nut 36 is screwed until the rod 48 contacts at its lower end the point of the bolt 44 and actuates F7.
F7 controls a second timer, which governs the re-ascent of the head 30 (actuator 32). At the end of this re-ascent F2 is actuated and causes the opening of the brake device 35, another reversal of the direction of rotation of the head 30 (which becomes anticlockwise again) and the recovery travel of the trolley 26 by means of the actuator 28 in relation to the waggon 10.
When the trolley 26 has recovered its position in relation to the waggon 10, the positioner device 19 is ready for a new cycle.
The stationary frame 126 comprises two limit switches F8 and F9 having a safety function according to the following methods; if the actuator 28 is almost fully extended (with the trolley 26 almost at the point of its greatest travel) but the actuator 32 has still not received the command to raise the head 30, F8 halts the working cycle and causes actuation of the re-ascent of the head 30 by means of the actuator 32. Lastly, if the actuator 28 has not been actuated or has been prevented from retracting, F9, as soon as it is reached by the trolley 26, causes the immediate stoppage of the waggon 10 for inspection.
The platelayer waggon 10 can be re-actuated by the operator with a manual control.
b) Final tightening step.
The movable trolley 27 bearing the head 31 is brought, during movement of the waggon 10, so as to correspond with the station for fixture of the bolt where the head 30 has carried out earlier the pre-screwing of a nut 36.
F10, F11 and F12 are connected up together and actuate the brake device 135 and also the descent of the head 31 (actuator 33). The head 31 engages the nut 36, which has already been partially screwed onto the bolt 44.
According to a preferred cycle, when a first pre-established value of torque has been reached, the speed of rotation diminishes until the prescribed number of revolutions per minute has been reached.
When the final torque laid down has been reached, the reascent of the head 31 is caused by means of the actuator 33.
F11 detects the re-ascent of the head 31, causes release of the brake device 135, brings the speed of rotation of the head 31 back to its original value and also causes the forward recovery travel of the trolley 27 by means of the actuator 29 in relation to the waggon 10.
The stationary frame 127 comprises two limit switches F13 and F14 having safety functions according to the following methods; if the actuator 29 is almost fully extended (with the trolley 27 near to the point of its maximum travel) but the actuator 33 has still not been caused to raise the head 31, F13 stops the working cycle and causes actuation of the reascent of the head 31 by means of the actuator 33.
Lastly, if the actuator 29 has not been actuated or has been prevented from retracting, F14, as soon as it is reached by the trolley 27, causes the immediate stoppage of the waggon 10 for inspection.
The platelayer waggon 10 can be re-started by the operator with a manual control.

Claims

1. Work unit (19) for a platelayer waggon (10) for rails, such work unit (19) having the task of placing and fastening nuts (36) on bolts (44) already positioned (13) together with clips and washers on rails (12), and comprising wrench means (20-21) being characterised by including two wrenches (20-21) positioned in series, of which the first (20) performs the withdrawal from the supply elements, the placement and the pre-screwing of the nut (36) onto the bolt (44), whereas the other (21) carries out the final tightening of the nut (36), the work unit (19) being connected with a hinge (22) to a front trolley (13) of the platelayer waggon (10), the hinge (22) permitting two degrees of freedom, namely horizontal and vertical respectively, the second wrench (21) including:

- a stationary frame (127),

- a movable trolley (27) cooperating movably (14) with the stationary frame (127) and bearing a final wrench head (31) on each side of the rail (12), and

- a brake (135) anchoring the movable trolley (27) to the rail (12) momentarily.

2. Work unit (19) for a platelayer waggon (10) for rails as claimed in Claim 1, in which the first wrench (20) comprises:

- a stationary frame (126),

- a movable trolley (26) cooperating in a movable manner (14) with the stationary frame (126) and bearing a withdrawal, placement and pre-screwing head (30) for nuts on each side of the rail (12),

- a device (118-39-41) to feed nuts (36),

- a device (34) to align bolts (44), and

- a brake device (35) which anchors the movable trolley (26) to the rail (12) momentarily.

3. Work unit (19) for a platelayer waggon (10) for rails as claimed in Claim 1 or 2, in which the withdrawal, placement and pre-screwing head (30) is able to slide vertically on guides (45) on the movable trolley (26) and comprises at least one of the following devices:

- a foil (50) to hold a nut (36),

- a positioner shaft (49) cooperating with the inside bore of the nut (36),

- a flange (51) which discharges faulty nuts and cooperates with a stationary abutment (151), and

- a rod (48) which monitors the end of the bolt (44) and cooperates with a limit switch (F7) (Fig. 7).

4. Work unit (19) for a platelayer waggon (10) for rails as claimed in any claim hereinbefore, in which the elements (118-39-41) to feed nuts (36) include in cooperation:

a movable end portion (118) of the guide (18) for nuts (36),

- an arm (39) to engage nuts (36) with a pin (40) to withdraw nuts (36), and

- a platform (41) to support nuts (36) momentarily, such movable portion (118) and such arm (39) to engage nuts (36) cooperating momentarily, even indirectly, with the movable trolley (26).

5. Work unit (19) for a platelayer waggon (10) for rails as claimed in any claim hereinbefore, in which the device (34) to align bolts (44) comprises:

- a movable arm (134) with an alignment fork (234), and

- an actuator (434).

6. Work unit (19) for a platelayer waggon (10) for rails as claimed in any claim hereinbefore, in which the final wrench head (31) can slide vertically on guides (145) of the movable trolley (27) and comprises an articulated key (131) to tighten the nuts (36).

7. Work unit (19) for a platelayer waggon (10) for rails as claimed in any claim hereinbefore, in which the wrench head (31) works with a variable number of revolutions per minute.

8. Work unit (1.9) for a platelayer waggon (10) for rails as claimed in any claim hereinbefore, in which the wrench head (31) can apply a variable torque.

9. Work unit (19) for a platelayer waggon (10) for rails as claimed in any claim hereinbefore, in which the movable trolleys (26-27) comprise actuators (28-29) which are active only in the phase of recovery of travel by the trolleys (26-27).

10. Work unit (19) for a platelayer waggon (10) for rails as claimed in any claim hereinbefore, which comprises a safety limit switch (F8-F13) to raise the wrench heads (30-31).

11. Work unit (19) for a platelayer waggon (10) for rails as claimed in any claim hereinbefore, which comprises a safety limit switch (F9-F14) to halt the platelayer waggon (10).