Abstract:
An apparatus transforms a motorized frame mounted on crawler tracks and having a rotatable horizontal platform, into a pipeline laying machine or the like. A first structure is hinged to the platform on a horizontal axis at one end, at its other end, has a coupling intended to be secured to a track guide carriage. A second structure which, at its free end carries a lifting member, is hinged on a horizontal axis to the coupling.

Description:
TECHNICAL FIELD 
   This invention relates to an apparatus by means of which a frame mounted on crawler tracks can be easily transformed into a machine for handling products and materials, such as a pipe laying machine, to which the invention relates in a particular but not exclusive manner. 
   BACKGROUND ART 
   For laying pipelines consisting of relatively large, heavy pipes, in particular of rigid type, it is known to use specific machines, known as pipe laying machines. 
   Pipe laying machines are known comprising, essentially, a frame with an internal combustion engine mounted on crawler tracks, a track guide carriage of which carries, hinged to its outside on a horizontal axis parallel to the longitudinal axis of the machine, the lower end of an arm arranged to swing in a vertical plane transversely to the machine, under the control of a respective motorized winch. 
   At the other end of the arm there is a lifting hook suspended from a cable which slides vertically under the control of another motorized winch, this also being supported by the frame. 
   On that side of the frame distant from that occupied by said arm, known machines sometimes present a counterweight which is hinged to the outside of the frame and of the respective track guide carriage by an articulated quadrilateral system controlled by an operating cylinder-piston unit. 
   Such known pipe laying machines have proved unsatisfactory because of their overall size. 
   In this respect, to transfer the machine from one operating position to another, typically by a bascule truck, the said arm has to be positioned almost vertically, which involves considerable complications seeing that when in said transporting configuration its upper end well exceeds the allowable limits for road transport. 
   Other dimensional drawbacks derive from the fact that the arm and any counterweight are hinged to the outside of the track guide carriage, i.e. beyond the transverse outline of the track-mounted frame. 
   Pipe laying machines also comprising a track-mounted frame with an internal combustion engine and a swinging arm with a lifting hook are known, in which the arm is supported by the frame by way of an interposed platform mounted on a thrust bearing. 
   Specifically, the base of the arm is hinged to said platform on a horizontal axis, the platform carrying at least one cylinder-piston unit for operating the swinging arm, a motorized winch for operating the hook, and a balancing weight situated on that side of the platform distant from the side occupied by said arm, and is arranged to slide between a position close to and a position distant from the platform. 
   By virtue of said thrust bearing device the swinging arm of such pipe laying machines has better manoeuvrability than the arm of the aforesaid pipe laying machines, and during machine transportation it can be advantageously orientated along the machine longitudinal axis in a flat position so that it lies within the allowable vertical dimension for road transport. 
   A problem inherent in such known machines derives from the fact that the entire load carried by the hook acts on the thrust bearing device, which means that it has to be dimensioned correspondingly, giving rise not only to cost problems but also to problems of reliability and durability. 
   The main object of this invention is to overcome the aforestated problems. 
   Another object of the invention is to attain this objective within the context of a simple, rational, low-cost, reliable and durable construction. 
   DISCLOSURE OF THE INVENTION 
   Said objects are attained by the characteristics indicated in the claims. In a totally general sense, the apparatus of the invention consists of a variable-profile system intended to be associated with a motorized frame mounted on crawler tracks and upperly provided with a platform mounted on a thrust bearing, in the manner of the frame of a usual bucket or shovel excavator, without requiring appreciable modifications to said frame. 
   Said variable-profile system, which will be described in detail hereinafter, comprises a first structure which at one end is intended to be hinged to the platform on a horizontal axis, and at the other end presents a coupling means to be connected to a track guide carriage, and a second structure which at one end is hinged to the first on a horizontal swing axis parallel to the preceding and close to said coupling means, and at its other end presents a lifting member, such as a hook. 
   Said system is arranged to assume a utilization configuration in which the first structure can be coupled to the outside of a track guide carriage, in order to discharge thereonto most of the load supported by said lifting member, and a non-utilization configuration in which the second structure can be positioned virtually coplanar with the first, at that moment released from the track guide carriage, i.e. in a configuration suitable for transferring the machine along the road. 
   The characteristics and the constructional and operational merits of the invention will be apparent from the ensuing detailed description, given with reference to the figures of the accompanying drawings which illustrate a particular preferred embodiment thereof by way of non-limiting example. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevation of a tracked vehicle equipped with the invention, this latter shown in its utilization configuration. 
       FIG. 2  is the section II—II indicated in FIG.  1 . 
       FIG. 3  is a view similar to  FIG. 1 , showing the invention in its non-utilization configuration, suitable for transportation of the tracked vehicle. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Said figures show a robust frame  1 , with the sides of which there are associated two carriages  2  for guiding respective crawler tracks  3 . 
   On said frame  1  there is positioned a thrust bearing device  4 , to the movable upper element of which there is fixed a platform  5  carrying an internal combustion engine unit  6 , typically diesel, an operating cab  118 , and all the hydraulic equipment for supplying pressurized oil to the control motors for the crawler tracks  3  and for the winches described hereinafter. 
   The platform  5  is of rectangular plan, its longitudinal axis being parallel to the axis of the frame  1  when the machine is arranged for transportation (see FIG.  3 ). 
   The combination which has just been described is of usual type, i.e. consisting of a track-mounted frame with an overlying platform mounted on a thrust bearing of the type typically used for bucket or shovel excavators. 
   According to the invention the said frame  1  is associated with the apparatus of the invention to form a pipe laying machine, without any need to modify the frame  1 . 
   As can be seen in  FIG. 2 , on the platform  5  there are defined two robust vertical holed lugs  50  and  51 , which lie in a vertical plane parallel to the longitudinal axis of the platform  3 . 
   Alternatively, said lugs  50  and  51  can be provided by a plate associated with the apparatus of the invention by being suitably fixed to the platform  5 , for example by bolts. The apparatus comprises a profiled structure  7  supporting a flat structure  8  which at its end carries a lifting hook  28 . 
   In side view (see FIG.  2 ), the structure  7  comprises a straight portion  70  lowerly hinged to the lug  50  on a horizontal axis  55  lying transversely to the platform  5 , and a downwardly curved portion  71  extending beyond the lug  51  and the corresponding end of the platform  5 , where it assumes the form of a fork  72  (see FIG.  1 ). 
   The arms of the fork  72  present respective terminal eyelets  66  the common axis of which is parallel to said horizontal axis  55 . 
   When in the utilization configuration of  FIGS. 1 and 2 , said fork  72  lies external to a track guide carriage  2 , its eyelets  66  being removably coupled to the lower longitudinal edge of the respective track guide configuration  2 . 
   This latter is provided with a usual longitudinal panel  11  to protect the lower rollers  23  of the respective crawler track  3 , according to the invention there being fixed to the panel  11  two plates  10 . Each plate  10  presents a pair of robust holed lugs  9  for receiving the respective eyelet  66 , and a locking catch  99  controlled by a hydraulic cylinder-piston unit  90 . 
   Said plates  10  and the relative accessories are preferably provided on both the track guide carriages  2 . 
   In addition between the lug  51  of the platform  5  and the arched portion  73  of the profiled structure  7  there is interposed a hydraulic cylinder-piston unit  12 , the function of which will be apparent hereinafter (FIG.  2 ). 
   In proximity to said eyelets  66  (see FIG.  1 ), the arms of the fork  72  are provided externally with respective angle brackets  44 , two eyelets  33  provided at the lower end of the flat structure  8  being permanently hinged to said arms and brackets  44  on a common horizontal axis  22  parallel to the axis of said eyelets  66 . 
   Said axis  22  constitutes the swing axis of said structure  8 , which is of trapezium shape ( FIG. 1 ) and is provided upperly with two swivel blocks  21  and  22  respectively. The metal cable  210  for adjusting the inclination of the structure  8  passes about the block  21 . The cable  210  has one end fixed to the drum of a respective winch  211  and its opposite end fixed to the block  21  after passing about a fixed cable terminal block  212 . 
   The metal cable  200  for raising and lowering the hook  28  passes about the block  20 , the cable  200  having one end fixed to the drum of a respective winch  201  and its opposite end fixed to the block  20  after passing about the movable cable terminal block  202  of the hook  28 . 
   Said fixed block  212  and said winches  211  and  201  are carried by the straight portion  70  of the profiled structure  7  (FIG.  2 ). 
   The aforedescribed pipe laying machine combines the special characteristics of the two types of pipe laying machines described in the introduction, i.e. discharge of most of the weight carried by the hook  28  onto elements not forming part of the thrust bearing  4 , and minimum vertical height because of the ability to lower the structure  8  along the longitudinal axis of the machine. 
   To arrange the pipe laying machine for road transfer by a suitable transporting vehicle, the procedure is as follows. 
   With the hook  28  practically completely raised, the catches  99  are firstly disengaged and the cylinder-piston unit  12  then extended, by which the eyelets  66  become positioned as shown to the left in  FIG. 2  by thin dashed lines. 
   Having done this the platform  5  is rotated through 90°, the winch  211  is operated to lower the structure  8  until the overall assembly falls within the allowable vertical contour, and the hook  28  is immobilized for example as shown in FIG.  3 . The reverse procedure is used to return the apparatus into the utilization configuration of  FIGS. 1 and 2 . 
   The merits and advantages of the invention are clearly understandable from the aforegoing and from an examination of the accompanying figures.