Abstract:
An improved arrangement for adjusting crawler-type transport assemblies in a self-propelled construction vehicle between two differing “home” positions. The crawler transport assembly comprises a steering mechanism including a collar assembly operated via an actuator mounted to the frame of the apparatus for driving steering rotation of the transport assembly via the collar assembly. The collar assembly comprises a driving element integrally coupled to the actuator and a driven element integrally coupled to the transport assembly. The driven element can be affixed to the driving element selectively in two differing dispositions corresponding to the two “home” positions of the transport assembly.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates generally to self-propelled construction equipment and, more particularly, to a self-propelled construction vehicle having a steerable transport assembly which is selectively adjustable for operation of the vehicle in two transverse, preferably perpendicular, transport directions.  
           [0002]    Self-propelled construction vehicles and other construction equipment of diverse types are well known. One type of such construction equipment are so-called slip-form paving machines essentially adapted to continuously form concrete or another flowable paving material along the ground or other base surface, for example, to form a roadway. Diverse forms of such machines have been described in prior patents, representative examples of which may be found in U.S. Pat. Nos. 3,175,478; 3,264,958; 3,637,026; 3,771,892; 3,970,405; 4,197,032; 4,360,293; 4,925,340; 4,948,292; 5,044,820; and 5,590,977.  
           [0003]    Conventionally, it is commonplace for paving equipment of this type to support the machine frame on a plurality of so-called crawler track assemblies, typically four such assemblies mounted in laterally and longitudinally spaced relation to one another at four comers of the machine frame, with each assembly having an endless ground-engaging self-propelled track supported by an associated steering mechanism for pivotable steering movement about a vertical steering axis which thereby facilitates steerable driving of the paving machine over substantially any ground surface along which a roadway is to be paved. The frame of the machine supported by the crawler assemblies may have various devices and mechanisms to perform various functions, including a substantially horizontally disposed undersurface, commonly referred to as a screed, for purposes of leveling and finishing concrete material. In basic operation, a continuous supply of concrete or other suitable paving material is deposited in front of the paving machine between its laterally spaced crawler assemblies as the machine is driven over the intended path of the roadway, whereby the concrete material is spread, leveled and finished by the screed.  
           [0004]    In some currently conventional machines, the crawler assemblies may be movable between a forwardly oriented (i.e. front-to-back) “home” position, while being steerable within a designated range from the home position, for driving the machine forwardly relative to the longitudinal extent of the frame, and a laterally oriented (i.e. side-to-side) “home” position, while also being steerable within a designated range from the home position, for driving the paving machine laterally, which optimally facilitates driving transport and movement of the machine from one location to another. Such movability in the “home” orientation of the crawler assemblies is particularly beneficial in larger paving equipment, such as equipment wherein the lateral spacing between the crawler assemblies is set so as to facilitate the paving simultaneously of two lanes of roadway side-by-side. Because of the substantial width of machines of this size, they cannot always be driven in a forward direction. For example, for purposes of transport from one location to another, such machines must be of a longitudinal front-to-back dimension which can be supported on a conventional flat-bed truck for transport over public highways and roads. Hence, such machines must be drivable in a lateral direction for loading onto and off of a transport trailer.  
           [0005]    Some prior paving machines have steerable crawler assemblies equipped to be adjustably switchable between forward and lateral “home” steering positions, but the mechanical arrangement for switching from one home position to the other home position is disadvantageously complicated and time consuming to accomplish. Steering of the crawler assemblies in such machines is commonly accomplished via a hydraulic piston-and-cylinder assembly extending from the machine frame to the crawler assembly for actuating pivoting movements of the crawler assembly about the vertical steering axis. In order to switch each crawler assembly from one home position to the other home position, the connection between the steering piston-and-cylinder assembly is operated to turn the crawler assembly about ninety (90) degrees into the new home position, and then the piston-and-cylinder assembly is disconnected and re-connected to a different mounting location on the crawler assembly. In conventional practice, this operation is time consuming and labor intensive to accomplish, even assuming no difficulty in aligning the steering piston-and-cylinder assembly with the crawler assembly for reconnection, and then the adjustment operation must be re-performed once the machine has been moved to a new position or a new paving location.  
           [0006]    Other paving machines are known which have steerable crawler assemblies which may be moved between forward and lateral “home” steering positions without the necessity of disconnecting and reconnecting any components of the steering arrangement. One such paving machine is disclosed in U.S. Pat. No. 5,590,977, wherein the steering arrangement is capable of moving the crawler assemblies through a range of motion greater than ninety (90) degrees without any reconfiguration of the steering arrangement. Disadvantageously, however, in order for the steering arrangement to have a desirable range of steering motion in the forward “home” position, yet still be movable approximately ninety (90) degrees into a lateral “home” position, the mechanical limitations of the steering arrangement enable only a much more limited range of steering motion with the crawler assemblies in the lateral “home” position which limits the usefulness and maneuverability of the machine in transverse steering operation. Other known conventional paving machines utilize a structure supporting the steered crawler assemblies commonly referred to as a “swinging leg” arrangement which rotates about a pin at the main frame of the machine. Such steering arrangements also are capable of moving the crawler assemblies through a range of motion greater than ninety (90) degrees so as to be capable of orienting the crawler assemblies in both forward and lateral “home” positions with a reasonable range of steering motion in each such position. However, upon switching between differing “home” positions, the steering and propulsion hydraulic systems for the paving machine must be modified to allow proper operation in the new direction of travel, all of which tends to be very time consuming to accomplish.  
           [0007]    Accordingly, it would be highly desirable to provide a more automated, simplified and streamlined means for easily switching a crawler assembly from one “home” steering position to another, so as to improve the efficiency and usefulness of the machine.  
         SUMMARY OF THE INVENTION  
         [0008]    It is accordingly an object of the present invention to provide an improved mechanical arrangement for changing a crawler assembly or other form of transport assembly, such as on a self-propelled construction vehicle, from one “home” steering position to another, which can be performed much more easily and quickly than with the conventional adjusting means described above and which otherwise overcomes the disadvantages of the known conventional arrangement.  
           [0009]    Briefly summarized, the present invention is basically applicable to any self-propelled construction or like vehicle having a frame supported on a steerable transport assembly comprising a ground-engaging structure, such as an endless track crawler assembly, depending from a steering mechanism moveable within a defined range of steering relative to a generally vertical steering axis. The steering mechanism will typically comprise an upstanding post integrally coupled to the ground engaging structure for unitary rotation thereof about the steering axis and a steering control assembly comprising a collar assembly coupled to the post and an actuator mounted to the frame and coupled to the collar assembly for driving rotation of the collar assembly and the post selectively in opposite rotational directions.  
           [0010]    In accordance with the present invention, the collar assembly basically comprises a driving collar element integrally coupled to the actuator and a driven collar element integrally coupled to the post. The driven collar element is affixable to the driving collar element selectively in a first disposition relative to the driving collar element for orienting the post and the ground engaging structure for steering the vehicle in a first transport direction and in a second disposition relative to the driving collar element for orienting the post and the ground engaging structure angularly spaced from the first disposition for steering the vehicle in a second transport direction.  
           [0011]    In a preferred embodiment, the driving and driven collar elements are disposed for relative rotation about the steering axis between the first and second dispositions when not affixed to one another. More specifically, the driving collar element preferably is disposed annually about the driven collar element for relative rotation therebetween. The driving collar preferably has two coupling locations angularly spaced from one another and the driven collar element has a coupling location adapted for affixation selectively to either of the coupling locations of the driving collar element. The actuator preferably is operable in each of the first and second dispositions of the collar elements for driving rotation of the collar assembly within a defined range for steering of the vehicle in a selected one of the transport directions. The upstanding post preferably is extendable for selectively controlling elevation of the ground engaging structure relative to the frame. Typically, the vehicle will comprise a plurality of the steerable transport assemblies, e.g. four such assemblies spaced laterally and longitudinally with respect to one another, and a steering control system for coordinated movement of the transport assemblies.  
           [0012]    The present invention is particularly adapted for use in a construction vehicle of the type configured for slip-forming a paving material along a ground surface, e.g., a roadway, as the vehicle is steered in a selected one of the transport directions.  
           [0013]    Other details, features and advantages of the invention will be described and understood from a description of a preferred embodiment of the invention set forth below with reference to the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a front perspective view of a slip-form paving apparatus equipped with adjustably switchable transport assemblies, each with a steerable endless track crawler assembly, in accordance with the present invention;  
         [0015]    [0015]FIGS. 2A and 2B are perspective views of one of the transport assemblies of the paving apparatus of FIG. 1 disposed in one “home” orientation for steerable forward travel of the paving apparatus;  
         [0016]    [0016]FIG. 3A and 3B are additional perspective views of the transport assembly of FIGS. 2A and 2B, but disposed in a second “home” orientation for lateral travel of the paving apparatus; and  
         [0017]    [0017]FIG. 4 is an exploded perspective view of the crawler assembly and the steering mechanism of the transport assembly of FIGS. 2A, 2B,  3 A and  3 B. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    Referring now to the accompanying drawings and initially to FIG. 1, a self-propelled slip-form paving apparatus in accordance with the present invention is indicated in its totality at  10 . The paving apparatus  10  basically comprises a structural framework  12  supported substantially horizontally on four front and rear transport assemblies  14 ,  16  disposed at the four comers of the structural framework  12  in laterally and longitudinally spaced relation to provide stable suspension of the framework  12 , and each preferably comprising a so-called crawler assembly  15  of the endless track type depending from a steering mechanism  17  movable within a defined range relative to a vertical steering axis A. An internal combustion engine (not shown) or other suitable self-contained power generator, preferably in conjunction with a hydraulic pump (also not shown), is mounted to the structural framework  12  to provide drive power to the transport assemblies  14 ,  16  and to otherwise supply operational power to the various systems of the paving apparatus in a known manner.  
         [0019]    The embodiment of the paving apparatus  10  depicted in the accompanying drawings is particularly adapted for use in road construction for the continuous slip-form paving of a slab-type concrete roadway, the lateral width of the apparatus  10  between the front and rear transport assemblies  14 ,  16  being sufficient for the formation simultaneously of two road lanes side-by-side one another. However, as those persons skilled in the art will understand, the essential features and inventive concepts forming the present invention are equally well-adapted to substantially any other form of self-propelled construction apparatus having a frame supported on a transport assembly or assemblies equipped with crawler or other steerable drive assemblies.  
         [0020]    The paving apparatus  10  is equipped with a screw-type auger assembly  18  transversely spanning the framework  12  at the forward leading side thereof and selectively driveable in opposite rotational directions, for laterally distributing a supply of concrete, or another suitable flowable paving material, deposited in front of the apparatus across the ground structure over which the roadway is to be paved. Immediately rearwardly of the auger assembly  18 , a vertically disposed plate  20 , commonly referred to as a strike-off plate, is supported by the framework  12  with a lower edge of the plate  20  extending laterally across substantially the full width of the apparatus  10  at an elevation essentially corresponding to the desired elevation to which the roadway slab is to be paved, to act as a metering gate controlling the level of concrete material passing underneath the strike-off plate  20 . A series of vibratory devices, only partially visible at  22  in FIG. 1, are mounted to the framework  12  at regular spacings across the transverse width of the paving apparatus  10  immediately behind the strike-off plate  20  to further assist in the leveling and settlement of the distributed concrete material by imposing a rigorous vibratory action on the concrete material passing under the strike-off plate  20 . A finish screed  24  (also known as a finishing pan) is disposed rearwardly of the vibratory devices  22  and is preferably in the form of a substantially horizontal plate extending transversely across the width of the paving apparatus  10  and rearwardly from the vibratory devices  22 .  
         [0021]    The front and rear transport assemblies  14 ,  16  not only provide motive power for propelling the paving apparatus  10 , but also provide for directional steering of the paving apparatus  10 . As best seen in FIGS. 2A, 2B,  3 A,  3 B and  4 , the crawler assembly  15  of each of the transport assemblies  14 ,  16  basically comprises a crawler sub-frame  26  supporting a pair of horizontally spaced sprockets  28  (or a sprocket and roller combination) carrying an endless track  30  thereabout with an individual hydraulic motor  32  for driving rotation of the sprockets  24  and, in turn, travelling movement of the track  30 . The crawler assembly  15  is suspended from the framework  12  of the paving apparatus  10  by the steering mechanism  17  which has a vertically upstanding post  34  affixed to the crawler subframe  26  by a clevis bracket  36  and supported for vertical sliding movement within an annularly encircling upstanding sleeve assembly  38  which is fixedly carried by the structural framework  12  of the apparatus  10 . For purposes of rotationally steering the crawler assembly, the post  34  is of a substantially square horizontal cross-section and extends through a correspondingly square opening formed centrally within a collar assembly  40  rotatably supported on the lower end of the sleeve assembly  38 , whereby rotation of the collar assembly  40  is transmitted to the post  34  about a vertical steering axis extending centrally through the post  34  and the collar assembly  40 . Rotational steering movement of the crawler assembly  15  is driven by an extensible and retractable linear actuator preferably in the form of a hydraulic piston-and-cylinder assembly  42  extending between a portion of the structural framework  12  of the apparatus  10  which is integral with the sleeve assembly  38  and the collar assembly  40 . Vertical sliding movement of the post  34  within the sleeve assembly  38  is controlled by another linear actuator also preferably in the form of a second hydraulic piston-and-cylinder assembly  44  affixed at one end within the post  34 , extending vertically therethrough, and affixed at its opposite end to the upper end of the sleeve assembly  38 .  
         [0022]    As depicted in FIG. 1, the front and rear transport assemblies  14 ,  16  are disposed during normal paving operation of the apparatus  10  with the crawler assemblies  15  oriented to extend in the longitudinal direction of the apparatus  10 , i.e., in a front-to-rear orientation. In such disposition of each transport assembly  14 ,  16 , the crawler assembly  15  thereof assumes a “home” position wherein the crawler subframe  26  and its track  30  extend in parallel relation to the longitudinal front-to-rear extent of the framework  12 , when the respective steering piston-and-cylinder assembly  42  is disposed with the piston essentially at the midpoint within its range of permissible extension and retraction, whereby each transport assembly  14 ,  16  can be steered within a predetermined range of rotational movement about its vertical steering axis A by increased extension or retraction of the piston within the piston-and-cylinder assembly  42 . Steering operation is controlled by a machine operator from an operator support platform (not indicated) via a centralized steering control system which coordinates the steering rotation of the transport assemblies  14 ,  16  in synchronism with one another.  
         [0023]    Thus, the basic operation of the paving apparatus  10  will be understood. As the paving apparatus  10  is self-propelled via the front and rear transport assemblies  14 ,  16  on the ground surface over which the roadway slab is to be formed, a suitable supply of concrete is maintained continuously in front of the auger assembly  18 . The operator of the paving apparatus  10  actuates and deactuates the auger assembly  18  in either direction as necessary to distribute the concrete material with general uniformity laterally across the forward side of the paving apparatus. As the paving apparatus  10  advances, the vertically-disposed plate  20  strikes off a limited amount of the concrete material, following which the vibratory devices  22  serve to expel any air bubbles from the concrete material and to further smooth the upward surface of the concrete material. As the paving apparatus  10  continues to advance forward, the screed  24  is then drawn over the vibrated depth of the concrete material, performing a final compacting and smoothing of its upper surface.  
         [0024]    However, it is also necessary under other circumstances than the normal paving operation of the apparatus  10  for the apparatus to be propelled in a lateral direction essentially perpendicular to the normal direction of transport during paving operations. For such purpose, the transport assemblies  14 ,  16  most be switched to a second “home” position spaced substantially ninety degrees from the first “home” position described above, wherein the crawler assemblies  15  extend perpendicularly to the longitudinal front-to-rear extent of the framework  12 . To do so conventionally, each steering piston-and-cylinder assembly  42  must be disconnected from its respective transport assembly  14 ,  16 , then the respective transport assembly  14 ,  16  turned substantially ninety degrees into the second “home” position, and finally each steering piston-and-cylinder assembly  42  reconnected to its respective transport assembly  14 ,  16  at a different location thereon at which the piston will be at the midpoint within its range of extension/retraction movements. As will be appreciated, the overall operation is not only quite time consuming and labor intensive but also can be problematic to actually accomplish because of the close alignment which must be accomplished between the piston-and-cylinder assembly  42  and its transport assembly  14 ,  16  in order to make the reconnection therebetween.  
         [0025]    Accordingly, in order to substantially simplify and shorten the time required for switching the transport assemblies  14 ,  16  between their two respective “home” positions, the present invention provides a novel and unique form of the collar assembly  40  which eliminates the conventionally necessity of disconnecting the piston-and-cylinder assembly  42 . Specifically, as best seen in FIG. 4, the collar assembly  40  basically comprises two relatively rotatable collar elements  46 ,  48 . The collar element  46  is rotatably disposed as above-described about the lower end of the sleeve assembly  38  and carries a laterally extending base plate  50  formed with the square opening  52  through which the post  34  extends, thereby for integral rotational movement of the collar element  46  and the post  34  and, in-turn, of the crawler subframe  26 . The collar element  46  also includes an upper annular plate  54  spaced from the base plate  50  to define therebetween an annular recess  53  about the collar element  46  within which the collar element  48  is received for relative movement rotationally with respect to the collar element  46 . The collar element  48  is formed with an outwardly extending mounting lobe  56  configured for attachment to the extending piston end of the steering piston-and-cylinder assembly  42 . The collar element  46  has a coupling block  58  pivotably affixed about a vertical axis between the base and upper annular plates  50 ,  54  and the collar element  48  carries two mating coupling blocks  60  either of which can be selectively bolted to the coupling block  58  on the collar element  46 .  
         [0026]    The methodology of switching any individual transport assembly  14 ,  16  between its two “home” positions shown respectively in FIGS. 2A, 2B and  3 A,  3 B, may thus be readily understood. Initially, the coupling block  58  of the collar element  46  is unbolted from the one of the two coupling blocks  60  on the collar element  48  to which it has theretofore been affixed, whereupon the respective steering piston-and-cylinder assembly  42  is actuated to either extend or retract, as necessary, its respective piston to rotate the collar element  48  relative to the collar element  46  until the other coupling block  60  is abutted with the coupling block  58 , whereupon the newly abutting coupling block  58 ,  60  are bolted together. In such disposition, the piston of the respective piston-and-cylinder assembly  42  will be at or close to either its fully extended or fully retracted disposition. Upon extension or retraction of the piston to move to the midpoint of its full range of movement, the collar element  48  drives the collar element  46  and, in turn, the post  34  and the crawler subframe  26  substantially ninety degrees into the other “home” position thereof. As will be understood, coordinated extension and retraction of the piston-and-cylinder assemblies  42  from either “home” position effects fine steering of the transport assemblies  14 ,  16  through driving of the collar elements  465  via the collar elements  48 .  
         [0027]    As can thus be appreciated, the present invention represents a substantial improvement over the known conventional means of adjustable switching of a crawler-type or other like drive assembly between two differing “home” positions. With the present invention, the transport assemblies may be adjustably switched essentially simultaneously in a minimal amount of time, with minimal labor and without any need to manually move the drive assemblies  14 ,  16 . Further, there are no problems or difficulties in aligning the coupling blocks  58 ,  60  for re-connection at the conclusion of a switching operation. Accordingly, the present invention will substantially improve the flexibility and efficiency in the operation of such paving and other construction apparatus.  
         [0028]    It will therefore be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to its preferred embodiment, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof.