VARIABLE-GAUGE TRACK-LAYING UNDERCARRIAGE

Abstract: One is considering a variable-gauge track-laying undercarriage comprising a central H-frame (3) with two lateral track-laying sub-frames (2), the frame (3) and the sub-frames (2) being fixed irreleasably together in correspondence with the ends (5a, 5b) of the frame (3) within which are fluid-dynamically telescopic cylinders (4) and slide frames (7a, 7b) for the track-laying sub-frames (2). These latter have hollow coupling appendages (19) shaped externally so as to be able to augment the movement between the maximum and minimum widths of the gauge and formed internally with prismatic guides (6, 9) which provide continuous support for the ends (5a, 5b) of the frame (3). The undercarriage further includes a mechanical locking device (17, 18) for locking the frame (3) and the sub-frames (2) against relative movement in a position of use so as to provide a further control for the geometric stability in use.

Description: VARIABLE-GAUGE TRACK-LAYING UNDERCARRIAGE The invention relates to a variable-gauge track-laying undercarriage. Track-laying undercarriages with hydraulic variation of the gauge at present on the market generally use two structural solutions . A first solution which is the subject of Patent Application No. B093U000175 in the name of the Applicant provides for the fraπes of the track-laying sub-frames to be fixed to cross-beams which move telescopically within the central frame and therefore the telescoping movement of the structures depends on that of the cross-beams. This solution does not provide optimum stability since the necessary play between the slide frame surfaces may cause instability which is often unacceptable. In fact even though devices for minimising it are provided, this play is concentrated at the periphery of, and within, the central frame whereby the effects of instability caused thereby are amplified at the outer lateral ends of the undercarriage, corresponding to the ground-contacting surfaces of the track-laying structures. This particular solution also has the disadvantage that it is difficult to construct and very expensive. A second solution, specifically devised for application to lifting apparatus, such as track-laying cranes, has an H-shaped frame and the track-laying sub-frames slide telescopically along the arms of the H-frame. In this solution, which at least provides greater stability, the drive cylinders for the variable gauge are not integrated in the structure and the safety operations, constituted by the engagement of locking pins for ensuring that there are no geometric variations in the gauge of the undercarriage during working, are manual both in terms of control and engagement of the stops. In addition and most importantly, this solution does not provide acceptable values of movement between the minimum and maximum gauge, at least not without manual intervention to modify the attitude of the entire machine, such as, for example, the removal or reduction of the bulk of the ends of the frame arms which otherwise would project laterally from the track-laying structures if the machine were used with a smaller gauge. The object of the present invention is to eliminate the disadvantages just mentioned. The invention as characterised by the claims solves the problem of use of a very stable structure with large telescopic movements while being localised solely on the track-laying structures. An integrated structural solution is thus provided in which all the components for varying the gauge of the undercarriage are within the supporting structure and distributed symmetrically so as not to destabilise the machine in use. Moreover safe, simple, remote guide systems are used, with the introduction of negative-type controls which operate in the case of damage to or breakdown of parts of the plant. The main advantage achieved by the invention lies essentially in the fact that, during the operation needed to vary the gauge, the attitude of the machine is not varied. The manner in which the invention is achieved also allows extremely rapid dismantling of the parts: the telescopic cylinders are in fact rapidly releasable and removable, as are also the lateral structures, without any need to act on the structural parts, which is particularly advantageous during transport or maintenance . Other significant operative advantages lie in the fact that each control operation relating to the variation n the gauge and activation of safety devices can be carried out directly by the operator in the cab by means of safe and efficient controls, without any need for manual operations and hence without the need for any operations from the ground. In particular this allows constant adjustment of the geometry of the structural parts even when the machine is moving. Finally it should be stressed that the system which is the subject of the invention has economic advantages over both of the solutions described above: it is simpler to manufacture than one and, with respect to the other, allows the width of the undercarriage gauge to be adjusted, with the machine stopped, without any manual operations. Further advantages and characteristics of the invention will become clearer from the detailed description which follows, given with reference to the appended drawings, which show one embodiment purely by way of non-limitative example, in which: Figure 1 is a schematic plan view of the invention from above; Figure 2 is a front elevational view of the invention; Figure 3 shows the invention in section taken on the line III-III of Figure 1; Figure 4 illustrates a section of the invention taken on the line IV-IV of Figure 1; Figure 5 illustrates the invention in a section parallel to that of Figure 3 but displaced towards the outer side of the invention. The invention relates to a variable-gauge track-laying undercarriage . It comprises a central K-frame (3) and two lateral track- laying sub-frames (2): the frame (3) and the sub-frames (2) are irreleasably fixed together in correspondence with ends (5a, 5b) of the frame (3) and slide frames (7a, 7b) of the track-laying sub-frames (2) . Within its ends (5a, 5b), the frame (3) contains fl id-dynamically controlled telescopic cylinders (4) for determining the width of the gauge. The slide frames (7a, 7b) of the sub-frames (2) have hollow coupling appendages (19) which are shaped externally so as to augment the movement between the maximum and minimum gauge widths and are shaped internally with prismatic guides (6, 9) for providing constant support for the ends (5a, 5b) of the frame (3) . As may be seen in Figure 1, the appendages (19) have outer portions which are longer than their inner portions so that they can house respective longer portions of the ends (5a, 5b) of the frame (3) while simultaneously avoiding these projecting and interfering with the central body of the frame (3) when the gauge is reduced. In Figures 3, 4 and 5 and in particular in the latter, it can be seen that each prismatic guide is formed with the use of a bottom face (6) of the respective slide frames (7a, 7b), which provides vertical support for the respective end (5a, 5b) of the frame (3) and a lateral face (9) of the slide frames (7a, 7b) complementary to a face (3) of the frame (3) and adapted to provide lateral support for this latter. It is clear that the formation of the relatively moveable parts in this manner enables them solely to slide in a direction corresponding to the widening or narrowing of the gauge. The particularly large movement achieved, notwithstanding the use of the H-frame (3) , is due to the shape of the appendages (19) which enables longer than usual telescopic cylinders (4) to be used. In Figures 1 and 2, the undercarriage (10) is shown with one track (2) completely extended and one completely retracted; in the left-hand part of both drawings, it can be seen that a rapid release and attachment device (29) for the telescopic cylinders (4) is located within the slide frames (7a, 7b) . There is easy access to these through apertures (23) in the walls of the slide frames (7a, 7b) facing the side of the sub-frames (2) and normally covered by covers (31). In this type of machine negative-action, luid-dynamic valves (12) are generally provided for controlling the operation of the telescopic cylinders (4) . For maximum safety, only when a control which pressurises the cylinders (4) is given can these be actuated to vary the gauge. Often, however, a second safety system is provided: at each of the four points at which the frame (3) is connected to the sub-frames (2) , there may in fact be a second type of mechanical locking device (17, 18) for locking the frame (3) and the sub-frames (2) against relative movement in a position of use so as to provide further control of the geometric stability in use. This second system is again of negative type, that is automatically engaged in the absence of a command which may be effected either by a remote control or manually. Figures 3 and 4 illustrate these two solutions respectively. In both cases, the mechanical locking device (17, 18) includes a movable geometric-interference element (11, 20) which can move from a first, extended position, in which it interferes geometrically with the surfaces (12, 13, 21, 22) of the frame (3) and the sub-frames (2), which are relatively movable therebetween, to a seccnd, retracted position in which it does not interfere with these surfaces; a spring (15, 23) for controlling the position of the movable, geometric-interference element (11, 20) biases it towards the extended position in the absence of external inputs and a control (39, 24), able to overcome the force of the spring (15, 23), allows the retraction of the movable, geometric-interference element (11, 20). In Figure 3 which shows the remote-control locking device (17), the movable, geometric-inter erence element (11) forms part of a fluid-dynamic cylinder (14) which also contains the spring (15) and, in the absence of pressure, maintains the movable, interference element (11) engaged with the relatively movable surfaces (12, 13), preventing a their movement. The relative remote control (39) is shown in Figure 1 on the central frame (3) in a position accessible to the operator. Again in the case of the manually-controlled locking device (18) of Figure 4, the positioning of the movable interference element (20) effected by the manual control (24) causes the locking or unlocking of the facing surfaces (21, 22). Rather than in the manner shown, the movable geometric-inter erence element (20) could be threaded and operated by a rotary control (24) rather than a pull control, which could in any case overcome the resistance of the spring (23). On the basis of what has been described, the operations required to vary the gauge are carried out in the following sequence: - the disengagement of the mechanical locking devica (17, 18) is controlled or actuated and consequently this no longer prevents the relative movement of the frame (3) and the sub-frames (2) ; - the remote control for the telescopic cylinders (4) actuates their movement and causes the ends (5a, 5b) of the frame (3) to slide relative to the slide frames (7a, 7b) of the sub-frames (2); - once this movement is completed, the remote control for the telescopic cylinders (4) is deactivated while the automatic operation of the fluid-dynamic valves (12) fixes the gauge in the position reached; - the second mechanical locking device (17, 13) is then actuated and its movable geometric-interference element (11, 20) returns to engage the surfaces (12, 13, 21, 22) , locking them in the predetermined position. The invention thus conceived can be modified and varied in numerous ways all of which fall within the scope of the inventive concept. Moreover all the details may be replaced by technically equivalent elements. In practice modi ications and/or improvements are obviously possible which fall however within the scope of the following claims.

Claims: CLAIMS 1. A variable-gauge track-laying undercarriage comprising an H-shaped central frame (3) and two lateral track-laying sub-frames (2) , the frame (3) and the sub- frames (2) being irreleasably fixed together in correspondence with the ends (5a, 5b) of the frame (3) and slide frames (7a, 7b) of the track-laying sub-frames (2), the undercarriage being characterised in that the slide frames (7a, 7b) of the sub-frames (2) have hollow coupling appendages (19) shaped externally so as to augment the movement between the maximum and minimum widths of the gauge and shaped internally with prismatic guides (6, 9) for providing constant support for the ends (5a, 5b) of the frame (3) . 2. A track-laying undercarriage according to claim 1, characterised in that the central frame (3) includes fluid-dynamically-controlled telescopic cylinders (4) within its ends (5a, 5b) for determining the width of the gauge. 3. A track-laying undercarriage according to Claim 1, characterised in that each prismatic guide includes a bottom face (6) of the respective slide frames (7a, 7b) adapted to provide vertical support for the respective end (5a, 5b) of the frame (3). 4. A track-laying undercarriage according to Claim 1, characterised in that each prismatic guide includes a lateral face (9) of the respective slide frames (7a, 7b) complementary to a face (8) of the frame (3) for providing lateral support for the latter. 5. A track-laying undercarriage according to claim 2, characterised in that, within the slide frames (7a, 7b) , it includes a rapid release and attachment device (29) for the telescopic cylinders (4) . 6. A track-laying undercarriage according to Claim 2, characterised in that it includes a mechanical locking device (17, IS) for locking the frame (3) relative to the sub-frames (2) in a position of use so as to provide further control for the geometric stability in use. 7. A track-laying undercarriage according to claim 6, characterised in that the mechanical locking device (17, IS) comprises: - a movable geometric-interference element (11, 20) adapted to move from a first, extended position, in which it interferes geometrically with the relatively movable surfaces (12, 13, 21, 22) of the frame (3) and of the sub- frames (2), to a second, retracted position in which it does not interfere with these faces; - a spring (15, 23) for controlling the position of the movable geometric-inter erence element (11, 20) to maintain it in its extended positio ; - a control (39, 24) for overcoming the thrust of the spring (15, 23) and allowing the retraction of the movable geometric-inter erence element (11, 20) . 8. A track-laying undercarriage according to Claim 6, characterised in that the control is a remote control (39) . 9. A track-laying undercarriage according to Claim 6, characterised in that the control is a manual control (24) . 10. A track-laying undercarriage according to the preceding claims and as described and illustrated with reference to the appended drawings and for the purposes indicated.

Inventors: GALLIGNANI LUIGI, GALLIGNANI, LUIGI
Applicants: GALLIGNANI LUIGI, GALLIGNANI, LUIGI
Application year: 1997
Main classification: B62D55
IPC codes: B62D55