A pneumatically-controlled lateral buffer for railway vehicles

Abstract: A lateral buffer (1) for railway vehicles includes a movable part (3) and a fixed part (2) for attachment to the body (C) of the vehicle or to the bogie and is interposed between the body and the bogie in order to limit their transverse relative displacement. The movable part (31) of the buffer (1) can be positioned relative to the attachment part (2) against the action of resilient return means (17), between an advanced position in which it is spaced from the attachment part, and a retracted position in which it bears against the attachment part. Selectively-operable, pressurised-fluid control means (4,14,16) are provided for positioning the movable part (3) in the retracted position, against the action of the resilient return means (17), under static conditions.

Description: The present invention relates to lateral buffers for railway vehicle suspension systems, of the type indicated in the pre-characterizing portion of annexed claim 1. Known lateral buffers usually have resilient members constituted by helical-spring or rubber devices which act in parallel with the secondary suspension of the vehicle. This solution does not enable the characteristics of the buffer to be modified and adapted to the modern operating requirements of railway vehicles provided with active lateral suspension systems which control the transverse displacement between the body and the bogie on bends, as described in the Applicant's Italian patents Nos. 821626 and 885653 In such applications, it would, in fact, be desirable to have lateral buffers with different intervention and resilience characteristics according to whether the active lateral suspension is effective or ineffective. CH-A-521 872 discloses a lateral buffer for railway vehicles which is fixed at one end to the body of the vehicle or to the bogie and is interposed between the body and the bogie to limit their transverse relative displacement. The buffer includes a fixed attachment part and a part which is movable relative to the fixed part, whereby the movable part can be positioned relative to the attachment part, against the action of resilient return means, between an advanced position in which it is spaced from the attachment part and a retracted position in which it bears against the attachment part. The buffer may be provided with a sprocket-type device for adjusting the action of the resilient return means. The object of the present invention is to provide an improved lateral buffer for railway vehicle suspension system having the features set forth in the characterizing portion of claim 1. By virtue of this concept, the lateral buffer according to the invention can be set in two different operating modes which have different intervention levels and resilience characteristics. In the first mode, which corresponds to the activated condition of the pressurised-fluid control means, the position of the buffer allows a larger lateral displacement of the body relative to the bogie before it intervenes. When the pressurised-fluid control means are deactivated, on the one hand, the intervention of the buffer is advanced since the movable part of the buffer is spaced from the attachment part, and the buffer also has a different lateral resilience characteristic due to the resilient return means interposed between the attachment part and the movable part of the buffer. By virtue of the fact that its intervention level and resilience characteristic can be varied, the later buffer according to the invention can be combined, to particular advantage, with active lateral suspension systems: in this case, the operation of the buffer is such that the first mode (pressurised-fluid control means activated) corresponds to the activated condition of the active lateral suspension system and the second mode (pressurised-fluid control means deactivated) corresponds to the deactivation of the active lateral suspension system. Conveniently, the cylinder is supported by the body or by the bogie of the vehicle by means of a pair of perpendicular connecting rods provided with respective resilient joints. Further characteristics and advantages of the invention will become clear in the course of the detailed description which follows, with reference to the appended drawings, provided purely by way of non-limiting example, in which: Figure 1 is a schematic front elevational view of a pneumatically-controlled lateral buffer according to the invention, Figure 2 is an axial section taken on the line II-II of Figure 1, and Figure 3 is a section taken on the line III-III of Figure 2. With reference to the drawings, a lateral buffer for railway vehicles, generally indicated 1, is intended to act in parallel with the secondary suspension system of the vehicle, in generally known manner. The buffer 1 comprises essentially an attachment structure 2 and a movable part 3 carried by a cylindrical body 4 which is connected to the attachment structure 2 in the manner made clear below. In the embodiment illustrated, the buffer 1 is carried by the structure of the body C beside the respective bogie with the movable part 3 facing the latter. The attachment structure 2 is connected rigidly, being fixed to the body C in a stationary condition by means of a pair of lateral flanges 5, whilst the cylinder 4 is connected to the body C so as to be movable in a direction A parallel to the transverse axis of the vehicle. The cylinder 4 is connected by means of a pair of perpendicular connecting rods 6, each articulated at one end to the cylinder 4 and at the opposite end to the body C by means of respective resilient joints, schematically indicated 7 and 8 respectively. As shown in greater detail in Figure 3, the movable part 3 carries a circular metal element 9 which bears against the end wall 10 of the cylinder 4 with the interposition of a block 11 of elastomeric material. When the buffer is in operation, the element 9 can therefore be retracted along the axis A against the resilient reaction of the block 11. It should be noted that the configuration of the element 11 may differ from that shown: it could, for example, be constituted by a resilient member with a helical spring or be eliminated. The cylinder 4 is sealingly slidable along a rod 12 articulated at 13 to the attachment structure 2 and extending along the axis A. The rod 12 carries a stationary piston 14 relative to which the cylinder 4 can slide sealingly and which defines a thrust chamber 16 with the wall 15 of the cylinder opposite its end 10. The thrust chamber 16 is connected to a compressed-air supply by means of a connector, indicated 16a in Figure 3. Conventional valve means (not shown) are inserted between the supply (not shown) and the pressure chamber 16 for selectively controlling the supply and the discharge of the chamber 16. A helical compression spring, indicated 17, is interposed axially between the wall 15 of the cylinder 4 and the attachment structure 2 and normally keeps the cylinder 4 and the attachment structure 2 spaced apart by an axial distance, indicated H. It should be noted that alternatively, the helical spring 17 could be replaced, by resilient members with an equivalent function. The buffer 1 operates as follows. In the absence of a supply to the thrust chamber 16 from the pneumatic source, the configuration is that shown in the drawings: the cylinder 4 is acted on by the spring 17 with its wall 15 bearing substantially against the piston 14, and is therefore spaced from the attachment structure 2 by the distance H. During the abutment between the structure of the bogie and the buffer 1, the resilience of the buffer is first afforded by the series consisting of the helical spring 17 and the element 11, if present, until the distance H is reduced to zero, that is, until the cylinder 4 bears frontally against the attachment structure 2. When this condition is reached, the resilience of the buffer is afforded only by the element 11, if present. In the condition in which the thrust chamber 16 is supplied by the pneumatic supply, however, the cylinder 4 is displaced from the opposite end and is kept in frontal contact with the attachment structure 2 against the action of the spring 17. When it bears against the bogie, the resilience of the buffer 1 therefore corresponds to that of the element 11, if present, since the spring 17 does not intervene. It is clear from the foregoing that both the intervention level and the resilience characteristic of the buffer 1 can be varied by changing the supply and discharge conditions of the thrust chamber 16. This variability makes the use of the buffer 1 on railway vehicles with active lateral suspension systems particularly advantageous: in this case, when the active lateral suspension system is engaged, the thrust chamber 16 is supplied by the pneumatic supply whilst, when the active lateral suspension system is disengaged, the chamber 16 is kept discharged so that, as explained above, the intervention of the buffer 1 is advanced and the element 11, if present, operates in series with the spring 17.

Claims: A lateral buffer for railway vehicles, which is fixed at one end to the body of the vehicle or to the bogie and is interposed between the body and the bogie to limit their transverse relative displacement, the buffer (1) including a fixed attachment part (2) and a part (3) which is movable relative to the fixed part (2), whereby the movable part (3) can be positioned relative to the attachment part (2), against the action of resilient return means (17), between an advanced position in which it is spaced from the attachment part (2), and a retracted position in which it bears against the attachment part (2), characterised in that the buffer (1) presents selectively-operable, pressurised-fluid control means (4, 14, 16) which are provided for positioning the buffer member (3) in the retracted position, against the action of the resilient return means (17), under static conditions, said control means comprising a rod (12) connected to the attachment part (2) and carrying a stationary piston (14) on which a cylinder (4) is sealingly slidable axially, the cylinder (4) carrying an external buffer plate (9) at one end and being reacted against at its opposite end by the resilient return means (17), and the stationary piston (14) defining in the cylinder (4) a pressure chamber (16) connectible to a compressed-air source. A lateral buffer according to Claim 1, characterised in that the cylinder (4) is supported by the body (C) or the bogie of the vehicle by means of a pair of perpendicular connecting rods (6) provided with respective resilient joints (7, 8). A lateral buffer according to Claim 1, characterised in that a resiliently yielding element (11) is inserted in the movable part (3). A buffer according to Claim 3, characterised in that the movable part (3) includes a rigid abutment (9) which is movable in a direction parallel to the axis (A) of a cylinder (4) against the action of a reaction block (11) of elastomeric material. A lateral buffer according to anyone of Claims 1 to 4, characterised in that the resilient return means are constituted by a helical spring (17) interposed between the cylinder (4) and the attachment part (2).

Inventors: CASALONE RINALDI ROBERTO, QUIRIGHETTI LUCIANO, CASALONE RINALDI, ROBERTO, QUIRIGHETTI, LUCIANO
Applicants: FIAT FERROVIARIA SPA, FIAT FERROVIARIA S.P.A.
Application year: 1990
Main classification: B61G11
IPC codes: B61G11, B61F5