Running gear with a single pair of independent left and right wheels and lateral stop means, and associated low floor rail vehicle

Abstract

A running gear for a low floor rail vehicle includes a frame, a single pair of independent left and right wheels, and a single pair of left and right rotation bearings attached to the frame that allow the left and right wheels to independently spin about a left and right spin axis, respectively. The running gear further includes a secondary suspension resting on the frame for supporting a vehicle body of the rail vehicle and lateral stop means fixed to the frame for laterally guiding the vehicle body of the rail vehicle. The lateral stop means includes a left and a right contact face facing a left and a right, respectively, transverse direction parallel to the transverse reference axis. The left and right contact faces are located between the left and right wheels.

Claims

1. A running gear for a low floor rail vehicle, the running gear frame comprising: a frame defining a transverse reference axis and a vertical transverse reference plane containing the transverse reference axis, a vertical longitudinal median plane perpendicular to the transverse reference axis and a horizontal reference plane containing the transverse reference axis; a single pair of independent left and right wheels, located on a left and a right side, respectively, of the vertical longitudinal median plane and equidistant from the vertical longitudinal median plane; a single pair of left and right rotation bearings attached to the frame, allowing the left and right wheels to independently spin about a left and a right spin axis, respectively, aligned with the transverse reference axis; a secondary suspension resting on the frame for supporting a vehicle body of the rail vehicle; and a lateral stop means fixed to the frame for laterally guiding the vehicle body of the rail vehicle, the lateral stop means comprising a left and a right contact face facing a left and a right transverse direction, respectively, parallel to the transverse reference axis, wherein the left and right contact faces are located between the left and right wheels, wherein the frame includes a pair of left and right longitudinal beams which each support a respective one of the left and right rotation bearings, a pair of front and rear transverse beams, each extending between respective ends of the left and right longitudinal beams on opposite sides of the vertical transverse reference plane, and at least one longitudinal support beam extending between the front and rear transverse beam, and wherein at least one of the left and right contact faces is supported by the longitudinal support beam.

2. The running gear of claim 1, wherein the vertical transverse reference plane crosses the left and right contact faces.

3. The running gear of claim 1, wherein at least part of the left and right contact faces is located below the horizontal reference plane.

4. The running gear of claim 1, wherein the left and right contact faces are equidistant from the vertical longitudinal median plane.

5. The running gear of claim 1, wherein the left and right contact faces are at least partially planar, with a planar zone parallel to the vertical longitudinal median plane.

6. The running gear of claim 1, wherein the left and right contact faces are fixed relative to one another.

7. The running gear of claim 1, wherein the lateral stop means comprise a set of one or more elastomeric bodies for connecting the left and right contact faces to the frame and for allowing limited movement of the left and right contact faces relative to the frame parallel to the transverse reference axis.

8. The running gear of claim 1, wherein the frame is integral with the pair of left and right rotation bearings.

9. The running gear of claim 1, wherein the longitudinal support beam supports the lateral stop means.

10. The running gear of claim 1, wherein the suspension comprises a set of left and right vertical suspension springs each located above a respective one of the left and right rotation bearings.

11. A low floor rail vehicle comprising: a vehicle body supported by a set of one or more running gears, including at least a first running gear according to claim 1, wherein an underbody of the vehicle body is provided with counter stop means comprising at least a first pair of lateral contact faces each facing a respective one of the left and right contact faces of stop means of the first running gear.

12. The low floor rail vehicle of claim 11, wherein the vehicle body rests directly on the secondary suspension of the first running gear.

13. The low floor rail vehicle of claim 11, wherein the set of one or more running gears includes at least a second running gear according to claim 1, wherein the vehicle body is provided with at least a second pair of lateral contact faces each facing a respective one of the left and right contact faces of the second running gear.

14. The low floor rail vehicle of claim 13, wherein the set of one or more running gears includes a pair of additional running gears, each with a single pair of independent left and right wheels, wherein each of the additional running gears is proximate a respective one of the first and second running gears, and preferably linked to the respective one of the first and second running gears.

15. The low floor rail vehicle of claim 11, wherein the underbody extends partially in a space between the pair of left and right wheels of the first running gear, below a horizontal plane tangential to an upper end of the left and right wheels of the first running gear, and below the horizontal reference plane of the frame of the first running gear.

16. A lateral buffer system for a rail vehicle having two subassemblies including a vehicle body and a running gear, the buffer system comprising: a first stop device and a second stop device, one of the first and second stop devices comprising lateral stop means for attachment to the running gear and the other one of the first and second stop devices comprising lateral counter-stop means for attachment to the vehicle body so as to limit the relative movement between the vehicle body and the running gear in a transverse direction of the rail vehicle, wherein the first lateral stop device comprises: a fixed support, a movable carrier provided with a pair of opposite contact faces and movable relative to the fixed support in two opposite directions parallel to a reference axis of the fixed support, and a set of one or more elastomeric bodies for resiliently connecting the movable carrier to the fixed support for allowing limited movement of the movable carrier relative to the fixed support parallel to reference axis on either side of a reference position of the movable carrier relative to the fixed support, and wherein the second lateral stop device comprises corresponding contact faces each facing one of the contact faces of the first lateral stop device at a distance thereof, and wherein the fixed support is formed as a tubular housing through which the movable carrier extends, and the pair of opposite contact faces of the movable carrier protrude from the ends of the tubular housing.

17. The lateral buffer system of claim 16, further comprising at least one pair of elastic buffer bodies arranged between the movable carrier and the fixed support so as not to interfere with the limited movement of the movable carrier relative to the fixed support parallel to the reference axis on either side of the reference position below a predetermined amplitude threshold and so as to resiliently counteract further movement of the movable carrier relative to the fixed support away from the reference position beyond the predetermined amplitude threshold, each in a respective one of the two opposite directions.

18. A rail vehicle comprising two subassemblies consisting of a vehicle body and a running gear, the rail vehicle further comprising the buffer system of claim 16, wherein the lateral stop means of said one of the first and second stop devices of the buffer system are attached to the running gear and the lateral counter-stop means of the other one of the first and second stop devices are attached to the vehicle body so as to limit the relative movement between the vehicle body and the running gear in a transverse direction of the rail vehicle.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Other advantages and features of the invention will then become more clearly apparent from the following description of a specific embodiment of the invention given as non-restrictive examples only and represented in the accompanying drawings in which:

(2) FIG. 1 is an isometric view of a running gear according to an embodiment of the invention;

(3) FIG. 2 is a schematic cross-sectional view of the running gear of FIG. 1 and of a corresponding part of an underbody of a rail vehicle according to the invention;

(4) FIG. 3 is detail of FIG. 2;

(5) FIG. 4, illustrates a rail vehicle according to an embodiment of the invention, provided with a set of running gears, some of which are similar to the running gear of FIG. 1;

(6) FIG. 5 illustrates a schematic cross-sectional view of the running gear and its interaction with a corresponding part of an underbody of a rail vehicle according to an alternative embodiment of the invention.

(7) Corresponding reference numerals refer to the same or corresponding parts in each of the figures.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(8) With reference to FIG. 1, a running gear 10 for a rail vehicle has a pair or left and right rotation bearings 12 for guiding a pair of independent left and right idle wheels 14, which are located between the left and right rotation bearings 12. The wheels 14 are independent wheels in the sense that they do not share a common wheel axle and can spin about their respective spin axes 100L, 100R independently from one another. The running gear 10 is provided with a rectangular frame 16, comprised of two longitudinal beams 18, each integrally formed with a respective one of the left and right rotation bearings 12, and two front and rear transverse beams 20 that extend, between the two front ends, respectively the two rear ends, of the longitudinal beams 18, so that the wheels 14 viewed from above are contained within the rectangular frame 16.

(9) To support the load of a vehicle body 22 of the rail vehicle, a vertical secondary suspension 24 is installed directly between the bogie frame 16 and the vehicle body 22, as schematically shown in FIG. 2. In this embodiment, the vertical secondary suspension 24 comprises a helicoidal spring 26 directly above each of the two rotation bearings 12 or a set of coaxial springs in series or in parallel. As an alternative, a set of two separate parallel vertical springs could be provided at the longitudinal ends of each of the two longitudinal beams 18.

(10) When the running gear 12 is in a standard operational position, i.e. a stationary position on a straight railway track, the frame 16 defines a transverse reference axis 100, which is aligned with the spin axes 100L, 100R of the left and right wheels 14, a vertical transverse reference plane T (i.e. the section plane of FIGS. 2 and 3) containing the transverse reference axis 100, a vertical longitudinal median plane V perpendicular to the transverse reference axis 100 and a horizontal reference plane H containing the transverse reference axis 100. As illustrated in FIGS. 2 and 4, the independent left and right wheels 14 are equidistant from the vertical longitudinal median plane V on a left, respectively right side of the vertical longitudinal median plane V. The transverse beams 18 are located on opposite sides of the vertical transverse reference plane T, at least partially below the horizontal reference plane H.

(11) The frame 16 is further provided with a median longitudinal support beam 28 which is cut by the vertical longitudinal median plane V. The longitudinal support beam supports lateral stop means 30 for laterally guiding the vehicle body 22 of the rail vehicle, which are illustrated in detail in FIGS. 2 to 4. The lateral stop means 30 are located between the left and right wheels 14 and comprise a fixed support formed by a cylindrical housing 32 aligned with a direction parallel to the transverse reference axis 100, but at a distance below the transverse reference axis 100. The housing 32 is provided with an inner partition wall 34, which extends in the vertical longitudinal median plane V. A transverse rod 36 extends through a hole in the inner partition wall 34 and through the housing 32 so as to protrude from both ends of the housing 32. The ends of the transverse rod 36 form a left and a right planar contact face 38 perpendicular to the transverse reference axis 100. The left and right contact faces 38 are located between the wheels 14, at least partially below the horizontal reference plane H, and face away from one another towards a left, respectively right, transverse direction parallel to the transverse reference axis 100. The housing 32, the rod 36 and its left and right contact faces 38 are cut by the vertical transverse reference plane of the frame 18. The left and right contact faces 38 are equidistant from the vertical longitudinal median plane V.

(12) As illustrated in FIG. 3, the lateral stop means 30 comprise a set of elastomeric bodies for connecting the transverse rod 36 with the housing 32, namely a set of relatively deformable annular elastomeric bodies 40 vulcanised to a cylindric portion of the rod 36 and a cylindric inner face of the housing 32, and a set of stiffer elastomeric stops 42 interposed between an associated flange 44 provided on the rod 36 and the intermediate partition wall 34 of the housing 32. The elastomeric stops 42 are attached to the associated flange 44 of the rod 36 and face the partition wall 34 at a distance thereof.

(13) The underbody of the vehicle body 22 is provided with counter stop means 45 formed by a pair of lateral contact faces 46, each facing at a distance a respective one of the left and right contact faces 38 of the lateral stop means 30 of the running gear 10.

(14) The running gear of the invention is particularly suitable for a low floor rail vehicle 220 as illustrated in FIG. 4, comprising a vehicle body 22 supported by one or more running gears, including at least a first running gear 101 as described above at a first end 221 of the vehicle body, and preferably a second running gear 102 as described above at a second end 222 of the rail vehicle 22, so that the lateral motion of the vehicle body 22 can be controlled at both ends 221, 222 of the vehicle body.

(15) As illustrated schematically in FIG. 2, the vehicle body 22 has an underbody that extends partially in a space between the pair of left and right wheels 14 of the first running gear 101, below a horizontal plane U tangential to an upper end of the left and right wheels 14 of the first running gear 101, and preferably below the horizontal reference plane H of the frame 14 of the first running gear 101. Similar considerations apply to the second running gear 102. The underbody is provided with a first pair of lateral contact faces 46 each facing a respective one of the left and right contact faces 38 of the first running gear 101, and with a second pair of lateral contact faces 46 each facing a respective one of the left and right contact faces 38 of the second running gear 102. The frame 16 of each running gear 101, 102 is connected to the vehicle body 22 by longitudinal connecting rods 48, vertical dampers 50 and transverse dampers 52, as is well known in the art.

(16) The low floor passenger rail vehicle 220 may further comprise a pair of additional running gears 111, 112, each with a single pair of independent left and right wheels 114, for supporting the vehicle body, wherein each of the additional running gears is proximate a respective one of the first and second running gears 101, 102. The additional running gear 111, 112 may also be provided with lateral stop means, or, as depicted in FIG. 5, be without lateral stop means.

(17) As will be readily understood, the lateral stop means 30 constitute with counter stop means 45 a lateral buffer system for limiting relative transverse movement between the vehicle body 20 and the running gear 10. A limited relative transverse motion between the running gear frame 16 and the vehicle body 22 with an amplitude less than the initial distance between the associated contact faces 38, 46 will have no effect on the lateral stop means 30. In such a case, the transverse forces are integrally transferred by the helicoidal springs 26 and the transverse damper 52 of the secondary suspension. As the amplitude of the transverse motion increases, a contact will be established between one of the contact faces 46 of the vehicle body and the respective contact face 38 of the lateral stop means 30. The contact force in the transverse direction will result in shear deformation of the annular elastomeric bodies 40 and a transmission of the applied force to the housing 32 with a dynamic damping of the higher frequency components. A higher contact force between the contact faces 46, 38 in the transverse direction will allow one of the stiffer elastomeric stops 42 to contact the partition wall 34 to limit the relative motion between the rod 36 and the housing 32, and hence between the frame 12 of the running gear 10, 101, 102 and the vehicle body 22.

(18) As a variant, illustrated in FIG. 5, the lateral stop means 30 on the frame 16 of the running gear 10 can be formed by two rigid contact faces 38 each formed on a dedicated intermediate longitudinal beam 28.1, 28.2 or the frame 16, whereas the counter stop means 45 includes a set of two contact faces 46 fixed to a rod 36 received in a housing 32 similar to the housing of the first embodiment.

(19) As another variant, both the lateral stop means 30 and the counter stop means 45 can be provided with elastomeric bodies.

(20) The housing 32 is not necessarily cylindrical. The stop faces 38 are preferably planar or convex.