Multi-purpose bogie for rail vehicles

Abstract: A drive and/or supporting bogie for rail vehicles consisting of a bogie frame (11) provided with a swinging cross-member (12) fixed to hangers (15) in such a manner as to be very close to the ground, ie to the rail plane, each wheel of the bogie being independent and driven separately by its own motor-reduction gear unit (29-30).

Description: This invention relates to a multi-purpose bogie for rail vehicles, and particularly to a bogie for tramway vehicles of the sunken floor type. Tramway vehicles of traditional type generally comprise four-wheel (two-axle) driving bogies having only one or possibly two motors, the mechanical energy of which is distributed to the two axles by a pair of reduction gears. (See for example the document US-A-4,644,872). Such a structure results in a considerable overall height, which totally determines the floor shape of the vehicle body, and in addition the axles are very large because they support the weight of the reduction gear and of the brake discs, which are of considerable size and weight, there being also difficulties of access to the bogie when the components of the motor-reduction gear unit require maintenance. The object of the present invention is to obviate the drawbacks of the said known art by providing a drive and/or supporting bogie for use in tramway vehicles especially of the sunken floor type, without creating size problems and thus enabling the total vehicle height to be reduced, whether this is of one or two-directional single or multiple body type, unidirectional or bidirectional, a bogie easy to upkeep being thus obtained. This object is attained by the features of the characterising part of claim 1. In a preferred embodiment, four motor-reduction gear units are associated with said four wheels and are arranged to independently drive each of said wheels. Said hanger acts via a suitable plate on a pair of elastic elements which in a preferred embodiment of the invention are helical springs of metal material. The technical characteristics and further advantages of the present invention will be more apparent from the following detailed description given with reference to the accompanying drawings in which: Figure 1 is a partly sectional front view of a carriage according to the invention; Figure 2 is a plan view of the bogie of Figure 1 from above; Figure 3 is a side view of the bogie of Figure 1; and Figure 4 is a side view of a further embodiment of the bogie of Figure 1. In the figures the reference numeral 10 indicates overall a bogie according to the invention consisting of a bogie frame 11 provided with a swinging cross-member 12 and a plurality of wheels 13. The swinging cross-member 12 is fixed to the bogie frame 11 by a pair of secondary suspensions 14 provided with hangers 15 pivoted at their lower end 16 to the cross-member and at their upper end 17 to plates indicated overall by 18 forming an integral part of the secondary suspension and acting on the elastic elements. On the swinging cross-member 12 there are also provided a thrust bearing 19 for connecting the bogie 10 to a body 20 of a rail vehicle (the body 20 being indicated only schematically) and two abutment elements 21 on which the body rests when travelling through curved rail portions. Each wheel 13 is independent of the others and is mounted on a swinging fork 22 connected to a horizontally reacting primary suspension 23. On each side of the bogie 10 the primary suspensions 23 of each wheel oppose each other via an interposed elastic block 24. The fork 22 is able to swing by virtue of its pivoting at 25 and its articulated connection 26 to the primary suspension 23. In addition, each wheel 13 is provided with a brake unit 27, the bogie being also provided with an electromagnetic braking device 28. In the case of a drive bogie, a motor unit 29 and respective reduction gear 30 supported by the fork 22 are associated with each wheel 13. In this manner the vertical reactions of the bogie 10 are transformed into horizontal thrusts which are absorbed by the primary suspension 23. Using a bogie 10 such as that described means that not only can both a supporting and a drive bogie be obtained by the same basic structure, but that by suitably shaping the bogie frame 11 and the swinging cross-member 12, the region between the wheels can be left free so that vehicles can be constructed with sunken floors which also include that region of the vehicle body in which the drive bogies are present. This is because according to the invention the centre line of the swinging cross-member is at a lower height than the axis of rotation of the wheels. The bogie structure according to the invention also enables the motor-reduction gear units to be housed in such a manner that their maintenance becomes simple, and in addition if one or more motor units develops a fault the vehicle still has sufficient power to continue operation. Each vehicle is generally provided with at least two drive bogies and consequently with at least eight individual motor-reduction gear units for each wheel, so that for example if two units are out of operation the vehicle will still have 6/8 of its full power available. Further according to the invention, the speed of any wheel can be varied independently of the others by acting on the respective motor-reduction gear unit for example by a computerized system. This has the advantage of eliminating the slipping which occurs between the wheel and rail when travelling through curves, so reducing friction, maintenance and costs. The present invention has been described by way of non-limiting illustration only, and modifications and replacements can be made thereto by experts of the art, but without leaving the scope of protection of the present invention.

Claims: A multi-purpose bogie for a rail vehicle, comprising a bogie frame (11) provided with a swinging cross-member (12) and a plurality of wheels (13), said cross-member (12) being connected to said bogie frame (11) by a secondary suspension (14) and being also provided with a thrust bearing (19) for connection to the vehicle, said plurality of wheels (13) being four mutually independent wheels (13) each mounted on an own fork (22) pivoted to the bogie frame (11) and connected to a primary suspension (23), said swinging cross-member (12) having a varying cross-section, characterised in that said swinging cross-member (12) is connected to said secondary suspension (14) by a hanger (15) in such a manner that the height of the centre line through said cross-member (12) is lower than the height of the axis of rotation of said wheels (13), and in that each fork (22) has arms departing from the wheel axis and respectively connected by articulated connections (25,26) with the bogie frame (11) and with a horizontally reacting primary suspension (23), the primary suspensions (23) on each side of the bogie (10) horizontally opposing each other via an interposed elastic block (24) above the bogie frame (11). A multi-purpose bogie as claimed in claim 1, characterised in that said arms of the forks (22) connected with the primary suspension (23) each support a motor unit (29) and a respective reduction gear (30). A multi-purpose bogie as claimed in claim 1 or 2, characterised in that said hanger (15) is connected to a plate (18) resting on two spaced apart helical springs of the secondary suspension (14) between which the hanger (15) is arranged. A multi-purpose bogie as claimed in claim 1, characterised in that said bogie (10) supports an electromagnetic brake (28) between the wheels (13) of a same side of the bogie (10) and below the respective primary suspension (23).

Inventors: MARZOCCO ALESSANDRO, MARZOCCO, ALESSANDRO
Applicants: SOCIMI, SO.C.I.MI SOCIETA COSTRUZIONI INDUSTRIALI MILANO S.P.A.
Application year: 1990
Main classification: B61F3
IPC codes: B61D17, B61F3, B61D13