AU7687396A - A rail vehicle - Google Patents

Description

TITLE: A RAIL VEHICLE

FIELD OF THE INVENTION

The present invention relates to a rail vehicle.

The invention has been developed primarily for use as a freight carrying vehicle

and will be described hereinafter with reference to that application. However, it will be

appreciated that the invention is not limited to this particular field of use.

BACKGROUND OF THE INVENTION

Freight trains are well known. Typically, anything from one to six or more

locomotives are coupled to a considerably larger number of freight carriages by means of

standard couplings. Whilst the locomotives are typically placed in groups of two or

three, at the front and rear of the train, typically they may also be positioned within the

train such that freight carriages are disposed on either side of them.

Due to the large engine and transmission components, such locomotives are

generally quite heavy, with their weight being distributed over typically four or six axles.

However, because ofthe large amounts of power which they must transmit through their

driven wheels to the tracks, especially where loads in the order of 30 tonnes per axle and power in the order of 3000 Hp per unit are involved, locomotives often carry ballast to

maximise traction. Unfortunately, the ballast remains in place whether the freight

carriages being hauled are empty or full, which means that the locomotive is placing its

full weight upon the tracks at all times. In other cases, where traction is of less concern,

it is desirable to minimise the weight ofthe locomotive, thereby reducing the load per

axle which it transfers to the tracks. Due to the relatively high mass per axle of locomotives, railway tracks which are

designed to carry freight must be built more ruggedly than, say, tracks designed to carry

passenger trains only. The relatively high cost of building such heavy duty railway

tracks means that in many circumstances where a rail track is built for the exclusive use

of one user such as a mine, the cost of building a second parallel line becomes

prohibitive. It is therefore not uncommon for only a single line to be built, with periodic

spurs and side tracks to enable trains heading in opposite directions to pass each other.

However, due to the typically high mass of most locomotives, irrespective of whether

the train itself is laden with goods, such configurations are both inefficient in terms of

overall speed and energy usage, as well as being considerably less safe than a dual parallel track system.

Yet another problem with freight trains of this type is the traction problems they

often experience with steep inclines and the like, especially when fully laden. The

grouping of locomotives together at either end of the train tends to magnify the effect of

localised low traction areas due to gradient, moisture or foreign substances on the tracks.

It is an object ofthe present invention to provide a rail vehicle which overcomes or

at least substantially ameliorates one or more ofthe disadvantages ofthe prior art.

DISCLOSURE OF THE INVENTION

Accordingly, in a first aspect the invention provides a rail vehicle comprising a

drive module having driven rail wheels to propel the drive module along a rail track, and

a freight module releasably coupled to the drive module for carrying a load, wherein at least part of the weight ofthe load is transferred to the driven rail wheels. Preferably, the modules are coupled by a turntable which allows the freight module

to pivot about a vertical axis. Preferably also, the turntable allows limited pivoting

between the two modules about a horizontal axis.

It is desirable that about half of the weight ofthe load is transferred to the driven

rail wheels.

Preferably, the drive unit includes control means for selectively varying the drive

applied to the driven rail wheels. It is further preferred that the drive unit includes some

form of traction control to reduce wheel slippage.

In one embodiment, the drive unit utilises a diesel engine and associated

transmission to provide drive to the driven wheels. Alternatively, other power sources

such as petrol, LPG or even electric motors may be used, depending upon the

circumstances.

In a preferred form, the drive module is coupled to an additional like freight

module wherein at least part ofthe load carried by the additional freight module is

transferred to driven rail wheels on the power module. It is particularly preferred that

there is provided a plurality of drive modules and freight modules, together forming a train. In one embodiment, all axles in the train bear at least some ofthe load ofthe

freight modules.

In a second aspect, the invention provides a train including one or more drive

modules and a plurality of freight modules, wherein all axles of the train bear at least

some of the load carried by the freight modules. BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of

example only, with reference to the accompanying drawings in which:

Figure 1 is a first embodiment of a rail vehicle according to the invention;

Figure 2 is a side view of an alternative embodiment ofthe invention; and

Figure 3 is a side view of another alternative embodiment ofthe invention.

PREFERRED EMBODIMENT OF THE INVENTION

Referring to the drawings, an articulated rail vehicle 1 includes a drive module 2

having driven wheels 3 to propel the drive module along a set of rail tracks 4. The rail

vehicle 1 also includes a freight module 5 releasably coupled to a drive module 2 via a turntable 7, at least part of the weight of a load 6 being transferred to driven wheels 3. In

the embodiment illustrated, around 50% ofthe weight of the load 6 is transferred to the

driven wheels. This proportion may vary significantly depending upon such factors as

proportion of driven to undriven axles on the drive and freight modules respectively, the

configuration of adjacent modules, and the amount of load being carried.

Each freight module includes a bogey 30 which includes undriven axles, each

including a pair of rail wheels 31. Whilst the present embodiment uses a pair of such

axles, any desired number may be used to increase the load bearing capacity ofthe freight module. Similarly, any number and combination of driven and undriven wheels

may be utilised with drive unit 2.

In the embodiment of Figure 1, a control cabin 8 houses controls (not shown) to

selectively vary the power applied by an engine 9 to driven wheels 3. Where additional drive modules are provided within the train, the one set of controls within cabin 8 may

be used to vary the drive to all wheels within the train simultaneously.

Referring to the drive module shown in Figure 2, wherein like numbers are used to

indicate like features, no control cabin is provided on board. Rather, the drive module is

designed to act as a "slave" unit to a remotely positioned control module which may be

associated with another drive module or alternatively may be a control module only.

This "slave" drive module is designed to have all wheels driven so that a freight module

may be coupled at either end ofthe drive module. Whilst this configuration is preferred

for its superior traction, in many circumstances it may be acceptable merely to drive one

ofthe two sets of wheels with the other set merely transferring weight to the tracks from

the adjacent load.

Turntable 7 is designed to allow freight module 5 to pivot in the horizontal plane

with respect to the drive module. This allows the rail vehicle to easily traverse bends in

the rail tracks 4 without imposing undue stresses on the tracks themselves or on either

module. The turntable also allows for limited vertical pivoting to enable sudden changes

in gradient to be traversed. Advantageously, the turntable may be sourced from standard components designed for heavy duty articulated semi-trailers. In the preferred

embodiment, the pivot point ofthe turntable is displaced from the pivot point ofthe

bogey towards the centre ofthe drive unit. This displacement, marked "d" in the

drawings, can be altered to vary the load transfer from the freight unit to the drive unit. In the embodiment shown, ballast 10 in the form of lead blocks or the like is

provided toward the front of drive module 2 to enable better weight distribution. The use of such ballast can be tailored to suit different loads and tracks, and will depend

upon the such factors as the pivot point displacement "d".

Whilst a hopper is illustrated in the diagrams, any type of freight carriage may be

used, including automobile carriages, refrigerated cars or flat bed carriages for

containerised cargo. Furthermore, a train formed by coupling together a number of drive

and freight modules may be interspersed with conventional freight modules where

desirable.

In this embodiment, module 5 includes a chassis 1 1 extending between a first end

12 and a second end 13. Chassis 1 1 supports a cradle 14 which in turn releasably

supports a bin 15 in which load 6 is carried. Bin 15 includes a base 16 having two longitudinally spaced apart discharge ports 17 and 18 to enable removal of load 6 from

bin 15. Bin 15 further includes a pair of parallel sidewalls 19 which are joined at their

adjacent ends by transversely extending inclined end walls 20 and 21. The end walls 20

and 21 allow bin 15 to be retained in cradle 14 under the influence of gravity.

Turning to Figure 3, in which like numbers designate like features, another

embodiment of the invention includes a leading car 32, and a number of drive and freight

units dispersed throughout the remainder of the train. Leading car 32 may be built

considerably lighter than a drive unit as it does not include any driven wheels. This confers a number of additional advantages over using a drive unit in conjunction with a

control cabin as a leading car. To begin with, unlike a drive unit embedded within the

train, a leading drive unit only transfers weight from a single freight carriage to its

rearward drive wheels. Whilst this does increase traction on those wheels, where all

axles are driven the front axles ofthe drive unit may need to be ballasted to gain adequate traction. This in turn reduces, at least for the leading car, some of the

advantages offered by the invention. Also, according to conventional construction

techniques, the control cabin can be a relatively uncomfortable place for drivers to spend

long periods of time, due to high noise and vibration from the adjacent engine.

By contrast, leading car 32 need not be engineered to withstand the forces

associated with transmitting power to the tracks. Accordingly, such a unit can be built

relatively cheaply using standard lightweight coachbuilding techniques. Furthermore,

the control cabin itself can be made considerably more comfortable through the use of

more supple suspension between the cabin and the tracks, and by separating it from engine noise and vibration. It will, of course, be necessary to include an additional drive

unit within the train to make up the required total power. However, the total cost is

unlikely to be considerably greater than using a powered leading car.

For the Figure 3 embodiment, it is envisaged that if a powered leading carriage is

utilised in a typical coal hauling situation, the non-powered axles on the freight units will

each bear around 2.5 tonnes, and the drive units inteφosed within the train will bear

around 4 tonnes per axle. However, with adequate ballasting, the front axles of the

leading carriage will bear a load of around 12.5 tonnes per axle, which requires a

substantially more ruggedly constructed track. By contrast, a leading carriage 32, even

with a relatively small number of axles, can easily be designed to place less than 4

tonnes per axle on the tracks. This brings the overall maximum axle weight for the train

to about 4 tonnes, which is a substantial reduction.

In some embodiments, leading carriage 32 includes a compact generator to provide

electricity for the control cabin and any ancillary functions on the drive and freight units. In other embodiments, a compressor is mounted in the leading car to provide compressed

air to the trailing carriages for braking.

Where the train is to be used to move back and forth between, say, a mine and a

processing centre, it will be usual to provide an additional leading carriage with

duplicate controls at the rear of the train for the return journey.

In all of the embodiments illustrated the drive modules incoφorate a traction control system to prevent undesirable wheel slippage. In this way, power wastage and

wear on both the driven wheels and the rail tracks are reduced. In the preferred form of

the invention where multiple drive units are interspersed throughout a train, the traction

control system enables the effects of localised traction problems, such as water or oil on a short portion of track, to be minimised.

The present invention allows the maximum mass per axle of a train to be reduced

substantially. The transfer of load mass to the driven wheels ofthe drive module

significantly reduces the need for additional ballast to gain traction. Furthermore, the

reduction of maximum mass per axle when the train is unladen means that relatively

light duty tracks may be used by the train. This enables a return track for single use lines

for mining and the like to be built relatively cheaply, which greatly increases safety and

efficiency of the trains. The invention therefore represents a commercially significant

improvement over the prior art.

Whilst the invention has been described with reference to a number of specific

examples, it will be appreciated by those skilled in the art that the invention may be

embodied in many other forms.

Claims (11)

1. A rail vehicle comprising a drive module having driven rail wheels to propel the

drive module along a rail track, and a freight module releasably coupled to the drive

module for carrying a load, wherein at least part ofthe weight ofthe load is transferred

to the driven rail wheels.

2. A rail vehicle according to claim 1 wherein the modules are coupled by a turntable

which allows the freight module to pivot about a vertical axis with respect to the drive

module.

3. A rail vehicle according to claim 2, wherein the turntable further allows the freight

module to pivot in a horizontal axis with respect to the drive module.

4. A rail vehicle according to any one ofthe preceding claims wherein about half of

the weight of the load is transferred to the driven rail wheels.

5 A rail vehicle according to any one ofthe preceding claims wherein the drive unit

includes control means for selectively varying the drive applied to the driven rail wheels.

6. A rail vehicle according to any one ofthe preceding claims, wherein the control

means includes a traction control system to reduce slippage of the driven rail wheels.

7. A rail vehicle according to any one of the preceding claims wherein the drive unit

utilises a diesel engine and associated transmission to provide drive to the driven wheels.

8. A rail vehicle according to any one of claims 1 to 6 wherein the drive unit utilises a

petrol, gas or electric motor, and associated transmission means to provide drive to the

driven wheels.

9. A rail vehicle according to any one ofthe preceding claims wherein the drive

module is coupled to an additional like freight module, and wherein at least part ofthe load carried by the additional freight module is transferred to driven rail wheels on the

power module.

10. A rail vehicle comprising a plurality of drive modules and freight modules in

accordance with any one of the preceding claims coupled together to form a train.

11. A rail vehicle according to claim 9 wherein each axle in the train bears at least part of the weight ofthe load ofthe freight modules.