The present invention relates to an apparatus and method for applying lubricant to railway vehicle wheels.

Railway vehicles have a number of wheels 3 that sit on and are guided by two substantially parallel rails 5 which together form a track. The rails 5 are linked to one another by a series of sleepers 7 that support the rails 5 via corresponding rail pads 9 that sit between the rail 5 and the sleeper 7. The rail pads 9 are arranged to support the rails S at a slight incline toward the gauge side 11 of the rail and away from the field side of the rail 13. The region of the wheel 3 that contacts the rail 5 is known as the wheel tread 15. This region is substantially frustroconical and has its largest diameter toward the gauge side of the rail 5 and its smallest diameter toward the field side of the rail 5 to help restrict the railway vehicle to the track. A wheel flange is formed on the gauge side of wheel 17 and is arranged to keep the wheels 3 from running off the rails 5 when in motion.

One of the largest costs in the rail industry relates to the renewal of railway vehicle wheels and track.. Railway vehicle wheels and track gradually become damaged and compromised due to the large forces generated by heavy vehicles travelling on a small contact area between the wheels and the track. Two of the primary causes of wheel and track damage are metal wear and rolling contact fatigue (RCF). Metal wear in the track rail and the wheel tends to occur due to slippage between the rail and the wheel, in a contact patch, under conditions of high pressure and friction. The contact patch leads to deformation of the metal of the rail in the direction of wheel slippage. Rolling contact fatigue occurs due to the combination of the rail profile, contact patch energy, rail metallurgy, rail bending moments and fluid entrapment in the rail's metal fatigued surface cracks. RCF occurs in both the wheel and the rail and, if left untreated, can lead to rail fracture and vehicle derailments. Friction between the wheel 3 and the rail 5 can cause thinning of the wheel flange 17 at regions known as the flange root 19 and flange face 21 which extend from the flange toe 23. It can also cause wear of the wheel tread 15 to the extent its conicity is removed, and the creation of a false flange on the field-side part of the tread 15 adjacent the field side chamfer area 24. The field side part of the tread 15 is the region adjacent the main rolling part of the tread that comes into contact with the rail when the wheel is on the low rail Friction between the wheel 3 and the rail 5 can also result in rail wear at regions of the rail 5 known as the gauge face 25, gauge corner 27, gauge shoulder 29, crown 31, field shoulder 33, field corner 35 and field face 37.

One approach to try and minimise wear and rolling contact fatigue is to apply a medium coefficient of friction lubricant to the top of the rail. However, this causes lubricant to be distributed and spread across the whole of the wheel's running tread 15 which can reduce braking efficiency without reducing the friction sufficiently to alleviate RCF in the wheel. Another approach is to apply a low coefficient of friction lubricant to the flange root and to apply a medium coefficient of friction lubricant to the central running tread of the wheel but this can again endanger braking performance without sufficiently reducing RCF. Trackside systems are also implemented which apply medium coefficient of friction lubricant to the rail top and a low coefficient of friction lubricant to the gauge corner which again does not tackle the problem of RCF in the wheel and can affect braking performance. Furthermore, existing lubrication systems are prone to applying too much or too little lubricant. Too much lubricant can result in soiling of the vehicle's underside and wastage of lubricant and too little lubricant fails to reduce wear, metal fatigue and noise.

One conventional lubrication system uses a closed circuit of lubricant which is dispensed onto the wheels via one or more nozzles. The lubricant is driven along the circuit to the nozzles by a motor where it is atomised using pressurised air to direct a cone of spray toward the wheel. Such systems are not very flexible and can take a very long time to charge owing to the requirement to fill relatively long pipes with lubricant. Another conventional lubrication system comprises one or more nozzles each of which is connected to a supply of lubricant by a respective pipe. Each pipe and nozzle is associated with a pump which is driven by compressed air to dispense lubricant into the pipe so that it can be ejected via the nozzle. Since one pump is required for each nozzle and since each pump is relatively expensive, a problem with such a system is that it is expensive and complicated to build and operate. Furthermore, where it is desired to dispense larger volumes of lubricant in a given time frame, a larger pump is required and hence a larger supply of lubricant to house the pumps. This adds further to the cost and also the footprint of the system which must be installed on a railway vehicle.

The prob!em of tackling wear and RCF is further compounded by variations in the contact area between the wheel and the rail as the vehicle travels along and encounters deviations in the track. It is an object of embodiments of the invention to reduce wear and fatigue of the rails and wheels whilst mitigating the above difficulties.

According to a first aspect of the present invention, there is provided apparatus for applying lubricant to a wheel of a railway vehicle, the wheel comprising a tread having a central running part, a field side part and a flange side part each of which may contact a rail, the apparatus comprising a supply of lubricant and a first nozzle through which lubricant from the supply of lubricant can be dispensed, characterised in that the first nozzle is arranged to deliver lubricant to at least a part of the field side part of the tread but not at least a part of the central running part.

Advantageously, the ability to apply lubricant specifically to the field side of the tread and not at least a part of the central running tread enables rolling contact fatigue in the wheel to be reduced without significantly affecting braking efficiency of the railway vehicle. By reducing rolling contact fatigue in the wheel, the frequency of wheel renewal is reduced and, thus, so too is the cost of renewal. The lubricant may be a low coefficient of friction lubricant. The lubrica nt may result in a coefficient of friction between the wheel a nd a rail of between 0.05 a nd 0.15. The lubrica nt may re sult in a coefficient of friction between the wheel and a ra il of 0.1.

There may be a second nozzle through which lubricant from the supply of lubricant ca n be di spensed, cha racterised in that the second nozzle is arra nged to deliver lubricant to a different part of the tread from the first nozzle. The second nozzle may be arranged to deliver lubricant to at least a pa rt of the flange side of the trea d but not at least a part of the central running tread.

The first and/or second nozzles may be a rranged so that they do not deliver any I ubricant to the ce ntra l running pa rt of the wheel tread.

The first and second nozzles may be connected to the supply of lubricant by a conduit and the a ppa ratus may further comprise means for introducing lubrica nt into the conduit a nd mea ns for introduci ng compressed air into the conduit to drive lubrica nt through the conduit.

Advantageously, the use of compressed air to dispense lubricant enables a high degree of contro l over the application of lubrica nt to the ra ilway vehicle wheels at appropriate track positions. Thus, wear of the wheels and rai ls, squealing a nd rol ling contact fatigue can be effective ly reduced thereby prolonging the life of the wheels and the rails a nd helping to reduce the cost of track and wheel renewal. Further, an air and grease based lubrication system is more robust beca use the pipes used in such systems a re larger in dia meter tha n a lubricant only system a nd therefore less prone to damage. Another key advantage is that it permits the use of priming cycles to vary the quantity of lubrica nt in the system to be dispensed. This enables accurate qua ntities of lubricant to be dispe nsed in a given time fra me as desired.

The means for introducing lubricant into the conduit may be a rranged to coat the inside surface of the conduit with a film of lubricant. The means for introducing lubricant may be operated by compressed air. The conduit may comprise a first valve operable to permit air to flow a nd entrain lubricant through the conduit to one or more nozzles. The conduit may further comprise a second valve opera ble to permit air and lubricant to flow through the conduit to one or more nozzles.

The a ppa ratus may be configured to operate the first valve to permit a volume of a ir to flow through the conduit so that a volume of lubricant is introduced into the conduit by the means for introducing lubricant, and the a pparatus may be further configured to operate both valves to release the a ir from the conduit.

There may be a second supply of lubricant containing a different lubricant from the first supply of lubricant a nd the first nozzle may be arra nged to dispense lubrica nt from the first supply of lubricant and the second nozzle may be arranged to dispense Iubricant from the second supply of lubricant. The lubricant in the second supply may be chosen such that its application results i n a coefficient of friction between the wheel and a rail which is different from the lubrica nt in the first supply of lubricant,

Each nozzle may comprise an orifice and the cross sectional area of the conduit relative to the cross sectional area of the or each nozzle orifice may be chosen such that the resista nce to flow of air through the conduit is low relative to the or each nozzle orifice.

The a pparatus may further comprise a control unit a rranged to selectively cause lubricant to be dispensed through the or each nozzle on to a wheel depending on the configuration of the track the wheel is on or approaching. The control unit may be softwa re driven. The apparatus may further com prise a sensor to determine the configuration of the track on which the railway vehicle is travelling or approaching so that the control unit ca n select the or each nozzle through which Iubricant is dispensed. The sensor may be an inertial sensor operable to determine the angular velocity of the railway vehicle about its vertical axis. There may be a speed sensor opera ble to determine the speed of the railway vehicle. The sensor may be a GPS sensor operable to determine the position of the ra ilway vehicle and the control unit may be operable to compare the determined position of the vehicle with stored information regarding the configuration of the track at that position. Alternatively, the sensor may be an RFID tag reader operable to determine the position of the railway vehicle relative to local RFID tags and the control unit may be operable to compare the determined position of the vehicle with stored information regarding the configuration of the track at that position.

Advantageously, it is possible to determine the position of a vehicle on a track without having to rely on satellite signals to determine when lubricant should be applied and to which regions of the wheel. Thus, accurate track position can be determined and, hence, accurate application of lubricant can be achieved in places where satellite signals are not receivable, e.g. underground. Further, many railway networks have existing RFID tags in place along the track so the installation costs necessary to determine vehicle position based upon relative RFID tag position is minimised. The use of bend sensors in combination with speed sensors can be used when RFID tag positioning and/or GPS positioning is not available to determine the tightness of a bend on which a railway vehicle travels so that the lubrication requirements can be ascertained and the wheels lubricated accordingly, on a variable time dispense basis.

There may be a second pair of nozzles through which lubricant can be dispensed and arranged in corresponding fashion in relation to the tread of a second wheel as the first pair of nozzles. The apparatus may be configured to dispense lubricant through the first nozzle of one pair when the wheel with which it is associated is on or is approaching the low rail of a bend and to simultaneously dispense lubricant through the second nozzle of the other pair when the wheel with which it is associated with is on or is approaching the high rail of a bend.

The at least a part of the central running part may comprise a substantial part. The substantial part may comprise around 90% of the central running part. According to a second aspect of the present invention, there is provided a method of varying the volume of lubrica nt to be a pplied to railway vehicle wheels comprising the steps of: providing apparatus havi ng a conduit, means for introducing compressed air into the conduit and a means for introducing lubricant into the conduit which is operated by compressed a ir; allowing compressed air to enter the conduit so that the mea ns for introduci ng lubrica nt introduces a volume of lubricant into the conduit for dispensing purposes; and allowing the compressed air to exit the conduit.

The apparatus may further comprise a first va lve associated with the conduit a nd arranged to permit or restrict air flow through the conduit, and the step of a llowing compressed air to enter the conduit may include operating the first va lve.

The appa ratus further comprises a second valve associated with the conduit a nd arra nged to permit or restrict air flow through the conduit, a nd the step of allowi ng the compressed a ir to exit the conduit may include operating the second va lve to permit the air to travel through the conduit.

According to a third aspect of the present invention, there is provided a method of applying lubricant to railway vehicle w heels comprising the steps of: using an RF1D tag rea der to determine the position of a railway vehi cle on a track; using the determined position to determine the lubrication requirements for the wheels on the ra ilway vehicle; a nd a pplying lubrica nt to one or more wheels depending on the lubrication requirements. I n order that the invention may be more clea rly understood embodiments thereof will now be described, by way of exam ple, with reference to the accompanying drawi ngs of which: Fig. 1 shows a ra ilway vehicle mono-block on a substa ntia lly straight railway track, wherein the centre of the wheel's running tread is touching the rail's gauge shoulder and ra il crown;

Fig. 2 shows an enlarged sectional view of an outer edge of a railway vehicle wheel;

Fig. 3 shows an enlarged sectional view of an outer edge of a ra ilway vehicle wheel seated on a rail;

Fig. 4 shows an aeria} view of a railway vehicle travelling along a ra ilway track a nd e ncountering a series of bends;

Fig. 5 shows an enlarged sectional view of a railway vehicle wheel in norma l wheel tread contact with a ra il when on a substa ntia lly straight region of track;

Fig, 6 shows an enla rged sectional view of a railway vehicle wheel in contact with the inner rail of a bend of track;

Fig. 7 shows an enlarged sectional view of a railway vehicle w heel i n contact with the outer rai l of a bend of track;

Fig. 8 shows an interna! schematic of a pneumatic circuit used as part of an apparatus according to the present invention;

Fig. 9 shows a schematic representation of an apparatus according to the present i nvention i ncluding the pneumatic circuit shown in Fig. 8;

Fig. 10 is a n enlarged view of two nozzles shown i n Figs. 8 and 9 mounted relative to a w heel;

Fig. 11 shows pa ri of a ra ilway vehicle to which is mounted appa ratus as shown in Fig. 9; Fig. 12 shows an internal schematic representation of a pneumati c circuit used as part of another apparatus a ccording to the present invention; and

Fig. 13 shows a schematic representation of an appa ratus according to the present invention including the pneumatic circuit shown in Fig. 12. With reference to the drawings, and initia lly to Fig. 8, there is shown a pneumatic circuit 100 which comprises pa rt of an a pparatus that can be installed on a railway vehicle 37 and arra nged to a pply lubricant to the railway vehicle wheels 3. The circuit 100 has a distribution unit 101 comprisi ng a valve block 102 which, in this example, is made from aluminium through which is formed a passage or i nlet 104 for the i ntake of air. The ai r inlet 104 leads to a n air solenoid valve 112 which controls the flow of air from the inlet 104 to an outlet passage 114 which is a lso formed through the block 102. In use, when the apparatus is installed on a railway vehicle, the air inlet 104 is connected to the vehicle's air compressor/reservoir 106 via a n a ir inlet supply pipe 108 to provide a supply of com pressed a ir to the inlet 104. The supply of ai r from the reservoi r 106 is controlled by an air pressure regulator 110 disposed in the air supply pipe 108 and a rranged to limit the passage of air supplied to the system to about 8 ba r.

The a ir outlet passage 114 is connected by a pipe 118, 126 to a second inlet passage 124 formed i n the valve block 102. The pipe 118, 126 extends from the outlet 114 to the inlet 124 via a grease (or other lubrica nt) tank 116. A grease outlet 122 from the grease ta nk 116 connects the ta nk to the pipe 126 extending from the tank 116 to the second i nlet 124 of the valve block 102. The grease tank comprises an air operated piston pump. The pump is connected to a n outlet 120 from the pipe 118 exte ndi ng from the outlet passage 114 of the va lve block 102 to the grease tank 116. The pump is driven by change in a ir pressure at the outlet 120. An increase in pressure ca uses the pump to deliver a qua ntity of grease via outlet 122 into the pipe 126 leading from the tank 116 to the valve block 102. The outlet 122 is arranged to distribute grease onto the inside wall of the pipe 126. To cause the pump to deliver a further quantity of grease, the air pressure at outlet 120 must be reduced, and increased again i n order to cause the pump to operate another cycle. The second inlet passage 124 in the valve block extends to a ma nifold within the block where it divides (i n this em bodiment) into four cha nnels 128 each having a respective air/grease solenoid valve 130 for controlling flow through the conduit to a respective outlet 132 from the block 102. The outlets 132 a re each connected to air/grease supply pipes 134. A divi der 136 is attached to the e nd of each supply pipe 134 and serves to split the pipe 134 into two separate nozzle supply pi pes 138 a long which air and grea se may flow . The pipes 108, 118, 126, 134, 138, in ts 104, 124 a nd outlets 114, 132 have a bore size of around 8mm whilst the valves 112, 130 have a bore size/inte rna i dia meter of a round 3mm.

The nozzle supply pipes 138 a re each connected to corresponding nozzles 140 having a bore size/internal diameter of around 1mm and ca pable of delivering a well-defined cone of grease pa rticles. Thus, each a ir/grease supply pipe 134 leads to a pair of nozzles 140. An adjusta ble dual nozzle mounting block 142 is provided to w hich two nozzles 140 may be mounted so that the position of the nozzles 140 relative to a wheel 3 can be a djusted. In the example show n in Fig. 10, one nozzle 140 is arranged to direct a cone of grease towa rd the ga uge/fla nge side periphery of the wheel tread 15 which includes the flange root 19 a nd the other nozzle 140 is a rranged to direct a cone of grease towa rd the field side 13 of the wheel tread 15.

The appa ratus further comprises an electronic control unit 144 which is connectab!e to the ra ilway vehicle's electrica l power supply 146 via a n electrical cable 148. The control unit 144 is connected to the railway vehicle's zero speed a nd forward signals 150 which a re used to determine when the vehicle is stationary and the di rection of travel . When the vehicle is stationary, the control unit is programmed to suppress the application of I ubricant from the system since this is unnecessa ry and would result in wastage of lubricant. Knowledge of the direction of travel is useful since this enables the control unit to apply lubrica nt only to the leading wheels i.e. the wheels at the front of the railway vehicle depending on the di rection of travel. Thus, when the railway vehicle travels in an opposite direction, the wheels at the opposite end of the vehicle are determ ined to be th e front wheels a nd l ubricant is dispensed toward those wheels accordingly. In addition, the control unit is connected to the railway vehicle's global positioning satellite or passenger information system 152 for determining railway vehicle position.

The electronic control unit 144 is also connected to the rai lway vehicle's GPS ante nna feed or its RF!D reader 154, and is equipped with a wheel speed detector 156 which may be used with the ra i lway vehicle's wheel speed encoder disc 158 to determine the speed of the vehicle. The detected ra i lway vehicle speed can be used to determine the dista nce travelled which enables lubrica nt to be dispensed at specific distance i ntervals. The electronic control unit 144 furthe r comprises inertiai detection electronics or bend sensors for measuring the rotation of the vehicle about the horizonta l pla ne and the rai lway vehicle yaw or a ngula r velocity about the vehicle's ve rtical axis, a nd ai r valve driver control electronics for controlling the operation of the solenoid valves 112, 130 and hence the flow of a ir and grease through the pneumatic ci rcuit 100. The control unit 144 is operated by software which determines and records the vehicle speed, position a nd angular velocity (yaw), and operates the valves accordingly to prime the pneumatic circuit 100 with grease and dispense an appropriate volume of grease to pa rticular regions of the wheel.

The a pparatus may be mounted to the underside or inside of the ra ilway vehicle during construction or it may be retrofitted. The nozzle mounting blocks 142 a re a rranged to the side of and about ha lfway up the vehicle wheels 3 so that, when the nozzles 140 a re mounted in place, they ca n direct a cone of grease towa rd the outer circumference of the wheel. In this embodiment, the nozzles 140 a re directed towa rd either the fla nge root area 19 of the wheel or the field side area of the wheel tread 15. Thus, when the wheels rotate a nd the nozzles 140 a re activated, the regions of the tread to which the nozzles are directed a re coated with I ubricant around the circumference of the whee l 3. One nozzle 140 of a pair of nozzles supplied by a single a ir/grease supply pipe 134 is mounted adjacent a first wheel on one side of the vehicle and directed towa rd the fla nge root region 19 of that wheel 3. The other nozzle 140 of the pair is mounted adjacent a second wheel on the opposite side of the vehicle a nd is directed toward the field side region of the wheel tread 15. Thus, when on a bend such that the first wheel is on the high rail 41 and the second wheel is on the low rail 43 the a pplication of grease through the pair of nozzles from the common supply pipe 134 ta rgets the appropriate portion of each wheel 3. Likewise, one nozzle 140 of a nother pa ir is mounted adjacent the first whee l 3 and is directed toward the field side of the wheel tread 15 a nd the other nozzle 140 of the pair is mounted adjacent the second wheel 3 a nd directed toward the flange side of the w hee l 3. Two other pairs a re mounted to a nother pair of wheels 3 on respective sides of the vehicle i n corresponding fashion. I n use, in order to dispense grease from the nozzles to the vehicle wheels 3 grease must first be introduced into the pipe 126 extending from the grease ta nk to the vaive block 102. To achieve this, the air inlet solenoid valve 112 is opened whilst the air and grease outlet solenoid valves 130 rema in closed. This causes the a ir pressure at the outlet 120 leading to the grease pump to increase and ca uses the pump to deliver a quantity of grease into the pipe. To deliver further quantities of grease i nto the pipe 126 the air pressure at the outlet 120 must be decreased and increased aga in. This is achieved by closing the air inlet solenoid valve 112 a nd opening one or more of the air a nd grea se outlet valves 130 to a llow compressed a ir to flow from the system. Release of compressed ai r tra pped within the system produces a relatively sma ll ai r flow from the nozzles, which will result in little or no grease being dispensed from the nozzles. This priming cycle can be repeated as often as necessa ry, briefly opening the inlet va lve 112 to pressurise the system and briefly opening one or more outlet valves 130 to release pressure, to introduce a desired qua ntity of grease into the pipework. In this way, the pipework acts as a rese rvoir for lubrica nt before it is dispensed. To dispense grease from the nozzles the air in!et valve 112 is opened and one or more selected air/grease outlet valves 130 are opened. This allows a significant volume of compressed a ir to flow from the a ir supply and out through two or more nozzies 140. The flow of air is sufficient to entrain grease disposed on the inside of the pipework a nd cha nnels downstream of the grease ta nk to p roduce a fi ne mist of grease from the nozzles. Since the grease has a slow flow rate through the pipes compa red to a ir, the volume of grease dispensed at each nozzle 140 is largely determined by the duration of air flow through the selected nozzles 140, So, the tota l q uantity of grease dispensed is a rrived at by controlling the quantity of grease introduced into the system from the grease ta nk a nd the duration of operation of the nozzles 140.

The in!et and outlet valves are operated under progra mmed control of the control unit 144. The control unit 144 is a rranged to operate the va lves, as discussed a bove, to prime the system with a desired quantity of grease. It subsequently ca uses grease to be dispensed from selected pairs of nozzles to apply lubricant to selected areas of the vehicle's wheels 3 when certain track conditions are met. Alternatively, the system may have a plura lity of nozzles each supplied by its own ai r/grease supply pipe via a respective second va lve such that each nozzle can be selected independe ntly of a ny other nozzle for the a pplication of grease.

Primarily, the control unit 144 is arranged to cause lubricant to be applied to the gauge corner of wheels 3 about to travel on the high rail of a bend a nd to the field side of whee ls about to travel on the low rail of the bend just before the wheels enter the bend. Lubrica nt may a lso be dispensed whilst the wheels travel a round the bend. The vol ume of l ubricant dispensed may be dependent on the radius of the bend.

The control unit 144 can determine the configuration of the track the vehicle is a pproaching by com pa ring the vehicle position determined by the GPS sensor, possibly in addition to th e vehicle's speed and/or dista nce travelled, measured from the vehicle's wheels, to stored information a bout the configuration of the track, effectively a ma p.

The control unit 144 may in addition, or as a n a lternative when GPS cannot be obtained, such as in a tunnel, determine the position of the vehicle by using the RFI D tag reader 154 to detect existing RFI D tags located periodically a long the railway network, for exa mple, on the datum plates. Knowing the position of each datum plate a long the network a nd detecting the datum plate to which the train is a djacent using the RFID tag reader ena bles the position of the rai lway vehicle to be determi ned. Specific RFID tags that are associ ated with datum plates that a re positioned before a bend can be used by the control unit 144 to trigger the application of lubricant from the nozzles 140 to the appropriate regions of the w heels 3.

A low coefficient of friction lubricant which gives rise to a coefficient of friction between the wheei a nd the track of around 0.1 ca n be directed towa rd the flange root area 19 of the wheel 3 before contact is made between the flange 17 and the ga uge shoulder 29 or gauge corner 27 of the railhead . The application of lubricant prior to contact between these regions of the wheel 3 a nd rail 5 reduces wheel flange wear, fla nge squeal and rolling contact fatigue in the railhead. A low coefficient of friction l ubrica nt ca n a lso be directed by a nozzle 140 towa rd the field side of the running tread of the wheel 3 at regions where rolling contact fatigue in the wheei 3 is known to occur such as on the low ra il of a be nd. Application of lubricant to this region of the wheel before it encounters a bend in the track reduces wear in the ra ilhead, squea ling a nd roiling contact fatigue in the wheel 3. To avoid affecting the bra king performance of the railway vehicle beyond normal limits, lubri cant is di rected by the nozzles to the edges of the wheel's main rolli ng surface rather tha n the main rolling surface itself where the majority of braking occurs.

The respective bore sizes of the pipes 108, 118, 126, 134, 138, valves 112, 130, i nlets 104, 124, outlets 114, 132 a nd nozzles 140 is such that the air resista nce of the pipework and valves is low relative to the nozzle orifices from which the grease is dispensed, Thus, almost the full regulated a ir pressure will drop across the nozzles 140 w hen they are selected by a corresponding air/grease solenoid va lve 130. Consequently, when a nozzle 140 is selected the air flow speed from the rese rvoir 106 through the distribution unit 101 to the nozzles 140 will be substa ntially consta nt a nd the dispense vol ume for a given dispense time will a lso be substantia lly consta nt. It is th erefore possible to dispense a known quantity of grease over a given period of time and thereby a pply an appropriate a mount of lubricant to a pa rticufar region of the wheel tread 15 a long a specific pa rt of the track.

The control unit 144 may also use data from the bend/yaw sensors to determine when the vehicle is running on straight or curved track. This ena bles information a bout the track to be determined when neither GPS nor RFID data is obta inable or where the local configuration of the track is not known to the control unit. A stra ight portion of track is defined as a yaw signal detected by th e bend sensor of 1 degree per second or less. When the railway vehicle is on a stra ight portion of track, the appa ratus is programmed to dispense lubricant at specific time interva ls such as every 60 seco nds or at specific distance intervals such as every 500 metres. A bend is defined as a yaw signa l detected by the bend sensor of greater tha n 1 degree per second. The system is configured to dispense lubricant on a variable time basis usi ng the bend sensor a nd speed measurements to determi ne the tightness of a bend and hence how often to apply lubricant to the train wheels. Thus, even when the railway vehicle's track location cannot be determined, it is stili possible to detect when the ra ilway vehicle is on a stra ight region of track or a bend a nd therefore adjust the application of lubrica nt accordingly. It will be appreciated that where the apparatus relies only on speed and bend sensors to give an i ndication of the radius of a bend it is only able to determine the instanta neous configuration of the tra ck rather tha n predict it The control unit 144 may be arranged to dispense lubricant to the wheels other tha n when bends a re encountered. For example, it may be arra nged to dispense lubricant when the vehicle trave ls over points. The points at which the lubricant is dispensed may be determined by GPS position with reference to a GPS ma p of stored locations.

With reference to Figs. 11 and 12, an alternative embodiment comprises two grease tanks 116, 216 both of which are connectable to the ra ilway vehicle's a ir reservoir 106 via a common inlet supply pipe 108 a nd respective inlets 104, a ir solenoid valves 112 a nd outlet pipes 114, 118. I n this embodi ment, one grease ta nk 116 supplies one set 160 of nozzles 140 and the other grease ta nk 216 supplies another set 162 of nozzles 140. Since the a pparatus is larger than that of the first embodiment, there are no dividers 136 present; rather there is one nozzle supply pipe 134 and a corresponding a ir/grease solenoid va lve 130 associated with each nozzle 140. This provides even greater control a nd flexibility over the dispensing of grease than the first embodiment since individua l nozzles 140 can be activated independently of any other nozzles 140 by operating the appropri ate air/grease solenoid valve 130. Such an arra ngement permits different lubricants to be applied to different parts of the wheel tread.

The appa ratus may be mounted to a railway vehicle such that each nozzle 140 of one set 160 is directed toward the fla nge root a rea 19 of a wheel 3 a nd each nozzle 140 of the other set 162 is directed toward the wheel tread area IS of a wheel 3. This is useful where it is desirable to apply different types of lubricant to different regions of the wheel 3. One such instance is where the objective is to reduce fla nge wea r a nd suppress wheel squeal. I n this case, a l ubricant having a coefficient of friction of around 0.1 (low coefficient) is stored in the first grease tank 116 and applied to the w heel fla nge root a rea 19 via the nozzles 140 of the first set 160. A lubrica nt having a coefficient of friction of around 0.2 to 0.4 (medium coefficient) is stored in the second grease tank 216 and applied to the centre of the wheel trea d a rea 15 via the respective nozzles 140 of the second set 162. The coefficient of friction of the second lubrica nt is chosen to keep friction between the wheel tread 15 and the rail 5 to an acceptable level without compromising the braking performance of the vehicle, since braking takes place at this region. Since the flange root area 19 of the wheel 3 is not used in the braking process, a low coefficient of friction lubricant may be used. It is of course to be understood that the above embodiment has been described by way of example only and that many variations are possible without departing from the scope of the invention as defined by the appended claims.