WO2013170278A1

WO2013170278A1 - Device for dispensing lubricant

Info

Publication number: WO2013170278A1
Application number: PCT/ZA2013/000033
Authority: WO
Inventors: Noel Ian CURRIN
Original assignee: Currin Noel Ian
Priority date: 2012-05-07
Filing date: 2013-05-07
Publication date: 2013-11-14

Abstract

The invention relates to a device (10) for dispensing lubricant which includes a casing (12) shaped and configured to define a lubricant inlet ( 14) and at least one lubricant outlet (16). A lubricant actuator, housed within the casing (12), alternatively displaceable between a first position and a second position and configured to define a first lubricant metering chamber (20) and a second lubricant metering chamber (22) within and in conjunction with the casing (12). The casing (12) houses a control actuator (24), alternatively displaceable between a base position and a control position in order to regulate lubricant flow and an biasing element (26) configured to bias the control actuator (24) toward the base position.

Description

DEVICE FOR DISPENSING LUBRICANT

TECHNICAL FIELD OF THE INVENTION

The invention relates to lubricating devices.

BACKGROUND TO THE INVENTION

Lubricant dispensing devices, also referred to as lubricant injectors, are used to supply timed, set amounts of lubricant, such as oil or grease and the like, to components and locations requiring lubrication. The inventor is aware of traditional lubricating devices that typically use a single acting cylinder which doses a specific amount of lubricant once each dosing cycle through filling a cavity with lubricant and discharging the contents of the cavity by applying pressure on the cylinder arrangement by means of a pressurised lubricant line. The inventor has identified limitations in this arrangement especially in association with the time between dosing cycles, as the pressure applied to expel lubricant from the cavity must be released or equalised before another cycle can be started. The inventor has also noticed that features and configurations aimed at reducing the time between the dosing cycles often greatly increases the size and cost of the device. Other lubricating devices of which the inventor is aware are actuated by means of two separately pressurised lubricant lines. In such an application each line is alternatively pressurised in order to actuate the dosing cylinder first in one direction and then in the opposite direction inside the lubricating device. SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a device for dispensing lubricant which includes:

a casing shaped and configured to define a lubricant inlet and at least one lubricant outlet;

a lubricant actuator, housed within the casing, alternatively displaceable between a first position and a second position and configured to define a first lubricant metering chamber and a second lubricant metering chamber within and in conjunction with the casing;

a control actuator, alternatively displaceable between a base position and a control position in order to regulate lubricant flow such that:

the first lubricant metering chamber is in fluid communication with the lubricant inlet when the control actuator is in the base position and alternatively the first lubricant metering chamber is in fluid communication with a lubricant outlet when the control actuator is in the control position;

the second lubricant metering chamber is in fluid communication with a lubricant outlet when the control actuator is in the base position and alternatively the second lubricant metering chamber is in fluid communication with the lubricant inlet when the control actuator is in the control position; and

a biasing element configured to bias the control actuator toward the base position.

The casing may be configured to connect to a lubricant supply reservoir, with the supply reservoir typically including a pump for delivering lubricant at increasing pressure. The pump may be used in conjunction with a pressure release valve which is typically configured to drain lubricant under pressure into the supply reservoir.

The lubricant inlet may be in fluid communication with the supply reservoir, which may be achieved through bolting the casing onto a lubricant supply block or manifold, with a supply bore defined within the block. The casing may be secured to the supply block by means of a bolt, and the bolt may be shaped to define an inlet bore in order to allow lubricant flow therethrough, this is also referred to as a manifold mounting method. The bolt and block are preferably configured such that the lubricant from the supply reservoir flows through the supply bore in the supply block and enters the lubricant inlet through the inlet bore in the bolt. The supply block may be configured to have a plurality of casings mounted thereon with the lubricant inlet of each casing in fluid communication with the supply reservoir.

Alternatively the casing may be configured to be mounted in accordance with a modular mounting arrangement with the inlet in direct fluid communication with the supply reservoir. The modular mounting method typically does not include a mounting bolt and the casing is attached to the supply block by other attachment means which may include the use of screws. The casing may consist of multiple sections or casing blocks, typically attached during assembly of the device. For one embodiment of the invention two separate blocks are attached by means of coinciding left hand and right hand screw-in thread arrangements pulled relatively towards each other by means of a hex key or Allen key. For a preferred embodiment, the casing is divided into three casing blocks namely the metering block which houses the lubricant or metering actuator, the control block which houses the control actuator and the spring holder block which houses the biasing element, usually in the form of a spring.

In the instance where there is a single lubricant outlet, it should be appreciated that the volume of lubricant delivered to the lubricant outlet is determined by the combined volume of the lubricant metering chambers. In the further event that each metering chamber is connected to a designated outlet, it should be appreciated that the volume of lubricant dispensed through the outlet is determined by the volume of the individual lubricant chamber. The two lubricant metering chambers may be defined by locating the lubricant actuator within a single larger chamber, such that the lubricant actuator divides the larger chamber into the two smaller metering chambers. It is to be appreciated that this arrangement allows for a configuration where the filling of one metering chamber under pressure ejects the contents of the other metering chamber.

The lubricant actuator may be a shaft and plunger arrangement such as a metering piston. The shaft may protrude from the casing; the inventor believes that one advantage of having the shaft protrude from the casing is that it provides a visual reference for the lubricant actuator's movement. The lubricant actuator's stroke may be adjustably limited in order to regulate the amount of lubricant dispensed to an outlet. This limitation may be achieved with the use of an adjustable screw in arrangement used to vary the volume of the lubricant chambers. The adjustable screw in arrangement may also include a securing mechanism for fixing the volume of the metering chambers after adjustment. The securing mechanism may include a grub screw or hex screws of differing lengths. Fluid communication between the lubricant chambers and both the lubricant inlet and one or more lubricant outlets may be established by means of lubricant tunnels or flow paths defined within the casing. Typically four tunnels or flow paths are defined, with two flow paths defined to link the lubricant metering chambers to the inlet and another two flow paths defined to link the lubricant metering chambers to at least one outlet. Sections of the flow paths may overlap for both the inlet flow path and the outlet flow path linked to one of the lubricant metering chambers.

The control actuator may be in the form of a shaft snugly housed within a bore defined by the casing. Sections of the shaft may be of reduced cross section, to form shaft reductions, which, depending on the relative position of the shaft within the bore, may be used to control the flow of lubricant transversely through the bore. The position of the control actuator may be used to determine whether a certain section of the flow path is in fluid communication with the inlet or the outlet. The shaft reductions allow lubricant flow through the bore within the casing when aligned with the flow paths when the control actuator is displaced, certain flow paths are blocked due to misalignment of the flow paths, thereby regulating flow of lubricant between the metering chambers, the inlet and one or more outlets.

The biasing element may be in the form of a coil or spring housed within the casing. The spring or coil may be attached to an end region of the control actuator and is typically configured to bias the control actuator toward the inlet. It will be appreciated that the force exerted by the biasing element will keep the control actuator in the base position until inlet pressure established by a pump near the supply reservoir overcomes the force of the biasing element.

The casing may also be shaped to define a back pressure chamber in fluid communication with the lubricant outlet. The back pressure chamber is included in a preferred embodiment of the invention in order to prevent an obstruction of the outlet from affecting the movement of lubricant and/or control actuator. The biasing element may be housed within the back pressure chamber.

In use, for one embodiment of the invention, the inlet is connected to the supply reservoir, whereupon the first lubricant metering chamber is filled with lubricant, moving the lubricant actuator from the first position to the second position, with the content of the second lubricant chamber ejected to the outlet. With the first lubricant chamber filled, inlet pressure increases as a result of the pump and continues to increase until the inlet pressure overcomes the force of the biasing element, resulting in the control actuator moving from the base position to the control position. With the control actuator in the control position, lubricant flows from the inlet into the second lubricant chamber, forcing the lubricant actuator back to the first position and ejecting the contents of the first lubricant chamber to the outlet. At this stage inlet pressure is reduced by deactivating the pump and lubricant is relieved back to the supply reservoir. Pressure at the lubricant inlet reduces until it no longer overcomes the force of the biasing member, which results in the control actuator moving back to the base position. With the control actuator returned to the base position at least some of the lubricant near the inlet and still under residual pressure fills the first lubricant chamber, dissipating the residual pressure at the inlet and readying the device for the next dosing cycle. It is to be appreciated that some of the content of the second metering chamber is ejected to the outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by means of a non-limiting example with reference to the accompanying drawings.

In the drawings:

Figure 1 shows a cross sectioned side view of a first embodiment of a device for dispensing lubricant, in accordance with the invention;

Figures 2 and 3 show cross sectioned views of the device in figure 1 depicting tunnels defined within the device;

Figures 4 and 5 show cross sectioned side views of the device depicted in figure 1 with certain features shown in greater detail;

Figure 6 shows a three dimensional perspective view of a device for dispensing lubricant, in accordance with the invention.

Figure 7 shows a three dimensional perspective view of a device for dispensing lubricant, in accordance with the invention;

Figure 8 shows a three dimensional perspective view of three different size of the device depicted in figure 6 in a mounted state;

Figures 9 to 13 show cross sectioned views of a second embodiment of a device for dispensing lubricant, in accordance with the invention, with a control actuator in the base position;

Figures 14 to 19 show cross sectioned views of the embodiment shown in Figure 9 with the control actuator in the control position; and

Figure 20 shows a schematic representation of a system which incorporates the device for dispensing lubrication. SPECIFIC DESCRIPTION OF THE INVENTION

Referring to the drawings the device for dispensing lubricant, in accordance with the invention, is generally depicted by reference numeral 10.

The device 10 shown in Figures 1 to 6 includes a casing 12 shaped to define a lubricant inlet 14 and a lubricant outlet 16. The casing 12 houses a lubricant actuator in the form of a metering piston 18, displaceable between a first position and a second position and housed within the casing 12 to define a first lubricant metering chamber 20 and a second lubricant metering chamber 22 in conjunction with the casing 12. The injector includes a control actuator in the form of a control piston 24, displaceable between a base position and a control position in order to regulate lubricant flow within the device 10. An biasing element in the form of a coil 26 is included in order to bias the control piston 24 toward the base position.

The casing 12 is connected to a lubricant supply reservoir (not shown), which includes a pump (not shown) for delivering lubricant with increasing pressure. The lubricant inlet 14 is connected in fluid communication with the supply reservoir (not shown), by bolting the casing 12 onto a lubricant supply block 28, which has a supply bore (not shown) defined therein. A bolt 32 securing the casing 12 to the supply block 28 is configured to define an inlet bore (not shown) such that the lubricant from the supply reservoir (not shown) flows through the supply bore in the supply block 28 and enters the lubricant inlet 4 through the inlet bore in the bolt 32. In figure 7 the supply block 28.1 is configured to have a plurality of casings 12 mounted thereon with the lubricant inlet 14 of each casing 12 in fluid communication with the supply reservoir (not shown).

The casing 2 consist of two casing blocks 34 and 36, attached during assembly of the device. Shown in detail in Figure 5 the casing blocks are attached by means of coinciding left hand and right hand screw-in thread arrangements pulled relatively towards each other by means of a hex key (not shown) located in the hex aperture defined in the first casing block 34.

The amount of lubricant delivered to the lubricant outlet 16 is determined by the volume of the lubricant metering chambers 20, 22. The two lubricant chambers 20, 22 are defined by the metering piston 18 positioned within a single larger chamber 36, subdividing the larger chamber 36 which allows for an arrangement where the filling of one chamber under pressure moves the metering piston and ejects the contents of the other chamber. The metering piston 18 includes a pin 38 and a plunger 40. The pin 38 protrudes from the casing 12 in order to provide visual confirmation that the metering piston 18 is moving. The pin 38 and plunger's 40 stroke can be adjustably limited in order to regulate the amount of lubricant dispensed to the outlet 16. The limitation is achieved through the use of a threaded screw-in arrangement 30 limiting the movement of the pin 38 which varies the volume of the lubricant chambers 20, 22.

The control piston 24 is made up of a shaft 46 snugly housed within a bore 48 defined by the casing 12. Sections of the shaft 46 are of reduced cross section, to form shaft reductions 50 in order to allow lubricant to flow past the shaft 46 through the bore 48. The location of the shaft reductions 50 in conjunction with the position of the shaft 46 within the bore 48 is used to control the flow of lubricant transversely through the bore 48.

With the control piston 24 in the base position the first lubricant chamber 20 is in fluid communication with the lubricant inlet 14 and the second lubricant chamber 22 is in fluid communication with the lubricant outlet 16. Alternatively when the control piston 24 is in the control position, the first lubricant chamber 20 is in fluid communication with the lubricant outlet 16 and the second lubricant chamber 22 is in fluid communication with the lubricant inlet 14. Fluid communication between the lubricant chambers 20, 22 and the both the lubricant inlet 14 and the lubricant outlet 15 are established by means of lubricant tunnels 52 defined within the casing 12. Depicted in Figure 3 when the control piston 24 is in the base position, a first flow path links the first lubricant chamber 20 with the inlet 14. Lubricant flows along lubricant tunnel 52.1 , through a first shaft reduction 50.1 and along lubricant tunnels 52.2 and 52.3 into the first lubricant chamber. Depicted in Figure 2 when the control piston 24 is in the control position a second flow path links the second lubricant chamber 22 with the lubricant inlet, lubricant flows along an area of the bore 48 vacated by the shaft 46 into lubricant tunnel 52.4 and along 52.5. A third flow path links the first lubricant chamber 20 with the lubricant outlet 16 when the control piston 24 is in the control position, lubricant flows along lubricant tunnel 52.3 and 52.2, through a second shaft reduction 50.2 and out along lubricant tunnel 52.6. A fourth and final flow path links the second lubricant chamber 22 with the lubricant outlet 16 when the control piston 24 is in the base position, lubricant flows along lubricant tunnel 52.5 and 52.4, through the second shaft reduction 50.2 and out along lubricant tunnel 52.6. It is to be appreciated that the lubricant flow paths and the flow within the tunnels depend on the position of the control piston 24.

The coil 26 housed within the casing 12 is attached to an end region of the control piston 24 and is configured to bias the control actuator toward the inlet 14. The force exerted by the coil 26 keeps the control piston 14 in the base position until inlet pressure established by the supply reservoir and pump combination (not shown) overcomes the force in the coil 26.

The casing 12 is shaped to define a back pressure chamber 54 in fluid communication with the lubricant outlet 16. The back pressure chamber 54 is included in order to prevent an obstruction of the outlet 16 from affecting the movement of lubricant metering piston 18 and/or control piston 24. The coil 26 is housed within the back pressure chamber 54.

The casing defines two outlets in parallel 16.1 and 16.2 such that lubricant can be injected into one of the outlets in order to provide lubricant to the other output directly. In use, the embodiment depicted in the drawings, is connected to the supply reservoir (not shown) with the inlet 14 in fluid communication with a lubricant supply (not shown). The first lubricant chamber 20 fills with lubricant, resulting in the metering piston 18 moving from the first position to the second position and the content of the second lubricant chamber 22 is ejected to the outlet 16. After the first lubricant chamber 20 is filled, inlet pressure increases as a result of the pump (not shown) and continues to increase until the inlet pressure overcomes the force of the coil 26, usually around 70 bar, resulting in the control piston being moved from the base position to the control position. With the control piston in the control position, lubricant flows from the inlet 14 into the second lubricant chamber 22, forcing the metering piston back to the first position and ejecting the contents of the first lubricant chamber 20 to the outlet 16. At this stage inlet pressure is reduced by de-activating the pump (not shown), pressure at the lubricant inlet slowly recedes until the force in the coil 26 is greater than the force exerted by the inlet pressure, causing the control piston 24 to move back to the base position. Importantly, some of the lubricant near the inlet 14 and still under some residual pressure now enters the first lubricant chamber 20, dissipating the residual pressure at the inlet 14 and readying the injector 10 for the next dosing cycle. As depicted in Figure 8 different sizes or different embodiments of the device 10,

100 can be mounted in parallel. Each device 10, 100 supplying measured amounts of lubricant to a specific location requiring lubrication.

Referring to Figures 9 to 24 the device for dispensing lubricant, in accordance with the invention, is generally depicted by reference numeral 210.

The device 210 includes a casing consisting of three casing blocks 212, namely a metering block 212.1 a control block 212.2 and a spring holding block 212.3. The control block 212.2 is configured to define a lubricant inlet 214 a first lubricant outlet 216.1 and a second lubricant outlet 216.2. A lubricant actuator in the form of a metering piston 218 is housed within the metering block 212.1 displaceable between a first position and a second position. The metering piston 218 is shaped and located to define a first lubricant metering chamber 220 and a second lubricant metering chamber 222 within and in conjunction with the metering block 212.1 and the control block 212.2. The device 210 further includes a control actuator in the form of a control piston 224 housed within the control block 212.2 that is alternatively displaceable between a base position and a control position in order to regulate lubricant flow within the device. A spring 226 is provided in order to bias the control piston 224 toward the base position as seen in Figure 9. The control piston 224 is arranged within the casing 212 such that the first lubricant metering chamber 220 is in fluid communication with the lubricant inlet 214 when the control piston 224 is in the base position and alternatively the first lubricant metering chamber 220 is in fluid communication with the first lubricant outlet 216.1 when the control piston 224 is in the control position. Similarly the control piston 224 is arranged within the casing 212 such that the second lubricant metering chamber 222 is in fluid communication with the second lubricant outlet 216.2 when the control piston 224 is in the base position and alternatively the second lubricant metering chamber 222 is in fluid communication with the lubricant inlet 214 when the control piston 224 is in the control position.

The metering piston 218 includes a pin 238 and a plunger 240 housed within the metering block 2 2.1 with the pin 238 projecting from the block in order to provide visual confirmation of the movement of the metering piston 218. The volume of lubricant dispensed through each outlet 216 is determined by the volume of the connected lubricant chamber 220, 222. The two lubricant metering chambers 220 and 222 are defined by locating the metering piston 218 within a single larger chamber 236, such that the plunder 240 divides the larger chamber 236 into the two smaller metering chambers 220 and 222. It is to be appreciated that this arrangement allows for a configuration where the filling of one metering chamber under pressure ejects the contents of the other metering chamber. The control piston 224 is made up of a shaft 246 snugly housed within a bore 248 defined within the control block 212.2. Sections of the shaft 246 are of reduced cross section, to form shaft reductions 250 in order to allow lubricant to flow past the shaft 246 through the bore 248. The location of the shaft reductions 250 in conjunction with the position of the shaft 246 within the bore 248 is used to control the flow of lubricant transversely through the bore 248.

Fluid communication between the lubricant chambers 220, 220 the lubricant inlet 214 and both the lubricant outlets 216 are established by means of lubricant tunnels 252 defined within the casing 212.

The spring 226 housed within the spring holding block 212.3 urges against an end region of the control piston 224 and is configured to bias the control actuator toward the inlet 214. The force exerted by the coil 226 keeps the control piston 224 in the base position until inlet pressure established by a supply reservoir and pump combination (not shown) overcomes the force in the coil 226.

The sequence in which the device operates will now be set out with reference to the Figures.

In Figure 9 with the control piston 224 in the base position, lubricant is pumped under pressure into inlet 2 4 from a supply reservoir (not shown). Lubricant flows along lubricant tunnels 252.1 and 252.2, then transversely through the bore 248 via a first shaft reduction 250.1 and along lubricant tunnels 252.5 and 252.6 seen in Figure 10 through lubricant tunnels 252.6 and 252.7 into the first metering chamber 220 as seen in Figure 11. When the first metering chamber 220 fills with lubricant under pressure from the inlet 214, the metering piston 218 and plunger 240 are displaced to eject the content of the second metering chamber 222 to the second lubricant outlet 216.2. As seen in Figure 11 lubricant flows along lubricant tunnels 252. 8 and 252.9 then in Figure 12 via 252.9 and 252.10 through a second shaft reduction 250.2 into the spring cavity 254 in the spring holder block 212.3. As seen in Figure 13 form the spring holder block 212.3 lubricant is expelled via lubricant tunnels 252.11, 252.12 and 252.13 to the second lubricant outlet 116.2.

In Figure 14 once the first metering chamber 220 is filled, the increasing pressure at the lubricant inlet 214 will at a specific level overcome the force within the spring 226 resulting in the control piston 224 moving from the base position to the control position. In this position lubricant flows along flow path 252.1 and 252.2 through the first shaft reduction 250.1 then as seen in Figure 5 and Figure 16 along 252.10 and 252.9 via 252.8 into the second metering chamber 222. The inlet pressure again forces the metering piston 218 and plunger 240 to be displaced, this time ejecting the content of the first metering chamber 220 to the first lubricant outlet 216.1. The lubricant flows from the first metering chamber 220 along lubricant tunnels 252.7, 252.6 and 252.5 depicted in Figures 17 and 18 and flows through the bore 248 at a third shaft reduction 250.3 and via lubricant tunnel 252.14 to the first lubricant outlet 216.1 as seen in Figure 19.

At this stage the pressure at the inlet is reduced, by switching off the lubricant pump and opening a lubricant pressure relief valve. The sequence depicted in Figures 9 through 13 is repeated once the force within the spring 226 overcomes the pressure at the inlet 214, the control piston 224 returns the base position again as shown in Figure 9. Lubricant again flows from the inlet 214 to the first lubricant metering chamber 220 due to the residual pressure within the lubricant supply line. At least some of the lubricant in the second metering chamber 222 is also again ejected to the second lubricant outlet.

Figure 20 shows a system for dispensing lubricant which consists of a pump, a vent valve, main line piping, injectors at various positions along the piping and a pressure switch. The system is controlled by a PLC or similar controller. When the controller starts the system, the pump is switched on and the vent valve is closed. Lubricant flows along the main line pipe until it enters each injector, in parallel. Within each injector, lubricant is directed to a metering piston via a control piston. The metering piston will move downwards, forcing lubricant from its lower end to travel via the control piston to outlet 2. This is connected by secondary piping to a bearing.

Once all the injectors have ejected grease, there is an increase in pressure in the main line pipe. When this pressure reaches 11 MPa (typically) the control piston will be forced downwards by the pressure. With the control piston in the down position, lubricant will be directed to the lower end of the metering piston, forcing it up. Lubricant on its top end will be forced via the control piston to outlet 2. This is connected by secondary piping to another bearing. When all injectors have ejected lubricant from outlet 1 , the pressure in the main line pipe will continue to increase (until, say 20 MPa), at which point the pressure switch will signal the controller that the cycle has been completed. The controller will turn off the pump and open the vent valve is opened back to the pump reservoir. When the pressure at any injector reaches about 8 MPa, the control piston will be returned by spring force to its up position. This will direct lubricant still under line pressure to flow via the control piston to the top end of the metering piston, forcing it downwards to some extent and ejecting lubricant from outlet . As the metering piston moves, it absorbs volume from the main pipe, causing an immediate drop in pressure. As the pressure in the main line drops at an injector, it causes a reduction in pressure at the next injector to below 8 MPA and the foregoing process is repeated for each injector.

The inventor believes that because this configuration for a lubricant dispenser results in partially absorbing residual pressure within the lubricant supply lines these embodiments will decrease time between lubrication cycles compared to some known devices, as there is no longer a requirement to wait for the pressure to reduce by way of drainage. It is to be appreciated that a lubricant injector in accordance with the invention is not limited to the precise constructional and functional details as set out herein.

Claims

1. A device for dispensing lubricant which includes:

a casing shaped to define a lubricant inlet and at least one lubricant outlet;

a control actuator, housed within the casing, alternatively displaceable between a base position and a control position in order to regulate lubricant flow within the casing; and

2. A device for dispensing lubricant as claimed in claim 1 wherein the control actuator is configured to regulate flow such that:

the first lubricant metering chamber is in fluid communication with the lubricant inlet when the control actuator is in the base position and alternatively the first lubricant metering chamber is in fluid communication with a lubricant outlet when the control actuator is in the control position; and

the second lubricant metering chamber is in fluid communication with a lubricant outlet when the control actuator is in the base position and alternatively the second lubricant metering chamber is in fluid communication with the lubricant inlet when the control actuator is in the control position.

3. A device for dispensing lubricant as claimed in either claim 1 or claim 2 wherein the casing consists of multiple casing blocks.

4. A device for dispensing lubricant as claimed in any one of the preceding claims wherein the lubricant actuator takes the form of a metering piston.

5. A device as claimed in claim 4 wherein movement of the metering piston from a first position to a second position enlarges the first metering chamber and expels lubricant from the second metering chamber.

6. A device as claimed in either claim 4 or claim 5 wherein movement of the metering piston from a second position to a first position enlarges the second metering chamber and expels lubricant from the first metering chamber.

7. A device as claimed in any one of claims 4 to 6 wherein the metering piston consists of a pin and a plunger.

8. A device for dispensing lubricant as claimed in claim 7 wherein the pin protrudes from the casing.

9. A device for dispensing lubricant as claimed in any one of the preceding claims wherein the control actuator takes the form of a control piston.

10. A device for dispensing lubricant as claimed in claim 9 wherein the control piston takes the form of a shaft housed snugly within a bore defined within the casing.

11. A device for dispensing lubricant as claimed in claim 10 wherein the shaft is shaped to define shaft reductions of reduced cross section in order to allow lubricant flow through the bore.

12. A device for dispensing lubricant as claimed in any one of the preceding claims wherein fluid communication between the lubricant chambers and both the lubricant inlet and one or more lubricant outlets is established by means of lubricant tunnels or flow paths defined within the casing.

13. A device for dispensing lubricant as claimed in any one of the preceding claims wherein the biasing element is in the form of a spring housed within the casing.

14. A device for dispensing lubricant as claimed in claim 13 wherein the spring is attached to an end region of the control actuator and is configured to bias the control actuator toward the inlet.

15. A device for dispensing lubricant as claimed in any one of the preceding claims wherein the casing is shaped to define a back pressure chamber in fluid communication with a lubricant outlet.

16. A device for dispensing lubricant substantially as described herein with reference to the accompanying drawings.