GB2310257A

GB2310257A - Lubrication of chain mechanisms

Info

Publication number: GB2310257A
Application number: GB9602956A
Authority: GB
Inventors: Bryan Haycock
Original assignee: PRECISION CHAINS; RCS
Current assignee: PRECISION CHAINS; RCS
Priority date: 1996-02-13
Filing date: 1996-02-13
Publication date: 1997-08-20
Anticipated expiration: 2016-02-13
Also published as: GB2310257B; GB9602956D0

Description

LUBRICATION OF CHAIN MECHANISMS This invention relates to an automatic lubricator for chains, particularly roller chains. It is particularly concerned to provide an automatic lubricator for the chain drive of an escalator or conveyor or the like but is not intended to be limited thereto.

Various types of automatic lubricator have been manufactured in the past ranging from simple oil drip feed tapes to more sophisticated grease gun types. Oil types present a major fire risk due to the fact that surplus oil can'combine with natural debris to produce a readily ignitable material.

Grease lubrication, although much safer from the fire prevention point of view, has other problems in that, to be effective, grease needs to be introduced into the chains under pressure through grease nipples at regular time intervals. This is usually effected by manual grease gun application. Although various automatic systems have been produced, they usually use a one or two reciprocating gun arrangement. This can only work satisfactorily on a single chain pitch with the chain moving at a very slow maintenance speed. The reciprocating action necessitates that the guns engage with the nipples in the chain, grease, disengage and move back to the starting point, all in one pitch movement. This is an almost impossible task considering the synchronisation required, even at very slow speed.

It is an object of the invention to provide an improved automatic lubricator which can synchronise with a moving chain at its normal operational speed.

Accordingly the invention provides an automatic lubricator for a main, e.g. roller chain, the lubricator comprising a continuous slave chain positioned to nun parallel to a portion of the main chain, means to synchronise the speed of the slave chain with that of the main chain, the slave chain carrying a plurality of link pins in the form of double acting cylinders each with hollow piston rod, a first end of each piston rod carrying a grease nipple coupling and the second end being attachable to a supply of lubricant, means to advance each hollow piston rod in turn into engagement with a grease nipple on the parallel portion of main chain and means to pump lubricant to the nipple, each hollow piston rod being disengagable from its corresponding nipple before it reaches the end of the parallel portion.

The lubricant will usually be a grease composition and will be referred to hereafter as grease, for convenience.

The grease is preferably supplied to each hollow piston rod via a series of flexible hoses, one end of each being attached to the aforesaid second end of its respective hollow piston rod and the other end to a rotary distributor which supplies the grease through each hose as required. The rotary distributor operates in synchronisation with the two chains.

Thus each link pin, i.e. cylinder and piston rod, becomes a grease gun which is automatically operated during each cycle of its continuous rotation while it faces a grease nipple during the parallel portion of chain sunning. This portion of the cycle can cover several pitches of the slave chain, usually determined by the distance between its main drive pick up wheel and its idler wheel.

As the slave and roller (main) chains are moving at exactly the same speed, each grease gun will remain in alignment with a respective nipple on the main chain for the whole of the parallel portion of the chains.

Conveniently, the slave chain is driven by a toothed pick up wheel on the same axle as a drive pick up wheel of the main chain to ensure accurate synchronisation.

The rotary distributor may conveniently be mounted on a support beam and synchronised to rotate at the speed of the main chain by means of a timing belt.

The lubricant grease will be supplied to a gun only during its engagement with a nipple on the main chain and this, and the cessation of flow of grease and the uncoupling of the gun and nipple can be controlled by cam-operated valves and/or a programmable logic controller (PLC).

The lubricator is preferably provided with means to accommodate varying distances between the guns and the nipples. Thus the extension of the hollow piston towards its desired grease nipple can be arranged to be continued until the pressure against the nipple is met. Of course, the piston rod must be of sufficient length to extend for the maximum distance to be encountered in the set up in which the lubricator is to be used.

It is not essential that the pitch of the lubricator slave chain be identical to that of the chain to be lubricated. For example, the pitch of the slave chain may be halved and the grease guns fitted at alternate pitches. By this means the overall size of the lubricator unit can be reduced.

The invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a side elevation of a portion of a lubricator of the invention for use with an escalator step chain; Figure 2 is a plan view of the lower run of the chains of Figure 1; and Figure 3 is a diagrammatic illustration in enlarged scale showing two of the double acting cylinders of the lubricator of Figures 1 and 2 adjacent two links of the main chain to be lubricated.

In Figures 1 and 2 there is shown a lubricator 10 of the invention and step chain 11 of an escalator. Chain 11 of the escalator comprises links 13 to some of which are connected step axles 12 in known manner. Each link has on one side face a grease nipple 14, which is of concave configuration. Step chain 11 is driven by a main drive pick up wheel 15.

Lubricator 10 comprises a continuous loop slave chain 16 formed of links 17 at an identical pitch to the step chain 11. Slave chain 16 is driven by drive wheel 18 and coupled to main drive pick up wheel whereby synchronous rotation of the two chains is achieved.

The two chains travel in the same direction and are parallel and adjacent over length A1 A2 between the drive wheel 18 and a slave chain idler wheel 19.

Each link of slave chain 16 comprises a double acting cylinder 20 containing a hollow piston rod 21 and piston 22 - see Figure 3. At its end 21A furthest from the step chain, each piston rod 21 is connected via a flexible hose (not shown) to a rotary distributor 23 for grease supply. Distributor 23 is mounted on a support beam 24 and is rotated in synchronisation with the chains by timing belt 25.

At the start A1 of the adjacent run A,-A2 of the chains, the control mechanism, not shown, drives piston rod 21 from the 'out' positions of Figure 3 to the 'in' position, i.e. until its end 21B mates with grease nipple 14 on a link 13. Grease is then pumped into that link 13 until it approaches position A2, when pumping stops and rod 21 is withdrawn to the "out" position.

Each link of chain 11 is lubricated in this manner as it travels from A1 to A2. Piston rods 21 accommodate any differences in the distance between the two chains, e.g. because of extended chain pins in main chain 11. The pressure-operated guns stop movement towards chain 11 once resistance against a grease nipple is encountered.

Thus grease is only supplied to rods 21, ie. guns, which are in the operational contact position, via porting in the rotary distributor 23 and the porting will have advanced to a cutoff position for the grease supply as a gun approaches position A2 The movement of the piston rods and the grease supply can conveniently be controlled by a programmable logic controller to pre-programme suitable greasing intervals.

Claims

1. An automatic lubricator for a main chain, the lubricator comprising a continuous slave chain positioned to run parallel to a portion of the main chain, means to synchronise the speed of the slave chain with that of the main chain, the slave chain carrying a plurality of link pins in the form of double acting cylinders each with a hollow piston rod, a first end of each piston rod carrying a grease nipple coupling and the second end being attachable to a supply of lubricant, means to advance each hollow piston rod in turn into engagement with a grease nipple on the parallel portion of main chain and means to pump lubricant to the nipple, each hollow piston rod being disengagable from its corresponding nipple before it reaches the end of the parallel portion.

2. An automatic lubricator according to Claim 1, in which the main chain is a roller chain.

3. An automatic lubricator according to Claim 1 or 2, in which the main chain is the chain drive of an escalator or conveyor.

4. An automatic lubricator according to Claim 1, 2 or 3, in which the lubricant is supplied to the hollow piston rods via a series of flexible hoses.

5. An automatic lubricator according to Claim 4, in which one end of each hose is attached to the second end of its respective hollow piston rod and the other end of each hose is attached to a rotary distributor for the lubricant.

6. An automatic lubricator according to Claim 5, in which the rotary distributor operates in synchronisation with the two chains and each link pin can be automatically operated as a grease gun during each cycle of its rotation while it faces a grease nipple during the parallel portion of chain running.

7. An automatic lubricator according to Claim 5 or 6, in which the rotary distributor is mounted on a support beam and is synchronised to rotate at the speed of the main chain by a timing belt.

8. An automatic lubricator according to any preceding claim, in which the slave and main chains can be constrained to move at exactly the same speed whereby each link pin will remain in alignment with a respective nipple on the main chain for the whole of the parallel portion of chain running.

9. An automatic lubricator according to any preceding claim, in which the slave chain is driven by a pick up means on the same axle as a drive pick up wheel of the main chain.

10. An automatic lubricator according to any preceding claim, in which the cessation of flow of lubricant to the link pins and the uncoupling of the link pins from the grease nipples is controlled by cam operated valves.

11. An automatic lubricator according to any preceding claim, in which the cessation of flow of lubricant to the link pins and the uncoupling of the link pins from the grease nipples is controlled by a programmable logic controller.

12. An automatic lubricator according to any preceding claim, which is provided with means to accommodate varying distances between the link pins and the grease nipples.

13. An automatic lubricator according to any preceding claim, in which the extension of each hollow piston rod towards its respective grease nipple is arranged to continue until pressure against the nipple is met.

14. An automatic lubricator according to any preceding claim, in which the pitch of the slave chain is half the pitch of the main chain and link pins are fitted at alternate pitches.

15. An automatic lubricator according to Claim 1, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

16. An escalator or conveyor comprising a main chain drive having an automatic lubricator according to any one of the preceding claims.