Lubrication circulatory

Machine-tool gears can be lubricated by oil-spray, mist, splash or cascade. Sealed oil baths are commonly used, or the gears may be lubricated by part of a larger circulatory system. 

Automatic lubrication systems may be divided broadly into two types circulatory and one-shot total-loss. These cover, respectively, those components using relatively large amounts of oil, which can be cooled, purified and recirculating, and those in which oil or grease is used once only and then lost. Both arrangements may be used for different parts of the same machine or installation. 

The circulatory systems used in association with machine tools are generally conventional in nature, although occasionally their exceptional size creates special problems. The normal installation comprises a storage tank or reservoir, a pump and filter, suitable sprays, jets or other distribution devices, and return piping. The most recent designs tend to eliminate wick feeds and siphon lubrication. 

One-shot metered lubrication is eminently suited to oiling systems and can be employed either in an all-loss arrangement or as part of a circulatory system. Sight-glasses or other indicators should be incorporated since such lubricating mechanisms are nowadays so reliable that a blockage or other failure might not be suspected until too late. 

Face lubricated-type seals must be connected from the source of lubrication to the tap openings in the seal gland before startup. This is another predetermined environmental control feature that is mandatory for proper seal function. Where double seals are to be operated, it is necessary that the lubrication feed lines be connected to the proper ports for both circulatory or dead-end systems before equipment startup. This is very important because all types of double seals depend on the controlled pressure and flow of the sealing fluid to function properly. Even before the shaft is rotated, the sealing liquid pressure must exceed the product pressure opposing the seal. Be sure a vapor trap does not prevent the lubricant from reaching the seal face promptly. 

The characteristic relaxation time t = 1 /(Hp was found to be insensitive to the droplet size a, weakly dependent on the continuous-phase viscosity, and perhaps weakly dependent on r and M also. Although the complete scaling law for r cannot be deduced from this limited set of data, it is evidently influenced by lubrication flow of liquid in the thin films between the deformed droplets, and perhaps also by the circulatory flow in the viscous droplets. 

In this type of pump, the avoidance of condensation is no longer an absolute requirement as for oil-lubricated pumps with circulatory lubrication, even though it is still desirable to prevent any condensation also in fresh-oil-lubricated rotary vane vacuum pumps (risk of diluting the fresh oil too much). In any case, condensate which forms here can be discharged, since the exhaust of these pumps is not located at the highest point as is the case for types with circulatory lubrication, but instead the exhaust is located at the lowest point. 

Rotary vane vacuum pumps are commonly provided with circulatory lubrication (chiefly in more physical or physical-industrial applications) in the chemical industry frequently with fresh oil lubrication and then of a multi-vane design. Rotary vane vacuum pumps of both types are characterised in that with these it is relatively simple to attain very low vacuum pressures. 

Given in Table 5.1 are some typical vapour tolerance values for a rotary vane pump with circulatory oil lubrication. 

As in these vacuum pumps the oil passes only once through the pump, the purity of the separated oil is of far less significance compared to rotary vane pumps with circulatory lubrication. Even so, also in the case of fresh-oil-lubricated pumps, the aspect of vapour tolerance must be taken into account because here too the oil may suffer from dilution or the oil film in the pump chamber may be even washed away with the result of very rapid and considerable wear within the pump chamber giving rise to high repair costs. 

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