Minimised Gear Lubrication by a Minimum Oil/Air Flow Rate

Abstract

The objectives of the research project were to investigate the limits concerning possible reduction of lubricant quantity in gears without detrimental influence on the load carrying capacity. The investigations covered the influence of the oil level in dip lubricated systems as well as the oil flow rate in spray lubricated systems namely oil-air supply systems on power loss, heat generation and load carrying capacity. The load carrying capacity in terms of characteristic gear failure modes was determined and was compared to the results using conventional lubricant volumes with dip lubrication. Therefore in back-to-back gear tests the parameters speed, load and oil quantity were varied for examination of the four main gear flank damages: scuffing, wear, pitting and micropitting. The investigations showed the application potential of oil/air lubrication also for heavy duty transmissions nevertheless there exists a natural limitation for lowering the oil quantity in transmissions without detrimental influence on the load carrying capacity.

Efficiency and temperature of spur gears using spray lubrication compared to dip lubrication

“…This is due to the reduction of load-independent losses by the removal of the oil sump which creates churning and windage losses in both the gears and the bearings, which has also been shown by other authors. 3,6 The total efficiency of dip lubrication is in line with previous work. 13 Overall, dip and spray lubrication have the same mesh efficiency from 0.5 to 20 m/s, Figure 4.…”

“…5 To use spray lubrication in which the lubricant is injected at the gears through a nozzle instead of dip lubrication, decreases the load-independent power losses inside the gearbox. 6 When using spray lubrication, the position of spray nozzles will affect the lubrication and cooling of the gears. It is recommended to spray into the mesh inlet for better film formation and at the mesh outlet for better cooling.…”

Thermal modelling of a back-to-back gearbox test machine: Application to the FZG test rig

“…Moreover, applying the standard formulas to optimise gear efficiency can lead to erroneous conclusions. In fact, reducing the immersion depth in order to reduce churning losses 22 can induce higher temperatures and consequently increase the risk of scuffing. It is to be noted that the thermal model can be extended to other gear geometries such as helical gears and lubrication processes (jet lubrication for instance).…”

Experimental investigations to establish correlation between Stribeck curve, specific film thickness and statistical parameters of vibration and sound signals in a spur gear system

“…The EHL regime provides a protecting layer between the gear tooth surfaces. The EHL film formation is decreased at high temperature and lower viscosities resulted in scuffing wear propagation on gear tooth surfaces An increase in the wear has an effect on the roughness of the gear teeth flanks (Ho¨hn and Michaelis, 2004;Rafik Sari et al, 2007;Ho¨hn et al, 2009) . A gradual increase in the gear tooth surface roughness values, the EHL and boundary lubrication regimes are observed during 400 h and 600 h of operation as shown in Figure 7(c).…”