Gears, correspondingly are also of different varieties - spur, single-helical, herring-bone bevel worm or hypoid. Each of the different types of bearings and gears perform in different ways and require individual lubrication qualities - or do they?

After carefully examining the performance of each of the above-mentioned bearings and gears, a minimum list of suitable lubricants can usually be worked out. The surface-to-surface contact characteristic of each class of bearings and gears provides a means for drawing up such a list.

Plain bearings
Consisting of two surfaces slipping against each other, plain bearings are normally lubricated by oil chosen to accommodate either journal speed or loading on the bearings.

Higher viscosity oils are usually required for once-through lubrication with small volumes of oil, start up lubrication and lubrication for heavy loads. And, if temperatures are at about the ambient-level, the selection of lubricating oil would be affected accordingly.

Lubricating grease should be used with plain bearings when: speed is slow, loads are heavy and temperatures are high; operation is intermittent and clearances are large; locations are inaccessible; they are easily contaminated with water or dirt.

It should be recognised that the oil viscosity and the oil's non-corrosive additives are very important to the life of plain bearings.

Anti-friction bearings
These bearings include ball, straight-roller, tapered-roller, ball-thrust and needle-roller elements. They use oil which is selected according to the inside diameter of the bearing, journal speed and temperature.

Grease lubrication, however, offers wide design versatility, because a single high-performance Omega grease may be used to handle all diameters of bearings, and all temperatures from -29 ^oC to 140 ^oC. A high quality grease, Omega 77, provides dramatically reduced inventories, downtime and maintenance costs.

Optimum bearing life can be achieved only be maintaining a clean lubricant in a clean bearing. Bearing design variations can increase the resistance to thrust, extremes of temperature, pressure and exposure to corrosive fluids.

Spur gears
These gears have teeth that cut straight across the face of the gear blank providing gear-to-gear contact parallel to the shafts. The consequent sliding and rolling in and out between the teeth builds up a substantial oil film.

Spur gears, therefore, can be lubricated with an uninhibited and less expensive oil. Omega 670 gives more flexibility than ordinary mineral oil.

Single-helical gears
These gears have shaft centerlines which are parallel to each other with gear teeth cut diagonally across the face of the blank. This type of gear enables longer tooth contact time as well as allow more than one set of teeth to be meshed at one time. These gears can cause considerable sideways thrust.

They can usually be lubricated with the same type of oil as used with spur gears - Omega 670 - but, depending on the usage, may sometimes require extreme-pressure (EP) additives - Omega 690.

Herring-bone gears
The V-shaped gear-tooth is the characteristic of herring-bone gears. These gears produce counter-balanced sideways thrust. Only a radial sliding and in-and-out contact between the two parts of the herring-bone gears are experienced. In this case, Omega 670 should be used.

Bevel gears
Bevel gears have intersecting shaft centerlines and usually have teeth resembling that of spur and herring-bone gears. These bevel gears can be lubricated with Omega 670.

Worm gears
These are used usually when shaft centerlines are at right angles to each other. Worm gears include a smaller driving member (a worm) and a larger driven member (the gear) with the worm meshing on the outer edges of the gear.

Such a gear arrangement can accomplish large reductions in driven output rpm, with the resultant increases in applied torque. There is a great deal of sliding near the line of contact between the teeth which interferes with the formation of a substantial film of oil.

For worm gears, therefore, Omega 680, with its limited slip differential performance, is the best lubricant.

Hypoid gears
Similar to a worm gear but the worm meshes on the side of the gear. This gear also tends to wipe away the protecting film of oil making lubrication difficult. It is essential that hypoid gears should be lubricated with Omega 690 gear oil suitable for severe loading.