Page 48 - MMI - MayJune2022 small-single

machines. While the moving Institute/American Gears Man- tors and anti-foaming additives
surfaces in other machines are ufacturers Association) stan- to keep the oils from thickening
either in sliding or rolling mo- dards into four classes, as illus- and losing their cooling capabil-
tion, in the case of a gear as- trated below: ity. Their life is limited because
sembly, both these movements R&O Gear Oil – It is prepared of the additives. They are best
are present simultaneously. with rust and oxidation (R&O) suited for gearboxes that oper-
Moreover, industrial gearboxes inhibitors as additives and is ate under high pressure. The
operate under harsh conditions supplied as a multi-purpose oil increased stress on the gears
of high temperature and heavy for various applications. causes them to wear faster. EP
loads. The environment also Rust-preventive gear oils are gear oils extend the life of high
consists of dust, humidity, and petroleum- or mineral-based load-bearing gearboxes.
exposure to water, chemicals, compounds containing rust in- Compound Type Gear Oil –
steam, etc. This is more promi- hibitors. These gearbox oils are These gear oils are most com-
nent for open gearbox applica- classified into monograde and monly used to lubricate en-
tions in industries such as Ce- multigrade gear oils. Monograde closed worm gear drives, where
ment, Steel, and Wind Turbine. gear oil is intended to be used at the solid sliding action of the
Lack of proper lubrication (in specific ‘normal’ temperatures, gear teeth necessitates the
terms of adequate frequency, whereas multigrade gear oil can introduction of a friction-re- Typical chal-
quantity, and chemical prop- be used at warmer or colder ducing compound to minimize lenges in the
lubrication
erties) can lead to excess wear ‘normal’ temperatures. heat and enhance efficiency. A of gearboxes
and damage to the gearbox These oils extend gear life while surface-active substance, such are quite
and associated components allowing the gears to operate at as a fatty or synthetic fatty oil, different
like bearings and shafts. This high temperatures. They per- inhibits sliding wear and pro- from those
reduces the overall perfor- form best in low-load gearboxes. vides the lubricity required to of other
mance of the assembly and, in EP Gear Oil – It contains ex- reduce sliding wear. machines.
the worst-case scenario, can treme pressure withstanding Synthetic Type Gear Oil – While the
lead to the breakdown of the agents such as Sulfur, Phos- Synthetic gear oil is a chem- moving sur-
manufacturing process, caus- phorus additives and is utilized ical-based gearbox oil. It is faces in oth-
ing heavy losses. in more significant quantities composed of polyalphaolefins er machines
than any other form of gear oil. (PAOs), esters oils, and poly- are either
in sliding
Types of gear oils Extreme pressure (EP) gear oils glycols. Synthetic gear oils are or rolling
Industrial gear oils are clas- are available with synthetic or multigrade and contain all the motion, in
sified as per ANSI/AGMA mineral bases. They are multi- preventive additives as part of the case
(American National Standard grade and contain rust inhibi- their composition. of a gear
They can operate at very high assembly,
or low temperatures and keep both these
rust, foaming inside the gear- movements
box, and gear wear at bay. They are present
are used in gearboxes that op- simultane-
erate in extreme sub-zero tem- ously.
peratures, wet climates, and
dusty or muddy weather.

Performance characteris-
tics of gear oils and their
testing methods
Surface characteristics
Sometimes, gearboxes may come
into contact with water. They
then form an emulsion with wa-
Source: Anand Engineers Pvt Ltd ter, leading to the formation of
scuffs in between the teeth of the
gears, thereby damaging them.
The ability of gear oils to sepa-
Demulsibility test (ASTM D 1401) Foaming Test (ASTM D 892) rate water and resist emulsion
is an important characteris-

48 | May-June 2022 Modern Manufacturing India