5
comments
The lubrication problems of
gearing in connection with quarrying
and handling rock, shale etc., for use
in cement manufacture will
be treated under the section
devoted to surface mining and
quarrying. In cement mills proper, grinding or pulverizing. Mixing, conveying
and heating of
ingredients are required and
most of these operations
employ gear drives
which in turn
need lubricants.
Dust of an
abrasive nature is an
ever present possibility
in the case of any
gear lubricants in
cement plants, even in
enclosed gear cases. In
some applications this
threat to lubricated
surfaces is countered
by the use
of circulating oil
systems. If this manner of application is used, filtration is possible.
This is true with some
types of rock crushers, such as
gyratory crushers or hydraulic
cone crushers. The gear
oil employed in either
of the above
can be a mild
EP type
having viscosities of 300
to 500 SUS at 100 degree F.
Whether the
process used for
cement manufacture is the
dry or wet one, agitators, conveyors, elevators, mixers,
grinders and various other
mechanisms are driven
by gear reducers from
electric motors. In the wet
process the listing
may include pumps for
handling slurries,
thickeners which may
have worm drives, as well as the first
types of machines. A general
recommendation, which
simplifies the storage
and handling of gear lubricants, is to
use a mild EP oil having a
viscosity of 300 to 500
SUS at 100 degree F. If
the EP agent
includes a lead
soap, such an oil might
be used for worm drives.
Open gears are also found in
cement plants. One illustration is a ring gear and pinion driving a ball or rod
mill. Here a residual
type of petroleum
product having a
viscosity of 2000 to
3000 SUS at 210 degree F can be used.
This lubricant will pick
up and carry with
it rock or cement dust, and since
this will be
true no matter what
the viscosity of the
product , the best procedure is
frequent application. By this means the excess lubricant will be rejected
and carry with it some of the abrasive material.
Cement kilns
are rotated by
a speed reducer, followed by a
pinion and girth gear. Different methods for lubrication of the
exposed pinion and gear have been used. While
dust and grit are
present, the main problem is heat,
radiated from the hot shell
of the kiln to the
gearing. High melting point
lubricating greases have been
used to some extent,
but require frequent application unless they
are in the form
of a brick which is pressed against
the pinion. This method has led to
excess consumption.
A
better procedure for lubrication of
cement kiln girth
gears and pinions is to provide
a bath for the latter. Cylinder stocks
or SAE 250 EP gear oils have been used in this bath. In this case,
the cylinder stock used
should have a
minimum flash point
of 600 degree F. However, perhaps the
most common method of
lubrication of such a drive is to use
residuum having a viscosity of
about 5000 SUS at 210 degree F. This can
be heated to aid in application. Also this
open gear lubricant may contain three
to five per
cent of graphite
or molybdenum disulfide, which of course are
no melting and will adhere
to the gear teeth and act
as a lubricant.
