Loudon free press. (Loudon, Tenn.) 1852-1855, 1854-08-16
Lubricating Substances.

Lubricating substances, as oil, lard, and tai
low, applied to rubbing surfaces, greatly lessen
the amount of friction, partly BY filling the min
ute cavities, and partly by separating the sur
faces.-In ordinary cases, or where the ma
chinery is simple, those substances are best for
this purpose which keep their places best
Finely powdered black lead, mixed with lard,
IS for this reason better for greasing carriage
wheels than some other applications. Drying
oils. as linseed soon becomes stiff by drying
and are of little service Olive oil, on the con-
trary, and some animal oils, which scarcely dry
at all, are generally preferred. To obtain the
full benefit of oil, tie application must bo FREE
quent.
According to the experiments made with
great care by Norm, at Paris, the friction of
wooden surfaces on wooden surfaces is from, one
quarter to onehalf the force applied; and the
friction of metals one Fl fth to one eseventh-vary-
inc in both cases with kinds used.-Wood on
wood was diminished by lard to about one-ffth
to one-seventh of what it was before; and the
friction of metal on metal was diminished to
about half what it was before; that is the frlc-
ton became about the same in both cases after
the lard was applied. To lessen the friction OF
wooden surfaces, lard is better than tallow by
about one-eig ghth or one-seventh; and tallow Is
better than dry soap about as two is to one
For iron on wood, talow is better than dry
soap about as five to two. For cast iron on
cast iron, polished, the friction with the differ
ent lubricating substances is as follows:
Water.
Soap, ....................'....'''.EV
Iallow, ..............................'
Lard ............................7
Olive oil,
Lard and black-lead, ...................."..5
When bronze rubs on wrought iron, the fr1c-
ton with lard and blacll-lead is rather mere
than with tallow. and about one-ffth more than
with olive oil With steel on bronze. the fric-
ton with tallow and with olive oil is about one
seventh less than with lard and black-lead. As
a general rule, there is least friction with lard
when hard wood rubs on wood, or metal on
metal-being about the same in each OF all
these instances.
Tn simple cases, as with carts and wagons,
where the friction at the axle is but small por-
ton of she resistance,* slight variation IN the
effects in the lubricating substance is of less
Importance than retaining its place. In more
complex machinery as horse powers for tn rash
inc machines, friction becomes very large
item, unless the parts are well fabricated with
the best materials.
Leather and hemp bands, when used on
drums for wheel-work, should possess as much
friction as possible, to prevent slipping, thus
avoiding the necessity Of tightening them so
much as to increase the friction OF the axeis.
Wood with rough surface has onehalt more
friction than when worn smooth; hence moisten-
ing and rasping small drums may be useiu,.
Facing with buff leather or with coarse timex
cloth also accomplishes useful purpose u ~
often happens that wetting or oillng bands viii
U,s prevent Slipping, by keeping the surfaces soft,
md cansing them to fit more closely the rough
snrface of the drum Thomas Farm lmPle-
ments.
*Ifthe friction at the axle be one-twelfth of
the force, and the diameter. of the wheels ten
times as great as the diameter of the axle, the
friction at the axles will be reduced to one
twelfth of tenth, or one hundred and twentieth
part of the force, according to the law of veocl-
ties as applied to the wheel and axle.