Year: 1888

page_text: I, MILTON BROWN KIRKER, of Pittsburgh, in the County of Allegheny, State of
Pennsylvania, and United States of America, engineer, do hereby declare the naturo.
of my said invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
The invention herein relates to certain improvements in the manufacture of single
trees, double trees, and neck yokes and other like articles and consists generally stated,
of a tubo tapering from its middle portion towards each end, and having suitable
fittings secured therein in such a manner as to avoid all liability of their becoming
loosened under ordinary conditions of wear or use, or by reason of exposure.
atmospheric influences.
to
In the accompanying drawings, which make part of this specification, Figure 1 is
a view in side elevation of a single tree embodying my invention.
Fig. 2, is a similar view of a double tree.
Fig. 3, is a longitudinal section through the double tree.
Fig. 4, is a transverse section on the line x-x, Fig. 2.
Single trees and double trees are ordinarily formed of somo tough wood, and the
fittings therefor are usually secured by shrinking them upon the wood or by means
of bolts or rivets. The latter method of securing the fittings, i.e. by bolts or rivets,
is objectionable not only on account of the weakening of the wood by the holes formed
In shrinking
by the rivets, but also on account of the bolts or rivets becoming loose.
the fittings on, they are heated to approximately a dark cherry red, then slipped on
to the wood, and rapidly cooled by the application of water. This manner of securing
the clips is temporarily unobjectionable, but as tho hot metal chars the surface of the
wood in contact therewith, the blows and other rough usage to which these articles aro
subjected, causes a comminution, or pulverization of the charred surfaces and a con-
sequent loosening and dropping off of the fittings.
Single trees and double trees have also been made of metal tubes, the fittings
therefor being either secured to the tubes by bolts or rivets, or else forged thereon,
both methods being objectionable on account of the time and labor required therefor.

page_text: In the practice of my invention, I take a wrought metal tube or pipe of suitablo
length and diameter, and by means of suitable tools gradually taper it from its middlo
portion towards its ends, thus forming the bar 1. The central fitting 2, formed of
cast iron and malleabilized, the internal diameter of the part thereof designed to
encircle the bar being a little less than the external diameter at its middle portion, is
heated to a cherry red, thereby expanding it, and is slipped over one end of the bar,
and being adjusted accurately in place on the middle portion of the bar, is cooled.
The contraction of the fitting will cause it to adhere so firmly to the bar, that nothing
short of its destruction or a re-heating, can move it from place. The tapering of
the bar from its center to the ends is expedient for facilitating the slipping on of the
middle fitting, for the reason that as the fitting is only a small fraction of an inch
larger than the bar, even when expanded, it would be liable to catch on the bar, at
some point other than that desired were the bar of uniform diameter throughout its
.entire length. I prefer to leave a portion 3, at the middle, equal in length to the
width of the fitting flat, and thereby avoid the necessity of giving a double taper to
the inner surface of the fitting in order to get a uniforin bearing on the bar, as would
be necessary if the tapering surfaces met and formed an angle at the middle of the
bar. The end fittings 4, having their sockets tapering to correspond to the taper of
the bar are secured in place in a similar manner.
As I do not wish to limit myself to any particular shape or construction of fitting,
n further description of the fitting scoms unnecessary. By the term "fitting" as
herein before used, I mean those devices which are placed on the middle and ends of
single trees and the draft bars of double trees for the purpose of connecting the
single trees to the draft bars, or of connecting the tugs or chains of a harness to
the single.
Neck yokes for wagons which are very similar to single trees can readily be made
in the manner above described, and are therefore considered as within the scope of the
invention herein.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1. A single tree or draft bar having in combination a metal tube tapering from its
middle toward the ends and malleable cast iron fittings shrunk upon the metal tubes,
substantially as set forth.
2. A single tree or draft bar having in combination a metal tube having a straight
middle portion and tapering thence each way to its ends and malleable cast iron fittings
shrunk upon the metal tubes, substantially as set forth.
Dated thin 10th day of Amunt A n 1000
Dated thin 10th
August
1800.
MILTON B. KIRKER.
Witnesses,
J. SNOWDEN BELL.
GEORGE REITER.