IMPROVEMENTS IN SELF LEVELING BERTHS
Year: 1881

page_text: LETTERS PATENT to Thomas Curtis Dunn, of Boston, in the County
Suffolk, State of Massachusetts, one of the United States of America, for an
Invention of "IMPROVEMENTS IN SELF LEVELING BERTHS." A communication
COMPLETE SPECIFICATION filed by the said Thomas Curtis Dunn at the
Office of the Commissioners of Patents on the 30th August 1881.
THOMAS CURTIS DUNN, of Boston, in the County Suffolk, State of Massa-
chusetts, one of the United States of America. "IMPROVEMENTS IN SELF LEVELING
BERTHS." A communication by William Miller, of Boston aforesaid.
This Invention has for its object to provide improved means for supporting a
vessel's berth and permitting the same to oscillate, so as to remain comparatively
level at all times. The Invention consists mainly in a bail or bent bar to which
the ends of the berth are pivoted, said bar being pivoted to a bracket over the
center of the berth so as to have a universal movement. A spring is provided to
partially check the vertical oscillations of the bar, and the ends of the bar are
provided with guides, which prevent any extreme lateral oscillations of the bar,
all of which I will now proceed to describe.
Of the accompanying Drawings, Figure 1 represents a top. view of a berth and
its casing embodying my Invention; Figure 2 represents a side view of the same;
Figure 3 represents a section on line x, x, of Figure 1; Figure 4 represents a section
on line y, y, of Figure 2.
In the Drawings, A repesents a vessel's berth; B represents a stout bail or bent
bar of any suitable construction & material having two ends, which are bent
substantially at right angles with its main portion. The ends of the berth are
pivoted to the bent ends of the bar at c, c, so as to be capable of rocking or oscillating.
laterally, and the bar is supported by a bracket d attached to the casing E and
projecting over the center of the berth. The bracket and bar are connected by a
universal joint so that the bar can oscillate in any direction. This joint is preferably
composed of a hemispherical socket f formed on the bracket, and a hemisphere g
.

page_text: formed on the under side of the bar, and of the proper size and fit to turn freely in
the socket. ii, represent guides attached to the ends of the casing. Each guide
consists of a plate having two flanges arranged to receive between them one of the
ends of the bar B. Each guide is preferably pivoted 'to a plate on the end of
the casing so as to be capable of a slight oscillating motion, which permits the bar B
to have a limited lateral oscillation, the purpose of the guides being to prevent any
such lateral oscillation of the bar as would cause the berth to vibrate laterally like
a pendulum in the arc of a circle of which the socket f is the center. The guides
also prevent the bar from turning horizontally, but do not interfere with the
longitudinal oscillations of the bar and berth.
S represents a spring which is secured to the bracket d and bears downwardly
upon the outer surface of the bar B at each side of the bracket. This spring is
intended to partially check the vertical oscillations of the bar B. It will be seen
that the berth is poised or suspended so as to maintain a level position under
almost all circumstances. The pivoting of the berth to the bar B enables it to
oscillate laterally on its own pivots in a direction at right angles to the direction of
oscillation of the bar when the vessel rocks laterally, and the bar B pivoted to
oscillate in any direction keeps the berth level longitudinally. The bent ends of
the bar B are preferably provided with friction rollers which run against the
sides of the guides.
When it is desirable to entirely prevent the oscillations of the berth it may bo
made fast by a hook on the casing engaging a staple on the side of the berth.
The bracket d may be attached to the side of the casing, as shown, or may be
formed to be attached to a ceiling over the berth.
In Figure 5 of the Drawings I have represented in side elevation, in Figure 6 a
section, and in Figure 7 a side view of the berth and bar, as modified in con-
struction. In these Figures B2 represents a bar or support rigidly attached to the
vessel above the bail B, while C¹, C¹, represent metallic plates attached to the said
support and extending downward therefrom, each plate being preferably a semi-
circle with a lug C³, while through the lower portions of the plates C¹, C¹, extends
a transverse bolt E¹ supported by such plates.
F, F, represent semicircular plates attached to the opposite sides of the bail B
so as to move with the latter, such plates having orifices through which the bolt E¹
passes, the bolt being the pivot on which the bail oscillates.
H', H, are friction rolls between the plates C, F', such rollers radiating from a
given point at the center of the bolt E¹, and each is the frustum of a cone, which
if continued would have its apex at the point in the center of the bolt E¹ from
which-the-rollers radiate.
The plates C¹, F¹, are provided with semi-circular_tracks C², F2, which are
beveled to bear closely upon the tapered rollers H³, such rollers being kept-in-
their radial position by webs or plates I¹ placed between the plates C, F₁, and
provided with radial slots J formed to receive the rollers H', and with orifices
through which the bolt E' passes loosely.
It will be seen that by the employment of the. plates C¹, F', and the interposed
friction rollers, the friction attending the oscillating motion of the bail B is reduced,
to the minimum.
The form of the rollers H' and their tracks C2, F2, is such that there will be no
slipping of any part of any roller on the tracks, hence friction from this cause is
First. The combination of the fixed socket f, the bail B supported by the socket
and adapted to oscillate longitudinally; fixed guides i, i, whereby the bail is pre-
vented from oscillating laterally and swinging horizontally, and the berth A
pivoted to the ends of the bail in such manner as to oscillate laterally or at right
angles to the direction of oscillation of the bail, as set forth.

page_text: Second. The combination of the bail B, the bracket d and the spring S secured
to the bracket and arranged to bear upon the bail at opposite sides of the bracket, as
set forth.
Third. The combination with the pivoted bar or bail B, having the berth pivoted
to its ends of the segmental tracks F2, F2, attached to the opposite sides of the said
bar, and concentric with the pivot E¹ thereof; the segmental tracks C2, C3,
attached to a fixed support and also concentric with the pivot E¹, the tapered
rollers H' interposed between said tracks and radiating from the pivot E¹, and
means for holding said rollers in their radial positions, as set forth.
Fourth. The combination of the fixed support B2; the plates C¹, C¹, attached to
said support and provided with the tracks C³, C; the pivot El, supported by the
plates C, C; the bar B adapted to oscillate on the pivot; the segmental tracks
F2, F2, attached to the bar B; the radial tapered rollers H¹ interposed between the
tracks C, C, and the slotted interposed webs or plates I¹, I', supported by the
pivot E¹ and holding the rollers H' in place, as set forth.
In witness whereof, I, the said Thomas Curtis Dunn, have hereunto set my
hand and seal, this Twelfth day of August, One thousand eight hundred
and eighty one.
THOMAS CURTIS DUNN. (L.S.)