Improvements in the Construction of Base Castings and Seat Supports of Revoluble Chairs.
Year: 1899

page_text: Date of Application, 12th Sept., 1899-Accepted, 16th Dec., 1899
COMPLETE SPECIFICATION.
Improvements in the Construction of Base Castings and Seat Supports
of Revoluble Chairs.
I, HARRY WILBUR BOLENS, of Number 200, Central Avenue, in the City of
Port Washington, County of Ozaukee and State of Wisconsin, United States of
America, Manufacturer, do hereby declare the nature of this invention, and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
This invention has for its object to improve that class of chairs organized to
have vertically adjustable and pivotal spring controlled tilting seats, and to
that end it consists in certain advantageous structural peculiarities of the base-
castings and seat supports for such chairs, all as hereinafter particularly set forth
with reference to the accompanying drawings, and subsequently claimed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 represents a vertical transverse section of a chair base-casting and
seat-support, embodying my invention, taken on the plane indicated by the
line 11 of Figure 2.
Figures 2 and 3 are plan views, partly in horizontal section on the planes
respectively indicated by lines 2-2 and 3-3 in Figure 1.
Figure 4 is a detail elevation of the upper part of the seat-standard with the
screw-threaded portion of the tension-rod in section on the line 4-4 of Figure 1.
Referring by letter to said drawings, A indicates my chair base-casting, having
a smooth bore therethrough. B is a screw-threaded spindle having free play in
said bore and provided with an exterior longitudinal groove c, and a head b of
increased diameter. C is a nut engaging the screw-thread of the spindle above
the base-casting, said nut having an annular flange d, overlapped by the head e of
a guard D, made separate from the casting A, and detachably secured thereto by
a set-screw E made long enough to have the inner end thereof engage within
the said groove c of the spindle, thus serving as a spline to permit longitudinal
movement of the spindle within the base-casting, but prevent rotation of the
spindle therein. The said inner end of the set-screw is preferably free from screw-
threads, and as the guard D) is detachable, should one become broken in use,
another can be readily supplied, the said guard preventing the nut and spindle
from being separated from the base-casting when the chair is lifted by its seat.
The nut flange d is formed with a notch large enough to clear the head e of
guard I), and hence, by simply bringing said notch into register with said head c,
the said nut and spindle and the parts attached to the latter may be readily lifted
free from the base-casting and guard, when it is desired to store or transport the
chair in detached condition.
The nut C is provided with a hand-wheel C₁ to facilitate rotation, whereby
spindle B is caused to have direct-vertical-adjustment, because of its groove being
engaged by the spline-end of set-screw E, and to prevent said spindle from
working down, incidental to movement of a person occupying the chair, the

page_text: opposing ends of said nut and base-casting are provided with inter-matching
irregularities to lock said nut against automatic rotation, as indicated by the
dotted waved line a.
The spindle B has its upper end provided with a socket 1 for the depending
pivot of the seat standard G to which the chair-seat spider H is pivotally
connected. The spindle-head b.is provided with an annular chamber f com-
municating with the aforesaid socket, and. intercepting this chamber is a vertical
channel in said spindle-head. A lateral lug on the pivot F has passage in
said channel, which latter is closed by inward adjustment of the screw arranged
transversely in the spindle-head above said chamber f, this screw preventing
accidental withdrawal of the standard-pivot F from socket & should the lug / be
in register with the vertical channel g when the chair is lifted by its seat, and said
screw may be turned to lock said spindle against rotation.
The upper end of spindle-head is counterbored to form a seat for a hard
steel cup I and clearance for a pin j, the latter having drive-fit in a transverse
aperture of the standard-pivot to form supporting lugs for said cup. Hard
steel balls are arranged in the cup I, and in contact with said balls is an
inverted hard steel cup K set in a counterbore of the base of the standard G,
whereby an all hard-metal bearing is formed intermediate of said standard and
spindle, and as neither cup of said bearing is made fast to an adjacent part, both
are free to slip, notwithstanding that they are ordinarily held fast in their respec-
tive seats as a result of superimposed weight.
The seat-standard G is formed with two vertical arms rising from the
standard-base g and connected by a forward projecting brace-yoke G having a
central boss m provided with a screw-threaded bore therethrough, to receive the
screw-threaded portion of a jointed tension-rod, the inner end of the part being
pivotally connected as shown at o, to the adjacent end of the rear portion of
said tension-rod. The chair-seat spider H is of ordinary form, to support a seat,
and has depending ears q, pivotally connected to the standard-arms by a trans-
verse rod r. The rear end of the section of the tension-rod carries a transverse
plate M held in place by a block s secured to said end of the rod by a bolt t,
said plate having bosses a to receive one end of the spiral springs N which control
the tilt of the seat, the other end of said spings being supported by bosses on the
depending rear stops of the spider H, which latter has also front stops, so that
the tilt of the spider H on the standard-arms & may be limited to the space
or distance between said front and rear stops. L represents the tension-nut on the
front portion of the tension-rod, said nut having a hand-wheel y for ready
adjustment thereof, so as to regulate the tension of the springs. To insure this
tension-adjustment of the springs, the opposing bearing surfaces of the tension-
nut Land of the boss m on the brace-yoke G of the standard are formed with the
intermatching irregularities, as shown at in Figure 4 and by the waved line
marked in Figure 1, the elevations of one of these surfaces fitting the depressions
in the other of said surfaces, to thereby lock said nut against automatic rotation.
Having now particularly described and ascertained the nature of my said.
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. The combination with a chair base-casting of a longitudinally grooved screw-
spindle loose therein, a flanged nut on said spindle bearing against one end of
said casting, a guard made separate from said casting but arranged therewith
to overlap the nut-flange, and a guard-securing set-screw having its inner end
engaging the spindle-groove.
2. The combination with a chair base-casting of a longitudinally grooved screw-
spindle splined in said casting, a nut on the spindle bearing against one end of said
casting, a notched flange on the nut, and a guard in detachable connection with
the aforesaid casting arranged to overlap the nut-flange, the notch in the latter
being of sufficient dimensions to clear the head of the guard.

page_text: 3. The combination with a chair base-casting of a longitudinally grooved
screw-spindle loose therein, a spindle-adjusting nut, a guard operative to insure
rétention of the nut in working position and a guard-securing device constituting
a spline engagable with the spindle-groove.
4: The combination with a chair base-casting, of a chair-spindle vertically
movable therein and having a counterbored socket; a seat-standard having a rigid
depending pivot supported in said socket; lugs projecting laterally from said
pivot into the counterbored part of said socket; and a ball-bearing comprising
a pair of cups loose on said pivot, with balls between them, the lower cup being
seated in the counterbored part of the socket above the said lugs, and the upper
cup having loose fit in a counterbore in the base of said seat-standard.
5. The combination with a seat-standard and a seat-spider pivotally connected
thereto, forming a seat-support for a revoluble chair, of a spring-controlled
tension-rod supported thereby and having a screw-threaded forward portion, a
brace-yoke on said seat-standard having a central boss in screw-threaded engage-
ment with said forward portion of said tension-rod, and a tension-nut on the
end of said forward portion of said rod bearing against said boss, the opposing
bearing surfaces of said nut and boss being formed with intermatching elevations
and depressions to thereby lock said nut against automatic rotation.
Dated this 12th day of September 1899.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.