US 258038 A
Description (OCR text may contain errors)
` J. JLBVARrS.
EXTENSION LAMP FIXTURE. 180,258,088. Patented M8318, 1882.
N, PETERS. Fhamulhugmpher, wnsmngwm Dy c.
i 'UjNrren States Parent. @trices f HUBBARD 'MANUFACTURING Y COMPANY, OF PLACE..
EXThEUNSION LAMP- FIXTURE.`
SPECIFICATION forming part of Letters Patent No;k 258,038, dated. May 16, 1882. Application filed December 19, '1881. (No model.)
`To `all ughom it may concern Beit known that I, JOHN` A. EVARTS, of Meriden, in the i county of New Haven, and State of Connecticut, have invented a new Im- 5 provement in Extension Lamp-Fixtures; and I do hereby declare the following, when taken` in connectionlwith the accompanying drawings and the letters of reference marked thereon, to be afull, clear, andA exact rdescription of the same, and which said drawingscoustitute partofthis specification, and represenain Figure ,1, vertical .\ce1'1tral.section; Figs. 2 and 3, vertical central sections 'of the clamping` device enlarged; Fig. 4, a transverse section of the same. This invention relates to an improvementin` that class of fixtures f or supporting lamps` which are designed to be attached to the ceiling, and which are made extensible, so that the lamp may be adjusted to different elevations, commonly called extension-xtures.7 Usually these fixtures are counterbalanced, and with a locking device which will lock them against accidental upward movement, but free to be pulled down. In such construction the counterbalance must be considerably heavier than the fixture, in order to insure its being re- `tained at its proper elevation, or so that it will not accidentally slip down, because the weight of the fixture is variable-thatis to say, when several founts are employed the oil which they contain, it' full, is so much heavier than when the oil is nearly exhausted, or in changing founts, chimneys, or shades, great variation is unavoidable. Hence the counterbalance must be at least equal' to the greatest possible weight, to prevent accidental slipping down. Devices have been arranged for rigidly locking the fixture at different points of elevation, but such devices are generally so complicated as to make them impracticable-such, for instance, as a clamping device which will force the inner tube into frictional contact with the outer tube. This necessitates makingthe inner surface of the outer tube and the outer surface of the inner tube smooth, in order to have the movement properly free; or if not so smooth, then the workin g is so rough as to be entirely unsatisfactory. 5o The object of this invention is to make a 4clamping device substantially.independentof the innertube,\and which shallbearranged within the inner tube, having its oppositeA sides inclined vwith a spring arranged to impart vertical movement to the said slide, com- 55 bined with `a pair of clamps arranged upon the inclines of the said slide and lheld 1in 1 their proper relati ve position tothe said slide, so that the vertical movement of said-slide will force the said clamps outward to engagefthe inner 6o .surface of the outertube with frictional contact, as more fully hereinafter described. -4
A represents the outer. tube, which` is secured to the ceilingin the'usual-vmanner. Within this stationary tube Ais the inner tube,\B,to
Vwhich thexture is attached below-say to the `ring or center G, which is attached to the lower end of the said inner tube. The inner tube is movable freely up and down within the outer tube, in the usualmanner for nthis class of x- 7o tures. Vertically through the inner tube, and preferably near its upper end, is a slide, a, its sides inclined, the widest part preferably being downward, asshown. From this slidea rod,
b, (or wire or chain,) extends down through the inner tube to near the bottom of the xture, and is there Aattached preferably to a cross-piece, d, extending through a slot, c,
in the inner tube. Over the inner tube is a sleeve, f, withwhich the cross-piecel d is con- 8o nected. A spring, h, is arranged on a seat, i,
in theinner tube to force the slide a upward.
To draw the slide downward the person takes hold of the lower end of the fixture and with the finger or lingers grasps the cross=piece d and pulls down thereon, which will draw the slide a down against the pressure ofthe spring h, as from the position in Fig. 2 to that seen in Fig. 3. 'Through openings in the inner tubea pair of clamps, Z Z, project, one upon each side 9o the inclined slide a, the external surface corresponding to the interior of the outer tube, as seen in Fig. 4. The inclined slide a works between the said two clamps as a wedge, the force of the spring driving this wedge-like slide between the two clamps forcing them assunder and into close frictional contact with the inner surface of the outer tube. When so engaged, if an attempt be m ade to draw the inner tube downward, it will tend to draw the roe v 2 25eme@ clamps downward upon the inclined slide a, the action of the sprin g being to force the slide upward. On the contrary, if the attempt be made to force the inner tube upward, the slide a holds firmly, the pressure upward upon the spring only tending to make that more strong, so that engagement with the clamps of the upper tubel isl substantially rigid against a downward pull or an upward push, the inner tube being substantially free as toits movement within the tube while the clamps are so engaged-thatis to say, the clamps do not depend upon the inner tube for their engagement, 0r no frictional contact whatever is made between theinner tube and the outer tube; but when the slide a is drawn down, as before described, then the clamps are loose and the inner tube is free to be lmoved up or down so long as the slide is held down from applying itsforce between the two clamps.
The slidegal may be inverted with'itsspring, so that-the pressure of the clamp will be downward. In that case it will require a pus-h upward to relieveit, instead of a push downward,
as before described. 1 therefore do not limit my invention tothearrangement of the incline of the slide a.v
While I prefer to make recesses on the opposite sides ofthe innertube through which the clamps l will operate, that bein ga simple means for so doing, they maybe arranged within a stirrup attached to the upper end of the tube and accomplish the same result, it only being essential that there shall be such a connection between the tube and clamps that, the clamps and tube may move together upA and down within the outer tube.
I am aware that extensionlamp-fixtures have been constructed with a clamping device and au internal central rod by which said clamping device may be operated to adjust the fixture to different elevations, l and therefore do not claim broadly such device.
1. In an extension-nxture, the combination of the outer and inner tube or parts, A B, the inclined slide a, the clamps l l, the spring to force said clamps asunder and into contact with the inner surface of the outer tube, and means, substantially such as described, to relieve said clamps froln the force ofthe inclined slide, substantially as and for the purpose described.
2. The combination of theouter stationary tube, the inner movable tube, the clamps l l, arranged in recesses in said inner tube, the inclined slide a and its spring arranged to force said slide between said clamps-and said clamps Witnesses: l
W. H. BRADLEY, W. R. Bloo'rn.
JOHN' A. EVARTS. y