Untitled record

Mo. 29,936.

J. ASK.

Dentist’s Chair.

Patented Sept. 4, 1860.

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[!. PETERS Pnc'Q-Li'no_Hrar^ei·. Wash.n^&lt;ra. 0. C.

UNITED STATES PATENT OFFICE.

3, --------------------------------------------, JUSTUS ASK, OF LYONS, NW YORK, ASSIGNOR TO JAMES H. CASE, OF SAME PLACE.

CONSTRUCTION OF DENTAL CHAIRS.

Specification of Letters Patent No. 29,936, dated September 4, 1860.

' To all whom it may concern:

Be it. known that I, Justus Ask, of Lyons, in the county of Wayne and State of New York, have invented a new and Tm5 proved Dental Chair; and I do hereby declare that the following is a full and exact description, reference being had to the ac, companying drawings, in which,

Figure 1, is a vertical longitudinal section 10 through the chair and footstool. Fig. 2, is a front view of the working parts and the front of the frame B, the seat and back being broken away to afford a better view. Fig. 3, is an inverted plan view of the work, 15 ing devices of the footstool.

Similar letters designate corresponding parts in all of the figures.

The general parts of my improved chair may be distinguished as follows. The frame 20 or legs A, the seat frame B, back C, elevating seat D, and footstool E. The elevation of the seat D, is effected by means of a sta-. tionary screw F, firmly attached to the bottom of the seat by bolts or screws a, a, and 25 the loose revolving nut-wheel G. This nutwheel is supported by an annular seat in a strong iron frame cl, securely fastened to the seat-frame B, by four arms δ, δ, extending from the annular portion to the back ³⁰ and front, of said frame. A cross bar or yoke c, c, is attached to the sides of the annular frame above the nut-wheel, and prevents its rising with the screw. A stud e, from the frame d, forms one of the bearings 35 of the crank shaft f, to which is attached the beveled pinion h, which works into the beveled gear of the nut wheel. By turning the crank cj, the revolutions of the wheel G, cause the screw to rise or fall, and conse⁴⁰ quently elevate or lower the seat D, according to the direction in which the crank is turned.

The seat .D, has no guides, but is held steady in its position by the screw alone, ⁴⁵ which is prevented from' vibrating laterally by the long hub or nut of the wheel G, and by the broad surface which it presents to the annular seat on which it rests, and by the yoke c, which holds its top in place.

⁵⁰ The seat frame B, is hinged to the legportion A, at each side about midway between the front and back which is made r arching to admit of its being inclined back more or less, as required for the purposes ^δ5 for which it is used. The mechanism by which this is effected consists first of an in verted bail K, which is hinged or pivoted to the forward arms δ, δ, which attach the annular frame to the seat frame B. This bail can swing forward or back on its pivots 60 j, j, and at the center of its bow or lower extremity, it is pivoted to the foot lever J, at or about the center thereof or to the arched piece t, which forms a portion of said lever. This pivot i, being at right 65 angles to those which attach the bail to its support, the two admit of free motion in two directions, sidewise, and forward and back; and this freedom of motion is important in order that the movable portion of 70 the chair shall not become constrained, and thereby interfere with its operation in other respects. The lever J, has a foot piece I, at one end, near which it passes through a guide slot in the piece M, which slot has a 75 rack on one side into which the lug o, (shown in Fig. 1) catches, the lever being pressed against the rack by a flat spring p, on the opposite side. The opposite end of the lever has its fulcrum on a pin r, which 80 passes through a slot s, in the end of the lever, which also passes through a slot in the guide piece which holds the pin. This slot in the arm of the lever, admits of its sliding on the pin as it is moved to raise 85 and lower the seat, in order to not interfere with the free actions of the seat, but to leave all the mechanism of this part of the chair free to act around the two centers of motion, the pivots i and j, j, in the bail. The op- 90 erator can thus with his foot adjust the inclination of the seat without leaving his position.

A flexible diaphragm R, formed like a bel-. lows, unites the seat with the frame B, which 95 from its form adapts itself to the contraction and expansion of the space between the two, as the seat is lowered or raised, thereby concealing the opening, and presenting an agreeable finish to the eye. 100

The movable seat is provided with supplementary arms S, Fig. 1, which, when the seat is down, fit the inner form of the permanent arms T, and serve as cushions thereto, but which being fixed to the seat, 105 rise with it, and always remain at the same height above its surface. As the seat is often raised as high as the top of the arms T, it is important for the safety of children, as well as the comfort of adults, that there HO should be barriers at the sides, which want is fully supplied by the supplementary arms

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S, without complicating the mechanism of the chair or impairing its symmetry.