US447487A - Dental chair - Google Patents

Description

(No Model.) 2 SheetsSheet 1.

ABRUSTLEQ DENTAL CHAIR.

No. 447,487. Patented Mar. 3 1891.

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(No Model.) 2 Sheets-Sheet 2.

LBRU STLE. DENTAL CHAIR.

No. 447,487. Patented Mar. 3, 1891.

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ANDREXV BRUSTLE, OF HYDE PARK, ASSIGNOR TO JOHN HOOD AND STEPHEN H. REYNOLDS, OF BOSTON, MASSACHUSETTS.

DENTAL CHAIR.

SPECIFICATION forming part of Letters Patent N 0. 447,487, dated March 3, 1891.

I Application filed May 12, 1890. Serial llo. 351,406. (No model.)

To aZZ whom, it may concern:

Be it known that 1, ANDREW BRtisTLE, of Ilyde Park, in the county of Norfolk and State of Massachusetts, have invented new and useful Improvements in Dental Chairs, of which the following, taken in connection with the accompanying drawings, is a specification.

This invention relates to improvements in dental chairs of that class in which the frame for supporting the seat, head, back, and foot rests is pivoted to the base in such a manner that it may be tilted to any desired position and there securely locked.

The invention has for its object the construction of a device for tilting the frame of the chair, which shall be efficient in looking it in position, and which shall be simple in construction and easily operated and present a neat appearance.

The invention has further for its object the novel construction, arrangement, and combination of parts, as will be hereinafter fully set forth, pointed out in the claims hereto appended, and illustrated in the accompanying d rawin gs.

In the accompanying drawings, in which similar letters of reference designate corresponding parts, Figure 1 is a side elevation of the base of a chair embodying the invention, showing the chair in its normal position. Fig. 2 is a similar view showing the chair tilted backward. Fig. 3 is a plan View. Fig. 4c is a detail view showing the frame for securing the segmental gears in their relative positions. Fig. 5 is an end elevation of one of the segmental gears with the frame attached.

Referring to the drawings by letter, A designates the base of the chair, provided with legs 13 B, on which it rests when in use. It is rotatably mounted on the pedestal O, and a cam O, operated by a lever C, is provided, so that the chair-frame can be raised until its legs clear the floor and then be rotated. The cam passes transversely through the base, having its ends journaled in the same and its fiat surface resting on the top of the pedestal, so that when it is operated by the lever the frame will be raised. From the front of the base projects a sleeve D, forming a journal for the shaft D, which passes through it and has its ends projecting from both sides. The se mental gears E are keyed on these projecting ends at their lower ends. base is pivoted the chair-frame, which has its side standards G extending below the pivotal point. Near the lower ends of these standards are pivoted at their lower ends the segmental gears E, which mesh with the gears E, secured to the shaft D, journaled in the base. In the present instance the gears are shown and described as segments of circles. By experiment, however, the inventor has found that a somewhat better result is ob-.

tained in the way of a smoother and more even movement by slightly cutting away the engaging surfaces ofthe upper part of the gear E and the lower part of the gear E and slightly extending the engaging surfaces of the upper part of the gear E and the lower part of the gearE. They are so nearly true segments, however, as stated before, that they are shown and described as such, as they will work very near as well as the modified form just referred to. To retain the gears in their relative positions a frame is provided, which is journaled at its ends on lugs M projecting from the center of the segments, one on each side of each pair of gears. This frame consists of a collar J, journaled on the bearings M, and has lugs K projecting from its opposite sides. These collars are connected by rods L, each rod passing through a lug of each collar, and may be secured in place in any suitable manner. A foot-lever F for operating the gears is keyed on the shaft D and To the top of the.

extends backward, so as to be easily reached by the operator. The free end of the lever is slotted and moves up and down on a curved rack F, secured to one of thelegs of the chair. To lock the lever on the rack a spring-catch F is provided.

If it is desired to tilt the chair backward from its normal position, the operator places his foot on the lever F, releases the catch, and allows the lever to gradually rise, the chair being moved by the hand, 01' ordinarily it will move by itself, the weight being backof the point where it is pivoted to the base. When it has reached the desired position, the catch is released and the lever locked on the rack, preventing any further movement of the gears, and thereby holding it firmly in place. To raise the chair again to its normal position the lever is pressed upon by the foot, the catch disengaged, and the lever forced down, which causes a partial rotation of the gears. One of the gears being attached to a shaft journaled in the base and the other to the frame at points near their peripheries, as the gears are turned downward these points will be forced farther apart, and as the former is immovable, being fast to the base, the lower end of the standard will he forced backward in consequence, and thereby bring the chairframe to its normal position.

Ilavin g thus described my invention, what I claim, and desire to secure by Letters Patent, is-

1. In a dental chair, the base, the side stand ards pivoted to the base, the segmental gears keyed on a shaft journaled to the base, the segmental gears pivoted to the side standards and meshing with the segmental gears pivoted to the base, and the lever for operating the same, substantially as and for the purpose :5 specified.

2. In a dental chair, the base, the frame pivoted to the base, the segmental gears pivoted to said frame and meshing with similar gears keyed on a shaft journaled to the base, and the frame connecting the intermeshing o gears, substantially as and for the purpose specified.

8. In a dental chair, the combination of the base, the frame pivoted to the base, the means for rotating said frame, consisting of the seg- 5 mental gears keyed on a shaft journaled to the base and meshing with similar gears pivoted to the standards of the frame, the lever for operating said gears, the curved rack, and the frames connecting the centers of the seg- 4o mental gears for holding them in their relative positions, substantially as and for the purpose specified.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, on this 6th day of May, A. I). 1890.

ANDREW BRUSTLE.

Witn esses:

PERRY M. BLAKE, GEORGE SANFORD.

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