Untitled record

Application filed August 29,1887. Serial No. 24^,181. (No model.)

To all whom it may concern:

Be it known that I, Dewell Stuck, of Big Rapids, in the county of Mecosta and State of Michigan, have invented certain new and use5 fnl Improvements in Dental Chairs; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use it, reference being io hadto the accompanying drawing, which forms part of this specification.

My invention relates to an improvement in dental chairs; and it consists in the combination of a suitable frame-work, a rod, which is 15 mounted thereon and has a free turning movement, the tube, which is connected to the bottom of the chair and passes down over the head, which is secured to the upper end of the rod, a roller and a friction device, which are 2c placed in recessesin the head, and which regulate the descent of the chair, and the two independent clutches which operate upon the tube, all of which will be more fully described hereinafter.

: The object of my invention is to produce a raising and lowering mechanism for a dental chair by means of which the chair can be raised and then made to slowly descend from the weight of the person sitting upon it when the 30 frictional clamps are operated for that purpose.

Theaccompanying drawing represents a vertical section of a chair embodying my invention.

A represents a suitable frame-work, which is here shown as circular in shape, and across the bottom of which extends the supporting cross piece B. Rising from the center of the - cross-piece B is the rod or post C, which has 40 an enlarged head, D, secured to its upper end, and which head D fits inside the tube E, secured to the under side of the chair, and acts as a guide for the tube in all of its movements. This post Chas a free turning movement upon the piece B, so that the chair can be freely turned in any desired direction. The screw x merely passes through the cross piece B and serves to secure the post in a vertical position, but allows it to be freely turned around with the chair. By this construction the post and tube turn together, so as to avoid any unnecessary friction of the tube upon the other parts. The length of this head is sufficiently great to prevent the slightest lateral movement of the tube, and hence as the chair risesand falls the 55 tube always maintains a vertical position. This head extends a suitable distance above the top of the frame, and in one side are made the two inclined recesses G H, of which the outer one, G, is longest. In this recess G is 60 placed the wedge shaped frictional device I, which has its thickest end uppermost, and is provided with aleather, a, orothersuitablecovering upon its outer side where it comes in contact with the inner side of the tube, for the 65 purpose of exerting a greater frictional contact upon the tube as the chair descends. This frictional device is shorter than the recess in which it is placed, so as to allow the device an endwise sliding movement. 70

When the chair is being raised upward, there is no need for any frictional contact of the de- . vice I with the inner side of the tube, and then the device I rises with the tube and is forced into the upper and deepest part of the recess 75 G, and is thus moved out of forcible contact with the side of the tube. As soon as the upward motion of the tube ceases the frictional device I drops in the recess G from its own gravity sufficiently far to again engage with 80 the inner side of the tube. The higher the frictional device is moved in the recess G the moreitis brought outof contact withtbetube, and hence the less it interferes with its movement in either direction. In direct propor- 85 tion as the frictional device drops in the recess G so is the movement of the chair retarded. In order to regulate the distance that this device L shall move upward in the slot, the setscrew L is passed down through the top of the 90 head into the upper end of the recess G, so as to act as a stop to the upward movement of the device I by resting against a spiral spring inserted in its upper end.

In the recess H, which is also made taper- 95 ing and inclined in the same direction as the one G, is placed a roller,N, which bears against the upper side of the device I for the purpose of forcing it outward against the inner side of the tube when the chair is descending. The 100 roller N has a suitable amount of movement in the recess H, and when it is moved upward

376,016 ⁶5 this head, aud which are placed one inside of the other and communicate together, the frictional roller placed in the inner recess, the wedge-shaped frictional device placed in the outer recess and bearing against the inner side of the tube and the outer side of the roller, and the vertically - moving tube which fits down over the head, substantially as shown.

2. The combination of the frame, the rod C, provided with a head upon its upper end into the deepest end of the recess by the upward movement of the device I in the recess G it forces the device I outward to a very slight extent. In proportion as the roller drops downward in the recess H, so it forces the device I outward in its recess, and thus causes it to exert a frictional contact against the inner side of the tube. This roller rises with the device I as the device is carried upward by the tube, and as the tube descends .

and carries the device I downward, so the ! which has two inclined communicating reroller sinks down iu its recess.

Placed around the tube, inside of the frame A, is the frictional clutch O, which is sup- i ported both by frictional contact with the tube | and by the connecting rod Q, which acts as a I support for one side, and transmits the motion j of the lever R to the clutch. Formed on one I side of this clutch is an extension, S, which | catches in a slot, T, made in the side of the I frame for the purpose of preventing the clutch j from turning upon the tube. Connected to । the clutch is the upper end of the spring U, | which is secured at its lower end to the crosspiece B, which spring draws the clutch downward as soon as it is left free to move after havingbeen raised upward; also, surrounding the tube to which the chair is connected is a second clutch, AV, which has its outer end passed through and held in the opposite side of the frame-work from the end of the clutch O. This clutch sinks downward with the tube, as shown in solid lines, so as to grip the tube and prevent any downward motion while the lower clutch, O, is descending for another hold. The upward movement of this clutch AV is regulated by the top of the frame A, against which it strikes. AVhen the lower clutch, 0, is raised upward to its full extent, it- strikes against the under side of the clutch AV and raises it against- the top of the frame, as shown in dotted lines. While the two dutches 0 W me held in this raised position they do not grip the sides of the tube, and hence the tube is left free to descend, being controlled only by the frictional devices placed inside of the tube for that purpose. I

It will be seen that the two clutches operate j independently of each other until the chair is | to be lowered, and then the lower clutch op- [ crates upon one, so as to leave the chair free i to descend. AVere it not for this upper clutch, each time that the clutch 0 is lowered for another hold the chair would sink downward.