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Publication numberUS413156 A
Publication typeGrant
Publication dateOct 15, 1889
Publication numberUS 413156 A, US 413156A, US-A-413156, US413156 A, US413156A
InventorsBasil M. Wilkkrson
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
US 413156 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

2l sheets-sheen `1. B. Ml WILKERSON.


310,413,156. f Patented 0 et. 15, w89.



near/fu. CHAIR.

SLPECFIGTION forming part oiaihetters Patent No. 413,156, dated October 15, V Application led March 14, 1879. (No model.) y

To @ZZ wwnfi'i'in/ty concern,.- J

Be it known that I, BAsIL M. WILKERSON,

of Baltimore, in the State of Maryland, havev invented certain neur and useful Improvements in Dentists Chairs, of which the following is a specification.

This invention relates to improvements applicable to that class of chairs the frames or bodies oit which are capable of being adj usted vertically and revolved horizontally about supporting pedestals or bases; and my improvements consist in certain organizations of parts and novel combinations et devices, as hereinafter fully set forth.

In my Letters Patent hie/197,441, dated November 20, 1877, I. have shown and described a dentists chair of this class, in which a vertically-m ovable support for the chai r frame or body and a mechanical lift for ele 7ating the same are combined with means distinct from and,indepei'nlent oi? the elevating meehanism, and which have no lifting function, but simply serve to uphold said supportant any point to which it is raised hy the elevating,l mechanism and to permit it, when desired, to pass gradually and without shock from that elevated point to alovverone. Under thai ar! rangement, however, the same instrumenial' ity through the medium of which the cho-irframe support was upheld was also the agent VVby Whose yielding` resistance under certain l tardefhwith a view to causing its descent to conditions the tall of the seat-snpport was rcbe gradual and easy. ln my present chair l retain-as far as possible the same conditions of movement, so as elevating and lowern ing,` are conenned, as in my said patented 4specification whenever l use the term retarding mechanism I intend the instrumen* tality or combination of elements Whicliects body itself and attach ments.

simply to oder yielding resistance to the downward movement of the chair-frame and not to either elevate or uphold and lock in posi lcion the said frame.

The retarding or lowering mechanism which, in illustration of myinvention', I have herein shown comprises a plunger (which may or mayvnot be the Vplunger or support that ear rires the chair frame or body) adapted tewerk in a. cylinder or'shell containing a liquid, suoli as oil. There need be no tight vfitting between the plunger and ease in which it Works, the intention being to permit the plunger te 'descend when the chairsupport is u.n'

locked audio displace the liquid in the case, the rate of displacement governing the speed of descent. ln other lwords, the body of liquid under the plunger is never entirely ooniined, thus permitting,` the descending plunger to move without encountering other than a yielding resistance due tothe displacement of the liquid. l have also devised other improveniente directed to the locking or upholding mechanism, to the lifting mechanism, to the manner of connect ing,r the chair-body 'ivith its support, und to the structure ot the chair These can best be explained and understood by reference to the accoinpanyinf.,v drawings, in which Figure l is a perspective view of one form of chair embodying' my invention, only so much of the 'chair being represented as needed in order to illustrate my improvements. Fig. 2 is a view, on an enlarged scale, partly in rvertical central lsection and partly in elevation. Fig. 3 is a perspective view oi the rotary cylinder which carries the seat-support and its adjunctsA section, on an enlarged scale, of the lower end or head of the retarding-plunger. Figs; 5 `to 9, inclusive, represent a modified arranged ment of parts, to be hereinafter 4referred to. Fig.. l0 is a plan view of the supportingbracket of-the upholding or locking mechanism, showing the guide-plate of said bracket for the chaiiframe support orplunger.

Referring; new to Figs'. 1 to 4f, A is the nonrotating pedestal or base sustaining the ro- `tary cylinder or main support B, which ear- Fig. l is a vertical central ries the vertically-adjustable chair-frame support, &c'., and is locked lin position by means Iside in contact with the Wall of the cylinder,

and by being embraced on the other sides by the upholding or clamping mechanism, and

i -by guides Afixed to the cylinder and in contact with the respectively adjoining faces of the support. This arrange'ment is shown plainly in Figs. 1, ,2, and '3, cii being a guide-plate, against which the support is pressed by an adjustable upholding-block e on theoppositeg side, and f being a bracket secured to the cyl inder B and provided with an inwardly-eX- tending portion, forming a guide-plate opposite'that side or face of the seat-support whose edges ay are in contact with the Wall of the cylinder. In these figures, in order to show more clearly the upholding or locking mechanism and also the retarding mechanism, I have omitted the elevating mechanism uwhich acts upon the chair-frame support. Itwillbe `understood that elevating mechanism such as described in my aforesaid Letters Patent, or other suitable elevating mechanis m--such, for instance, as that hereinafter describedcan be used. i

The upholding orlocking mechanism, which ,Y kin the present instance is used to lock the frame-support in any positionyertically that Imay be desired, is automatic to the extent i that it permits the support to be raised freely;

but it loc-ks it firmly against descent, and must be operated by some positive means in order to releasethe support and permit it to descend and bring the retarding mechanism into action.

The locking mechanism consists of a block e, whose plane face is held against the correspending face or side of the support (l by means of a rod g, provided at one end (sce Figs.1,3,`9,and l0) with a rounded extremity that seats itself in a like socket or depression in the block and at the other end with a concavity or socket which is entered by the end of. a screw 7i, which screws through a .bearinglug t' ofthe bracket f, attached to the cylindery B. The rod g is slightly inclined, having` itsend which engages the block e a little higher than the other end', which engages the screw. This arrangement, so far as the parts le g h are concerned, is most plainly shown in section in Fig. 9. Under this arrangement it will be seen that the upholding or locking` mechanism will readily and automatically yield toupward passage of the support (l but the moment the elevating mechanism ceases to act and the support C tends to descend, this will have thev effect of tending to straighten out andbring into line the kneejointed parts g 7i, with the result of forcing the clamp-block e tightly against the support, which will thus be firmly locked between the block. e on the one side and the plate d on the other; and the greater the do iWa-rd pressure on the seat-support the tighter will it be locked. The screw h is used to regulate the adjustment of'theparts of the knee-jointed support.,v 'The block c is capable of slight vertical movement in a guideway at j in the bracket f,and is pressed down (so as to keep the parts in proper position) by means of a spring 7c. A lever D, pivoted to the cylinder B and working therethrough against the underside of the block, as indicated in Fig. 3, serves to lift the block against the stress of the spring' whenever it is desiredy to unlock and release the support C. This lever, it will be seen, is supplemental to and independent of the locking or clamping devices in so far as their clamping action is concerned, the lever serving simply to trip the clamping devices to permit of the descent of the support.

In the modification of the locking or holding mechanism shown in Fig. 9, and also in perspective in Fig. 5 and in plan in Fig. 7, the lever or treadle D is provided with a pin Z, which extends through a slot Z in a boxlike housing B', fixed to the top' of the cylinder B, and engages the block e. l The block is raised to release the seat-support by means of the lever acting again-st the stress of a spring 7n', which exerts downward force on the short end of the lever and serves to depress' that end when pressure by the hand or foot is removed from the opposite end of the lever.

A convenient form of lifting mechanism is shown in Figs. 5, (i, 7, and S. It has the general characteristics of the mechanism for the same purpose described in my aforesaid Letters Patent, in that it is a lifting mechanism operated by a treadle or foot-lever E, catoliinghold after hold and raising the chair step by step. It, however, differs in details from the patented mechanism. 'lhelever E,which is operated by downward pressure upon its outer end to effect the raising of the seat-sup port by a step-by-step movement, is pivoted or has its fulcrum in the housing or box B.

is entered by a pin n', projecting laterally from a cam fn., pivoted to one en'd of a bar o, which is provided at its opposite end with a Hange or hook o and forms one jaw of a clamp for engaging the support C. On the clainp-bar o is mounted the slide-block p, which acted on by the cam n and constitutes the other jaw of the clamp. This arrangement is shown plainly in Fig. 8, which is a perspective view of' the clamp and a p'ortion of its actuating-lever. The clamp-jaws are adapted to enga-ge the support C, as shown IOO IIO

' lts inner end is provided with a slot m,which in Fig. 7. When the lever E is depressed it lock the support in the clampbodily, and with it the seat-support which it grasps. The pressure of the foot is now 'released 'from `the, lever and the latter,

through the instrumentality of a spring shownv inffFig. as secured to the housing B and .acting 'on the lever, is returned to its normal .andltoj .lift it another step, when the pedal end of the foot-lever is again depressed and .the elevating' operation continued to the ex tent desired: While the lifting devices release Athe support and retnrnwto position to Ctake a fresh hold' the upholding or locking mechanism before described acts to securely position to which it has already been lifted.

' The mechanisms thus far described answer `admirably the purposes for which they are intended; but it Will be seen that were the plunger or chair-body support left entirely l free Vto descend when it is unlocked its descent 'would be sudden' and violent. Therc-l fore means are provided to render that descent gradual and easy.. To effect this is the voiice of the herei nbefore-inentioned retarding mechanism, one form of which I now proceed to describe.

In Figs. l to e the retarding mechanism comprises an auxiliary plungerv F, which moves with the Achair-support C and is connected therewith andiits in acylinder or well G, fixed to and arranged in the rotary cylinder B. rlhe cylinder Gis closed at the bottoin and is intended to contain oil or other liquid; The plunger is notrequired to lit its cylinder accurately'and no packing between the two is needed. The plunger may be closed atthe head or bottom, in which event the only escape for the liquid before the deseen d- Ving plunger is by leakage past or by the l plunger-head into the space which exists be- 4foratcd diaphragme s s.

tween the plunger and the'walls of its cylin der; or various other ways, which will readily suggest themselves, may be employed to provide for gradual displacement of the-liquid as the plunger descends. A convenient arrangement for the purpose consists in 1naking the auxiliary plunger hollow andinproviding `its lower end with a valve vll', which has aislight play between two centrally-per- Wh'en the valve drops, as shown in lfig. Al, its spaced bottom lugs or feet fWhold it up from the lower diaphragm and liquid is free to pass by way of the spaces between the feet from one side of the valve to the other through the central openings in the diaphragms.. This is the po sition occupied by the valve ger rises, thepassageway formed bythe opendoin.

ings between the valve-feet being of suiii- Vciently largev area to permit liquidto pass the valve with entire freefrom above below 4 When, on the other hand, the valve is closed againstthe upper diaphragm, nomliqlcarried by the chair.

when the plunuid can pass through it from when, as is the case here, the valve is provided itself with a' small `central opening, which, as shown, is covered by. a partiallyclosing smaller valve t. This opening need. not be covered at all butthe valvetis added, to showhow the o )ening whichit covers may be graduated iu accordance with the weight The supplementalvalve which opens downward, normally stands-fully open,` but is made of spring metal, or is acted on by a spring, torendei it self-adjusting, so kthat in case of the, chair carrying more weight than ordinarily, as when it is occupied'by aheavy person, the pressure induced'by the Weight will have the eiect of partly closing the valve, and so reduoing'the size ofV the opening. Inthis way the rate of movement in descent can be made even and below, save 1 uniform, no matter what may be the weight of the person occupying ever the locking mechanism is released, the plungermoves down. through the liquid, the latter oozing through the small central valve opening and also up outside of the plunger between it and the wall of the cylinder, and gathering in the upper parts of the cylinder and the hollow plunger. l is provided in the top oi the plunger for escape of confined air. p

I make the head or lower end ot the plunger of greater diameter than theplungenbody, and forni above this enlarged end one or openings n in the end of the liquid lnaypass freely in and out of the plunger. I thus provide a mechanism which, While it does not act to lock. or sustain the support in an elevated position, and does not consequently require that nice and accurate fitting a nd delicate adjust in cnt which it would require were it used for that purpose, yet acts to retard the fall of thc chair-frame support when thc latter is released from the locking mechanism, and to malte its descent gradual and easy. l

ln lieu of employing an vauxiliary plunger, i can make the main plunger or chair-franixe support C answer thc two purposes of support the plunger, so that the chair.` Whenr A small rent-hole J more Ioo


ing the chair and rctarding itsdescent. Such 4 an arrangement is shown in Figs. 5 to19. -Thc rotary cylinder B inthis instance is closed at the bottom, so as to contain ccivcs the hollow plunger C, at the bottoni with a valve arrangement resembling that on the auxiliary plunger and similarly lettered.

box B', fixed on top liquid, and reof the cylinder Aand containingvworking parts of thelifting and lockn ing mechanism, will receive, if need be, such` of thedisplaced liquid` as can not bri-contained in the cylinder or' plunger. The operation of this retardin'g mechanism is whole, prefer this last arrangementgas it is.

which is provided 'lhe housing` or vcovered similar to that which has already been described.- 1I, on the simpler and `enables me t dispense with anv Y.auxiliary plunger.

In 9d have represented the .upper-'bean ings of the seat-supporting plunger as consisting of 'two friction-rollers w i0, mounted some llittle distance apart from one another in the box B'. The block e, on the other side of the plunger, is arranged opposite the space between the 'roller-bearings, and in this way the plunger may be clamped very tightly, at

l the same time that it is in condition to move freely and without friction when the clampblock e is tripped. The upper bearings for the plunger are so located that when the plunger is at its lowest position they are very near its top, the'object being to obtain a vertical range of movement as extended' as possible.

The chairframe or body proper H is fixed to or forms part of a plate II, pivoted atj to the side of the plunger or vertically-adjust able support C. The chair-frame which is and forth on the point m as an axis.- In order to secure the chair-frame at any desired angle of inclination,I make use of means which automatically clamp it, comprising a set-l screw or clam ping-screw y, which screws into the support C and passes loosely through a curved slot .e in the plate H.v Thescrew is provided with a bearing-Hange y', which rests against the chair-frame plate. By turning the screw in one direction its clamping face or ange y will be drawn against the plate and so will clamp the latter against the scat- Isupport. When the screw is turned in the other direction, its pressure will be relaxed and the chair-frame will be free to tilt. In order to better insure clamping action,I form on the-support C two raised bearings y2 y2, The clamping-face o f the screw is on the side of the plate opposite that next these bearings and in a position intermediate between said bearings, so that when it.iS screwed up the plate will be held between the points @fig/2 'and 'y'. On the outer end of the screw y is fixed a lever I, and a spring J, of proper strength and suitably arranged, is provided, which acts on the lever to move it in the direction required to cause the screw to exercise clamping-pressure. That pressure, whenever it is desired to change the angle of in- 5o clination of ,the chair, is relieved by turning A the lever against the stress of the spring.

The moment the lever is released the springl A6o cally movable, and is provided with aclamp- `ing or locking device M, which constitutes also a handle by which said back may also be `raised. The back L, however, not only is vertically adj ustable,but can tilt laterally on the clamping-screw M as an axis. This screw passes into`the' chair-back through a vertical thus carried bythe support C can tilt back\ slot in the supportihg-standard N of the chair-4 "j r frame. v

I find it advantageous tomake one-or both arms of the chair adjustabledaterally, and. also vertically as Well.` I also find it of advantage, in order to furnisha lseat or support vided with a horizontal part P', extending' under the chair and, 'longitudinally slotted,

as at 3. From the chairframe extends a` l vertically-slotted plate R, to which the part P is attached by a s`et-screw 4, that passes through the slots' at their intersectiomand is provided with a handle 5, by which it may .be loosened or tightened. The slotted barP permits the chair arm and stem to be moved bodily to and from the chair-seat. The slotted supporting-plate R permits the arm to be vertically adjusted, and the set-screw4serves as a pivot on which the arm and its support` ing-stem can move as an axis. The-arm under this arrangement can be iutned down, so as to be secured in a positionvwhere it may serve as a seat or rest 'for the operator. This pivoted arrangement can b e used 'to advan tage, whether one or both of the parts P R .y

be slotted, or, indeed;vl if the slotted connection be disp'eiiscdmith and the parts have simply a pivotal connection. have one or both of its arms made adjustable in this way.

I have described the manner yin which prefer to carry my improvements into effect.

.100" The chair may It will be understood, however, that the details of construction may be varied to a con siderable extent without departurefrom the invention. I do not limit myself, therefore, to the particular details herein described in illustration of my invention; lbpt lWha-t I claim, and desire to secure by Let-- ters Patent, isy Y l."l`he combination, substantially as set forth, of a liquid-carrying cylinder,-a plnger movable up and down in the liquid in the cylinder, the plunger-head by which the liquid above and below it communicates at all times, and `the chair-frame .connected with the plunger and partaking of its movements, whereby the descent of the chair-f1ane,when the plunger is free to move downward, may

automatically be retarded by gradual displacement of the liquid beneath the'plungerhead and its passage upward.

2. The combination, substantially as set forth, of a liquid-carrying cylinder, a hollow plunger movable up and' down in the cylinder, the plunger-head, an automatically-.acte ing valve seated in the pln`nger-head and by which communication is at, all times mairnl` .tained between liquid above and below said elaine- 5 head, and the chair-frame connected with and partaking ot' the movements of the plunger, whereby descent of th e ehair-fran1e,when the plunger is free to move downward, may automatically be retarded by gradual displacement of the liquid beneath the plungerhead and its passage upward.

3. The combination,` substantially as set forth, of a liquid-carrying cylinder, a hollow plunger movable up and down in the liquid in the cylinder, the plunger-head by which the liquid above and below it in the cylinder communicates at all times, an automaticallyaeting valve seated in the plunger-head and ,by which communication is at all times maintained between liquid in the plunger and in the cylinder, and the chair-frame connected with and pai-taking of the movements of the plunger, whereby the descentl ol' the chairf1"z1n1e,when the plunger is allowed downward movement, may automatically be retarded by gradual displacement of the liquid beneath, the plunger-head and its passage upward around and into the plunger.

4. 'lhc combination of the liquid-carrying cylinder, a hollow plunger movable up and down in the cylinder, the chair-frame connected with and partaking of themovcments of the plunger, the plunger-bead, an automatically-acting main valve seated in the plunger-head, and by which communication is at all times maintained between liquid above and below said head, andthe automatically-acting supplemental valve for varying the area of the communicating way or passage alforded by the main valve, substantially as and for the purpose set forth.

The combination of a liquid-carrying cylinder, a chair-frame support or plunger movable up and down in 'the cylinder, having bearings at the upper end thereof and lit-ting loosely at its lower end or headtherein below said bearings to allow of constant communication between the liquid above and below said head, the lifting devices, and the looking or upholding devices, substantiallyas and for the purpose set forth.

G. The combination of the pedestal or base,

the chair-frame support or plunger carriedv thereby, the lifting devices, the automatic clamping devices sustained by connection with the pedestal or base, consisting of the clamp-block and the self-adjusting kneejointed support therefor, said clamping devices yielding to allow the chair-frame support or plunger to ascend but preventing its descent, and the lever for tripping` the clamping devices to release said plunger, substantially set forth,

7. The combination, substantially set forth, of the chair-frame support or plunger, the clamp-bar provided with the end ilange for engaging the plunger at one side, t-he slideblock for engaging the plunger at the opposite side, the lever, and the cam by which the .lever is connected with the clamp-bar and slide-block, whereby the clamp-bar flan ge and vslide-block may be caused to grip theplunger for elevating it.

8. The combination, substantially as set forth, of the pedestal or base, the verticallyadjustable support or plunger carried thereby, the clamp-block acting on said plunger, and the adjustable thrus ing'jointed support of said block, said supp'o'rt yielding to allow upward movement of the plunger.

E). The etnnbination, substantially as set forth, of thepedestal or base, the verticallyadjustable plunger carried thereby, the clam pblock acting on said plunger, the self-adjusting thrusting-support for the clamp-block, said support yielding to allow upward movement of the plunger and acting on said block to automatically loelr the plungerl against d'escent, and thelever actin g on the clamp-block to release the plunger.

lO. The combination ot the seat, the arm, the supporting standard or stem of the arm, and the pivot extending parallel, ornearly so, with said arm, and passing through said stem to connect it with the seat, whereby the arm may be swung in a plane transverse to the seat and adjusted toward and `from it, substantially as and for the purpose set forth.

ll. The combination of the vertically and centrally slotted ehair-frame-baek standard, the vertically-adjustable and laterally-tilting chair-back, and the screw-clamp secured to and carrying or moving 'up and down with the chair-back, and engaging with and movable inthe slot of said standard, whereby the chair-back may be moved up and down by ,and swung about said clamp, substantially as and for the purpose set forth.

In testimony whereof I have hereunto signed myname in the presence of `two subscribing witnesses.


Witnesses: l

Roer. W. SMITH, Jr.,



Referenced by
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Cooperative ClassificationA47C7/402