US3472488A - Foldable lift device - Google Patents

Description

Oct. 14., 1969 J, NAUGHTON 3,472,488

FOLDABLE LIFT DEVI CE Filed July 5, 1967 2 Sheets-Sheet 1 JOHN L A m/w/m/v Oct. 14, 1969 J. L. NAUGHTON FOLDABLE LIFT DEVICE 2 Sheets-Sheet 2 Filed July 5, 1967 //v V1VT0A7 Jamv L. Amum/ra/v 5 @z A0. M

47'70F/VEY United States Patent O 3,472,488 FOLDABLE LIFT DEVICE John L. Naughton, Des Moines, Iowa, assignor to Den- Tal-Ez Chair Manufacturing Co., Des Moines, Iowa, a corporation of Iowa Filed July 5, 1967, Ser. No. 651,252 Int. Cl. A47c 3/20; B66f 3/22 US. Cl. 254-122 6 Claims ABSTRACT OF THE DISCLOSURE The lift device is used for raising and lowering chairs, such as a dental chair and includes a pair of transversely spaced oppositely arranged upright lazy tong assemblies, each of which has upper and lower pairs of tong members. One of the tong members in each lower pair is pivoted at its free end to a base means and the other lower tong member has its free end movably supported on the base means for movement longitudinally thereof. A horizontal lift pad for supporting a chair is pivotally connected to the free end of one of the tong members in each upper pair. The other upper tong member has its free end movably connected with the lift pad for movement relative to the pad in a direction longitudinally of the base means. A carriage unit longitudinally movable on the base means carries a lift means at a position between the lazy tong assemblies. The lift means is attached to the pivots which connect together the lower pairs of tong members and is guided for vertical up and down movement so that the lazy tong assemblies are vertically extended and retracted in response to the up and down movement of the lift means to raise and lower the lift pad in a horizontal position therefor.

SUMMARY OF THE INVENTION The lift device of this invention provides for the raising and lowering of a dental chair between limits such that a patient therein can be comfortably worked upon by a dentist from either a seated or a standing position. The lift or chair supporting pad at the upper end of the lift device, for all moved positions of the lift device, is maintained in a horizontal position and stabilized against tipping movement out of a horizontal plane. An adjusted position of the chair relative to the pad is thus continuously maintained. The lift device operates to efficiently raise and lower a dental chair with a patient therein, and is of a compact construction so as not to interfere with the freedom of movement of the dentist about the chair and may be readily substituted for the usual supporting base or standard for a chair.

DETAILED DESCRIPTION OF THE INVENTION Further objects, features and advantages of this invention will become apparent from the following description when taken in connection with the accompanying drawing in which:

FIG. 1 is a perspective view showing a dental chair in assembly relation with the lift device of this invention;

FIG. 2 is an enlarged sectional view taken substantially on line 22 in FIG. 1 showing the lift device in side elevation and in a raised position therefor;

FIGS. 3, 4, and 6 are detail sectional views as seen on the lines 33, 44, 5-5, and 66, respectively, in FIG. 2; and

FIGS. 7 and 8 are diagrammatic side elevational views showing the lift device in raised and lowered positions, respectively.

Referring to the drawings, the lift device, indicated generally at 10, is shown in FIG. 1 for use with a contoured dental chair 11. The lift device is mounted for rotational movement on a floor plate 12 and is held in a rotated position by means including a foot actuated locking lever 13.

The lift device 10 (FIGS. 2 and 5) inclhdes a base member 14 of a rectangular shape and a pair of like transversely opposite upright lazy tong assemblies 16 sup ported on the base member and having a lift pad 17 carried on and extended between the upper ends thereof. The lift pad 17 constitutes a mounting plate for the dental chair 11. A lift means, designated generally as 18, is mounted on a movable carriage unit 19 at a position between the lazy tong assemblies 16 and is connected with the tong assemblies 16 to provide for their extension and contraction to raise and lower the lift pad 17.

The base member 14 (FIG. 5) is suitably mounted on and secured to a bearing plate 21 that has a depending hub 22 rotatably received within the floor plate 12. The carriage unit 19 (FIGS. 2 and 5) is received within a longitudinally extended guideway 23 formed in the top surface of the base member 14 for movement longitudinally of the base member. Supporting rollers 24 on the carriage unit 19 are ridable on the bottom wall 26 of the guideway 23.

Since each of the lazy tong assemblies 16 is of a like construction and operation only one thereof will be described in detail with like numerals being applied to corresponding parts. A lazy tong assembly 16 includes a lower pair of tong members 27 and 27a (FIG. 2) and a pair of upper tong members 28 and 28a. The lower tong members 27 and 27a are pivotally connected together at 29 intermediate the ends thereof to provide for their relative movement in what may be called a scissors action. The pivot means 29 (FIG. 5) includes a sleeve bearing 31 inserted within aligned openings 32 extended transversely through each tong member 27 and 27a for receiving a pivot bolt 33 the inner end of which is threadable within a horizontal ring collar 34 located between the pivot means 29 and forming part of the lift means 18. As best appears in FIG. 2 the sections of the tong members 27 and 27a located upwardly from the pivot means 29 are of a shorter length than the sections thereof that are located below the pivot means 29.

The lower end of the tong member 27 (FIGS. 2 and 5) is pivotally connected at 36 to one end 37 of the base member 14 for pivotal up and down movement about an axis extended transversely of the base member. The lower end of the tong member 271; carries a roller 38 operatively associated with a track assembly 39 (FIGS. 2 and 3) for movement longitudinally of the base member 14. Coacting portions on the roller 38 and track means 39 maintain the roller 38 against vertical and transverse movement relative to the base member 14, during movement of the roller longitudinally of the base member. It is seen, therefore, that when the tong member 27 is pivoted about the pivot 36, the lower end of the tong member 27a is concurrently moved longitudinally of the base member 14 to provide for a scissors action of the tong members 27 and 27a.

The upper pair of tong members 28 and 28a are pivotally connected together intermediate their ends by a transversely extended pivot bearing 41.. As seen in FIG. 2 sections of the tong members 28 and 28a upwardly from the pivot 41 are of a shorter length than the sections thereof located below the pivot 41. The lower ends of the tong members 28 and 28a are connected by transverse pivots 42, with the corresponding upper ends of the lower tong member 27 and 27a.

The lift pad 17 (FIG. 2) includes a horizontal body member 43 that is provided at one end with a centrally located depending lug 44 of a generally hook shape. The upper ends of the tong members 28 are bent inwardly toward each other to positions adjacent the opposite sides of the lug 44 to which they are pivotally connected by a transversely extended pivot means 46. Rollers 47 (FIGS. 2 and 4) are carried at the upper ends of the tong members 28a for ridable engagement in a track means 48 provided at the end of the lift pad 17 remote from the pivot means 46. The upper ends of the tong members 28a are thus movable relative to the lift pad 17 in a direction longitudinally of the base member 14.

It is to be noted that the axes of the rollers 47 are in a horizontal plane common to the axis of the pivot means 46. The lift pad 17 is thus retained in a horizontal plane for all relatively moved positions of the tong members 28 and 28a. In this connection it is also to be noted that the axes of the rollers 38 on the tong members 27a are in a horizontal plane common to the axes of the pivots 36 for the tong members 27. With the rollers 38 and 47, and the pivot connections 29, 36, 42, 41 and 46 in one lazy tong assembly 16 being in coaxial alignment with the like rollers and pivot connections of the other of the lazy tong assemblies 16 the axes therefore are always maintained in horizontal planes for all moved positions of the assemblies 16.

The lift means 18 includes an upright screw shaft 49 (FIGS. and 6) coaxial with the ring collar 34 and having its lower end rotatably supported in a bearing 51 carried in the top side of the carriage unit 19. An upright lower or stationary cylindrical sleeve member 52, in a concentrically spaced relation about the shaft 49 is formed at the bottom thereof with a laterally extended annular flange 53 for mounting on the top side of the carriage unit 19. The flange 53 is rigidly secured to the carriage unit by any suitable means such as cap screws 54 (FIG. 2).

An outer cylindrical sleeve member 56 (FIG. 5) is in a concentrically spaced relation about the stationary sleeve member 52 and carries on the inside of its bottom end a ring bearing 57 for slidable bearing engagement with the outer peripheral surface of the stationary sleeve member 52. Opposite the ring bearing 57 and secured to the outside surface of the outer sleeve member 56 is a supporting collar 58. The ring collar 34, that is secured to the pivot bolts 33, is in a nested relation about the outer sleeve member 56 and rests directly on the supporting collar 58. A usual friction screw (not shown) is threadable through the ring collar 34 and into engagement with the outer sleeve member 56 to retain the ring collar 34 and into engagement with the outer sleeve member 56 to retain the ring collar 34 on the supporting collar 58.

An inner sleeve member 59 is telescopically received within and in bearing engagement with the inner peripheral surface of the stationary sleeve member 52. Provided within and secured to the sleeve member 59 at its lower end is a lift nut 61 in operative association with the screw shaft 49. The upper portion of the outer sleeve member 56 is formed with a section 62 of a reduced diameter for engaging the upper end of the inner sleeve member 59. The sleeve members 56 and 59 are connected together at their upper ends by screws or the like 63 for concurrent movement relative to the stationary sleeve member 52.

It is seen, therefore, that the movable sleeve members 56 and 59, during their concurrent movement relative to the lower or stationary sleeve member 52, are continuously guided for vertical movement by virtue of their bearing engagement with the inner and outer peripheral surfaces of the stationary sleeve member. Since the lift nut 61 is secured to the inner sleeve member 59, and the ring collar 34 is connected to the pivot bolts 33, the lazy tong assemblies 16 are positively guided for extension and contraction in parallel vertical planes to raise and lower the lift pad 17. The sleeve assembly 52, 56, and 59 thus functions as a stabilizing mechanism to maintain a vertical raising and lowering of the lift pad 17 and a holding of the lift pad in a horizontal plane for all moved positions thereof.

Rotation of the screw shaft 49 to raise and lower the lift pad 17 is accomplished by means including a reversible electric motor 64 (FIGS. 2 and 6) mounted on the carriage unit 19 to one side of the stationary sleeve member 52. A gear unit 66 operatively associated with the motor drive shaft (not shown) includes a drive sprocket 67 located in the horizontal plane of a driven sprocket 68 mounted at the lower end of the screw shaft 49 and connected with the drive sprocket 67 by a sprocket chain 69. The lower end of the stationary sleeve 52 is cut away to form openings 71 (FIG. 5) to accommodate opposite lengths of the sprocket chain 69. The motor 64 is operated by means including a switch having a foot actuated lever 72 (FIG. 1).

As shown in FIG. 7, on operation of the motor 64 to extend the lazy tong assemblies 16, the tong members 27 are pivoted relative to the pivots 36 concurrently with the movement of the lower ends of the tong members 27a longitudinally and inwardly of the base member 14. This relative pivotal movement of the tong members 27 and 27a takes place by virtue of the elevating of the pivots 29 by the lift nut 61. The relative pivotal movement of the lower tong members 27 and 27a is in turn transmitted to the upper pair of tong members 28 and 28a through the pivot connections 42. During this relative pivotal movement between the tong members 28 and 2811 the tong members 28 pivot relative to the lift pad 17 at the pivot connection 46, and the free ends of the tong members 28a move relative to the lift pad 17 at the roller and track assembly 47 and 48. The carriage unit 19, stationary cylinder 52 and motor 64 are moved together longitudinally of the base member 14 in a direction towards the pivots 36. This movement is indicated in FIG. 7 by the travel of the axis 73 of the stationary cylinder 52 from its position indicated by the dash line A to a position indicated by the dash line B.

On lowering of the lift pad 17 to a contracted or folded position of the lift device 10 the lazy tong assemblies 16, carriage unit 19 and lift pad 17 are moved to their relative positions shown in FIG. 8.

In one embodiment of the lift device 10, the pad 17, in its lowered position, is at an elevation of about eleven inches above the floor surface, and is extendable to a raised position to a height above the floor surface of about twenty-eight inches. During this lowering and raising of the lift pad 17, the lift device 10 is maintained substantially within the dimensional confines of the base member 14 which is about twenty-four inches long and thirteen inches wide. As shown in FIGS. 1, 2 and 5 the entire lift device 10 is enclosed within an accordion or bellows type housing 74 having the locking lever 13 and motor actuating lever 72 projected therefrom at positions conveniently accessible for foot actuation.

Although the invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited since changes can be made therein which are within the full intended scope of this invention as defined by the appended claims.

I claim:

1. A lift apparatus comprising:

(a) a base means,

(b) a pair of upright transversely opposite aligned lazy tong assemblies each of which includes upper and lower pairs of tong members, with one tong member of each lower pair of tong members pivotally connected at one end to said base means, and the other tong member of each lower pair of tong members movably supported at one end on the base means for movement longitudinally thereof,

(0) a lift pad,

(d) a first tong member of each upper pair of tong members pivotally connected at one end to said lift pad, and the second tong member of each upper pair of tong members movably connected at one end to said lift pad for movement relative thereto in a direction longitudinally of said base means,

(e) a carriage structure supported on said base means for movement longitudinally thereof,

(f) a vertically movable lift means mounted on said carriage means intermediate said pair of lazy tong assemblies, and

(g) means connecting said pair of lazy tong assemblies to said lift means for vertical movement to unfolded and folded positions therefor in response to up and down movement, respectively, of said lift means.

2. A lift apparatus according to claim 1 wherein:

(a) said lift means is connected to each of said lower pair of tong members and located within the vertical height of said lazy tong assemblies when said assemblies are in either the folded position or the unfolded position therefor.

3. A lift apparatus comprising:

(a) base means,

(b) a pair of like transversely spaced lazy tong assemblies, with all of the pivot connections connecting together the tong members in one of said assemblies being in coaxial alignment with all of the corresponding pivot connections in the other of said assemblies, each of said assemblies including upper and lower pairs of tong members,

(0) a lift pad,

(d) a first tong member in each upper of tong members pivotally connected at one end to said lift pad and the second tong member in each upper pair of tong members movably connected at one end to said lift pad for movement relative thereto in a direction longitudinally of said base means,

(e) a carriage unit movably supported on said base means for movement longitudinally thereof,

(f) a first tong member in each lower pair of tong members pivotally connected at one end to said base means, and the second tong member in each lower pair of tong members movably supported at one end on said base means for movement longitudinally thereof,

(g) vertically movable lift means mounted on said carriage unit intermediate said tong assemblies, and (h) means connecting a pair of said coaxially aligned pivot connections to said lift means for vertically movement of said tong assemblies to unfolded and folded positions therefor in response to up and down movement, respectively, of said lift means.

4. A lift apparatus according to claim 3 wherein:

(a) said lift means includes an upright screw shaft rotatably supported on said carriage unit,

(b) a lift nut for said screw shaft connected to said pair of coaxially aligned pivot connections, and

(c) a reversible motor means mounted on said base means in a driving relation with said screw shaft.

5. A lift apparatus according to claim 4 including:

(a) a vertically extended telescoping means mounted on said carriage unit and guidably associated with said lift nut to stabilize the lift nut for vertical travel on said screw shaft.

6. A lift apparatus according to claim 5 wherein said vertically extended telescoping means includes:

(a) a first upright cylindrical sleeve member mounted on said carriage unit in a concentrically spaced relation about said screw shaft,

(b) an inner cylindrical sleeve member telescopically received within said first sleeve member in bearing engagement therewith,

(c) an outer cylindrical sleeve member for telescopically receiving said first sleeve member in bearing engagement therein,

(d) means connecting together the upper ends of said inner and outer sleeve members for concurrent movement axially of said first sleeve member,

(e) means rigidly connecting said lift nut to the lower end of said inner sleeve member in coaxial alignment with said three sleeve members, and

(f) means adjacent the lower end of said outer sleeve member connected to said pair of coaxially aligned pivot connections.

References Cited UNITED STATES PATENTS 956,189 4/1910 Schwarz 187-18 ROBERT C. RIORDON, Primary Examiner D. R. MELTON, Assistant Examiner U.S. Cl. X.R.

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