US3093409A

US3093409A - Rocker chair

Info

Publication number: US3093409A
Application number: US37402A
Authority: US
Inventors: Peter S Fletcher
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-06-20
Filing date: 1960-06-20
Publication date: 1963-06-11
Anticipated expiration: 1980-06-11

Description

P. s. FLETCHER RocKER CHAIR Filed June 20, 1960 June 11, 1963 United States Patent 3,093,409 ROCKER CHAIR Peter S. Fletcher, Delray Beach, Fla., assigner to Anton Lorenz, Boynton Beach, Fla. Filed June 20, 1960, Ser. No. 37,402 5 Claims. (Cl. 297-89) The present invention relates to reclining chairs, and in particular to a rocker type of reclining chair which includes a rst or normal sitting position wherein the chair may be rocked and a second tilted or sitting position wherein the chair may be rocked. Advantageously, the chair may incorporate a leg-rest which is moved into an elevated leg-supporting position in dependence upon movement of the chair into the tilted sitting position wherein the chair is rocked with the leg-rest in its elevated leg-supporting position.

It is generally known to provide a rocker chair which comprises a base which is engaged by a rocker member having a body-supporting unit thereon, such that the chair occupant may, when seated in the body-supporting unit, rock back and forth. It has further been suggested that such rocker chair be provided with a leg-rest which is mounted on the chair for movement from a stored or retracted position to an elevated leg-supporting position. In such chair, the leg-rest may either be spring-biased to move to the extended leg-supporting position upon release of a locking mechanism by an actuating handle, or may be manually moved into the extended leg-supporting position by manipulation of a handle. Further, chairs of this type have been provided with means for locking the same in a tilted back position, with the legrest extended or retracted in accordance with the desires lof the chair occupant, such means usually requiring the provision of a second handle to be operated by the chair occupant. Apart from the inherent complexity introduced by the provision of independent means for manually releasing or actuating the leg-rest and/or locking the chair in one of a number of positions, the need for one or more handles to be operated by the chai-r occupant to establish the various chair positions is a deterrent to the widespread commercial acceptance of a rocker chair of this type. The average consumer, particularly in the field of home furnishings, is reluctant to purchase or use a chair which is not completely automatic and requires the facility to operate mechanisms associated with the chair, no matter how simple such mechanisms may be in the use of the chair (Le. the manipulation of one or more handles). Quite apart from this, the handles, which must be external to the chair proper and in an easily accessible location, for example at the side of the chair frame, are relatively unsightly and are tell-tale evidence of the mechanical nature of the chair.

Broadly, i-t is an object of the present invention to provide a rocker type of reclining chair which obviates one or more of the aforesaid diiculties. Specifically, it is within the contemplation of the present invention to provide a rocker chair which is constructed to establish a irst sitting position wherein the chair occupant may rock, and by merely pushing against the chair frame may establish a tilted sitting position wherein a leg-rest incorporated in the chair is moved to an elevated leg-supporting position, and in which tilted sitting position the chai-r occupant may rock. Such tilted sitting position is particularly appropriate for reading, sewing, television viewing and like activities.

' In accordance with an illustrative embodiment demonstrating objects and features of the present invention, there is provided a rocker chair comprising a base, a rocker member having a rocker cam engaging the base to rock thereon, and a seat and back-rest unit mounted 3,093,409 Patented .lune 1l, 1963 'lee on the rocker member for rearward movement out of a normal sitting position. The rocker cam is operable in the normal sitting position to rock the rocker member and the unit upon actuation by the occupant of the chair to realize a first rocking motion. The rocker cam is 0perable during rearward movement of the unit to tilt the unit on its base to provide a stable tilted sitting position wherein the rocker cam is operable to provide a second rocking motion similar to the rst motion but centered about the tilted sitting position of the rocker member 0n the base. As a feature of the invention, a leg-rest is provided which is movable from a stored or retracted posiltion to an elevated leg-supporting position, with provision for moving the leg-rest to the elevated leg-supporting position in dependence on the rearward movement of the unit.

When in the normal sitting position, the chair occupant can rock or tilt back by pushing against the floor with his or her feet. When the chair occupant desires to establish the tilted sitting position (commonly referred to in the trade as the T.V. position), the occupant merely pushes with his or her hands on the arm rests of the chair such as t0 move the seat and back-rest unit rearwardly, which in turn tilts the arm rests and the unit into the tilted sitting position and moves the leg-rest into the elevated leg-supporting position. To achieve a rocking motion in the tilted sitting or T.V. position, it is merely necessary for the chair occupant to rock his or her body, or a part thereof, and the entire structure, including the seat and back-rest unit, the leg-rest and the arm rests, Will rock on the chair base.

The above brief description, as Well as Ifurther objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of an illustrative embodiment according to the present invention, when taken in conjunction with the accompanying drawings, wherein:

FIG. l is a side elevational view, with the adjacent arrn rests removed, and with parts broken away and sectioned, showing an improved rocker chair embodying features of the present invention, the full lines showing the first or normal sitting position, and the respective dotdash and dash lines and the directional arrows showing the chair rocked rearwardly and forwardly; and

FIG. 2 is a side elevational view similar to FIG. 1 but showing the chair in the tilted sitting or T.V. position, with the leg-rest moved into the elevated leg-supporting position, the dot-dash and dash ylines and the directional arrows showing the chair rocked rearwardly and forwardly.

Referring now specically to the drawings, there is shown in FIGS. l and 2 a rocker chair constructed in accordance with the present invention, and generally designated by the reference numeral 10, which comprises a base 12, a chair frame or support 14 and a seat and back-rest or body-supporting unit 16 having a back-rest 18 and a seat 20 which is mounted on the support 114 for movement between a first or normal sitting position illustrated in FIG. l, and a second tilted or T.V. position shown in FIG. 2. Disposed beneath the forward end of the seat 20 of the unit 16 is a leg-rest 22 which is mounted by a leg-rest mounting and control arrangement 24 for movement to an extended and elevated leg-supporting position forwardly of the seat 20 in response to movement of the unit 16 from the normal sitting position of FIG. l into the tilted sitting position of FIG. 2.

In this illustrative embodiment, the base 12 includes a pedestal having four legs 26 which extend radially and downwardly from a swivel assembly 28. The swivel assembly, which is of conventional construction and subject to a latitude of variation and change, includes a stationary plate serving as a stationary raceway, to which the legs 26 are secured. Substantially coextensive with the stationary plate Sii is a movable plate 32 which serves as a movable raceway, with ball bearings 34 being interposed therebetween. Axially of the movable plate 32 is a depending stub shaft 36 which is received within an appropriate bearing opening centrally of the stationary plate 30, and is held against removal from the assembled position by a lock nut or washer (not shown). Although the base -12 has been illustrated as incorporating a swivel assembly 28, it will be appreciated that the chair has useful application with or without the swivel assembly.

The chair frame 14 includes opposed upstanding spaced arm rests 38 which are interconnected by one or more cross braces, such as the intermediate cross brace 4G and the rear cross brace 42. Resting on the cross braces 4G, 42, and secured thereto, is a rocker member 44 which is provided with a curved rocker cam 46 on its under surface. It will be appreciated that the rocker member 44 and rocker cam 46 is a unitary part of the support 14, and in this sense the entire support 14 may be considered to provide a rocker member. The rocker cam 46 rests upon and engages a base member 48 having a camsupporting surface 50 on its upper face. The rocker cam 46 makes successive contact with the cam-supporting surface Si) as the chair is rocked back and forth in the positions illustrated in FIGS. l and 2 respectively. Interposed between the base member 4S and the rocker member 44 are front and rear pairs of springs (only one of each of the front and rear pairs of springs being shown in the drawings and designated by the reference numerals 52, 54). The springs are received in respective cut-

outs

44a, 48a, provided in the rocker member 44 and in the base member 43. The cut-

outs

44a, 48a open through the rocker cam 46 and cam-engaging surface Sil, and together define a housing for the front and rear pairs of

springs

52, 54. Suitable means (not shown) are provided for securing the opposite ends of the

springs

52, 54 to the top and base Walls respectively of the cut-

outs

44a, 48a, of the rocker member 44 and the base member 48.

A control linkage mounts the body-supporting unit 16 on the rocker member 46 for rearward movement from the rst or normal sitting position of FIG. 1 to the second or tilted sitting position of FIG. 2. In this illustrative embodiment, the control linkage includes a front guiding link 56 disposed in an upwardly and forwardly inclined attitude in the sitting position of the chair and having a front pivotal mount 58 at its lower end on the rocker member 44 and a front pivotal connection 60 at its upper end to the seat 2t) of the body-supporting unit 16. Spaced rearwardly of the front guiding link 56 is a rear guiding link 62 which is disposed in a forwardly inclined attitude in the sitting position of the chair and has a rear pivotal mount 64 on the rocker member 44 and a rear pivotal connection 66 to the seat 20 of the body-supporting unit 16. The control linkage, including the front and rear guiding

links

56, 62 and their respective pivotal mounts and pivotal connections between the rocker member 44 and the body-supporting unit 16, mounts the bodysupporting unit for rearward movement with substantially no change in the pitch of the body-supporting unit 16 relative to the rocker member 44. Further, as will be appreciated by progressively inspecting FIGS. l and 2, and as will be speciically described, the rocker cam 46 of the rocker member 44 stabilizes at a different position on the cam-engaging surface 50 of the base member 48 in the position illustrated in FIG. 2 such as to impart, in conjunction with the control linkage, the desired pitch to the body-supporting unit in the FIG. 2 position. The center of gravity of the body-supporting unit 16 in the first or normal sitting position of FIG. l, establishes a first stable position of the rocker member 44 on the base member 48 such that the body-supporting unit 16 may be rocked about the rst stable position, as shown in FIG. l by the dot-dash and dash line showings. In this connection, it is to be noted that the front and rear pairs of springs 50, S4 are substantially unstressed in the stable position illustrated by the full lines in FIG. l, with the rear pair of springs 54 being placed in compression when the chair is rocked rearwardly to the dot-dash position, and with the front pair of springs 52 being simultaneously placed in tension. Conversely, as the chair is rocked forwardly, the front pair of springs 52 is placed in compression and the rear pair of springs 54 is placed in tension.

Movement of the body-supporting unit 16 rearwardly on 4the rocker member 44 under the control of the control linkage -is effective to shift the center of gravity of the body-supporting unit rearwardly as the bodysupporting unit moves into the second or tilted sitting position illustrated in FIG. 2. In this illustrative embodiment, the front and rear guiding links 56, `62 respectively move through ascending arcs and then move through descending arcs into the position illustrated in FIG. 2 wherein a stop 68 on the rear guiding link 62 abuts the rocker member 44 to block further movement of the four-bar `control linkage which includes, as a relatively stationary link thereof, the portion of the rocker member 44 intermediate the front and rear

pivotal mounts

58, 64, and as movable links thereof, the front guiding link 56, the portion of the seat intermediate the front `and rear

pivotal connections

60, 66 and the rear guiding link 62. The rearward movement of the center of `gravity includes a rst or locked phase during which the center of gravity rises such that there is a tendency for the body-supporting unit to remain in the rst or normal sitting position of FIG. 1, `and further includes a second or self-balancing phase during which the center of gravity is lowered to compensate for the movement of the leg-rest 22 into the elevated leg-supporting position. The locked phase is characterized by a definite, but small, rise in lthe center of gravity of the unit and chair occupant at the start of the rearward movement from the normal sitting position, as shown in FIG. 1, to the tilted sitting position, as shown in PIG. 2, which rise Itends to urge the body-supporting unit 16 into the normal sitting position and necessitates effort on the part of the occupant to move the center of gravity upwardly through the locked phase and into the self-balancing phase wherein the center of gravity is lowered. The selfbalancing phase provides for a movement of the bodysupporting unit 16 which will balance the movement of the leg-rest 22 as it carries the legs of the chair occupant upwardly to the elevated leg-supporting position forwardly of the seat 20. This motion is characterized by a dropping of the center of gravity of the unit 16 and the part of the body of the chair occupant supported thereon as the leg-rest 22 and the legs of the chair occupant are moved upwardly. In determining the path of movement of the center of gravity during the successive locked and self-balancing phases, it will be appreciated that the whole weight of the body of the chair occupant is on the body-supporting unit 16 during the rst or locked phase and only part of the body of the chair occupant is on the body-supporting unit 16 during the second or self-balancing phase. Substantially no change in pitch or tilt is imparted to the unit 16 by the control linkage in either of the phases, 'in .that the change in pitch is produced almost completely by the tilting action of the rocker member 44 under the influence of `the rearward shifting of the center of gravity of the chair occupant's body and of the weight of the body-supporting unit 16. Although a simple lfour-bar control linkage has been shown in this illustrative form of the invention, it will be appreciated that other types of linkages and their equivalent pin-and-slot guiding mechanisms may be employed in the chair to establish first and second stable positions for the rocker member 44 on the base member 48 in which stable positions the body-supporting unit may be rocked under control of the chair occupant. As is seen in FIG. 2, the center of gravity of the bodysupporting unit in the tilted sitting or T.V. position is disposed sufficiently rearwardly of the center of gravity in the normal sitting position of lFIG. '-1 to establish the second stable position about Iwhich the body-supporting unit 16 may be rocked with the leg-rest Z2 elevated. In the -second stable position illustrated in FIG. 2, the rear pair of springs '4 are placed in compression, while the front .pair of springs 52 are placed in tension, with the rocker member 48, the chair frame -14 and the bodysupporting unit 16 rocking back and for-th about such second stable position. 'I'he degree of tilting of the rocker member 48 and of the unit 16 may be readily controlled by the amount of rearward shift of the center of gravity inciden-t to movement of the body-supporting unit from the FIG. 1 position to the FIG. Z position. In the previous reference to the center of gravity, it will be appreciated that the design must take into account Ithe weight of the ybody-supporting unit and its associated `frame and linkage mechanisms, as well as the weight of the average chair occupant.

In this illustrative embodiment, the leg-rest mounting and control 4arrangement 24 includes three pairs of mounting links having their adjacent ends pivotally connected together, with the links crossing over each other and being pivotally mounted on the seat and pivotally connected to the leg-rest 22 to provide the well known lazy tong or scissor type of leg-rest mounting linkage. It will of course be appreciated that the leg-rest mounting linkage is subject to Va latitude of modication `and change as will be `apparent by considering the patents owned by the assignee of the instant application related to leg-rest mounting linkages. Specifically, the leg-rest mounting linkage 24 includes a

iirst link pair

70, 72 having their adjacent ends pivotally connected at a pivotal connection 74, a

second link pair

76, 78 having their adjacent ends pivotally connected at a pivotal connection 80, and a

third link pair

82, 84 having their adjacent ends interconnected at a pivotal connection `86. The rst link 70 of the irst link pair has a pivotal mount 88 on the forward portion of the seat, while the first link 76 ot the second link pair has a pivotal connection 90 on the seat at Va point spaced forwardly of the pivotal connection `88. The second link 72 of the iirst link pair crosses over the lirst link 76 of the second link pair and has a pivotal connection 92 thereto, with the forward end of the second link 72 of the

first link pair

70, 72 having a pivotal connection '94 to the rst link 82 of the third link pair. The second link 78 of the second link pair has a pivotal connection 96 to the rst link 82 of the third lin-k pair intermediate its ends and a pivotal connection l90 at its -forward end to the leg-rest 22. Finally, the second link S4 of the third link pair has a pivotal connection 100' at its forward end to the leg-rest 22. The leg-rest mounting and control arrangement is completed by a direct actuating link 102 which has a pivotal connection '4 at its forward end to the link 70 and a pivotal mount 106 on the chair :frame 14. In response to rearward movement of the body-supporting unit 16 relative to the chair frame 14 and to the rocker member 44 which is a part thereof, the

pivotal connections

88, 90 of the leg-rest mounting linkage will be displaced rearwardly and will turn to an upward and forward 4arc to thereby move -the leg-rest Z2. from its stored position illustrated in FIG. 1 to an elevated leg-supporting position spaced forwardly of the seat 20 of the bodysupporting unit 116.

In order to facilitate a more thorough understanding of the present invention, lreference will now be made to a typical sequence of ope-rations:

When the chair is in the normal sitting position illustrated in FIG. l with the leg-rest 22 in the retracted or stored position, the chair occupant can rock back and forth or move the body-supporting unit 16 to a tilted attitude, by pushing against the floor with his or her feet, as shown by the dotted line showings in FlG. 2

and indicated by the directional arrows. When the chair occupant desires to move the body-supporting unit 16 into the tilted sitting or T.V. position, the occupant pushes with his or her hands on the arm rests or sides 38 of the chair and the body-supporting unit 16 will move rearwardly to bring the body-supporting unit into the tilted sitting position. Incident to such rearward movement, the leg-rest 22 moves to the elevated legsupporting position and the rocker cam 46 of the rocker member 44 assumes a second stable position on the camengaging surface 50 of the base member 48. In such second stable posit-ion, with the leg-rest 2.2r elevated and the body-supporting unit V16 pitched in accordance with the degree of rearward shift of the center of gravity of the unit, the entire assembly of the body-supporting unit 16, the leg-rest 22, the chair 4frarne 14 and the associated -mechanisms may be rocked back and forth, as shown by the dotted line showings in FIG. 2 and indicated -by the directional arrows. When the chair occupant desires to restore the chair to the normal sitting position, it is merely necessary to lean forwardly and push against the leg-rest, which will cause the chair to return from the T.V. position illustrated in FIG. 2 to the normal sitting position illustrated in FIG. l, with a corresponding movement of the center of gravity through the self-balancing and locking phases respectively.

From the foregoing, it will be appreciated that there has been provided, in accordance with the present invention, a rocker chair which has two stable rocking positions, namely a iirst position wherein the body-supporting unit is in a substantially upright attitude, with the legres-t of the chair stored, and a second position wherein the body-supporting unit is tilted back at an appropriatey pitch relative to the support for television Iviewing, reading and the like, and with the leg-rest elevated to a legsupporting position. Movement to either of the positions by the chair occupant is achieved in a simple manner, requiring no manual manipulation such as the operation of handles or the like. Further, the mechanisms employed for establishing the mode of operation of the chair and its respective stable Arocking posit-ionsare relatively simple, thereby facilitating mass production manufacture at relatively -low unit cost, and ease of assembly.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

What I claim is:

l. A rocking chair comprising a base, a body-supporting unit, a rocker member mounted on said base for rocking thereon, mounting means mounting said bodysupporting unit on said rocker member for rearward movement thereon from a normal sitting position to a tilted sitting position, a leg-rest, a leg-rest control linkage operatively connected between said body-supporting unit and said rocker member to move said leg-rest from a retracted position to an elevated leg-supporting position in response to said rearward movement of said bodysupporting unit on said rocker member to said tilted sitting position incident to rearward pressure against said back-rest by the chair occupant, said body-supporting unit and said rocker member when in said normal sitting position with said leg-rest in said retracted position having a tirst stable equilibrium position and being rockable on said lbase lforwardly and rearwardly about said first stable equilibrium position under control of the chair occupant, the rearward movement of said bodysupporting unit relative to said rocker member under cont-rol of said mounting means causing said rocker member to rock rearwardly to assume a second stable equilibrium position relative to said base, the combined effect of the rearward rocking of said rocker member to said second stable equilibrium position and the rearward movement of said body-supporting unit under control of said mounting means causing said bodysupporting unit to assume said tilted sitting position, said leg-rest being moved to said elevated leg-supporting position in response to the rearward movement of said bodysupporting unit into said tilted sitting position, said bodysupporting unit and rocker member when ,in said tilted sitting position with said leg-rest in said elevated legsupporting position being rockable on said base forwardly and rearwardly about said second stable equilibrium position of said rocker member `on said base u-nde-r control of the chair occupant.

2. A rocking chair according to claim 1 wherein the movement of said body-supporting unit rearwardly relative to said rocker member under control lof said mounting means is effective to shift the center of gravity of said body-supporting unit rearwardly, said rocker member engaging said base at a first location in said normal sitting position of said body-supporting unit, said rocker member engaging said base at a second location spaced behind said -rst location in said tilted sitting position.

3. A rocking chair according to claim 2 wherein the rearward shift of said center of gravity includes a locked phase during which said center of gravity rises such that there is a tendency for said body-supporting unit to remain in said first sitting position when said body-supporting unit is rocked therein and further includes a selfbalancing phase during which said center of gravity is lowered `to compensate for the movement of said legrest into said elevated leg-supporting position.

4. A rocking chair comprising a base, a body-supporting unit, a rocker member mounted on said base for rocking thereon, a four-bar mounting linkage mounting said body-supporting unit on said rocker member for rearward movement thereon from a normal sitting position to a tilted sitting position, Ia leg-rest, a leg-rest control linkage operatively connected between said vbody-supporting unit and said rocker ymember to move said leg-rest from a retracted position to an elevated leg-supporting position in response to said rearward movement of said body-supporting unit on said rocker member to said tilted .sitting position incident to rearward pressure against said back-rest by the chair occupant, said body-supporting unit and said rocker member when in said normal sitting position with said leg-rest -n said retracted position `having a first stable equilibrium position and being rockable on said base forwardly Aand rearwardly about said first stable equilibrium position under control of the chair occupant, the rearward movement of said body-supporting unit relative to said rocker member under control of said mounting linkage causing said -rocker member to rock rearwardly to assume a second stable equilibrium position relative to said base, the combined effect of the rearward rocking of said rocker member to said second stable equilibrium position and the rearward movement of said `body-supporting unit under control of said mounting linkage causing said body-supporting unit to assume said tilted sitting position, said leg-rest being moved to said elevated leg-supporting position in response to the rearward movement of said 'body-supporting unit into said tilted sitting position, lsaid body-supporting unit and rocker member Awhen yin said 4tilted sitting position with said legr-est in said elevated leg-supporting position being rockable von said ybase forwardly and rearwardly about said second stable equilibrium position of said rocker member on said base under control of lthe chair occupant.

5. A rocker chair according to claim 4 including a pedestal and a swivel `interposed fbetween said pedestal and said base such that said base may be turned about a vertical axis when said body-supporting unit is in said sitting positions.

References Cited in the file of this patent UNITED STATES PATENTS 2,940,510 Schliephacke June 14, 1960 2,951,528 Maurer Sept. 6, 1960 2,963,077 Knabusch et al Dec. 6, 1960 FOREIGN PATENTS 498,671 Canada Dec. 22, 1953

Claims

1. A ROCKING CHAIR COMPRISING A BASE, A BODY-SUPPORTING UNIT, A ROCKER MEMBER MOUNTED ON SAID BASE FOR ROCKING THEREON, MOUNTING MEANS MOUNTING SAID BODYSUPPORTING UNIT ON SAID ROCKER MEMBER FOR REARWARD MOVEMENT THEREON FROM A NORMAL SITTING POSITION TO A TILTED SITTING POSITION, A LEG-REST, A LEG-REST CONTROL LINKAGE OPERATIVELY CONNECTED BETWEEN SAID BODY-SUPPORTING UNIT AND SAID ROCKER MEMBER TO MOVE SAID LEG-REST FROM A RETRACTED POSITION TO AN ELEVATED LEG-SUPPORTING POSITION IN RESPONSE TO SAID REARWARD MOVEMENT OF SAID BODYSUPPORTING UNIT ON SAID ROCKER MEMBER TO SAID TILTED SITTING POSITION INCIDENT TO REARWARD PRESSURE AGAINST SAID BACK-REST BY THE CHAIR OCCUPANT, SAID BODY-SUPPORTING UNIT AND SAID ROCKER MEMBER WHEN IN SAID NORMAL SITTING POSITION WITH SAID LEG-REST IN SAID RETRACTED POSITION HAVING A FIRST STABLE EQUILIBRIUM POSITION AND BEING ROCKABLE ON SAID BASE FORWARDLY AND REARWARDLY ABOUT SAID FIRST STABLE EQUILIBRIUM POSITION UNDER CONTROL OF THE CHAIR OCCUPANT, THE REARWARD MOVEMENT OF SAID BODYSUPPORTING UNIT RELATIVE TO SAID ROCKER MEMBER UNDER CONTROL OF SAID MOUNTING MEANS CAUSING SAID ROCKER MEMBER TO ROCK REARWARDLY TO ASSUME A SECOND STABLE EQUILIBRIUM POSITION RELATIVE TO SAID BASE, THE COMBINED EFFECT OF THE REARWARD ROCKING OF SAID ROCKER MEMBER TO SAID SECOND STABLE EQUILIBRIUM POSITION AND THE REARWARD MOVEMENT OF SAID BODY-SUPPORTING UNIT UNDER CONTROL OF SAID MOUNTING MEANS CAUSING SAID BODYSUPPORTING UNIT TO ASSUME SAID TILTED SITTING POSITION, SAID LEG-REST BEING MOVED TO SAID ELEVATED LEG-SUPPORTING POSITION IN RESPONSE TO THE REARWARD MOVEMENT OF SAID BODYSUPPORTING UNIT INTO SAID TILTED SITTING POSITION, SAID BODYSUPPORTING UNIT AND ROCKER MEMBER WHEN IN SAID TILTED SITTING POSITION WITH SAID LEG-REST IN SAID ELEVATED LEGSUPPORTING POSITION BEING ROCKABLE ON SAID BASE FORWARDLY AND REARWARDLY ABOUT SAID SECOND STABLE EQUILIBRIUM POSITION OF SAID ROCKER MEMBER ON SAID BASE UNDER CONTROL OF THE CHAIR OCCUPANT.