US3161395A

US3161395A - Adjustable strut

Info

Publication number: US3161395A
Application number: US179027A
Authority: US
Inventors: Lewis D Carter
Original assignee: CARTER CRAFT Inc
Current assignee: CARTER CRAFT Inc
Priority date: 1962-03-12
Filing date: 1962-03-12
Publication date: 1964-12-15
Anticipated expiration: 1981-12-15

Description

Dec. 15, 1964 n. CARTER ADJUSTABLE STRUT Filed March 12, 1.962

F I G 4 III F I G 3 r W M 0 w L w 2 a 6 w F United States Patent 3,161,395 ADJUSTABLE STRUT Lewis B. Carter, Richardson, Ten, assignor to (latter Craft, ind, Plano, Tex a corporation of Belaware Filed Mar. 12, 1962, tier. No. 179,027 Claims. (Cl. 248- 35d) This invention relates to a ratchet system and more particularly to an adjustable supporting strut system.

It is oftentimes desirable and sometimes necessary to tilt the top of a desk or table. A desk or table top that is tiltable and is hinged at the front edge may be supported by one or more struts at the rear edge or on the sides. In most instances, the strut is adjustable within certain limits to provide a reasonable range of angles of tilt. There are many types, of struts which are purported to be suitable for such purposes. However, they are not entirely satisfactory because they generally involve arms and the like which must be folded or unfolded, or they employ screw devices which must be engaged or employed.

In contrast to such systems, the present invention relates to an adjustable strut which operates automatically when actuated in the preferred manner and includes a positive stop at any of a plurality of angles. By the present invention a strut is quickly and easily adjustable and operates'withont manipulation other than to raise the top to the desired position.

disengaged, and in some other types frictional devices are 1 Accordingly, it is an object of the present invention to provide an improved adjustable ratchet support strut.

Another object of the invention is to provide a wholly adequate ratchet support strut which is operable without manipulation other than movement of its supported member to a desired attitude.

A furtherobject of the invention is to provide a support strut with a minimum number of parts and at a minimum cost.

More particularly, in accordance with the present invention, there is provided a pair of inner andouter telescoping elongated members movable with respect to each other between extended and retracted positions. The outter memberincludes a pair of opposed arcuate structures abutting along one longitudinal edge while the other pair of edges overlie and support an elongated ratch. The

ratch includes a pair of inwardly facing notches spaced.

apart a predetermined distance by a plurality of inwardly facing ratchet teeth. A detent is pivotally supported on the inner member resiliently biased toward the ratch for positive engagement with the ratchet teeth.

In a more specific.aspect of the invention, there is provided an adjustable strut which comprises a tubular structure having a longitudinal, toothed rack with theteeth thereon facing inwardly and having an elongated slotextending parmlel to the rack in spaced circumferential relation. An armor is provided for the structure which spans the slot and is secured to the structure on opposite sides of the slot. A tubular member telescopes within thestructure and includes a pawl pivotallymounted thereon as to engage the teeth on the rack. A guide element is mount ed on the tubular member for travel in the" slot to main-.

ice

GURE 1;

FIGURE 3 is a sectional view taken along line 33 of FIGURE 1;

FIGURE 4 is a schematic perspective view showing one installation of the invention;

FIGURE 5 is a fragmentary longitudinal sectional view of another embodiment of the invention; and

FIGURE 6 is a sectional view of FIGURE 5 taken along lines 6-6 with certain parts omitted.

Referring now to FIGURES l, '2 and 3, an adjustable rigid strut device 11 comprises an inner cylinder 13 which is formed by two

semicylindrical members

15 and 17, FIGURES 2 and 3. Members has an integrally formed outwardly extended plate portion 21. Member 17 has a plate portion 23, which is substantially parallel with plate 21. A bar 25, having substantially rectangular cross section, is disposed between and fixedly attached to the opposed inner surfaces of the

plates

21, 23. The inwardly directed face 27 of the bar has two

rectangularlyshaped notches

29 and 31, FIGURE 1, which are spaced apart a predetermined distance. A plurality of ratchet teeth 33 are formed in the surface 27 of the bar 25 between

notches

29 and 31.

Telescoped in the cylinder 13 is a tubular member 3-5, FIGURE 1, which extends from the top end of the cylinder 13. The lower end of the member 35 is cut away to provide an integral, downwardly projecting arcuate member 39 which supports a pair of spaced

parallel plates

41 and 43, FIGURE 3. A detent 45 is mounted between the plates 4.1.and 43. Detent 45 is free to rotate about a pivot pin 47 supported by the

plates

41, 43. The pivot pin 4! is located near the lower end of the

plates

41, 43. The detent is biased by spring 49 to engage the ratch 33 as member 35 is moved axially in the first member 13. Coil spring 49 encircles the pivot pin 47 and is so arranged that one end 51 is secured to the detent 45 while the other end 53 is secured to the plate 41. Coil spring 49 keeps the detent 45 in engagement with the teeth 33.

A longitudinal slot 53 is formed in cylinder 13 opposite teeth 33. The slot 53 thus formed is approximately equal in length to the distance between the upper end of notch 31 and the lower end of notch 29.

A bolt 55 is threaded in the arcuate member 32 along its longitudinal axis. The head 57 of bolt 55 slides in slot 53. Bolt head 57 is constrained to move longitudinally only within the slot '53. By this means member 35 may extend from cylinder 13 only so far as permitted by the bolt heat 57 working in the slot 53. In like manner, the extent to which member 35 telescopes into the cylinder 13 is limited by the bolt head 57 abutting the lower extremity of the slot 53.

A slotted cylindrical jacket 59 having an inner diameter corresponding to the outer diameter of the cylinder 13 partially surrounds cylinder 13. Jacket 59

couples elements

15 and 17 together, maintaining the longitudinal edges 19 in abutting relation.

An aperture 61 of diameter slightly greater than the bolt head 57 is provided near the upper end of the jacket 59. Aperture 61 is in registration with the bolt head 57 when in its uppermost position. The presence of the aper-.

An anchor hole 63 is formed at the bottom of cylinder 13 and jacket 59. A similar anchor hole 65 is formed near the top of the member 35.

Holes

63, 65 receive pivot pins (not shown) for mounting the strut.

Apertures

63 and 65 are axially aligned and are in quadrantal relationship to the aperture 61.

FIGURES and 6 illustrate an embodiment of a modi fication of the present invention wherein a tube 67 is mechanically worked to form a ratchet structure 73 in a wall thereof. The ratchet structure is terminated in two sockets such as socket 79, only one socket being shown. A channel-shaped structure 75 is provided with a pair of outwardly extending

flanges

87, 89 which overlie and are attached to the outer periphery of the cylinder 67 An inner tubular structure 91, which is similar to the structure 35, telescopes the outer tubular member 67. The inner structure 91 is provided with a detent 93 and a coil spring 95 in engagement therewith. A pair of supporting plates such as plate 97 are mounted on an arcuate extension 101 of the structure 91.

The embodiment shown and described in connection with FIGURE 5 will be quite adequate in many applications. However, where great weight is to be supported or where inordinate forces are applied as may be encountered in school use and the like, the device of FIGURE 1 will be more suitable. The reinforcement provided by a double wall structure where the jacket 59 is wrapped around and secured to

elements

15 and 17 permits the device to withstand great abuse. Tendency to deform the cylinder to an oval shape is overcome and a cylindrical slideway for the member 35 is maintained.

To understand the manner in which the invention is used, reference is made to FIGURE 4. The device 11 is pivotally connected to a base structure 103 by a pivot pin 105 through the aperture 63. The device 11 is pivotally connected, likewise, to the tiltable top 107 by a pin 109 through the aperture 65. When the top 107 is hinged at its front hinged edge 111, the device 11 may be extended longitudinally. As inner tubular member 35 is withdrawn, the detent 45 engages the ratchet teeth 33 as shown in FIGURE 1. The top 107 will remain at the selected angle of tilt because the upwardly and inwardly directed force developed between the detent and the ratchet teeth 33 is resolvable into a force countering the downward force of the table top and any load which may be imposed thereon. As the table top 107 is further raised upwardly, the detent 45, under urging of the coil spring 59, continues to engage the ratchet teeth 33.

In order to lower the table top 107 to its initial position, which may not necessarily be horizontal, it is only necessary to raise the rear edge 113 until the second tubular structure 15 is extended so that the detent 45 rotates upwardly in the upper notch 31 as shown in FIGURE 5. Thereafter, the top may be brought to its initial position without the detent 45 engaging the ratchet teeth 33. Thereafter, upward movement of the rear edge 113 causes the detent 45 to reverse itself in the lower socket 29 to reengage the ratchet teeth 33 in the manner described hereinbefore.

It will be clear that the device 11 operates automatically as the top 107 is tilted upwardly and that special manipulation of the device is not necessary.

Thus, it will be seen that, in the embodiments shown and described, the invention is characterized by a pair of extensible inner and outer telescoping tubular members, the inner one supporting a pivotable detent which is urged by resilient bias apparatus into engagement with a ratch structure supported by the outer member in confronting and abutting relation thereto. In a preferred embodiment of the invention, the telescoping tubular members are of metal such as steel, aluminum and the like, while the ratch, pawl and resilient bias apparatus are also of the same metal. Other materials may be found more suitable and effectively used without'limitation.

Having described the invention in connection with certain embodiments thereof, it is understood that further modifications may suggest themselves to those skilled in the art and it is intended to cover such modifications as fall within the scope of the appended claims.

\Vhat is claimed is:

1. An adjustable strut which comprises:

(a) an elongated toothed rack,

(b) a tubular structure having a first longitudinal slot to receive said rack, and being secured thereto with the rack teeth facing inwardly, said structure having a second longitudinal slot extending parallel'to said first slot in spaced circumferential relation,

(0) an outer armor encircling said structure and secured thereto adjacent to the edges of said first slot,

((1) a tubular member telescoping in said structure and including a pawl pivotally mounted thereon to engage said teeth, and

(e) a stop element mounted on said tubular member for travel in said second slot to maintain a predetermined rotational orientation between said pawl and said rack.

2. An adjustable strut which comprises:

(a) an elongated toothed rack,

(b) a pair of semicylinders abutting at one pair of edges and flanged at the opposite pair of edges to form a tubular structure having a first longitudinal slot between the flanged edges in which said rack is secured with the crowns of the teeth thereon facing inwardly, said structure having a second elongated slot extending parallel to said first slot in spaced circumferential relation,

(c) a slotted cylinder encompassing said structure in intimate relation and secured thereto along the base of the flanges at said flanged edges,

(e) guide means mounted on said tubular member for travel in said second slot to maintain a predetermined rotational orientation between said pawl and said rack.

3. An adjustable strut which comprises:

(a) a tubular structure having a longitudinal toothed rack with the crowns of the teeth thereon facing inwardly, said structure having an elongated slot extending parallel to said rack at a position spaced circumferentially therefrom,

(b) an outer armor for said structure spanning said slot,

(0) a tubular member telescoping in said structure and including a pawl pivotally mounted thereon to engage said teeth, and

(d) an element mounted on said tubular member for travel in said slot to maintain a predetermined rotational orientation between said pawl and said rack.

4. An adjustable strut which comprises:

(a) a tubular structure having a longitudinal toothed rack with the crowns of the teeth thereon facing inwardly and an enlarged indentation at each end of said rack,

- (b) an outer armor encompassing said structure,

(0) a tubular member telescoping in said structure and including a pawl pivotally mounted thereon to engage said teeth and reversible when positioned in each said indentation, and

(d) guide means for maintaining a predetermined r0- tational orientation between said pawl and said rack.

5. An adjustable strut which comprises:

(a) a tubular structure having a longitudinal toothed rack with the crowns of the teeth thereon facing inwardly with an enlarged indentation at each end of said rack and an elongated slot extending parallel to said rack and spaced circumferentially therefrom,

(b) an outer armor encompassing said structure,

(c) a tubular member telescoping in said structure and including a pawl pivotally mounted thereon to engage said teeth and reversible when positioned in each said indentation, and

6. An adjustable strut which comprises:

(a) a pair of semicylinders each having an outwardly directed flange at one edge,

(b) an elongated toothed rack secured between the flanges on said cylinders to form a tubular structure with the teeth on said rack facing inwardly and an elongated slot extending parallel to and diametrically opposite said rack,

(c) a slotted cylinder encompassing said structure and secured thereto along the bases of said flanges,

(a') a tubular member telescoping in said structure and including a pawl pivotally mounted thereon to engage said teeth, and

(e) guide means mounted on said tubular member for travel in said slot to maintain said pawl in alignment with said rack.

7. A support strut comprising:

(a) a pair of inner and outerJtelescoping elongated members with said inner member being capable of longitudinal movement relative to said outer member between extended and retracted positions, said outer member including a pair of arcuate structures abutting along one longitudinal edge and having spaced other edges,

(b) an elongated ratch supported between said spaced other edges in confronting relation to said inner member, said ratch including a pair of inwardly facing notches separated by a plurality of inwardly facing ratchet teeth,

(0) a detent pivotably supported by said inner member in biased engaging relation with said ratchet teeth, (d) resilient bias meansfor maintaining said detent in engagement with said ratch,

(e) an arcuate elongated member engaging in confronting relation the outer periphery of said outer member and maintaining said longitudinal edges in abutting relation, and

(f) means for limiting the extensibility of said inner member with respect to said outer member between said extended and retracted positions.

8. A support strut comprising:

(a) a pair of inner and outer telescoping elongated members with said inner member being capable of longitudinal movement relative to said outer member between extended and retracted positions, said outer member including a pair of arcuatestructures abutting along one longitudinal edge and having spaced other edges,

i (b) an elongated ratch supported between said other spaced edges in confronting relation to said inner member, said ratch including a pair of inwardly facing notches separated by a plurality of inwardly facing ratchet teeth,

(0) a detent pivotably supported by said inner member in biased engaging relation with said ratchet teeth, (d) resilient bias means for pivoting said detent in one said notch into disengaging relation to said'ratchet teeth when said members are in extended position,

and pivoting said detent in said other notch into engaging relation with said ratchet teeth when said members are in retracted position, and

(e) an arcuate elongated member engaging in confronting relation the outer periphery of said outer member and maintaining said longitudinal edges in abutting relation.

9. A support strut comprising:

(a) an elongated outer tubular member,

(b) a pair of elongated longitudinal slots in said tubular member,

(c) an arcuate structure overlying the outer periphery of said outer tubular member in confronting relation thereto and having a pair of outwardly projecting and inwardly facing sockets each disposed opposite an end of said slot with said sockets being separated by a plurality of inwardly facing ratchet teeth,

((1) closure means overlying said other slot,

(e) an elongated inner tubular member telescoping said outer tubular member and movable relative thereto between extended and retracted positions,

(f) a detent pivotably supported by said inner member,

(g) resilient biased means engaging said detent so as to engage said ratchet teeth,

(h) resilient biased means engaging said detent so as to pivot said detent in one said socket into disengaging relation to said ratchet teeth when said inner tubular member is in extended position and to pivot said detent in said other socket into engaging relation to. said ratchet teeth when said inner tubular member is in the retracted position, and

(1') means for containing said inner member within said outer member between extended and retracted positions.

10. A support strut comprising:

(a) a pair of inner and outer telescoping elongated members with said inner member being capable of longitudinal movement relative to said outer member between extended and retracted positions, said outer member including a pair of arcuate structures each abutting the other along one longitudinal edge and having spaced other parallel edges,

(11) an elongated ratch supported between said other spaced parallel edges in confronting relation to said inner member, said ratch including a pair of inwardly facing notches displaced by a plurality of inwardly facing ratchet teeth,

(c) a detent pivotally supported by an arcuate elongated member connected to said inner member,

(0.) means for maintaining said detent in engagement with said ratch, and

References Cited in the file of this patent UNITED STATES PATENTS 2,377,949 McMenamy June 12, 1945 2,480,382 Pagliuso Aug. 30,1949

2,892,647 ONeil June 30, 1959 FOREIGN PATENTS 10,368 Great Britain July 17, 1888

Claims

1. AN ADJUSTABLE STRUT WHICH COMPRISES: (A) AN ELONGATED TOOTHED RACK, (B) A TUBULAR STRUCTURE HAVING A FIRST LONGITUDINAL SLOT TO RECEIVE SAID RACK, AND BEING SECURED THERETO WITH THE RACK TEETH FACING INWARDLY, SAID STRUCTURE HAVING A SECOND LONGITUDINAL SLOT EXTENDING PARALLEL TO SAID FIRST SLOT IN SPACED CIRCUMFERENTIAL RELATION, (C) AN OUTER ARMOR ENCIRCLING SAID STRUCTURE AND SECURED THERETO ADJACENT TO THE EDGES OF SAID FIRST SLOT, (D) A TUBULAR MEMBER TELESCOPING IN SAID STRUCTURE AND INCLUDING A PAWL PIVOTALLY MOUNTED THEREON TO ENGAGE SAID TEETH, AND