MXPA97009902A - Pneumatic height adjustment column for unasi - Google Patents

Abstract

The present invention relates to a pneumatic height adjustment column for a chair, characterized in that it comprises: a support tube having an upper end which is generally open, and a lower portion adapted to be mounted to the base of a chair, the The lower portion includes an opening with a smaller diameter than that of the support tube, a carrier tube having an upper portion adapted to be mounted to a support housing, the upper portion includes an opening with a smaller diameter than that of the carrier tube, the carrier tube also has a generally open lower end which is telescopically coupled to the upper end of the support tube, a pneumatic cartridge having a cylinder that is positioned inside the carrier tube, the cylinder has a diameter greater than that of the opening in the tube carrier: an arrow that extends down from the cylinder, the arrow has a lower end that passes through of the opening in the lower part of the support tube, a mass arranged on an upper portion of the cylinder which passes through the opening in the upper part of the carrier tube, a reusable mallet holder releasably couples the hub, said support hub being adapted to uncouple and re-engage successively with the hub, whereby the position of the hub is maintained through the opening in the upper portion of the carrier tube when said hub holder is coupled with the hub and thereby allowing the hub passes through the opening in the carrier tube when said hub holder disengages from the hub, and an arrow clip attached to the lower end of the arrow, whereby the position of the lower end of the arrow is maintained at through the opening in the bottom of the torpor tube

Description

PNEUMATIC HEIGHT ADJUSTMENT COLUMN FOR ONE CHAIR BACKGROUND OF THE INVENTION The present invention relates generally to support columns for chairs and u and particularly for pneumatic height adjustment columns. In general, the seating surface of a chair, or seat, is kept on a raised level to provide the user with seating. Typically, the seat is raised by interposing a support structure between the seat and the surface and above it < which is placed. Support structures have a variety of shapes. For example, a plurality of limbs can support the seat. In another form, the support structure consists of an individual support column, which minimizes the need for multiple load support members and improves the chair's ethics. Adjustable height support columns have also been made to accommodate a variety of users as well as a variety of uses for the chair. For example, the adjustable height chair can be raised or lowered to accommodate users of different heights. Similarly, the height-adjustable chair can be raised or lowered to provide a fixed seating surface in a plurality of stations of high work. Therefore, a user can use the chair at different heights, regardless of their height characteristics. To accommodate a wide variety of users and use < Therefore, it is important to increase the distance of the support column, say *, the difference between the lower elevation and the greater elevation of 5 1a s111. The height-adjustable chairs typically include a pneumatic adjustment column to support the chair. A pneumatic height adjustment column generally includes a pneumatic cartridge disposed in a telescopically movable lfl carrier tube that engages a support tube. Generally, the pneumatic cartridge includes a cylinder and an arrow and is retained in the tube by securing a lower part of the cylinder to the carrier tube using a fastener such as a nut or staple. Other fasteners can secure the upper part of the cartridge to the carrier tube, but are typically placed inside the tube. The fastener prevents the cartridge from falling out of the tube during installation and prevents the cartridge from disengaging from the carrier tube when the chair is lifted. The element of The holder can also maintain the relationship of the pneumatic cartridge within the tube so that an unintentional loosening of the column is avoided in a reliable manner when the chair is lifted by the tube structure. However, secure the pneumatic cartridge inside the tube structure has many disadvantages. For example, when the clamping element is fixed to the lower part of the cartridge barrel, the height of the support column in a fully compressed position necessarily includes the height of the cylinder of the compressed pneumatic cartridge and the < ltura of the fastening element. Therefore, the total travel of the support column is reduced by * the amount of internal space occupied by the nut or other fastening element within the structure of the tube. This is also true for fasteners that interconnect the upper part of the pneumatic cartridge and the carrier tube to be positioned '*, inside the carrier tube. In addition, the typical support column secured to the bottom of the cylinder may experience premature failure in the seal facing the cylinder and the arrow in the pneumatic cartridge. This failure occurs when the cylinder is forced to undertake bending stresses. For example, when the user sits outside the center of the chair, a moment of bending is applied to the support column. This moment can be carried by the support column to the base. By securing the pneumatic cartridge to the tube at both ends of the cylinder, the pneumatic cartridge is forced to absorb some of the bending moment and the bending stresses imposed on the tube. Since pneumatic cartridges can be damaged or worn out, it is important that the cartridge is easily removed from the cylinder. Accordingly, the clamping element must releasably couple either the cartridge or the carrier tube so that the cartridge can be disengaged from the tube. For example, a spring clip may be mounted within the carrier tube and adapted to fit the flexible cartridge. Aiternat Lvarnentte, many of the common fastening devices perform sliding fittings when coupling nuts arranged on the pipe of the car-tucho. For example, the Patent of E.U.fl. No. 4, 940, 202 entitled "Non-stepped Adjustable Vertical Mover" and issued to Hosan et al., Discloses a pneumatic cartridge having a fastener attached to the top thereof. The pneumatic cartridge is removed by rotating the pneumatic cartridge and the clamping element through an internal rose on the top of the spout tube. However, if the threads are damaged, the carrier tube may have to be discarded. In a similar way, if a spring clip is placed inside the feed tube, it may be necessary to discard the entire carrier tube - if the clip is damaged. Finally, most of the fastening elements, whether they are placed inside or outside the carrier tube, interconnect only the pneumatic cartridge and the carrier tube and do not additionally connect the carrier tube and the seat. For example, the fastening element disclosed in the patent to Hosan et al., Does not secure the carrier tube to the seat. In fact, when placed inside the carrier tube, the fastening element is unable to make this connection. Therefore, most of the fastening elements do not provide a secondary holding device 10 to prevent the seat from uncoupling from the support column.

BRIEF DESCRIPTION OF THE INVENTION Said in a few p Labras, the invention is directed to a pneumatic height adjustment column for a chair. The column includes a support tube, a tubing tube, a pneumatic cartridge, a club clamp and an arrow adjuster. The support tube has an upper end * which is generally open and a lower portion * which is adapted to be mounted to be mounted to a chair base. The lower portion has an opening with a diameter smaller than that of the support tube. The carrier tube has an upper portion - to be mounted on a chair seat that includes an opening has a smaller diameter than that of the carrier tube. The carrier tube has a generally open lower portion that telescopically engages the upper end of the support tube. The pneumatic cartridge includes a cylinder that is positioned within the carrier tube and has a diameter greater than that of the opening in the carrier tube. The cartridge also has an arrow that extends down from the cylinder. The arrow has a lower end passing through the opening in the lower part of the support tube. The pneumatic cartridge also has a hub that passes through the aperture in the upper part of the carrier tube. The mallet holder slidably engages the hub and maintains the position of the hub through the opening in the top * of the carrier tube. The arrow clip is attached to the arrow and maintains the position of the lower end * of the arrow through the opening in the bottom of the support tube. An object of the present invention is to provide a pneumatic adjustment column by which the travel of the column is maximized. By providing a hub and externally securing the pneumatic cartridge to the carrier tube * at the top * of the carrier tube *, the hub holder * does not increase the internal height of the support column when fully compressed, despite the thickness of the fastener . Similarly, the fastener does not interfere with the maximum extension of the support column. Therefore, the present invention provides a significant advantage over other support columns. Another object of the present invention is to provide a support column by which the bending moment effected by the pneumatic cartridge is greatly reduced, thereby prolonging the life of the cartridge. By fixing the upper part of the pneumatic cartridge to the upper part of the charging tube, instead of fixing it to the cartridge tube in the lower portion of the cylinder, the cartridge is prevented from effecting the bending moment and the resulting bending stresses. In a preferred embodiment, the hub arranged on the upper part of the cylinder of the pneumatic cartridge has a round groove. The hammer holder has a Y shape, which has two stic members and an elongated portion. The sticos members form an opening between them. When installed, the plastic members are arranged in a slot and engage the hub, whereby the cylinder is prevented from falling inside the carrier tube when the support column is lifted by the carrier tube. In addition, the clip is curved so as to deflect the cartridge up against the carrier tube, thereby eliminating any slackening or rattling when the chair is lifted. In addition, the aza fastener engages the seat, thereby preventing the seat from uncoupling from the raiser tube. The present invention also provides a method for assembling a pneumatic height adjustment column. The method includes inserting the pneumatic cartridge into the carrier tube so that the hub passes through the opening in the upper part of the carrier tube. The pneumatic cartridge is secured to the car-tucho tube by fastening the mallet clip to the hub. The carrier tube and the pneumatic cartridge are then inserted into the support tube. When inserting the carrier tube and the pneumatic cartridge into the support tube, the end effector of the arrow passes through the opening in the lower portion of the support tube and the lower end is secured with an arrow fastener. When the preferred embodiment is used, the mallet clip can be removed without destroying it, which allows repeated use of the fastener throughout the life of the chair. The present invention together with additional objects and advantages will be better understood with reference to the following detailed description turned in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective, with its Lfl parts detached for clarity, from the adjustable height chair, including a base, a pneumatic height adjustment column and a seat. Figure 2 is a cross-sectional view of the pneumatic height adjustment column in a fully extended position 5 with a base a seat support applied thereto. Figure 3 is an enlarged representation of a cross-sectional view of the upper part of the pneumatic height adjustment column with a seat applied to the same. Figure 4 is an enlarged representation of a cross-sectional view of the lower part of the pneumatic height adjustment column in a fully extended position as shown in Figure 2. Figure 5 is a cross-sectional view of the Pneumatic height adjustment column in a fully compressed position with a base and a seat applied to it. Figure 6 is an enlarged representation of a cross-sectional view of the lower part of the pneumatic height adjustment column in a fully compressed position as shown in Figure 5. Figure 7 is a top and later view of the maza-bra Figure 8 is a view of the pneumatic cartridge. Figure 9 is a cross-sectional view of the pneumatic tire taken along Line 9-9 of Figure 8.

DESCRIPTION OF THE PREFERRED MODALITY With reference to the drawings, Figures 2 and 5 show a pneumatic height adjustment column 1 including a support tube 7, a carrier tube 13, a pneumatic cartridge 17, a hammer fastener 35 and an adjuster 51 of arrow. As shown in Figures 2 and 3, the carrier tube 13 has an upper portion to be mounted on a saddle seat 5. The chair seat 5 includes a support housing 6 having a tapered hole 4 adapted to receive the upper portion 14 of the carrier tube 13, which is also tapered, as shown in Figures 2 and 3. The carrier tube 13 is mounts to accommodation 6 LO of support by adjusting by * pressure The upper portion 14 of the carrier tube 13 inside the tapered hole 4. Because the weight of the user is transferred from the seat 5 to the carrier tube 13 at the tapered interface, the corresponding tapers of the upper portion 14 of the carrier tube 13 and the hole 4 in the support housing prevent the tube 13 from At the end of the hole 4 a user occupies the seat 5. As shown in Figure 2, a base 3 also has a tapered hole 77 adapted to receive a lower-tapered portion 9 of the support tube 7. The support tube 7 is adjusted by pressure in the tapered hole 77 of the base 3, whereby an adequate load transfer is provided between the support tube 7 and the base 3. As shown in Figures 2 and 5, the raiser tube 13 includes an end end 16 which is generally open. The lower end 16 of the carrier tube 13 is received telescopically at a generally open upper end 8 of the support tube 7. As the pneumatic height adjustment column moves between a fully extended position, as shown in Figure 2, to a fully compressed position, as shown in Figure 5, the carrier tube 13 engages slidably in the tube. 7 of support. In a fully extended position, a portion of the carrier tube 13 must remain engaged with a portion of the support tube 7 in order to provide a surface area of 1 L. enough contact to react against the moment of f-lexion produced by * a user who sits outside the center of the seat. In a preferred embodiment, about 5.08 crn of the carrier tube 13 are pre-coupled with the support tube 7 in a fully extended position., as shown in figure 2. As shown in the figures? and 5, a pneumatic cartridge 17 is disposed in the carrier tube 13. The pneumatic cartridge 17 includes a cylinder 19, an arrow 23 and a hub 3 (1. The cylinder 19 has an upper surface 55 and a lower surface 53. The lower surface 53 of the cylinder 19 has a hole 57 adapted to receive a Wick. 23, which extends downwards from the cylinder 19 as shown in FIGS. 8 and 9. The arrow 23 connects diametrically the cylinder 19 and is connected to a piston disposed inside the cylinder 19. When the column of height adjustment tires 1 is in a fully extended position, a substantial portion of the arrow 23 extends downwardly from the cylinder 19 as shown in Figure 2. When in a fully compressed position, a subscial portion of the arrow 23 is disposed inside the cylinder 19 as shown in figure 5. A seal 34 is interposed between the arrow 23 and the cylinder 19 in the lower surface 53 of the cylinder 19 as shown in figure 9. As shown in FIGS. 2 and 3, the hub 30 of the pneumatic cartridge is disposed on the upper surface 55 of the cylinder 19. When the pneumatic cartridge 17 is disposed on the carrier beam 19, the aza 30 passes to the tr-birds of the aperture 15. in the upper portion 14 of the tubing 13. The diameter of the opening 15 in the carrier tube 13 is less than the external diameter of the cylinder 19 that the upper surface 55 of the cylinder is coupled to a shoulder 59 of the carrier tube 19 as shown in the figure. 3, thereby preventing <; * 1 cylinder 19 passes through the opening and provides a load path to transfer a downward vertical load from the carrier tube 19 to the pneumatic cartridge 17. As shown in FIGS. 2 and 3, an actuator button 33 extends through the hub 30 and slidably engages the cylinder 19. When depressed, the actuator button 33 acts as a gas spring contained in the cylinder 19, allowing the column to be lifted or lowered. As shown in Figures 2 and 3, the hub holder 35 releasably engages the hub 30 as it protrudes through the opening 15 in the carrier tube 19. The pin holder 35 maintains the position of the pneumatic cartridge 17 in the carrier tube 13 when the chair is lifted. When the chair is lifted, the support housing 6 transfers a force upwards to the carrier tube 13. If the pneumatic cartridge 17 was not secured to the carrier tube 19, the carrier tube 13 would slide up into the support tube 7 until the carrier tube 13 and the support tube 7 were decoupled. The hammer holder 35 is required to maintain the position of the pneumatic cartridge L7 in the carrier tube 13 and to ensure that the carrier tube 13 remains slidably engaged with the support tube 7. This is achieved by securing the carrier tube 13 to the pneumatic cartridge 17 using a hub holder 35 and securing the support tube 7 to the pneumatic cartridge 17 using the arrow holder 51. The hammer holder 3 also functions as a secondary holding device which secured the support housing 6 to the carrier tube 13. As shown in Figure 3, the hub holder 35 is larger than the upper opening of the tapered hole 4 in the support housing 6. Accordingly, the mallet holder 35 engages The upper surface 75 of the bearing housing 6. Therefore, if the tapered portion 14 of the carrier tube 13 is to be released from or not properly secured within the tapered bore 4 in the support housing 6, the hub holder 35 ensures that the support housing 6 can not be uncoupled from the holder. the upper portion L4- of the carrier tube 13. Therefore, the mallet holder 35 functions as a secondary retainer device between the column l and the support housing 6. As shown in the preferred embodiment of FIG. 7, the mallet holder 35 has a pair of elastic members 37 and an enlarged portion 39. The elastic members 37 have the bevelled ends 38 to facilitate the installation of the hub holder 35, the hub holder 35 defines an opening 61 therebetween and has three engaging Tabs 40 extending inwardly in the opening 61. When the hub 30 is disposed in the opening, the coupling tabs 40 engage the hub 30. When the hub holder 35 is installed, the beveled ends 38 are placed against the hub 30 and an inward force is applied to the hub. enlarged portion 39, whereupon they are deflected toward the force Elastic members 37 as the members move past the mace 30. The beveled ends 38 provide an initial guide for placing the mallet clip 35 on the hub 30 and facilitate the method of msatalation by providing a striking msatalation force, with which the force inward applied to the hammer holder 35 is necessarily increased as the limbs 37 are placed on the body. they pass by passing the mace 30 and are diverted outwards. Therefore, less force is required at the beginning of the installation, which corresponds appropriately to the point in time at which the hub holder 35 is not stabilized by the hub and is guided only by the user. When the aza 30 is disposed in the opening, the resilient members 37 return to their original position so that the coupling tongues 40 engage the aza 30. The mallet holder 35 is removed by applying a force outwardly to the enlarged portion 39. As the mallet holder 35 moves outwardly, the elastic members 37 are deflected outwardly by the mace 30. When uncoupled from the 30th gear, the elastic members 37 return to their original position. Therefore, the aza * fastener can be used repeatedly without destroying it. In addition, because the hub holder 35 is not fixedly attached to either the hub 30 or the carrier tube 13, it can be reattached easily and inexpensively without having to correspondingly replace the carrier tube 13 or the cartridge 17 neurnat ico. To replace and replace the pneumatic cartridge 17, the hub holder 35 is removed and the seat 5, the support housing 6 and the carrier tube 13 are disengaged from its support tube 7 and the pneumatic cartridge 17. The arrow holder 51 is then removed, whereby the cartridge 17 tire can be removed. Therefore, the pneumatic cartridge 17 can be replaced without having to remove the bearing housing 6 from the carrier tube 13 in order to gain access to the hub 30. In a preferred embodiment, the hub has a defined round slot 0 31. by a lower shoulder 63 and a shoulder 65 supepor. The elastic members 37 are disposed in the slot 31 and engage the upper shoulder 65 thus preventing the hub 30 from passing down through the opening 15 in the carrier tube 13. In the preferred embodiment, the 5-yo fastener 35 is curved and has a lower concave surface 67 that is biased against the support housing 6 and an upper surface 75 of the carrier tube 13 as shown in Figures 2, 3 and 5. The hub holder 35 also has a convex surface 69 that is biased against the upper shoulder 65 of the hub 30. The aza gripper 30 is curved to deflect * the cartridge 1? up against the shoulder 59 of the carrier tube 13, thereby eliminating any unintentional loosening or rattling of the chair when it is lifted by the seat 5. Furthermore, the gripper 35 acts as a secondary retainer as previously described . Because the bevelled ends 38 and the enlarged portion 37 of the hub holder 35 engage the support housing 6, the support housing 6 is disengaged from the pore tube 13. In a preferred embodiment the mallet holder 35 is made of steel and has a thickness of about 0.076 to 0.127 centimeters. However, it should be understood that a variety of other materials and thicknesses are acceptable for the purpose of the fastener. Because the aza is located externally with respect to the carrier tube 13, its thickness does not interfere with the travel of the column or decrease it. As shown in Figures 4 and 6, the arrow 23 of the pneumatic cartridge 17 is fixed to the support plate 12 which is mounted to the lower end 10 of the support tube 7, the lower end 10 of the support tube 7 is generally open and includes a shoulder 71. The support plate 12 couples the shoulder 71 formed in the lower end 10 of the support tube 7 as shown in FIGS. 4 and 6. The tube 7 is folded up from the support plate 12. I'll assure you. Alternatively, the support plate may be welded to the support tube. In another mode, the lower end does not include a shoulder. Instead, the pad of support is placed in the opening of the lower end and is attached to the support tube. In yet another non-klad, the support plate is threaded and the corresponding threads are arranged in the so-or-te tube. The arrow 23 has a lower end 27 which passes through an opening 14 in the support plate 12. The lower end 27 of the arrow 23 has a slot 29. An arrow fastener 51 is disposed in the slot 29 to prevent the arrow 23 from passing back through the opening 14 in the support plate 12. Preferably, the arrow holder 51 comprises a clip. Alternatively the arrow may have a hole in the lower end adapted to receive a split pin. The lower end can also be threaded to receive a nut. The arrow 23 also includes a shoulder 25 located near the lower end 27 of the arrow 23. The shoulder 25 is an integral part of the arrow 23. In alternative embodiments, the shoulder is composed of a threaded nut on an arrow or a welded washer to the arrow. A support frame 41 is disposed on an arrow 23 between the support plate 12 and the shoulder 25 as shown in the fi les 4 and 6. The support frame 11 includes a first washer 42, a second washer 43. and a plurality of ball bearings 44 captured between the washers. The support frame 44 enables the pneumatic cartridge 17 and the carrier tube 13 to rotate about a vertical axis as the user rotates the seat 5 around that axis. The support frame also prevents the shoulder 25 from passing through the opening 16 in the support plate 12. Alternatively, the shoulder can have a larger diameter than the opening and can resist the support plate. As shown in Figures 4 and 6, a cushion member 45 is located on the arrow 23 around the shoulder 25 and extends above the upper surface of the shoulder 25. Preferably, the cushion member 45 is made of rubber. . The cushion 45 is interposed between the lower surface 53 of the cylinder 19 and the shoulder 25 when the column is in a fully compressed position. The cushion 45 prevents the shoulder 25 from coming into contact with the lower surface 53 of the cylinder and damaging it. When the seat 5 is occupied by the user, the seat imparts a vertical load to the porator tube 13 which transfers the load to the pneumatic cartridge 17 through the shoulder 59 of the carrier tube. The pneumatic cartridge 17 carries the vertical load through the arrow 23 and transfers it to the support frame 41 through the shoulder 25 on the arrow 23. The support frame II then transfers the vertical load to the support hub 7 through The support plate 12. Finally, the load is transferred from the support tube 7 to the base 3. Because the cartridge 17 is secured within the carrier tube 13 in the upper part of the carrier tube 13, the cartridge 17 is not forced to carry any bending load. . If the lower portion of the tube of the carrier is made, the cartridge is forced to resist the moment of flexion applied to it by exerting a coupled reaction force, a reaction force exerted at the point of the union of the dL. ndro and the other at the point where the arrow joins the support tube. Such an arrangement forces the cartridge to carry the moment of bending and react against it. The resulting force that is exchanged between the arrow and the cylinder would accelerate the wear and degradation of the seal that faces those two elements. Conversely, when the cylinder is attached to the top of the carrier tube, the cartridge is not forced to carry the moment. The present invention also relates to a method for assembling the pneumatic height adjustment column. The method includes inserting the pneumatic cartridge into the carrier tube 13 so that the hub passes through the opening 15 in the upper portion 14 of the carrier tube 13. When so positioned, the upper surface of the cylinder 19 engages the shoulder 59 of the carrier tube 13. A mallet holder 35 is then attached to the hub 30 to secure the pneumatic cartridge 17 within the carrier hub 13. A cushion 45 is placed over the arrow 23 around the shoulder 25 and a support frame 41 is disposed over the end of the arrow 27 below the shoulder. The carrier tube 13 and the fixed pneumatic cartridge 17, including the cushion 45 and the support frame 41, are then inserted into the support tube 7. The support tube 7 is pushed down until the lower end 27 of the arrow passes through the aperture 14 in the support plate 12, thus capturing the support frame 41 between the shoulder 25 and the plate 12 of support. An arrow fastener 51 is then attached to the end of the arrow 23 to secure the arrow to the support plate 12. It should be understood that an order is not required to carry out these steps and that they can be rearranged to achieve the same result. Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes in shape and details can be made without departing from the spirit and scope of the invention. As such, it is intended that the above detailed description be considered as illustrative rather than limiting and that the appended claims, including the equivalents thereof, are intended to define the scope of the invention.

Claims (29)

NOVELTY OF THE INVENTION CLAIMS

1. A pneumatic height adjustment column for a chair characterized in that it comprises a support tube having an upper end - which is generally open and a lower portion adapted to be mounted to the base of a chair, the lower portion includes an opening with a smaller diameter than that of the support tube; a carrier tube having an upper portion adapted to be mounted to a support housing, the upper part includes an opening with a smaller diameter than that of the carrier tube, the carrier tube also has a generally open endless end which telescopically engages the upper end of the support tube; a pneumatic cartridge includes a cylinder that is placed inside the carrier tube the cylinder has a diameter greater than that of the opening in the carrier tube; an arrow extending down from the cylinder, the arrow having a lower end passing through the opening in the lower part of the support tube; a hub arranged on top of the cylinder passing through the opening in the upper part of the carrier tube; a hub holder slidably engages the aza, whereby the position of the aza is maintained through the opening in the upper part of the carrier tube; and an arrow clip attached to the bottom of the arrow, whereby the position of the arrow is * * > Holds through the opening in the bottom of the support tube.

2. A column in accordance with the claim 1, further characterized in that the hammer compresses a groove and the hammer fastener comprises an elastic member disposed in said groove and an enlarged portion extending from the elastic member to prevent * the hammer from passing back through of the opening in the upper part of the port tube.

3. A column in accordance with the claim 2, characterized further because the slot is a round slot around the hub.

4. A column according to claim 2, further characterized in that said hub holder is made of a steel strip having a thickness of about 0.076 to 0.127 centimeters.

5. A column according to claim 2, further characterized in that said hub holder is curved.

6. A column in accordance with the claim 1, further characterized in that the cartridge further comprises an actuator button extending through the hub.

A column according to claim 1, further characterized in that the lower portion of the support tube comprises a lower end which is generally open and a support plate mounted to the lower end, said support plate having an opening with a smaller diameter than that of the support tube.

8. A column in accordance with the claim 7, further characterized in that said arrow further comprises a shoulder placed near the lower end of said arrow and wherein said pneumatic cylinder further comprises a supporting frame disposed on said arrow, the support frame captured between said shoulder and said plate of support, with which the pneumatic cartridge can rotate around- an ee vert cal.

9. A column in accordance with the claim 8, further characterized in that the support frame comprises a first washer, a second washer and a plurality of ball bearings interposed between said washers.

10. A column in accordance with the claim 8, further characterized in that it comprises a cushion member disposed between the arrow about said spacing, the cushion member engaging a lower surface of said cylinder when the pneumatic cartridge is subjected to pressure.

11. A column in accordance with the claim 1, further characterized in that the mallet clip comprises a Y-shaped member having a pair of elastic members defining an opening and an enlarged portion fixed to said elastic members, said elastic members engaging said hub of the pneumatic cartridge when the mallet It is placed inside said aber-tura.

12. A column according to claim 11, further characterized in that the hub holder * has three engaging tabs extending inwardly in the opening, said tabs elastically engaging the mass of said pneumatic carcase.

13. A column according to claim ll, further characterized in that said elastic members have bevelled ends.

14. A column according to claim 13, further characterized in that said bevelled ends and said enlarged portion are coupled to the support housing, whereby said carrier tube is secured to said support housing.

15. A column according to claim 1, further characterized in that the hub holder is adapted to be coupled to said support housing, whereby said carrier tube is secured to said support housing.

16. A pneumatic height adjustment column for a chair characterized in that it comprises a support tube; a carrier tube disposed in said support tube, said carrier tube having an opening; a pneumatic cartridge disposed in said carrier tube, the pneumatic cartridge having a cylinder and a hub disposed on an upper portion of said cylinder, said hub passing through the opening of the carrier tube; a mallet holder slidably engaging the hub, whereby the position of the hub is maintained three fingers away from the opening in the upper part of the carrier tube.

17. A column in accordance with the claim 16, further characterized in that the hub comprises a groove and the gripper comprises an elastic member disposed in said groove and an enlarged portion extending from the elastic member to avoid- with that the hub passes back through the body. the opening in the upper part of the tube carrying

18. A column in accordance with the claim 17, character-hoisted further because the slot is a round slot around the hub.

19. A column according to claim 17, further characterized in that said hub holder is made of a steel strip having a thickness of about f) .06 to 0.127 centimeters.

20. A column according to claim 16, further characterized in that the cartridge further comprises an actuator button extending through the hub.

21. A column in accordance with the claim 16, furthermore made up of the fact that the gripping bracket comprises a Y-shaped member having a pair of elastic members defining an opening, said elastic members engaging said hub of the pneumatic cartridge when the rnaza is placed within said opening.

22. A column according to claim 21, further characterized in that the hub holder has three engaging tabs extending inwardly in the opening, said tabs engaging the mass of said pneumatic tire.

23. A column in accordance with the claim 21, further characterized in that said resilient members have bevelled ends

24. A column according to claim L6, further characterized in that said nose fastener is curved.

25. A column according to claim 16, further characterized in that the hub holder is adapted to engage said support housing, whereby said carrier tube is secured to said support housing.

26. A method for assembling a pneumatic height adjustment column, the method characterized in that it comprises: providing a support tube having an upper end that is generally open, and a lower portion adapted to be mounted to a chair base, the lower portion having an opening with a smaller diameter than that of the support tube; providing a carrier tube having an upper portion adapted to be mounted to a support housing, the upper portion including an opening with a smaller diameter than that of the carrier tube, the carrier tube also having a lower end which is generally open; providing a pneumatic cartridge comprising a cylinder, a gear sanded to the top of the cylinder and an arrow extending downwardly from said cylinder, said arrow comprising a lower end * and a shoulder located near the lower end; inserting the pneumatic cartridge into the carrier tube so that the hub passes through the opening in the upper portion; to unload the hub with a mallet clip to secure the pneumatic cartridge in the carrier tube; insert the tube in the support tube ?; passing the lower end of the arrow through the opening in the lower portion of the support tube; Secure the lower end of the arrow with an arrow fastener.

27. A method of compliance with the claim 26, further characterized in that it comprises: arranging a support frame on the lower end of the arrow and capturing said support frame between the lower portion of said support tube and the shoulder of said arrow.

28. A method in accordance with the claim 27, further characterized in that it comprises: arranging a cushion on the arrow around said shoulder.

29. A method according to claim 26, further characterized in that the step of releasably engaging the hub further comprises applying an inward force to an enlarged portion of the nose fastener whereby a pair of resilient members is deflected outwardly by the grip as the ham fastener is placed on the hammer. SUMMARY OF THE INVENTION A pneumatic height adjustment column is provided for a chair; the column includes a support tube, a delivery tube, a pneumatic cartridge, a hammer holder and an arrow adjuster; the support tube has an upper end which is generally open and an inner portion that is adapted to be mounted to a chair base; the mfepoi portion has an opening with a smaller diameter * than that of the support tube; the carrier tube has an upper portion to be mounted on a support housing for a saddle seat; the upper portion has an opening that has a diameter less than that of the carrier tube; the carrier tube has a generally open lower end that telescopically engages the upper end of the support tube; the pneumatic cartridge has a cylinder placed inside the support tube, an arrow and a ring; the cylinder has a diameter greater than that of the opening in the carrier tube; the arrow extends downward from the cylinder and has a lower end passing through the opening in the lower part of the support tube; the hub is disposed on an upper portion of the cylinder and passes through the opening in the upper part of the carrier tube; the hammer holder slidably engages the hub and carrier tube; The arrow clip is fixed to the arrow and maintains the position of the lower end of the arrow through the opening in the bottom of the support tube. 33 P97 / 1356F