GB2304790A - Positioning device for a pair of telescopically retractable bars - Google Patents

Abstract

A positioning device for a pair of telescopically retractable bars of a trolley generally includes a pair of outer tubes 12, a pair of inner tubes 14 slidably received therein, a sleeve member 16 securely interconnecting the outer tubes and defining a channel 162 in which two slide blocks 20 are received and a knob assembly 50 pivotally received in the sleeve member. The knob assembly has a rectangular bar 56 with a first short width and a second long width by which, in an unlocked position, the second long width is vertical. In a locked position, the knob is pivoted so that the second long width urges each slide block 20 outwardly so that protections formed at a distal tip thereof securely enters holes 142 defined in the inner tubes. Springs 30 bias the slide blocks to the retracted position.

Description

ppSITTnTCL fl1TC FOR L PTR OF LrSOpTrL RZTRlCTAntE VRTICAt 1RS or I The present invention relates to a control or positioning device for a pair of teleacopically retractable vertical bars of a trolley to adjust and retain an upper tube of each bar at a desired extension with respect to a lower tube of each bar.

Trolleys having adjustable or retractable telescoping bars are generally known, such as in the Applicant'8 U.S.

Patent Application Serial Number 08/410,341 filed on March 24, 1995, to meet the various needs of people. In the Applicant' 8 trolley, a positioning device for the pair of telescopically retractable bars basically utilizes a frictional contact between inner and outer tube"" of the bar as is imparted and maintained by an external force. Since application of the external force is in a direction substantially perpendicular to that of the impending sliding movement between the pair of bar., a forced retraction of one bar with respect to the other bar is to occur such as when one leaning or resting with his/her weight force against or upon the upper bar.

Another type of trolley discloses a positioning device comprising a resilient member and a latch attached to one end of the member for each of the pair of bars. The opposite end of the resilient member is fixed to an inner wall of the inner, upper tube. Holes are provided on the inner ad outer tubes so that the latch can be biased to enter the aligned holes of the tubes to thereby locking the tubes in position from a relative sliding movement. To permit a relative movement, the latch is manipulated to yield by hands while at the same time moving the inner, upper tube to disengage the latch carried by the inner tube from the hole on the outer tube.In this design, it is noted that during positioning the inner tube with respect to the outer tube both hands are required to manipulate the protruded latch and then almost at the same time slidingly move the inner tube over the outer tube. This is cumbersome and might be difficult to perform by oneself. Moreover, the locking condition achieved by the resilient member and integral latch in combination with the holed disposed on the two tubes is believed not positive and reliable such that relative movement between the two tubes is apt to occur.

The present invention provides a positioning device for a pair of telescopically retractable vertical bars of a trolley of the type in which each retractable bar is consisted of an outer tube and an inner tube slidable within the outer tube, the positioning device comprising a pair of slide blocks each having a protrusion means for entering into one of a number of holes provided on the inner tube to positively and securely lock the inner tube.

To lock the inner tube, a knob assembly is provided to easily move the slide blocks; to unlock or disengage the pair of slide blocks from the inner tubes, a spring is provided to urge each slide block after the knob assembly is manipulated.

These and various other advantages and features of novelty which characterize the positioning device are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.

In the drawings: Fig. 1 is a perspective view, in part, of a trolley depicting a positioning device for a pair of telescopically retractable bars in accordance with the present invention; Fig. 2 is an exploded view the positioning device shown in Fig. 1; Fig. 3 is a cross-sectional view of the positioning device of Fig. 1 in an unlocked position; and Fig. 4 is a cross-sectional view of the positioning device of Fig. 1 in locked position.

Referring to the drawings, and particularly to Pigs. 1 and 2, a positioning device for a pair of telescopically retractable vertical bars of a trolley in accordance with the present invention is clearly shown and is generally identified by reference numeral 10. In this type of trolley to which the invention pertains, the retractable bar is consisted of an outer tube 12 and an inner tube 14 slidable within the outer tube 12. A sleeve member 16 constituting a part of the positioning device 10 is provided to securely interconnect between the two lower outer tubes 14 to thereby define a channel 162 with upper and lower plates 164 and 166.This arrangement can be generally seen in, for example, the aboe-mentioned Applicantfis U.S. Patent Application Serial Number 08/410,341 hereby incorporated by reference.

The positioning device 10 comprises, in addition to the sleeve member 16, a pair of slide blocks 20 received within the channel 162 and a knob assembly 50 disposed within and in contact with the pair of slide blocks 20. As will be further described hereinafter, the slide blocks 20 whioh each have protrusion means for entering into one of a number of holes 142 on the inner tube 14 can be operated by the knob assembly 50 to anchor the inner tubes 14 in a positive and secure manner.

The slide block 20 has a wide recess 202 at one side thereof. A spring 30 is to be disposed within the recess 202, with the spring being in a slightly compressed state.

To hold the spring 30 under a functional state, a pin 40 is disposed within the channel:162 on the sleeve member 16 at a position corresponding to the recess 202 so that, when the slide blocks 20 with the springs 30 thereon are mounted within the channel 162, the pin 40 will be disposed between adjacent coils of the spring 30, In a preferred arrangement, the relative position between the pin 40 and the recess 202 of the slide block 20 iB such that the pin 40 is disposed to a far side 302 of the spring 30 so that an efficient utilization of the spring is obtained while enabling an easy assembly of the slide blocks and springs into the channel 162.

A protrusion means of the slide block 20 for entering into and thereby anchoring the inner tubes 14, ae previously mentioned, may preferably be in the form of a solid ball or protrusion 24 affixed to a side of the block 20 which faces adjacent inner tube 14. The slide block 20 has, at the side the solid ball 24 is affixed, a partial cylindrical face 28 complementary in contour with an outer wall face of the tube 14. This can be clearly seen in Figs. 3 and 4.

To permit disengagement of the inner tube 14 from the ball 24, the slide blocks 20 have to be moved or retracted in a direction away from the tubes 14. This can be done by the rotating the knob assembly 50. The knob assembly S0 comprises a knob 52, a stop pin 53 and a rectangular bar 54.

The knob 52 has a first race, a second face and a bore. The stop pin 53 is fixedly received in the second face near a peripheral tip thereof. The rectangular bar 54 has a rectangular body 56 with a long projection integrally extending from a first end and a sbort boss extending from a second end. The rectangular body 56 defines a first short width and a second longer width. Edges of the body defining the second longer width are radiused. The longer projection is securely receivable in the bore of the knob 52 with the rectangular bar 54 extending from the second face of the knob 52.

The plate 60 has 5 (five) faces integrally formed from one sheet of material, such as metal, a top vertical face, a first horizontal portion extending therefrom, a middle vertical face extending therefrom, a second shorter horizontal portion extending in a direction opposite to the first horizontal portion and a bottom vertical face extending from the second horizontal portion. A large aperture 62 is defined centrally and transversely through the middle vertical face and is sized to receive the long projection of the rectangular bar 54. The plate 60 is sized to mount over the upper and lower plates 164 and 166.

Further holes are defined through the top vertical face and bottom vertical face for attachment by screws extending therethrough to engage threadedly with the sleeve member 16.

In assembly the springs 30 are received in respective recesses 202 and held in a slightly compressed state by respective pins 40. The protrusions 24 each enter appropriate holes 142 in the inner tubes 14. The rectangular body 54 is extended with the second longer width vertically disposed between the slide block 20 so that the boss 58 can extend pivotally through a hole defined in a rear of the sleeve member 16 and is retained in position by means, such as a C-clip 70.

The plate 60 is fitted to the sleeve member 16 by the middle vertical face being mounted over the upper and lower plates 164 and 166 thereby enclosing the channel 162. The long projection of the rectangular bar extends through the aperture 62 in the plate 60. The knob 52 is securely attached to the long projection.

When the second longer width is in a vertical position the inner tubes 14 can be raised or lowered as the protrusions 24 are only urged into respective holes 142 by the slight tension of the springs 30 which can be overcome by manual force of a user. When the knob assembly 50 is pivoted to a second position whereby the second longer width is pivoted 90 , the rectangular body 56 urges against the slide blocks 20 to provide a greater force by which the protrusions 24 will remain secure in the holes 142.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims (11)

1. A positioning device for a pair of telescopically

retractable vertical bars of a trolley, each retractable bar being consisted of an outer the and an inner tube slidable within the outer tube, the positioning device comprising: a sleeve member securely attached to the outer tube, the sleeve member having a channel defined between the pair of inner tubes; a pair of slide blocks received within the channel, each slide block including protrusion means for entering into and thereby anchoring the inner tube; and means for moving the pair of slide blocks to anchor the inner tubes.

2. The positioning device as claimed in claim 1, further comprising means for urging the pair of slide blocks to disengage from the inner tubes.

3. The positioning device as claimed in claim 2, wherein: the means for urging the pair of blocks to disengage from the inner tubes comprises a pair of pins disposed within the channel of the sleeve member and a spring associated with each pin; and the slide block has a recess for sccommodating each pin and the associated spring.

4. The positioning device as claimed in claim 3, wherein the pin is disposed to a far side of the associated spring.

5. The positioning device as claimed in claim 1, wherein: the protrusion means of the slide block comprises a solid ball affixed to a side thereof; and the inner tube is provided with a plurality of holes spaced along a length thereof.

6. The positioning device as claimed in claim 5, wherein the slide block has, at the side the solid ball is affixed, a partial cylindrical face substantially complementary with an outer wall contour of the inner tube.

7. The positioning device as claimed in claim 1, wherein the moving means comprises a knob assembly disposed between and in contact with the pair of slide blocks, the knob assembly comprising: a knob; and bar integral with the knob, the bar being rotatable between a first position in which the inner tubes are slidable relative to the outer tubes and a second position in which the slide blocks are moved by the bar to anchor the inner tubes.

8. The positioning device as claimed in claim 7, wherein the bar is substantially rectangular shaped to define a first width and a second width large than the first width, the pair of slide blocks being spaced from each other by the first width when the stud is in its first position and the pair of slide blocks being spaced from each other by the second width when the stud is in its second position,

9. The positioning device as claimed in claim 7, further comprising a stop fixed on the knob assembly to prevent a further forward rotational movement of the knob assembly, after the bar is rotated from the first position to the second position.

10. The positioning device as claimed in claim 1, further comprising a plate to cover an access opening of the channel of the sleeve member.

11. A positioning device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.