GB2290841A

GB2290841A - Retractable linkage assembly for simultaneous actuation of a pair of brakes mounted on a foldable trolley

Info

Publication number: GB2290841A
Application number: GB9413128A
Authority: GB
Inventors: Chi-An Lo
Original assignee: LO CHI AN
Current assignee: LO CHI AN
Priority date: 1994-06-30
Filing date: 1994-06-30
Publication date: 1996-01-10
Also published as: GB9413128D0

Abstract

A linkage assembly for simultaneous actuation of a pair of brakes mounted on a foldable trolley e.g. a baby-stroller includes two first tubes (90), two connectors (80), a shaft member (70), and first and second engaging units [(800, 92), (71, 73)]. Each of the first tubes (90) has a first end to be connected to a brake lever (41), and a second end slidable in a space (820) defined by a respective connector (80). The first engaging unit (92, 800) prevents the first tube (90) from disengaging from the respective connector (80) when the former is pulled outwardly from the latter. The shaft member (70) has two opposed end portions, each of which is inserted slidingly into an internal tube (81) from the rear end (85) of a respective connector (80). The second engaging unit (71, 73) prevents the shaft member (70) disengaging from the respective connector (80) when the former is pulled outwardly from the latter. <IMAGE>

Description

RETRACTABLE LINKAGE ASSEMBLY FOR ACTUATING A PAIR OF BRARES MOUNTED ON A FOLDABLE TROLLEY The invention relates to a retractable linkage assembly, more particularly to a retractable linkage assembly which is used for linking and actuating a pair of brakes that are mounted on a trolley.

Referring to Figures 1 and 2, a conventional retractable linkage assembly (1) is shown to comprise an elongated connector (11) and a pair of elongated plates (12). Each of the plates (12) has a first end portion provided an engaging opening (122) and a second end portion provided with a barbed hook (121). The elongated connector (11) is formed with two spaced longitudinal channels (111) which extend through the connector (11). The first end portions of the plates (12) are respectively inserted into the channels (111) from opposed ends of the connector (11) and extend out from the other ends of the same without disengaging from the connector (11) because the barked hooks (121) engage inner portions of the other ends of the channels (111).A fastener screw (not numbered) extends through an opening (122) in the first end portion of the respective plate (12) and is threaded to a respective brake actuating lever (14) which is associated with the brake (not shown) for braking a wheel (13). Thus, when it is desired to stop the wheels (13), the rectangular connector (11) is pressed downward to compress the lever (14), thereby braking the wheels (13).

The conventional retractable linkage assembly is used to connect a pair of brakes mounted on a foldable trolley, such as a stroller, a pushcart and the like.

When the trolley or the stroller is at a folded condition, the plates (12) retract into the rectangular connector (11), thereby minimizing the required storage space, as shown in Figure 3.

Some of the drawbacks that result with the use of the conventional retractable linkage assembly are as follows: (I) The connector (11) has a relatively weak strength due to the presence of the longitudinal channels (111). Thus, the connector (11) may crack or break into pieces when compressed downward for braking the wheels (13).

(II) The plate (12) is generally thin in order to avoid further weakening of the connector (11). During the braking action of the wheels (13), the whole compression force is concentrated around the section "A" of the plate (12), which eventually leads to snapping of the plate (12) at the section "A" or to bending or winding of the section "A" of the plate (12). The bent section hinders smooth retraction of the plates (12) interiorly of the connector (11).

The main object of the present invention is to provide a retractable linkage assembly which has a particular structure that provides a considerable strength so that it does not easily break or bend when a force is applied thereon.

Accordingly, the retractable linkage assembly of the present invention is used to actuate a pair of brakes mounted on a foldable trolley and includes a pair of first tubes, a pair of connectors, a shaft member, and first and second engaging units. Each of the first tubes has a first end to be connected to a respective one of the brakes and a second end opposite to the first end. Each of the connectors has an external tube and an internal tube which are integral at a rear end thereof to form a first receiving space and a second receiving space. The first receiving space is confined by the internal tube and extends through the connector. The second receiving space is confined cooperatively by the external tube and the internal tube and is accessible from a front end of the connector.The second end of each of the first tubes is inserted slidingly into the second receiving space via the front end of the respective one of the connectors. The first engaging unit prevents the first tubes from disengaging the connectors when the first tubes are pulled outwardly from the front ends of the connectors. The shaft member has two opposed end portions, each of which is inserted slidingly through the first receiving space of the internal tube via the rear end of the respective connector. The second engaging unit prevents the shaft member from disengaging the respective connector when the shaft member is pulled outwardly from the rear end of the respective connector.

In the disclosed embodiment, the internal tube has a longitudinal length shorter than that of the external tube. The first engaging unit comprises an elongated axial slot which is formed through a wall body that constitutes the external tube and which is adjacent to the front end of each connector, and a protrusion which is formed on an external surface of each first tube adjacent to the second end of the first tube. The protrusion is preferably a barked hook. After the first tube is inserted in the respective connector, the barbed hook is received movably in the axial slot of the external tube. When the first tube is pulled outwardly from the front end of the respective connector, the barked hook of the first tube engages an end of the axial slot adjacent to the front end of the respective connector.

The second engaging unit comprises a threaded projection that extends axially from the end portion of the shaft member and an internally threaded nut which is screwed on the threaded projection. The threaded nut prevents the shaft member from disengaging the respective connector when the shaft member is pulled outwardly from the rear end of the connector.

The shaft member is made of metal and is further provided with a stopper at an intermediate portion thereof. The connectors and the first tubes are preferably made of plastic.

Since each of the connectors employed in the retractable linkage assembly of the present invention has two tubes which are integrally connected at one end of the same, the connectors possess good rigidity. The strength of each connector is further enhanced by the second end portion of the first tube and the portion of the shaft member which are inserted within the first and second receiving spaces of the connector. Thus, the connectors in the linkage assembly of the present invention do not easily crack or snap when compared to the conventional retractable linkage assembly. In addition, the shaft member is a solid metal rod which is much stronger when compared to the thin plate of the conventional retractable linkage assembly.

Other features and advantages of the present invention will become more apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, in which: Figure 1 is an exploded view of a conventional retractable linkage assembly; Figure 2 shows the conventional retractable linkage assembly at a stretched position and connecting two brakes of a foldable trolley; Figure 3 illustrates the conventional retractable linkage assembly of Fig. 2 when the assembly is at a retracted position; Figure 4 shows the retractable linkage assembly of the present invention when connected to a pair of brakes which are mounted on a foldable trolley; Figure 5 shows a cross sectional view of the retractable linkage assembly of the present invention when in a stretched position; ; Figure 6 shows a cross sectional view of the retractable linkage assembly of the present invention when in a retracted position; and Figure 7 shows an enlarged view of the retractable linkage assembly of Figure 6.

Referring to Figures 4 and 5, a retractable linkage assembly of the present invention is shown to be connected to a pair of brakes that are mounted on a foldable trolley, such as a baby-stroller, a pushcart and the like. The linkage assembly includes a pair of first tubes (90), a pair of connectors (80), a shaft member (70), and first and second engaging units.

To facilitate understanding of the present invention, only one first tube (90) and a connector (80) will be used in the specification. Each of the first tubes (90) is made of plastic and has a first end which is provided with an engaging hook (91) inserted engageably into a respective brake lever (41) of a brake. Each of the connectors (80) is a one-piece plastic molded unit and has an internal tube (81) and an external tube (82) which are integral at a rear end (85) thereof to form a first receiving space (810) and a second receiving space (820). The first receiving space (810) is confined by the internal tube (81) and extends through the connector (80). The second receiving space (820) is confined cooperatively by the external tube (82) and the internal tube (81) and is accessible from a front end (86) of the connector (80).

A second end of the first tube (90) is inserted slidingly into the second receiving space (820) via the front end (86) of the connector (80).

The shaft member (70) is a solid metal rod which has a stopper (72) mounted fixedly at an intermediate portion of the same and one end portion inserted slidingly through the first receiving space (810) of the internal tube (81) via the rear end (85) of the connector (80).

In the preferred embodiment, the first engaging unit comprises an elongated axial slot (800) which is formed through a wall body that constitutes the external tube (82) and which is located adjacent to the front end (86) of the connector (80), and a protrusion (92) which is formed on an external surface of the first tube (90) adjacent to the second end of the same. The protrusion (92) is preferably a barked hook. After the first tube (90) is inserted in the connector (80), the barbed hook is received movably in the axial slot (800) of the external tube (82) such that when the first tube (90) is pulled outwardly from the front end (86) of the connector (80), the barked hook engages an end of the axial slot (800) adjacent to the front end (86) of the connector (80). Thus, the first tube (90) is prevented from disengaging the connector (80).

The second engaging unit comprises a threaded projection (71) that extends axially from the end portion of the shaft member (70) and an internally threaded nut (73) which is screwed on the threaded projection (71). The threaded nut (73) is larger than the inner diameter of the internal tube (81) so as to prevent the shaft member (70) from disengaging the connector when the shaft member (70) is pulled outwardly from the rear end (85) of the connector (80).

Referring to Figure 4, when it is desired to stop the rotation of the wheels (4), the shaft member (70) is stepped downward to actuate the brake lever (41), thereby braking the wheels (4) to stop. When storing the trolley, the trolley is folded such that the first tube (90) and the shaft member (70) are retracted into the connector (80), as shown in Figure 6. Under such a condition, the stopper (72) permits each of the connectors (80) and the first tubes (90) to be disposed uniformly on both sides thereof while the second engaging unit (71, 73) mounted at the end portion of the shaft member (70) is exposed exteriorly of the connectors (80).

Since each of the connectors employed in the retractable linkage assembly of the present invention has two tubes which are integrally connected at one end of the same, the connectors possess good rigidity. The connectors are further strengthened by the second end portion of the first tube (90) and the shaft member (70) which are inserted within the first and second receiving spaces (810, 820) of the connectors 80.

Thus, the connectors (80) of the linkage assembly of the present invention do not easily crack or snap when compared to the conventional retractable assembly. In addition, the shaft member (70) is a solid metal rod which is much stronger when compared to the thin plate of the conventional retractable linkage assembly.

Thus, the shaft member (70) does not bend or wind due to the force applied thereon so that the shaft member (70) retracts easily into the connector (80).

Note that a portion of the first tube (90) and the shaft member (70) extends into the connector (80), which consequently strengthens the rigidity of the connectors (80). The applied force for actuating the shaft member (70) is not concentrated at a point but is transferred evenly and uniformly to the connectors (80). The internal tube (81) is constructed to possess a longitudinal length slightly shorter than that of the external tube (82) to further strengthen the connectors (80).

Claims

CLAIMS:

1. A retractable linkage assembly for actuating a pair of brakes mounted on a foldable trolley, said retractable linkage assembly comprising: a pair of first tubes, each of which having a first end to be connected to a respective one of said pair of brakes and a second end opposite to said first end:: a pair of connectors, each of which having an external tube and an internal tube which are integral at a rear end thereof and forming a first receiving space which is confined by said internal tube and which extends through said connector, and a second receiving space which is confined cooperatively by said external tube and said internal tube and which is accessible via a front end of said connector, said second end of each of said first tubes being inserted slidingly into said second receiving space via said front end of a respective one of said connectors; first engaging means for preventing said first tubes disengaging from said connectors when said first tubes are pulled outwardly from said front ends of the respective one of said connectors;; a shaft member with two opposed end portions, each of said end portions of said shaft member being inserted slidingly into said first receiving space of said internal tube from said rear end of a respective one of said connector; and second engaging means for preventing said shaft member disengaging from said respective one of said connectors when said shaft member is pulled outwardly via said rear end of said respective one of said connectors.

2. The retractable linkage assembly as defined in Claim 1, wherein said internal tube has a longitudinal length shorter than that of said external tube.

3. The retractable linkage assembly as defined in Claim 1, wherein said first engaging means comprises an elongated axial slot which is formed through a wall body constituting said external tube and which is adjacent to said front end of each said connector, and a protrusion which is formed on an external surface of each said first tube adjacent to said second end thereof and which is received movably in said axial slot.

4. The retractable linkage assembly as defined in Claim 3, wherein said protrusion is a barbed hook which engages an end of said axial slot adjacent to said front end of the respective one of said connectors when said first tubes are pulled outwardly from said front ends.

5. The retractable linkage assembly as defined in Claim 1, wherein said second engaging means comprises a threaded projection extending axially from said end portion of said shaft member which is inserted through said internal tube of the respective one of said connectors and an internally threaded nut which is screwed on said threaded projection, said threaded nut being large enough to prevent said shaft member from disengaging the respective one said connectors when said shaft member is pulled outwardly from said rear end of the respective one of said connectors.

6. The retractable linkage assembly as defined in Claim 1, wherein said shaft member further has a stopper at an intermediate portion thereof.

7. The retractable linkage assembly as defined in Claim 1, wherein said connectors and said first tubes are made of plastic and said shaft member is made of metal.

8. The retractable linkage assembly substantially as described hereinbefore with reference to and as illustrated in Figures 4 to 7 of the accompanying drawings.