Castor having efficiently locking function

[0001] 1. Field of the Invention

[0002] The present invention relates to a castor and, more particularly, to a castor for a chair and the like.

[0003] 2. Description of the Related Art

[0004] A conventional castor in accordance with the prior art shown in FIGS. 6 and 7 comprises a main body 1, two rollers 10 each rotatably mounted on the main body 1 and each having an inside formed with a locking slot 12, and a control member 11 pivotally mounted on the main body 1 and provided with a locking rod 13 movable in the locking slot 12 of each of the two rollers 10.

[0005] In operation, when the control member 11 is located at the position as shown in FIG. 6, the locking rod 13 of the control member 11 is located at the lower end of the locking slot 12 of each of the two rollers 10, so that the two rollers 10 are rotatable freely, and the castor is movable on the ground. On the contrary, when the control member 11 is located at the position as shown in FIG. 7, the locking rod 13 of the control member 11 is located at the upper end of the locking slot 12 of each of the two rollers 10, so that the two rollers 10 are locked by the locking rod 13 of the control member 11, and the castor cannot be moved on the ground.

[0006] However, when the two rollers 10 are locked by the locking rod 13 of the control member 11, the two rollers 10 are still rested on the ground, so that the castor easily slips on the ground by applying a pulling force on the castor, thereby causing inconvenience to the user. In addition, the locking rod 13 of the control member 11 rubs the locking slot 12 of each of the two rollers 10 frequently, so that the locking rod 13 of the control member 11 and the wall of the locking slot 12 of each of the two rollers 10 are easily worn out during a long-term utilization, thereby decreasing the locking effect of the castor.

[0007] In accordance with the present invention, there is provided a castor, comprising a main body, two rollers each rotatably mounted on the main body, a stop member movably mounted in the main body and movable between a first position where the stop member is located at a height higher than that of each of the two rollers and a second position where the stop member is located at a height lower than that of each of the two rollers, a slide slidably mounted in the main body and rested on the stop member to move the stop member, and a control member pivotally mounted on the main body and connected to the slide to move the slide.

[0008] The primary objective of the present invention is to provide a castor having an efficiently locking function.

[0009] Another objective of the present invention is to provide a castor, wherein when the stop member is movable downward to rest on the ground, the two rollers are suspended in the air, so that the castor is locked exactly without slipping or moving on the ground.

[0010] Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.

[0018] Referring to the drawings and initially to FIGS. 1-3, a castor in accordance with the preferred embodiment of the present invention comprises a main body 20, two rollers 24 each rotatably mounted on the main body 20, a stop member 21 movably mounted in the main body 20 and movable between a first position as shown in FIG. 3 where the stop member 21 is located at a height higher than that of each of the two rollers 24 and a second position as shown in FIG. 4 where the stop member 21 is located at a height lower than that of each of the two rollers 24, a slide 22 slidably mounted in the main body 20 and rested on the stop member 21 to move the stop member 21, and a control member 23 pivotally mounted on the main body 20 and connected to the slide 22 to move the slide 22.

[0019] The main body 20 has a bottom formed with a slideway 203 to allow movement of the slide 22 and a receiving chamber 202 (see FIG. 3) connected and perpendicular to the slideway 203 to allow movement of the stop member 21. The main body 20 has a central portion formed with a shaft hole 201 and has a periphery formed with a mounting hole 200.

[0020] The stop member 21 has a side formed with a receiving space 210 connected to the slideway 203 of the main body 20 to allow movement of the slide 22. The receiving space 210 of the stop member 21 has a bottom provided with a tapered pressing face 215 facing the slide 22. The pressing face 215 of the stop member 21 is formed with an arch-shaped receiving recess 212 to receive a metallic rod 213. The receiving space 210 of the stop member 21 has a top provided with a ramp 211. The ramp 211 of the stop member 21 has an end provided with a perpendicular face 214 (see FIG. 5).

[0021] The slide 22 has a first end having a bottom provided with a tapered pressing face 220 that is movable to press the pressing face 215 of the stop member 21 to press the stop member 21 downward relative to the main body 20 and a top provided with an oblique push portion 221 that is movable to press the ramp 211 and the perpendicular face 214 of the stop member 21 to press the stop member 21 upward relative to the main body 20. The pressing face 220 of the slide 22 contacts with the metallic rod 213 on the pressing face 215 of the stop member 21 to prevent the stop member 21 from directly touching and rubbing the slide 22 constantly. The slide 22 has a second end formed with a cutout 222 and provided with a driven stub 223 located in the cutout 222.

[0022] Each of the two rollers 24 has a central portion formed with a shaft hole 240 and has a side face formed with an annular groove 241 for mounting a washer 25 and a mounting hole 242 for mounting a cover 27.

[0023] The control member 23 has a first end pivotally mounted on the main body 20, a mediate portion provided with a drive flange 232 connected with the driven stub 223 of the slide 22 and a second end provided with an outwardly extending press portion 231. The first end of the control member 23 is provided with two opposite pivot ears 230 pivotally mounted on two opposite sides of the main body 20 and located between the two rollers 24. Each of the two pivot ears 230 of the control member 23 is formed with a shaft hole 234. The two pivot ears 230 of the control member 23 have different sizes, and one of the two pivot ears 230 of the control member 23 is located at an open side of the receiving chamber 202 of the main body 20. The drive flange 232 of the control member 23 is pivotally mounted in the cutout 222 of the slide 22 and formed with a through hole 233 pivotally mounted on the driven stub 223 of the slide 22.

[0024] A metallic plate 235 is mounted in the through hole 233 of the drive flange 232 of the slide 22 and contacts with the driven stub 223 of the slide 22 to prevent the drive flange 232 of the control member 23 from directly touching and rubbing the driven stub 223 of the slide 22 constantly.

[0025] A shaft 26 is extended through the shaft hole 240 of each of the two rollers 24, the shaft hole 234 of each of the two pivot ears 230 of the control member 23 and the shaft hole 201 of the main body 20.

[0026] In operation, referring to FIGS. 4 and 5 with reference to FIGS. 1-3, when the stop member 21 is located at a height higher than that of each of the two rollers 24 as shown in FIG. 3, the two rollers 24 are rotatable freely.

[0027] As shown in FIG. 4, when the press portion 231 of the control member 23 is pressed downward, the control member 23 is pivoted toward the main body 20 to push the slide 22 toward the stop member 21 so that the pressing face 220 of the slide 22 is movable to press the pressing face 215 of the stop member 21 to press the stop member 21 downward relative to the main body 20 until the stop member 21 is located at a height lower than that of each of the two rollers 24 so as to suspend the two rollers 24 by the stop member 21. Thus, when the stop member 21 is movable downward to rest on the ground, the two rollers 24 are suspended in the air, so that the castor is locked exactly without slipping or moving on the ground.

[0028] As shown in FIG. 5, when the press portion 231 of the control member 23 is pulled upward, the control member 23 is pivoted outwardly relative to the main body 20 to move the slide 22 outwardly relative to the stop member 21 so that the push portion 221 of the slide 22 is movable to press the ramp 211 and the perpendicular face 214 of the stop member 21 to press the stop member 21 upward relative to the main body 20 until the stop member 21 is located at a height higher than that of each of the two rollers 24. Thus, the stop member 21 is suspended in the air, and the two rollers 24 are rested on the ground, so that the two rollers 24 are rotatable freely to move the castor.

[0029] Accordingly, when the stop member 21 is movable downward to rest on the ground, the two rollers 24 are suspended in the air, so that the castor is locked exactly without slipping or moving on the ground. In addition, the metallic rod 213 is located between the pressing face 215 of the stop member 21 and the pressing face 220 of the slide 22 to prevent the stop member 21 from directly touching and rubbing the slide 22 constantly, thereby preventing the stop member 21 and the slide 22 from being worn out due to frequent friction. Further, the metallic plate 235 is located between the drive flange 232 of the control member 23 and the driven stub 223 of the slide 22 to prevent the control member 23 from directly touching and rubbing the slide 22 constantly, thereby preventing the control member 23 and the slide 22 from being worn out due to frequent friction.

[0030] Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the true scope of the invention.