Retaining structure for a track device

Abstract

A track device comprises a first track, a second track slidably received in the first track, and a third track slidably received in the second track. The first track includes a retaining block having an upper side and an underside side. Each of the upper side and the underside side of the retaining block has a first end having an inclined surface tapering toward a longitudinal axis of the retaining block. Each of the upper side and the underside side of the retaining block further has a second end with an engaging portion. The second track is slidably received in the first track and has a clamping member mounted thereto. The clamping member includes a main body with two opposite sides and two resilient legs each having an intermediate portion connected to an associated side of the main body. Each resilient leg further includes a first end extending beyond the main body and a second end extending beyond the main body. A distance between the first ends of the resilient legs is smaller than that between the second ends of the resilient legs. The first ends of the resilient legs are releasably engaged with the retaining block and releasably retained on the engaging portions of the retaining block.

What is claimed is:  
     
         1 . A track device comprising: 
 a first track including an upper longitudinal lip and a lower longitudinal lip, the first track further including a retaining block having an upper side and an underside side, each of the upper side and the underside side of the retaining block having a first end having an inclined surface tapering toward a longitudinal axis of the retaining block, each of the upper side and the underside side of the retaining block further having a second end with an engaging portion; and    a second track slidably received in the first track and guided between the upper longitudinal lip and the lower longitudinal lip of the first track, the second track including an upper longitudinal lip and a lower longitudinal lip, the second track further including a clamping member mounted thereto, the clamping member including a main body with two opposite sides and two resilient legs each having an intermediate portion connected to an associated said side of the main body, each said resilient leg further including a first end extending beyond the main body and a second end extending beyond the main body, a distance between the first ends of the resilient legs being smaller than that between the second ends of the resilient legs, the first ends of the resilient legs being releasably engaged with the engaging block and releasably retained on the engaging portions of the retaining block.    
     
     
         2 . The track device as claimed in  claim 1 , wherein each of the upper side and the underside side of the retaining block further has an intermediate portion between the engaging portion and the inclined portion, the retaining block having a maximum width defined between the intermediate portions of the upper side and the underside thereof.  
     
     
         3 . The track device as claimed in  claim 1 , wherein the first track includes a first stop provided on an end thereof, the second track including a second stop for cooperating with the first stop of the first track for preventing disengagement of the second track from the first track.  
     
     
         4 . A track device comprising: 
 a first track including an upper longitudinal lip and a lower longitudinal lip, the first track further including a retaining block having an upper side and an underside side, each of the upper side and the underside side of the retaining block having a first end having an inclined surface tapering toward a longitudinal axis of the retaining block, each of the upper side and the underside side of the retaining block further having a second end with an engaging portion;    a second track slidably received in the first track and guided between the upper longitudinal lip and the lower longitudinal lip of the first track, the second track including an upper longitudinal lip and a lower longitudinal lip, the second track further including a clamping member mounted thereto, the clamping member including a main body with two opposite sides and two resilient legs each having an intermediate portion connected to an associated said side of the main body, each said resilient leg further including a first end extending beyond the main body and a second end extending beyond the main body, a distance between the first ends of the resilient legs being smaller than that between the second ends of the resilient legs, the first ends of the resilient legs being releasably engaged with the retaining block and releasably retained on the engaging portions of the retaining block; and    a third track slidably received in the second track and guided between the upper longitudinal lip and the lower longitudinal lip of the second track.    
     
     
         5 . The track device as claimed in  claim 4 , wherein each of the upper side and the underside side of the retaining block further has an intermediate portion between the engaging portion and the inclined portion, the retaining block having a maximum width defined between the intermediate portions of the upper side and the underside thereof.  
     
     
         6 . The track device as claimed in  claim 4 , wherein the first track includes a first stop provided on an end thereof, the second track further including a second stop and a third stop, the second stop cooperating with the first stop of the first track for preventing disengagement of the second track from the first track, the third track including a fourth stop cooperating with the third stop of the second track for preventing disengagement of the third track from the second track.  
     
     
         7 . The track device as claimed in  claim 4 . wherein the second ends of the resilient legs press against an upper inner wall surface of the third track and a lower inner wall surface of the third track, respectively and the first ends of the resilient legs are disengaged from the retaining block when the track device is in a fully collapsed state.  
     
     
         8 . The track device as claimed in  claim 7 , wherein the second track and the third track move together relative to the first truck when the track device is extended from the fully collapsed state.  
     
     
         9 . The track device as claimed in  claim 8 , wherein the first ends of the resilient legs are engaged with the engaging portions of the retaining block and the second ends of the resilient legs are disengaged from the upper inner wall surface and the lower inner wall surface of the third track when the second track reaches its outermost position relative to the first track.  
     
     
         10 . The track device as claimed in  claim 9 , wherein the first ends of the resilient legs of the clamping member are respectively engaged with the engaging portions of the retaining block when the track device is in a fully extended state.  
     
     
         11 . The track device as claimed in  claim 10 , wherein an engaging force between the first ends of the resilient legs and the engaging portions of the retaining block is greater than a frictional force between the second ends of the resilient legs and the third track.  
     
     
         12 . The track device as claimed in  claim 11 . wherein the third track is firstly retracted inward relative to the second track when the track device is collapsed from its fully extended state.  
     
     
         13 . The track device as claimed in  claim 12 . wherein the second track is allowed to retract into the first track when the third track reaches a predetermined position.