Deceleration device of a tape rule

Abstract

A deceleration device of a tape rule is equipped with a speed reduction gear wheel in the tape rule housing. The speed reduction gear wheel is in mesh with a transmission gear wheel of a reel for coiling a measuring tape such that the rotational speed of the reel when retrieving the extended tape is retarded thereby preventing the danger of scratching the user's finger or damaging the tape itself by abrasion or impingement. Engagement of the speed reduction gear wheel and the transmission gear wheel can be released by operating a flat pusher plate provided on the housing.

What is claimed is:  
     
         1 . A deceleration device of a tape rule comprising: 
 a housing composed of two sub-housings, an axle being erected on the center portion of one of the two sub-housings, and an aperture being provided nearby said axle;    a reel with a through hole at its center thereof, said axle being penetrating via said through hole such that said reel being rotatable about said axle in said housing driven by a transmission gear wheel coaxially fitted to said reel such that said reel is able to extend a measuring tape coiled on it, or retrieve the extended tape back; and    a deceleration unit whose speed reduction gear wheel being set up in said sub-housing via said aperture and being in mesh with said transmission gear wheel of said reel for retarding the rotation of said reel.    
     
     
         2 . A deceleration device of a tape rule comprising; 
 a housing composed of two sub-housings an axle being erected on the center portion of one of the two sub-housings, and an aperture being provided nearby said axle, while a post and a circular hole is provided on the outer surface of said sub-housing;    a reel with a through hole at its center thereof, said axle being penetrating via said through hole such that said reel being rotatable about said axle in said housing driven by a transmission gear wheel coaxially fitted to said reel such that said real is able to extend a measuring tape coiled on it, or retrieve the extended tape back, and    a deceleration unit with a speed reduction gear, one terminal of said deceleration unit has a through hole, while the other terminal thereof is formed into a hook;    said speed reduction gear wheel is set up in said sub-housing via said aperture and is in mesh with said transmission gear wheel of said reel for retarding the rotation of said reel, after aligning said through hole with said circular hole provided on said sub-housing, and penetrating a hinge pin therethough, said deceleration unit is hinged to the outer surface of said sub-housing and is displaceable to and fro thereon so as to engage or disengage said speed reduction gear wheel with said transmission gear wheel.    
     
     
         3 . The deceleration device of  claim 1 , wherein said deceleration unit is tightly engaged with said sub-housing by screw combining two tapped holes provided at both sides of said sub-housing near said aperture with two tapped holes provided at both sides of said deceleration unit.  
     
     
         4 . The deceleration device of claims  1  and  2 , wherein said deceleration unit is operated with oil pressure or pneumatic pressure, or by other mechanical means.  
     
     
         5 . The deceleration device of  claim 2 , wherein said aperture formed on said sub-housing has a size slightly larger than that of said speed reduction gear wheel for allowing room for said speed reduction gear wheel movable to and fro therein.  
     
     
         6 . The deceleration device of  claim 2 , wherein a flat pusher plate is provided for said speed reduction gear wheel so as to push said speed reduction gear wheel movable to and fro. Wherein the surface of said flat pusher plate has a plurality of slip-stop striples.  
     
     
         7 . The deceleration device of  claim 2 , wherein said post and said circular hole are correspondingly formed on said sub-housing nearby said aperture.  
     
     
         8 . The deceleration device of  claim 2 , wherein said hook provided at the terminal of said deceleration unit is used to hook onto said post provided on the outer surface of said sub-housing so as to fix said deceleration unit stably at its position.