Tape rule brake mechanism

Abstract

Tape rule brake mechanism consists of a brake device and a positioning member. The rim of the reel on which a measuring tape being coiled around is provided with at least one trammeling block accompanied with a confinement slot. When the brake machanism is actuated, a detent formed at the tip of the brake device drops into the confinement slot and halt the reel rotation by mating with the trammeling block of the reel so as to indirectly stop motion of the tape coiled on the reel. The tape is stably fixed at the position without slipping away by secure engagement of the positioning member with the detent of the brake device. The reset action of the brake device is assisted by the restoring force of a compressed spring.

What is claimed is:  
     
         1 . A tape rule brake mechanism comprising: 
 a tape rule housing divided into an upper housing and a lower housing, a first and a second slots being formed in succession at the upper rear edge of said lower housing, a positioning post being erected on said first slot, and a pivot bearing being standing in front of said positioning post, a stopper plate accompanied with a tongue piece being formed in front of said pivot bearing, a fixed pole being standing in front of said second slot; similarly, another first and another second slots being formed in succession along said upper housing's edge, a positioning post being extended downward from said upper first slot, and a hollow column being provided in front of said positioning post, when said upper and said lower housing being coupled together, their first slots and second slots being also coupled together so as to form continuous first and second cavities, at this time, said pivot bearing being inserted into said hollow column of said upper housing such that said two housings being able to engage firmly with each other.    a reel for coiling an a measuring tape being provided at least one trammeling block formed along its rim thereof, each trammeling block being provided with a confinement slot, said reel being accommodated in said tape rule housing for extending and retrieving said tape by rotation;    A positioning member being provided with a push button at its top surface thereof, the bottom of said push button being formed into a notch, and an eye hole being formed under said notch, the end part of said positioning member being formed into a hook arm with two claws at its tip and rear end, when said eye hole of said positioning member is fitted over said pivot bearing, said notch under said push button can be hinged to said positioning post of said tape rule housing so that said push button is emerged out of said combined first slot of said upper and said lower housings, while said hook arm at the bottom of said positioning member is detained by said stopper plate with its tongue piece engaging with the top claw of said hook arm;    a hollow braking device being provided with a push plate at its top portion thereof, and a via hole being formed at its middle portion thereof, the bottom portion thereof being bifurcated into a pair of detents, an open trough with a stopper strap being provided at one side of said brake device;    for assembling said brake device on said tape rule housing the central via hole of said brake device is fitted over said fixed pole of said lower housing so as to emerge said push plate out of said combined second slot of said upper and said lower housings, and face said stopper strap against said positioning member and a compressed spring whose one end secured to the side surface of said fixed pole, while the other end thereof the upper inner wall surface of side brake device is provided for said brake device to serve its restoring force for the brake device to reset.    
     
     
         2 . The tape rule brake mechanism of  claim 1 , wherein a reel axle is erected from the center portion of said lower housing, said reel is provided with a central through hole to fit over said axle such that said reel is rotatable about said axle in said tape rule housing to stretch or retrieve the measuring tape.  
     
     
         3 . The tape rule brake mechanism of  claim 1 , wherein said combined second slot formed by coupling said upper and lower housings is larger than said first one.  
     
     
         4 . The tape rule brake mechanism of  claim 1 , wherein said detents of said brake device is able to be engaged with the trammeling block of said reel so as to detain the rotation of said reel together with said measuring tape coiled thereon, and said brake device is positioned by engaging said tip claw of the hook arm with said stopper strap of the brake device and compressing said compressed spring in said brake device.  
     
     
         5 . The tape rule brake mechanism of  claim 1 , wherein said positioning member is displaceable forward and backward with respect to said pivot when being fitted thereof.  
     
     
         6 . The tape rule brake mechanism of  claim 1 , wherein said push button of the positioning member is provided with several friction stripes on its top surface thereof so as to prevent slipping when being operated.  
     
     
         7 . The tape rule brake mechanism of  claim 1 , wherein said brake device is movable up and down by fitting its central via hole over the fixed pole of said lower housing.  
     
     
         8 . The tape rule brake mechanism of  claim 4 , wherein one end surface of the trammeling block provided along the rim of said reel is formed into approximately a planar portion while the other end surface an arcuate portion, besides, one end of each bifurcated detent is formed into a chamfered edge, while the other end thereof is formed into a detention block, with this structure, each of said detents brings its chamfered edge into the confinement slot of said reel along said arcuate surface of said trammeling block thereby reel is blocked and can not rotate to stretch or retrieve said measuring tape.  
     
     
         9 . The tape rule brake mechanism of  claim 4 , wherein when the rear claw of said hook arm is disengaged from the stopper strap of said brake device, said brake device is reset to its initial position by the restoring force of said compressed spring.