Thick plate type joint lock for ladder connection

Abstract

A think plate type joint lock for ladder connection comprises an inner plate and an outer plate connected in a relatively rotating way, and a positioning shaft sleeve for locking the inner plate and the outer plate. In addition, a rotation limiting column is arranged on the outer plate, and a groove for resisting the limiting column is arranged on the inner plate. The limiting column and the groove restrict rotation of the inner plate relative to the outer plate, thus improving a load bearing capability and security of a ladder.

1 - 5 . (canceled) 
     
     
         6 . A thick-plate hinge for a ladder joint, comprising:
 an inner plate having a slot,   an outer plate having a stop stub and rotatably connected to the inner plate, wherein the stop stub is configured to limit the rotation of the inner plate and the slot is configured to engage the stop stub, and   a positioning shaft sleeve in communication with the inner plate and the outer plate, wherein the position shaft sleeve has a locking pin and configured to lock the inner plate and the outer plate at a predetermined position.   
     
     
         7 . The thick-plate hinge for a ladder joint according to  claim 6  wherein the stop stub enters into the slot when the inner plate and the outer plate are in an unfolded position. 
     
     
         8 . The thick-plate hinge for a ladder joint according to  claim 6  wherein the stop stub is a column stub and the slot is an inwardly slot. 
     
     
         9 . The thick-plate hinge for a ladder joint according to  claim 8  wherein the stop stub is a cylindrical stub and the slot is an inwardly concaved arc slot. 
     
     
         10 . The thick-plate hinge for a ladder joint according to  claim 9  wherein the radius of the slot is greater than or equal to the radius of the stop stub. 
     
     
         11 . The thick-plate hinge for a ladder joint according to  claim 9  wherein the depth of the slot is greater than or equal to the radius of the stop stub. 
     
     
         12 . The thick-plate hinge for a ladder joint according to claim  1  wherein the stop stub will enter into the slot at least partially when relative rotation angle between the inner plate and the outer plate reaches 180°.