Quick joint of front loader

1. A quick joint of a front loader, the quick joint comprising:

a coupling member ( 30 ) having a hook shape and pivotally connected to a first pivot point (P 1 ) of a boom post ( 20 ) through a first pivot shaft ( 31 );

a spring member ( 32 ) for applying an elastic force in a direction of releasing the coupling member ( 30 ) from a coupling target shaft ( 14 ) disposed on a boom post support ( 10 ) which is attached to a tractor ( 1 );

a lock unit ( 34 ) having a part making contact with the coupling member ( 30 ) to rotate about a fixed pin ( 33 ) which is provided on a side surface of the boom post ( 20 ), and provided with a lock pin ( 36 ) for restraining behavior of the coupling member ( 30 ) at a coupling position (A 1 ); and

a guide slot ( 38 ) having an arc shape and formed in the boom post ( 20 ) to define a moving path of the lock pin ( 36 ) when the lock unit ( 34 ) rotates,

wherein a fixing groove ( 380 ) is formed in the guide slot ( 38 ) and aligned on a same line with the coupling position (A 1 ), and

the lock pin ( 36 ) is inserted into the fixing groove ( 380 ) to restrain the behavior of the coupling member ( 30 ) when the rotating lock unit ( 34 ) reaches the coupling position (A 1 ).

2. The quick joint of claim 1 , wherein a part of a lower side of the lock pin ( 36 ) makes contact with a force transfer surface ( 302 ) located along a straight line from an upper surface of the coupling member ( 30 ).

3. The quick joint of claim 1 , wherein the lock unit ( 34 ) includes:

a lock lever ( 35 ) having a slot ( 350 ) into which the fixed pin ( 33 ) is inserted;

the lock pin ( 36 ) perpendicularly connected to a front end portion of the lock lever ( 35 ) such that a part of an outer surface of the lock pin ( 36 ) makes contact with a force transfer surface ( 302 ) of the coupling member ( 30 ); and

a lock spring ( 37 ) for connecting the fixed pin ( 33 ) to the lock pin ( 36 ) and applying an elastic force to the lock pin ( 36 ) toward the fixed pin ( 33 ), and

as the lock pin ( 36 ) moves along the moving path defined by the guide slot ( 38 ) according to the rotation of the lock lever ( 35 ) about the fixed pin ( 33 ), the lock pin ( 36 ) restrains the behavior of the coupling member ( 30 ) or releases the restraint on the behavior of the coupling member ( 30 ).

4. The quick joint of claim 3 , wherein the lock pin ( 36 ) is automatically inserted into the fixing groove ( 380 ) of the guide slot ( 38 ) at the coupling position (A 1 ) by the elastic force of the lock spring ( 37 ).

5. The quick joint of claim 1 , wherein the coupling position (A 1 ) is a rotational position of the lock unit ( 34 ) when the coupling target shaft ( 14 ) is inserted into a predetermined binding position of the coupling member ( 30 ).