Hook Latching Device

The present invention relates to latching device for a hook used for transportation work by means of a crane or the like, and specifically to a latching device provided with a safe locking mechanism which will prevent a wire rope or the like suspended from the hook from being removed therefrom during use, and which is adapted to improve the safe carrying out of transportation work of kind otherwise exposed to accident.

It is well known to provide a latching arm across the opening in the curved portion of a hook. A latching device of this kind prevents the wire rope or the like from falling off from the hook as the loop of the wire rope or the like is contacted against the latching arm when the loop suspended from the hook is elevated relative to the hook by loosening of the rope during work. When the loop of the wire rope or the like is to be suspended from the curved portion, the latching device is adapted to open the opening of the curved portion by turning the latching arm downwardly by depressing action of the loop against the upper side of the latching arm. Therefore, the wire rope or the like is apt to be removed from the hook when the latching arm is pulled downwardly from the back side (upward) thereof by the loop, when the loop becomes twisted upwardly and biased to one side of the hook during work. The object of the present invention is to provide a device which eliminates such defects.

Reference will now be made to the accompanying drawings in which;

FIG. 1 is a front view of a hook according to the present invention;

FIG. 2 is a side view, partially sectioned, of the same;

FIG. 3 and 4 are side views of the same showing now a wire rope or the like suspended from the hook is loosened, and

FIG. 5 is a plan showing another embodiment of device according to the present invention.

In FIG. 1 and 2, 4 is a bracket located below the hanger 1 of the hook and provided integrally with the hook in a position directed to the tip 3 of the curved portion of the hook. In the upper and lower portions at the front side of the bracket 4 are formed upper recess 5 and lower recess 6 adapted to engage with the pawl 15 of the locking lever 10 as described hereinafter. 7 is a locking arm disposed across the opening for rope to move into the curved portion 2 of hook, and as arm 7 is pivoted at the base end thereof to a pin 8 fixed to the bracket 4 with the axis thereof horizontal, the tip of the latching arm is turnable upwardly and downwardly. At the front end of the latching arm 7 is formed cap 9 which is integral with opposite side plates of the latching arm 7 and the back plate disposed therebetween, and the cap 9 is constructed to be engageable with the tip 3 of the curved portion as described hereinafter. Locking lever 10 is disposed in the interior of latching arm 7, and as it is pivoted to a pin 11 fixed to the side plates of the latching arm 7 with the axis thereof horizontal, it is rockable upwardly and downwardly. The locking lever 10 is urged upwardly (clockwise in FIG. 2) at the back side end thereof by a spring 14 being mounted around pin 11, contacting at one end thereof against a recess 12 formed on the lower side of the locking lever 10 and contacting at the other end thereof against an engaging portion 13 provided at the lower portion of the latching arm 7. Pawl 15 is formed in the top of locking lever 10. FIG. 2 shows a state wherein the tip of the latching arm 7 is lowered, and the cap 9 thereof is engaged with the tip 3 of the curved portion, thereby closing the opening of the curved portion 2. At this time, the pawl 15 of the locking lever 10 is engaged with the lower recess 6 of the bracket 4 and locks the latching arm 7 in this position. And then, when the locking lever 10 is turned in the direction of arrow A against the elastic force of restitution of the spring 14, the pawl 15 of the locking lever 10 is disengaged from the lower recess 6, and the locking of the latching arm 7 is released.

When the latching arm 7 is lifted up in the direction of arrow B in this state, the opening of the curved portion 2 which had been closed is opened. When the latching arm 7 is further turned upwardly above the bracket 4 to the position shown by the dashed line in FIG. 2, the pawl 15 of the locking lever 10 slides on the front side of the bracket 4 and is turned downwardly (in the direction opposite that of arrow A in the drawing) by the energizing action of the spring 14 and is engaged with the upper recess 5 of the bracket 4, and the latching arm 7 is locked in this position so that it will not move downwardly. Then, when the opening of the curved portion 2 is closed again, as the latching arm 7 is depressed, the locking lever 10 is naturally turned downwardly slightly, and the pawl 15 is disengaged from the upper recess 5 of the bracket 4, however, if the depression force is heavy, the locking lever may be positively turned downwardly (in the direction of arrow A in the drawing) to disengage the pawl 15 from the upper recess 5. And, when the latching arm 7 is depressed further continuously, the back plate of the cap 9 formed at the tip of latching arm 7 is contacted against the upper surface of the tip 3 of the curved portion and hereon the turning is stopped, and the latching arm is locked again in this position.

When the opening of the curved portion is closed, as shown in FIG. 3, even if the loop 16 of the wire rope or the like suspended from the curved portion 2 is elevated relative to the hook due to loosening and the like of the wire rope and pushes up against the latching arm 7 from the underside thereof, the pawl 15 of the locking lever 10 is forced more into the lower recess 6, so that the opening of the curved portion closed by the latching arm 7 cannot be opened. Under such a condition with the opening of the curved portion closed, as shown in FIG. 4, even when the loop 16 of the wire rope or the like is twisted upward during work and biased to one side of the hook, and thereby the latching arm 7 is pulled downwardly from the reverse or upper side thereof, the latching arm 7 is engaged at the cap 9 with the tip 3 of the curved portion, and the back plate of the cap 9 is abutted against the upper surface of the tip 3 of the curved portion, so that the latching arm 7 cannot be turned downwardly, and consequently the loop 16 can never be removed through the opening of the curved portion.

As shown in FIG. 2, the cap 9 of the latching arm 7 forms a small space 17 of a few milimeters in distance between cap 9 and the tip 3 of the curved portion when it is engaged with the tip 3 of the curved portion 2. Consequently when the opening of the curved portion 2 has been widened, as shown with the imaginary line in FIG. 2, due to use over a long period or fatigue of the metallic material caused by an excessive load, the closing operation of the latching arm 7 can not be carried out smoothly. In other words, when the closing operation of the latching arm 7 becomes more difficult, the user of the hook will know that the hook has been subjected to metallic fatigue. If the hook is removed at this time, accidents caused by breakage of the hook may be prevented from occuring. And, in the embodiment above, the bracket 4 is shown as formed integrally with the hanger 1 at the underside thereof. But as shown in FIG. 5, the whole device according to the present invention may be formed as a unit separate from the hook and the bracket 4 of the device shown in FIG. 5 may be attached to the lower portion of the hanger 1 by using, for example, means such as strap or belt 18. The members indicated with the same numbers as shown in FIG. 5 are the same members as shown in FIG. 1 and 2. And, various hooks such as a double pawl hook, a C-type hook or the like may be used for the hook of this invention.

As described abobve in detail, when the hook latching device according to the present invention is used, the accident removal of wire rope or the like may be surely prevented, and also the operation of the latching device is extremely simple, so that there may be brought about no delay in operation efficiency.