Abstract:
This invention relates to a rescue hook assembly that utilizes a spring-loaded gate across the opening into the hook and has an improved safety locking mechanism to prevent accidental opening of the gate. The locking mechanism works independently from the gate, thus allowing the gate itself to be opened and closed multiple times while the locking mechanism is disengaged. With the locking mechanism engaged, however, the gate is kept in its closed position. The locking mechanism can be operated with one hand and color-coded indicators let the operator know if the mechanism is in the locked or unlocked position.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a load-carrying rescue hook assembly intended to function at the end of a cable or rope, which is raised by a hoisting apparatus. The hook carries a load, which is typically attached to the hook in the form of a sling or similar attachment strap. 
     Known hook assemblies of this type comprise a hook member designed to carry a sling or similar load-bearing attachment strap. The sling or attachment strap is engaged to or disengaged from the load-bearing portion of the hook through a gap provided between one side of the hook and an opposed tip portion of the hook. For safety, a gate or latch of some type typically bridges this gap. In most cases, this gate is pivotally attached to the side of the hook opposite its tip and is spring loaded in such a manner that the gate is biased into the closed position to prevent accidental disengagement of the sling or strap. 
     Known hook assemblies of the above-mentioned type have considerable disadvantages. For instance, the spring used in the spring-loaded gate has a finite size constraint due to the dimensions of the hook and gate. This size constraint, in turn, limits the maximum allowable spring rate. At times when this type of hook is lifting a load, the load may oscillate a considerable amount. Though rare, these oscillations may cause the portion of the sling or attachment strap that is inside the hook to come into contact with the gate, overcome the spring force of the gate, and cause an accidental disengagement of the load in what is commonly referred to as “roll-out”. In addition, if the gate is snagged by anything during use and the spring force is overcome, the gate can open. Thus, there is a potential for either an accidental disengagement of the load or accidental engagement of whatever snagged the gate. 
     To address the disadvantages caused by an accidental gate opening, some hooks employ a mechanism that locks the gate into the closed position in conjunction with spring-loaded retention. Operation of these gates usually involves a two-step operation, where the first step is to unlock a locking mechanism and the second step is to open the spring-loaded gate. When the gate is allowed to return to the closed position, the locking mechanism is automatically engaged and the process must be repeated in order to open the gate again. 
     Known hook assemblies that incorporate a locking mechanism are often difficult and cumbersome to operate. Because the operator of a rescue hook will often be wearing gloves, and because the hook may be used in adverse conditions such as cold weather, at night, in water, or a combination of the three, a two-step locking mechanism operation has proven to be difficult and can cost valuable time during a rescue operation. In addition, this operation must be repeated each time the gate needs to be opened, thereby increasing the number of times this difficulty must be overcome. Moreover, the locking mechanism of known hook assembles often requires a level of manual or digital dexterity that an operator may not possess when his or her hands are cold. 
     It is an object of this invention to provide a rescue hook assembly that utilizes a spring-loaded gate in conjunction with a locking safety mechanism to prevent accidental gate opening. 
     It is another object of this invention to provide such a locking safety mechanism that can be toggled from the “locked” to “unlocked” position or vice versa easily and with one motion, and that will remain in the “locked” or “unlocked” position as long as may be desired. 
     It is a further object of this invention to provide a locking safety mechanism that can be operated without requiring a high level of digital dexterity. 
     In particular, this invention provides a locking safety mechanism that operates separately from the spring-loaded gate, thus allowing the gate to be opened and closed numerous times while the locking mechanism is in the “unlocked” position, while not allowing the gate to open while the locking mechanism is in the “locked” position. 
     Further objects and advantages of the invention are set forth below or are apparent to those skilled in the art. 
     SUMMARY OF THE INVENTION 
     With these objectives in mind, the present invention provides a rescue hook assembly with a safety locking mechanism. The rescue hook is suited for, inter alia, helicopter search and rescue (SAR) operations. The rescue hook is comprised of a hook body having a curved, inner load-bearing surface at its lower portion and an attachment stem at its upper portion for attachment to a cable or rope of a hoisting apparatus. 
     An opening or gap into the curved, load-bearing surface is defined by a space between the hook&#39;s tip end and the hook body opposite the hook tip. This gap allows the introduction of items into the load-bearing section of the hook body. 
     A spring-loaded gate is pivotally attached to the hook body and bridges the gap, and is biased by a spring towards the hook tip, thereby keeping the gap closed. The gate can be opened by applying pressure on the gate towards the hook body, and the gate will return to the closed position when the pressure is removed (e.g., when a load or sling is “snapped” into the hook). In order to keep the gate in the closed position when unwanted pressure might attempt to open the gate, this invention incorporates a safety mechanism. A sliding latch mechanism saddles the edge of the hook body and is located in such a way that it prevents the gate from opening when in a locking position. 
     The latch has two distinct positions: locked and unlocked. Each position is defined by the mating of the spring-loaded ball of a ball-detent plunger with an indentation on the inside face of the latch. When the indentation of the latch is mated with the ball-detent that corresponds to the locked position, the latch prevents the gate from opening even when pressure is applied to the gate. By applying pressure to the latch and sliding it, the latch moves away from the locked position until the indentation is mated with the ball-detent corresponding to the unlocked position. The gate is then allowed to freely open and close until the operator moves the latch back to the locked position. 
     Red and green pins made from fiber optic material or other suitable plastic are located in the hook body in such a manner that when the latch is in the locked position, the green pin is visible and the red is not. Likewise, when the latch is in the unlocked position, the red pin is visible and the green is not. The combination of the latch mechanism that can be easily moved between the locked and unlocked position along with color-coded indicators makes this rescue hook easy to operate with very little training. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The attached drawings form a part of this specification, and reference numbers used in the drawings correspond to reference numbers contained in the written description: 
     FIG. 1 is an isometric, exploded view of a preferred embodiment of the Rescue Hook of the invention. 
     FIG. 2 is a front view of a preferred embodiment of the Rescue Hook with the gate closed and the latch in the locked position. 
     FIG. 3 is a front view of a preferred embodiment of the Rescue Hook with the latch in the unlocked position and the gate open. 
     FIG. 3 a  is a front view of a preferred embodiment of the Rescue Hook with the latch in the unlocked position, the gate closed, and showing a load sling in place. 
     FIG. 4 is an isometric view of the body of a preferred embodiment of the Rescue Hook. 
     FIG. 5 is an isometric view of a ball-detent plunger (3× scale of FIG.  4 ). 
     FIG. 6 is an isometric view of a latch (2× scale of FIG.  4 ). 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The Rescue Hook has a hook body  10  with a curved, lower inside edge  11  and an opening (hereafter referred to as gap)  12  between the hook tip  13  and the upper inside edge  14  of said hook body. A threaded attachment stem  15  is located at the top of said hook body  10  and serves as an attachment to mate with a hoisting apparatus, connecting swivel or other connecting device. The particular means by which the Rescue Hook is mated with a line connecting it to a hoist is not part of the invention, however. As persons skilled in the art will recognize, other attachment methods would also be possible. A multi-purpose hole  16  located at the bottom of the hook can serve as an attachment location for an accessory or safety line. 
     Gap  12  is bridged by a triangular-shaped gate  17 , which gate is pivotally attached to said hook body  10  by means of a rivet style fastener  18  or similar fastening device. As shown in FIG. 1, gate  17  comprises two essentially triangular plates  17   a  and  17   b  which are joined on one side by side  22   a . Fastener  18  passes through holes  19  bored through two opposing sides  17   a  and  17   b  of gate  17  at its upper end and also passes through holes  20  bored through two ears  21  that extend from hook body  10 . A cut-out  22  in the lower portion of the side  22   a  of gate  17  allows gate  17  to cover a portion of hook tip  13 . The upper edge of cut-out  22  (i.e., the lower edge of side  22   a ) makes contact with hook tip  13  and serves to limit the rotation of gate  17  away from hook body  10 . 
     A torsion spring  23  is located between ears  21  and serves to bias gate  17  toward hook tip  13 . When the Rescue Hook is assembled, torsion spring  23  rests between ears  21 ; fastener  18  passes through the coil portion of torsion spring  23 . One distal end  23   a  of torsion spring  23  rests against the inside face of side  22   a of gate  17 , while the other distal end  23   b  of torsion spring  23  rests against the portion of hook body  10  between ears  21 . Gate  17  has two operating positions: closed and open. In the closed position (as shown in FIG. 2 with side  22   a  shown with hidden lines), the upper edge of cut-out  22  is held against hook tip  13  by the force of torsion spring  23 . In the open position (as shown in FIG.  3 ), gate  17  is rotated toward the main portion of hook body  10 . 
     In order to maintain gate  17  in the closed position when so desired, this invention incorporates a safety locking mechanism in the form of a latch  24 . Said latch  24  is in the form of a saddle that is slidably attached to said hook body  10  by means of two protruding rails  25  on the opposing inside faces of latch  24 . Rails  25  mate with two grooves  26 , which grooves are cut into opposing sides of hook body  10  and are parallel with the upper outside edge  27  of hook body  10 . 
     The amount by which latch  24  may travel along grooves  26  is limited by an upper stop-pin  28  and a lower stop-pin  29 . Upper stop-pin  28  is placed through a hole  30  bored through hook body  10  at the upper end of grooves  26 . Lower stop-pin  29  is placed through a hole  31  bored through hook body  10  at a point along grooves  26  approximately 1.25 inches below the centerline of upper stop-pin  28 . The ends of stop pins  28  and  29  are flush with the sides of hook body  10 , but form obstructions within grooves  26  that restrict the extent to which latch  24  may slide in said grooves. 
     Within its range of sliding motion, latch  24  is held in two distinct positions with the aid of a threaded, upper ball-detent plunger  32  and a threaded, lower ball-detent plunger  33 . Such pre-formed ball-detent plungers are well known in the art. Such ball-detent plungers, an outer view of which is shown in FIG. 5, generally comprise a threaded outer body portion encasing a spring and ball, with the ball biased by the spring through an opening in one end of the ball-detent plunger. Such a ball-detent plunger is available from McMaster-Carr Supply Company, part no. 340A95. Upper ball-detent plunger  32  is threaded into a tapped hole  34  bored through hook body  10  in an area between grooves  26  and upper outside edge  27  of hook body  10 . In a similar manner, lower ball-detent plunger  33  is threaded into a tapped hole  35  bored through said hook body  10  approximately 0.45 inches below the centerline of upper ball-detent plunger hole  34  in a direction parallel to grooves  26 . 
     A small indentation  36  on the inside face of said latch  24  is designed to mate with the spring-loaded ball  37  of ball-detent plungers  32  and  33 . When indentation  36  is mated with said spring-loaded ball  37  of upper ball-detent plunger  32 , latch  24  is in the locked position (as shown in FIG.  2 ). In this position, the lower edges of latch  24  prevent gate  17  from rotating to the open position. When indentation  36  is mated with the spring-loaded ball  37  of lower ball-detent plunger  33 , latch  24  is in the unlocked position (as shown in FIG.  3 ). In this position, gate  17  is free to rotate between the open and closed positions. The spring-loaded force of the balls  37  of ball-detent plungers  32  and  33  serve to retain latch  24  in the locked and unlocked positions, respectively. Said spring forces can be overcome, however, by exerting a moderate sliding force on latch  24  in directions A (FIG. 2) and B (FIG. 3 a ). Ease of moving latch  24  from the locked position to the unlocked position and vice versa is enhanced by the addition of grippers  38  formed into the sides of latch  24 . The configuration of a sliding latch allows an operator to lock or unlock the Rescue Hook, even if the operator&#39;s fingers are cold and/or numb, by moving latch  24  with the palm of the hand. 
     Indentation  36  on the inside face of latch  24  can be created by boring a hole  39  through the opposite side of latch  24  and then using the tip of the drill to create indentation  36  in a procedure commonly referred to as “spot facing”. Hole  39  also allows access to ball-detent plungers  32  and  33 . This access allows the tension of the ball-detent plungers  32  and  33  to be adjusted while mated with indentation  36 . 
     Persons skilled in the art will recognize that numerous alternative means may be employed to retain latch  24  in its locked and unlocked positions, the use of ball-detent plungers being merely the preferred embodiment. By way of example only, a spring-loaded cam-type follower could be adapted to an inside portion of latch  24  and configured to rest in depressions formed on body  10 . 
     To facilitate ease of use by less skilled operators, this invention further includes colored pins made from fiber-optic material, plastic or other suitable material, and that indicate whether latch  24  is in the locked or unlocked position. Preferably, a red pin  40  is placed through a hole  41  bored through hook body  10  inside said grooves  26  just below upper stop pin  28 . When latch  24  is in the unlocked position, red pin  40  is visible, indicating this position as unsafe. A green pin  42  is placed through a hole  43  bored through hook body  10  inside grooves  26  just above lower stop pin  29 . When latch  24  is in the locked position, green pin  42  is visible, indicating this position as safe. The ends of both pins  40  and  42  are flush with the bottoms of grooves  26 , thereby not interfering with the motion of latch  24 . 
     Hook body  10 , gate  17  and latch  24  can be made from any material or materials that will provide the strength and corrosion-resistance properties needed for a particular application. Possible materials include 15-5PH or 17-4PH stainless steel. 
     The foregoing description is of a preferred embodiment of the Rescue Hook, and is intended to instruct those skilled in the art how to make and use the invention. Such persons will appreciate, however, that there are many possible variations and modifications to the above-described embodiment of the invention. The invention is not limited by the preferred embodiment, but instead includes all modifications, variations and equivalents, and is limited only by the attached claims, which claims are to be given the widest scope consistent with the principles disclosed and as may be allowed by the prior art.