Snap hook

A snap hook having a hook shank and a gate keeper. The hook shank includes a main body and a hook member. The hook member has a hook bowl and a hook bill with the hook bill and the main body defining a gateway opening therebetween. The gate keeper has an open position and a closed position. When in its closed position the gate keeper encloses the gateway opening and when in its open position the gate keeper allows passage of an object through the gateway opening. The snap hook further includes a first and a second pivot point such that movement of the gate keeper from its closed to its open position requires at least partially rotating the gate keeper about its first pivot point and thereafter at least partially rotating the gate keeper about its second pivot point.

FIELD OF THE INVENTION

This invention relates to snap hooks of the type that may be used on safety belts, safety harnesses, safety lines or any of a wide variety of other applications. In one particular embodiment, the invention relates to a snap hook having a new and improved gate keeper and hook shank design that enhances the ability of the gate keeper to withstand loading in multiple directions and that helps prevent an unintentional opening of the hook.

BACKGROUND OF THE INVENTION

Snap hooks in the safety and lifting industries take a variety of different forms and have an equally wide number of different applications. Such applications include use in fall arrest systems and in the lifting of heavy objects by means of a crane or other lifting devices.

The safe lifting of heavy objects and the prevention of falls is of primary importance on construction sites and in situations where individuals may be working at heights, around areas of excavation, or where a personal fall or the dropping of an object that is being lifted could result in property damage, serious injury or death. Furthermore, in many jurisdictions the employment of a fall arrest system to prevent personal injury is not only desirable, but is a statutory requirement. Commonly fall arrest systems involve the placement of a harness or belt around an individual and then the subsequent use of a rope, cable or strap to secure the harness or belt, and hence the individual, to a solid structure. For example, individuals working on bridges, towers or tall buildings will commonly wear belts or safety harnesses that include a lifeline typically comprised of a rope or strap having its free end secured to the structure upon which they are working. In the logging industry, and in situations where individuals are working on utility poles, a worker is often fitted with a safety belt or harness having a rope or strap that is connected to the belt or harness at one end, is passed around the tree or pole, and that has its free end connected to an opposite side of the belt. At least one end of the rope or strap is usually fitted with a snap hook to enable it to be readily engaged and disengaged from the safety belt or support structure.

In theory, should a worker slip or fall while wearing a safety belt or a harness that is securely attached by way of a lifeline to a solid structure, the worker will only be allowed to fall a short distance after which his decent will be stopped and he will be suspended until he can regain his balance or be rescued. In practice the safety harness and fall arrest systems currently in use do not always function as designed and accidents, injuries and fatalities sometimes occur. One type of failure that can have disastrous results is a failure of the hook used on the end of a lifeline. Similarly, the failure of a hook used in the lifting of heavy objects can be equally dangerous.

Due to their convenience and ease of use, snap hooks having a gate keeper that encloses the hook bowl are probably the most widely used method to secure the end of a lifeline to an object. For the same reasons such hooks are commonly used in a extremely wide variety of other applications, including for the lifting of objects. Unfortunately, simple snap hooks can become unintentionally opened through the application of a force against their gate keeper. As a result, others have proposed and developed a variety of different locking mechanisms that assist in maintaining the gate keeper in a closed position (for example, see U.S. Pat. No. 4,062,092 dated Dec. 13, 1997; U.S. Pat. No. 4,122,585 dated Oct. 31, 1978; U.S. Pat. No. 5,257,441 dated Nov. 2, 1993; U.S. Pat. No. 5,579,564 dated Dec. 3, 1996; and U.S. Pat. No. 5,896,630 dated Apr. 27, 1999.) While such locking mechanisms have reduced the likelihood of an unintentional opening of the hook, they are generally limited in their ability to prevent the gate keeper from becoming dislodged from the end of the hook bowl or bill through the application of forces or loads that may be applied directly to the gate keeper.

For ease of use, many gate keepers require the application of a single force to either the keeper or its lock in order to “open” the hook. In some instances others have designed keeper and lock structures that require the application of two discrete forces to open the hook, one force directed to the lock and one force directed to the keeper. Nevertheless, even in such cases it has been found that situations as innocuous as leaning against a hook that is bearing against a solid surface can be sufficient to cause an accidental disengagement of the gate keeper from the hook's bill. Where that occurs the hook may unintentionally become dislodged and present a significant threat to the safety of personal and equipment.

SUMMARY OF THE INVENTION

The invention therefore provides an improved snap hook that provides an increased level of security and that helps to minimize the likelihood of an accidental or unintentional disengagement of the gate keeper from the hook's bill

Accordingly, in one of its aspects the invention provides snap hook comprising a hook shank including a main body and a hook member, said hook member having a hook bowl and a hook bill, said hook bill and said main body defining a gateway opening therebetween; and, a gate keeper having an open position and a closed position, when in said closed position said gate keeper enclosing said gateway opening, when in said open position said gate keeper allowing passage of an object through said gateway opening, said snap hook further including a first and a second pivot point such that movement of said gate keeper from said closed to said open position requires at least partially rotating said gate keeper about said first pivot point and thereafter at least partially rotating said gate keeper about said second pivot point.

In a further aspect the invention provides a snap hook comprising a hook shank having a main body, a hook bowl and a hook bill, said hook bill and said main body defining a gateway opening therebetween; and, a gate keeper rotationally secured to said hook shank and movable from a closed position wherein said gate keeper encloses said gateway opening to an open position wherein said gate keeper allows passage of an object through said gateway opening, said gate keeper movable from said closed position to said open position through sequentially rotating said gate keeper about at least two separate pivot points and through the successive application of a first, a second, a third and a fourth force to said gate keeper, each of said forces applied to said gate keeper at a different angle.

In another aspect the invention provides a snap hook comprising a hook shank including a main body and a hook member, said hook member having a hook bowl and a hook bill, said hook bill and said main body defining a gateway opening therebetween; and, a gate keeper having an open position and a closed position, when in said closed position said gate keeper enclosing said gateway opening, when in said open position said gate keeper allowing passage of an object through said gateway opening, one of said main body and said gate keeper including a pivot pin and the other of said main body and said gate keeper including a slot for receiving said pivot pin, said gate keeper rotationally secured to said hook shank such that movement of said gate keeper from said closed position to said open position requires the application of four successive forces to said gate keeper, said successive forces causing the relative movement of said pivot pin within said slot permitting the controlled rotational movement of said gate keeper relative to said main body.

Further aspects and advantages of the invention will become apparent from the following description taken together with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention may be embodied in a number of different forms. However, the specification and drawings that follow describe and disclose only some of the specific forms of the invention and are not intended to limit the scope of the invention as defined in the claims that follow herein.

A snap hook constructed in accordance with one of the preferred embodiments of the present invention is shown in the attached drawings and represented by reference numeral1. Snap hook1includes a hook shank2that is in the form of a main body3having a hook member4position generally at one of its ends. The opposite end of main body3is typically formed with an eye5or with a clevis or other means to secure the hook to a rope, cable, belt, chain or other object. In most instances main body3, hook member4and eye5will be of unitary construction and formed from a high strength alloy steel or other metal. The structure may also be forged to further increase strength.

In general, hook member4has an arched shape and is of a relatively standard configuration for snap hooks. Hook member4includes a hook bowl6and a free end7that defines a hook bill8. The distance or “opening” between hook bill8and main body3defines a gateway opening9that permits hook bowl6, and hence hook1, to be received about a device or object such as an eye bolt, safety cable, lanyard, etc. Hook1further includes a gate keeper10rotationally secured to said hook shank to enclose gateway opening9and to prevent hook1from sliding off a cable or other device over which it has been placed. As is traditional with snap hooks, the gate keeper has an open position and a closed position, such that when it is in its closed position the gate keeper extends across the gateway opening and generally encloses the opening to hook bowl6. When in its open position gate keeper10allows passage or entry of an object through gateway opening9and into hook bowl6.

The manner of attachment of gate keeper10to hook shank2and the operational features of the gate keeper are shown in the cross-sectional views ofFIGS. 7 through 11. In the embodiment of the invention shown, gate keeper10is generally in the form of a planer or plate-like element, partially received within a slot or hollow interior11within shank2. Depending upon the method of manufacture of hook shank2, slot11may be formed through casing the shank with an internal slot or the slot may be machined into the shank. In the embodiment shown in the attached drawings shank2is formed through riveting together a series of plate like structures to form a laminated product with a hollow interior portion that forms slot11.

Regardless of the means of manufacture of shank2, it has been found that retaining the gate keeper within slot11contributes to the strength and side load capacity of the gate keeper through the formation of a sandwich or laminated type structure. Gate keeper10is rotationally secured to shank2through the use of one or more pivots or pins such that at least a portion of the gate keeper remains within slot11at all times during use of the hook. Accordingly an enhanced side load capability is realized whether the gate keeper is open or closed. While it will be appreciated by those skilled in the art that the pins about which the gate keeper rotates may effectively form part of the shank, or alternately that they may be formed on or otherwise secured to the gate keeper, in the embodiment of the invention shown in the attached drawings the pins or pivot points are in the form of rivets passing through the hook shank. Specifically the drawings show a first pivot point or pin12and a second pivot point or pin13. From a complete understanding of the invention described hereunder it will become apparent that movement of gate keeper10from its closed to its open position will require initially at least partially rotating the gate keeper about first pivot point or pin12which is located on hook bill8, and then subsequently at least partially rotating the gate keeper about second pivot point or pin13which is positioned on main body4of hook shank2.

In a preferred embodiment of the invention, first pivot point or pin12is positioned on hook bill8and is in the form of a post or rivet that is at least partially received or held within a receiver14formed on the free end15of the gate keeper when the gate keeper is in its closed position. The interaction of first pivot point12with receiver14enhances the load bearing capacity of the gate keeper and helps to prevent free end15from being dislodged from the hook bill. Similar to the manner in which hook shank2is formed with a slot to partially receive the gate keeper, free end7of hook bill8is also preferably formed with an internal slot or hollow opening into which the free end or tip15of the gate keeper may be received. In this fashion, with the gate keeper in its closed position and first pivot point or pin12at least partially received within receiver14, the ability of the tip of the gate keeper to withstand both side loading and loading directed outwardly from hook bowl6will be enhanced.

Second pivot point or pin13is preferably secured to either main body3or gate keeper10. The other of the main body and the gate keeper includes a slot16for receiving second pivot13. In the embodiment shown inFIG. 7, second pivot point13is secured to main body3with slot16formed within gate keeper10. With pivot point13received within slot16the gate keeper will thus be secured to the hook's main body while still being permitted to move between its open and closed positions by means of rotational movement about the main body. It will, of course, be appreciated the rotational movement of the gate keeper will be to a significant extent controlled by the movement of second pivot13within slot16. It will also be appreciated that while not shown in the attached drawings, the relative positioning of the pivot and slot could be reversed with the pivot situated on the gate keeper and the slot formed within main body3.

As in the case of many snap hooks, the snap hook of the present invention is normally biased to a configuration where gate keeper10is in its closed position. To accomplish this the hook preferably includes at least one return spring17tending to bias the gate keeper closed. In the embodiment shown in the attached drawings, return spring17has one end fixed to an elongate arm18formed upon gate keeper10and a second end secured to main body3by means of a pin, post or rivet19. Rotational movement of the gate keeper about second pivot point13will thus require the application of a force in excess of the force applied by return spring17. The use of a pin, post or rivet to secure the return spring to the main body permits the spring to freely rotate within slot11of shank2, as may be necessary during the movement of the gate keeper.

To assist in the controlled movement of the gate keeper, snap hook1may further include a guide pin20received within a guide channel21. As in the case of second pivot point13and slot16, the guide pin could be positioned on either main body3or gate keeper10, with guide channel21located on the other of the two structures. In the embodiment shown in the attached drawings guide pin21is formed on or secured to main body3with guide channel21formed within gate keeper10. As will be appreciated from an understanding of the operation of the snap hook, guide pin20and guide channel21together assist in controlling rotational movement of the gate keeper about second pivot point13. For ease of assembly, it is expected that in most instances first pivot point12, second pivot point13, pin19and guide pin20will all be comprised of rivets received through the sides of hook shank2.

The manner in which gate keeper10is moved from its closed to its open position will now be described in detail in order to more fully demonstrate the function of the component parts of hook1. Moving gate keeper10from its closed to its open position will require the application of four separate and successive forces to the gate keeper. In these regards reference is first made toFIG. 7which shows gate keeper10in a closed configuration. Here, receiver14on the free end15of the gate keeper is partially received about first pivot point12with return spring17biasing the gate keeper in a generally longitudinal direction away from the first pivot point. In this configuration return spring17has the effect of driving second pivot point13and guide pin20into blind ends,22and23respectfully, of slot16and guide channel21. The dimensions of the gate keeper are preferably such that with second pivot point13and guide pin20in contact with blind ends22and23, receiver14is still at least partially received about first pivot point12such that the interaction of the receiver and the first pivot point enhance the load bearing capacity of the gate keeper, as described above.

InFIG. 8snap hook1is shown in cross-section where the gate keeper is in an initial stage of being opened. Here a first force has been applied to the gate keeper in a direction generally parallel to the longitudinal axis of the hook's shank and to the gate keeper. When the first force exceeds the biasing force applied by return spring17gate keeper10will effectively slide in a direction parallel to the longitudinal axis of the hook shank and toward first pivot point12until pivot point12is seated fully within receiver14and second pivot point13and guide pin20are free from blind ends22and23. At this point the application of a second force to gate keeper10in a direction generally perpendicular to the direction of the first force (ie generally perpendicular to the longitudinal axis of hook shank2) will have the effect of causing the gate keeper to rotate or pivot about first pivot point12with second pivot point13and guide pin20sliding within a transverse leg (31and32respectively) in each of slot16and guide channel21until second pivot point13and guide pin20come to rest within corners24and25of slot16and guide channel21. First pivot point12will still be situated within receiver14and the hook will be in the stage of opening shown inFIG. 9.

To the continue with the opening of gate keeper10a third force is next supplied to the gate keeper in a direction that is generally opposite to the direction of application of the first force. That is, the gate keeper is slid in a downward direction, generally parallel to the longitudinal axis of the hook shank, to effectively pull receiver14away from first pivot point12. This movement will drive second pivot point13and guide pin20into longitudinally oriented portions26and27of slot16and guide channel21. As shown in the attached drawings, slot16is generally of a “J” shaped configuration and it has received within its longitudinally oriented portion26a compression spring28. Spring28will have the effect of limiting movement of second pivot point13within longitudinally oriented portion26and, as described below, will also assist in returning the gate keeper to its closed position. A spring retainer29may be situated between second pivot point13and spring29in order to help retain the spring in place and to present a surface upon which second pivot point13may bear.

FIGS. 10 and 11show gate keeper10in its final stages of being opened. Following the application of the third downwardly oriented force, the gate keeper will have slid in a downward direction away from first pivot point12to a position where receiver14is free and clear of the first pivot point to thereby enable the gate keeper to rotate about second pivot point13while guide pin20travels along an arcuate leg30of guide channel21. Rotation of the gate keeper in this manner requires the application of a fourth force to the keeper. This fourth force is in general a rotational force applied to the exterior face of the keeper. As the fourth force is applied the gate keeper will rotate about second pivot point13and guide pin20will progressively travel along arcuate leg30. At the same time, the free end15of the gate keeper will be rotated outwardly and away from hook bill8, effectively “opening” the hook. When guide pin20bottoms out against the end of arcuate leg30(seeFIG. 11) gate keeper10will be at that point in a fully open configuration. Movement of the keeper in the above described manner may be facilitated through the incorporation of a thumb rest33on the upper exterior surface of the gate keeper.

Moving the gate keeper to its closed configuration merely requires the release of the gate keeper allowing compression spring28and return spring17to close to keeper. Once the gate keeper is released return spring17will cause the gate keeper to rotate in opposite direction to that as occurs when the keeper is being opened, with the keeper rotating about pivot point13and guide pin20traveling backwardly along arcuate leg30. When the guide pin has traversed the entirety of arcuate leg30the gate keeper will be forced to move in a longitudinal direction toward first pivot point12through the operation of compression spring28until receiver14is once again received about first pivot point12. Next, return spring17will cause the gate keeper to pivot outwardly away from the hook shank about first pivot point12with second pivot point13and guide pin20traversing legs31and32of slot16and guide channel21until they eventually come to rest in blind ends22and23. At this point the gate keeper will be in its closed position, as shown inFIG. 7.

From an understanding of the structure and function of the component parts of snap hook1, it will be appreciated that a hook structure is provided that exhibits inherent safety previously unavailable in snap hooks. The construction of the hook and its gate keeper greatly enhances the side and vertical loading capabilities of the hook while the movement of the keeper from its closed to its open position requires the application of four separate, distinct and successive forces. Preventing the keeper from becoming opened except in the case of the specific application of four forces in the proper order presents a hook that has an extremely low probability of becoming unintentionally opened during use.

It is to be understood that what has been described are the preferred embodiments of the invention and that it may be possible to make variations to these embodiments while staying within the broad scope of the invention. Some of these variations have been discussed while others will be readily apparent to those skilled in the art.