AU650371B2

AU650371B2 - Dual latch safety hook

Info

Publication number: AU650371B2
Application number: AU27127/92A
Authority: AU
Inventors: Alan Travers
Original assignee: Moxham Industrial Pty Ltd
Current assignee: Moxham Industrial Pty Ltd
Priority date: 1991-10-30
Filing date: 1992-10-16
Publication date: 1994-06-16
Anticipated expiration: 2012-10-16
Also published as: AU2712792A

Description

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P/00/0011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT 650 371

ORIGINAL

Name of Applicant: MOXHAM INDUSTRIAL PTY. LTD.

Actual Inventor: ALAN TRAVERS Address for service in Australia: CARTER SMITH BEADLE, Qantas House, 2 Railway Parade, Camberwell, Victoria, 3124, Australia, Attorney Code CD Invention Title: DUAL LATCH SAFETY HOOK S Details of Associated Provisional Applications: Nos: PK 9226 The following statement is a full description of this invention, including the best method of performing it known to us: CARTER SMITH BEADLE All rights reserved 1992 -1- This invention relates to safety hocks which are commonly known as latch type hooks or snap hooks. Snap hooks are used extensively in situations where it is desired to connect a hook to some apparatus or load in a manner whereby the hook is substantially prevented from accidental disengagement.

Known snap hooks generally engage with a connection ring or loop and have a spring biased one-way gate or latch which extends across the hook opening. The latch is allowed to open when the connection loop is forced against the outside of the latch allowing the loop to pass through the latch and attach to the hook. The latch is closed by the bias and prevented from opening when the loop is forced against the latch from the inside of the hook.

To detach the connection ring from the hook the latch must first be opened by pressing against the outside of the latch before the ring can pass through the opening in the hook.

A common use for snap hooks is to attach a suspension strap to a harness supporting a person. It has been found that the conventional snap hooks can, in some circumstances, be opened by being caught or bumped on other equipment worn by the person being suspended.

It has further been found that the gate for conventional snap hooks can be pried open, when the connection ring is twisted while attached to the snap hook, Consequently these types of snap hooks have the problem of unintentional disconnection from the ps2B/8667.spe 11992 10 3 connection ring.

Improvements of the basic snap hook have been developed which requires two separate actions to connect and disconnect a connection ring. However, these hooks known as double acting hooks comprise a latch and a lock and rely on a close interaction of moving parts. This close interaction of moving parts makes existing double acting hooks prone to failure resulting in the latch sticking open and the connection ring not being retained. This is particularly concerning as snap hooks or safety belts and harnesses are often used in environments where dust, dirt etc. are present to compound the problem.

Therefore, it is an object of the present invention to provide a snap hook which overcomes one or more of the aforementioned problems.

Accordingly the invention provides a snap hook comprising a hook member having an opening through which a load support member passes for engagement and disengagement, a first gate means extending substantially across the opening and capable of opening inwardly against first biasing means, and a second gate K L means extending across the opening and capable of opening outwardly against a second biasing means, said first gate means having an abutment which co-operates with said second gate means when both gate means are in a closed position to prevent said first gate means being opened sufficiently to allow disengagement of said load support member.

ps28/8667 spe 1992 10 L I I 4 In the preferred form, if an attempt is made to pivot the first gate means to the open position while the second gate means is in the closed position, the abutment on the first gate means contacts the second gate means. The abutment and consequently the first gate means is thereby prevented from further rotation.

Therefore, the provision of the second gate means greatly reduces the possibility of a load support member unintentionally disengaging itself from the hook member whilst still allowing for a simple procedure to engage and disengage the snap hook from the load support member.

The foregoing and other features objects and advantages of the present invention will become more apparent from the following description of the preferred embodiment and accompanying drawings in which:- Figure 1 is a front elevational view of a snap hook according to the invention, shown in the closed position; Figure 2 is a side elevational view of the snap hook shown in Figure 1; Figure 3 is a side view of the snap hook shown in Figures 1 and 2, showing the first and second latches in the open position; and Figure 4 is a sectional view along line 4-4 of Figure 2.

Referring to the drawings, the snap hook 1 is shown to comprise a hook menmber 2 usually produced in a stamp forming operation or other suitable steel forming or ps28/8667 spe 1992 I0 4 In the preferred form, if an attempt is made to pivot the first gate means to the open position while the second gate means is in the closed position, the abutment on the first gate means contacts the second gate means. The abutment and consequently the first gate means is thereby prevented from further rotation.

Referring to the drawings, the snap hook 1 is shown to comprise a hook member 2 usually produced in a stamp forming operation or other suitable steel forming or ps28/8667 spe 1992 10 5 forging operation. The hook member 2 has an attachment member 3 for connection to a load bearing web 16 or like load bearer in a conventional manner. Hook member 2 forms almost an enclosed loop with an access opening 4 which allows the hook member to be attached directly to a connection ring such as a D-ring 5 or like load connecting member.

The access opening 4 is capable of being closed by means of a first gate means in the form of latch 6. The latch 6 is pivotally connected to the hook member 2 by means of a pin 7 which passes through an aperture in base portion 8 of the hook 2. The first latch 6 is biased to close across the access opening 4 by a torsion spring 9 attached to the latch. The end of the latch is shaped to overlap with the nose 10 of the hook member 2 to provide additional support to the latch against unintentional opening when the latch is in the closed position.

A second gate means or latch 11 is provided across the access opening 4 and comprises spring steel wire formed into a substantially elongated loop shape and connected at points 12, 13 to nose 10 of the hook member 2. The connection points for the latch are aligned such that the latch 11 is biased to close across the opening.

In other words the latch 11 normally assumes a position in a plane through the connection points 12, 13 and is therefore biased to this position.

The base of the first latch 6 is provided with an abutment 14 which co-operates with the second latch 11 ps28/6667.spo 1992 10 6 when the second latch 11 is in the normal or closed position. When the second latch 11 is in the closed position, the abutment on the first latch contacts the second latch and prevents further rotation of the first latch about pin 7.

To operate the snap hook in accordance with the invention the second latch 11 is first rotated in the direction of arrow 15 (shown in Figure 2) to allow first latch 6 to be able to pivot about pin 7 against the action of spring 9. The load support member or connection ring 5 is passed under open second latch 11 and pressed against first latch 6. As second latch 11 is in the open position, first latch rotates in the direction of arrow 17 and opens allowing the load support member or connection ring 5 to pass through the access opening 4 and engage within the hook member 2.

Once the ring 5 is fully engaged within the hook member 2 the first and second latches revert back to the position shown in Figure 2 (due to spring bias) wherein the second latch 11 prevents opening of the first latch 6 and accidental disengagement of the ring is prevented.

To disengage the load support member or connection a ring 5, it is first necessary to open the second latch 11 to prevent its interference with the abutment 14 at the base of the first latch 6. The first latch 6 is then able to pivot inwardly of the hook about pin 7 to clear the access opening 4 to thus allow the support member or connection ring 5 to disengage the hook member. The disengaging action can be performed by the ps20/0667. spe 1992 10 IL. ~L c L 7 user by working the thumb under the second latch and sliding the thumb onto the first latch to press the first latch open. This procedure is almost as simple as opening a single latch snap hook but the provision of the second latch 11 greatly reduces the possibility of a load support member or connection ring unintentionally disengaging itself from the hook member.

The nose portion 10 of hook 2 has a guide surface 19 inclined in a direction towards the intrados 18 of the hook 2. The surface 19 guides the ring 5 into the intrados and avoids the possibility of the ring catching on the outside of the nose portion between the nose portion and the second latch 11.

The size of a conventional single acting snap hook is dependent upon the size of the co-operating connection ring. The size of the single acting snap hook relative to the connection ring should be such that if one part of the ring is placed in the intrados of the hook and the ring rotated, the opposite part of the ring will only contact the latch or hook body on the outside of the pin which acts as a pivot for the latch. That part of the latch which bridges the opening of the hook is considered to be inside the pin.

In the case of a single acting snap hook, if the relative sizes of the hook and connection ring are such that when rotated, the connection ring will contact the latch on the inside of the pin towards the top of the hook, the ring can cause the latch to open.

Consequently, the ring can be unintentionally ps2B/8667. spe 192 10 c 8 disengaged.

In accordance with the present invention, if the connection ring is of a relative size such that when placed in the intrados of the hook and rotated, it is capable of contacting the first latch inside the pin, the provision of the second latch prevents the ring from contacting the first latch inside the pin thereby preventing accidental opening of the first latch.

The snap hook of the present invention can also be produced at approximately the same size as a conventional single acting snap hook and made compatible with any size ring.

It should be evident from the description hereinabove that the snap hook of the present invention provides an improved snap hook which has additional safety features when compared with a conventional snap hook and prevents the unintentional disengagement of a connection ring.

ps28/8667. spe 1992 10

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Claims

1. A snap hook comprising a hook member having an opening through which a load support member passes for engagement and disengagement, a first gate means extending substantially across the opening and capable of opening inwardly against first biasing means, and a second gate means extending across the opening and capable of opening outwardly against a second biasing means, said first gate means having an abutment which co-operates with said second gate means when both gate means are in a closed position to prevent said first gate means being opened sufficiently to allow disengagement of said load support member.

2. A snap hook as defined in claim 1 wherein said first gate means and said second (ate means are pivotably connected to said hook member on opposite sides of said opening respectively.

3. A snap hook as defined in claim 1 or 2 wherein said abutment is caused to contact said second gate means in a manner preventing said first gate means being opened when both said gate means are in said closed position and an attempt is made to open said first gate means.

4. A snap hook as defined in claim 3 wherein said hook member comprises a base portion and a body portion extending from the base portion and defining an intrados, said body portion having a nose at a free end thereof, and said orening being a space between said nose and said base portion, said first gate means being ps28/8667.spe 1992 10 10 10 connected to said base portion and sai second gate means being connected to said nose.

A snap hook as defined in claim 4 wherein said nose has a guide surface facing towards said intrados for guiding said load support member in a direction towards said intrados.

6. A snap hook as defined in claim 4 or 5 wherein said first gate means is a spring biased latch extending across said opening, the free end of the latch bearing on an inside surface of said hook member adjacent said nose when said first gate means is closed.

7. A snap hook as defined in any one of the preceding claims wherein said second gate means is a torsion clip substantially in the form of an elongate wire loop having spaced longitudinal sides for spanning the hook member and a gap in the loop at one end thereof, the free ends of said loop at said gap being turned inwardly at right angles to the longitudinal direction of the loop and being parallel to each other, one said free end being located in a hole in one side face of the hook member and the other free end being located in a hole in the opposite side face of the hook member, said holes being offset whereby said clip is biased to a normal position wherein the plane of the loop extends through both said holes, said normal position being said closed position of said second gate means.

8. A snap hook as defined in any one of the preceding claims wherein said hook member is formed from ps28/8667.spe 1992 10 L 11 flat steel plate by a stamp forming operation or other suitable steel forming operation or a forging operation.

9. A snap hook substantially as hereinbefore described with reference to the accompanying drawings. in Th -sjep- in the accompanying -pecificctiou or drawings, DATED this 16 October 1992 CARTER SMITH BEADLE Fellows Institute of Patent Attorneys of Australia Patent Attorneys for the Applicant: MOXHAM INDUSTRIAL PTY. LTD. CA, ps28/8667.spe 1992 10 r, n ~e .L C 12 ABSTRACT A safety hook in the form of a snap hook has dual latches (11) which provide additional safety against unintentional disengagement of the hook from a load support member such as D-ring A first pivotal gate or latch extends across the opening of the hook member and is biased by torsion spring into a closed position (Figure A second gate or latch (11) extends across the opening from the opposite side and is biased to a normal or closed position wherein it bears on the first gate. The first gate has an abutment (14) which bears on the second gate to prevent opening of the first gate unless the second gate is pivoted away from the first. Thus accidental opening of the first gate is virtually impossible as two distinct gate opening operations are required in order to clear the opening and facilitate disengagement of the hook. ps28/8667.spe 1992 10