AU681485B2 - A latch assembly - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicants: Actual Inventor: Address for Service: GRAHAM WILLIAM STRONG SHELLEY LORRAINE STRONG GRAHAM WILLIAM STRONG CULLEN CO., Patent Trade Mark Attorneys, 240 Queen Street, Brisbane, Qld. 4000, Australia.

A LATCH ASSEMBLY a Invention Title: Details of Associated Provisional Application: No. PM4220 filed 4 March 1994 The following statement is a full description of this invention, including the best method of performing it known to us: i 2 THIS INVENTION relates to a latch assembly. In particular, the invention is directed to a gate latch suitable for use in rural fencing applications, such as in feedlots, although the invention is not limited to such particular applications.

In feedlots and other livestock enclosures, the cattle or other livestock must be securely fenced as loss of livestock through open gates can result in significant financial losses. In feedlots, fence gates are regularly opened and closed to move cattle between fenced paddocks, or to give them access to feed. It is therefore important that the gates be opened easily, yet still i provide reliable and secure closure when closed.

Conventional barrel-bolt type gate latches are not particularly suitable for rural fencing since, with soil movements and animal contact, the bolt on the gate soon becomes misaligned with the bolt hole on the gate :post. For this reason, chain latches are normally used to lock gates in livestock fencing applications.

20 Such chain latches comprise a length of chain eo~ Shaving one end tied around, or otherwise secured to, the gate post, and a steel latch plate connected to the gate, S" the plate having a vertical slot therein open at its top end. The width of the slot is wide enough to receive a chain link in an upright orientation, but narrow enough to prevent the adjoining (horizontal) links from passing through the slot. By dropping the chain into the slot, the chain is captively held by the plate, and the gate is secured to the gate post in a simple and effective manner. The chain slack provides sufficient tolerance for relative movement between the gate and gate post.

The gate can be unlocked easily, even by a person on horseback or on motorbike without dismounting, simply by lifting the chain out of the slot.

However, the ease with which the gate can be unlocked gives rise to a significant disadvantage of such chain latches. Namely, the gate can be opened by livestock, particularly cattle. It has been observed I c-~ that the cattle lick the end of the chain dangling from the plate and, with an upward licking movement, the cattle are able to lift the chain out of the slot, thereby allowing the gate to open.

Although this problem could be overcome by securing the chain positively to the plate, e.g. with a padlock, the gate would then be difficult to unlock by an operator, particularly a person on horseback or on motorbike. Since the gates are being continually opened and closed, any gate locking arrangement which is not able to be opened quickly would result in annoying delays and would not find consumer acceptance.

i ~It is an object of this invention to provide a latch assembly, particularly suitable for rural fence gates, which overcomes or ameliorates the abovedescribed problems, or which at least provides the consumer with a useful choice.

:In one broad form, the present invention provides a latch assembly comprising a base member having a slot therein, the slot having an open end adapted to receive a securing line, a latch arm pivotally connected to the base S" member, the latch arm being pivotable between an open position, and a closed position in which it prevents removal of the securing line through the open end of the slot; a locking member connected to the latch arm and engageable with the base member to lock the latch arm in its closed position, and a latch handle connected to the locking member, the latch handle permitting quick release of the locking member from its engagement with the base ~mber to thereby enable the latch arm to be opened.

The base member is typically a steel plate of the type commonly used in conventional chain latches.

This plate is fixed to the gate at a suitable location, e.g. by welding.

The securing line is typically a chain, or a cr I ICi~l~~ loop of cable, wire or the like.

The latch arm is typically connected to the latch plate by a pivot pin connection, and the locking member is suitably a lock arm which is connected to the free end of the latch arm using a pivot pin connection.

The pivot pin connection between the lock arm and the latch arm is preferably spring-loadel.

The lock arm is suitably provided with a hooklike formation which engages a latch pin on the latch plate. Preferably, the hook-like formation has an outer cam surface which abuts the latch pin when the latch arm is moved to a closed position. With the gate closed but unlocked, the cam surface of the lock arm rests on the :"pivot pin under gravity. However, by pushing on the 15 latch handle, the lock arm is caused to pivot relative to the latch arm, against the bias of the spring loaded connection, as the cam surface of the lock arm follows oO..

:the latch pin, until the latch pin locates in the hook recess of the lock arm. The latch can therefore be locked with a simple pushing action. The spring loaded connection between the lock arm and the latch arm keeps the lock arm engaged with the pin, thereby preventing S"accidental opening of the latch assembly.

To open a latch assembly, the latch handle is simply pressed down against the bias of the spring-loaded connection, such that the latch pin is released from the lock arm, enabling the latch arm to be opened.

The latch assembly can be opened and closed with one hand in a quick movement, rendering the assembly suitable for use by a person on horseback or on motorbike without dismounting. Yet, when closed, the latch assembly ensures that the chain is not released by the latch plate.

In order that the invention may be more fully understood and put into practice, a preferred embodiment thereof will now be described by way of example, with reference to the accompanying drawing.

The attached drawing is a perspective view of a latch assembly according to one embodiment of the invention.

As shown in the drawing, the latch assembly comprises a base member in the form of a latch plate 11 having an open-ended slot 12 therein. The slot is preferably orientated vertically, but may be inclined or even horizontal. The mouth of the slot 12 may be widened, as shown, to facilitate placing a flexible securing line (not shown) through the slot 12.

The securing line is typically a link chain.

The slot 12 has a width which is larger than the thickness of chain link, but smaller than the width of the chain link. In this manner, the chain link may be dropped into slot 12 under gravity, and captively retained therein as the links on either side will be unable to pass through the slot 12.

The other end of the chain is suitably secured to a gate post (not shown). The chain slack compensates S. for any misalignment between the gate and the gate post, and also allows some play in the gate closure while still S maintaining a secure connection between the latch plate 11 and the gate post. Furthermore, as this chain S"latching arrangement is similar to that already in common use in rural fencing, users will be familiar and comfortable with its operation.

The latch assembly 10 further comprises a double-sided latch arm 13 which is pivotally mounted to the latch plate 11 by a pivot pin 14, as shown in the drawing. A lock arm 15 is pivotally connected to the free end of latch arm 13 by pivot pin 16. Both pivot pins 14, 16 are shown schematically in the drawing.

The pivotal connection between lock arm 15 and latch arm 13 is spring loaded such that lock arm is biased in a clockwise direction about pivot pin 16, when viewed from the right hand side of the drawing. The clockwise travel of lock arm 15 is arrested by transverse pin 17 against which the lock arm 15 abuts. The spring loaded connection can suitably be provided by a coil I g Illllrsql

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spring wound around pivot pin 16 and having its ends abutting the pin 17 and lock arm 15, respectively.

A latch handle 18 is connected to one end of the lock arm 15, and angled obliquely thereto. The latch handle 18 may suitably comprise an extension of the lock arm 15, or may be a separate piece welded or otherwise fastened to the lock arm The lock arm 15 may suitably be formed in bifurcated or double-sided configuration as shown in the drawing, with the two parallel side portions of the arm being located on opposite sides of the latch plate 11.

Each side portion of the lock arm 15 has a i hook-like portion 22 defining a detent or recess 19. The outside of each hook-like portion 22 is provided with a wedge-like or curved cam surface 20 leading to each **recess 19. The purpose of the cam surface will become apparent from the following description.

:A latch pin 21 is provided for each recess 19, on a respective side of the latch plate 11. The latch pin 21 is typically a short rod fitted through an aperture in the latch plate 11 and welded in position.

In use, a chain is placed through the slot 12 "so that it is captively retained laterally therein, and the latch arm 13 is swung over to close the slot. (If the end of lock arm 15 is already resting on latch pin 21, the curved free end of lock arm 15 enables the chain to be pulled thereunder and into slot 12, without having to lift latch arm 13 separately).

Each of the twin end portions 22 of the lock arm 15 rests lightly under gravity on its respective latch pin 21. When latch handle 18 is pushed down however, the downward force will cause a cam follower action between the cam surface 20 and the latch pin 21 such that the latch arm 13 and lock arm 15 splay apart, against the bias of the spring-loaded pivot connection between the two. The moment force on the latch handle 18 also assists in pivoting the lock arm 15 against the spring bias.

With further downward movement of the latch arm 13, the latch pin 21 on either side of the latch plate 11 will locate in its respective recess 19 in the lock arm In this position, the hook-like portion 22 at the end of the lock arm 15 is hooked onto its latch pin 21, and prevents the latch arm 13 from being raised. With the latch arm locked closed, the chain cannot be lifted from the slot. The spring-loaded pivot connection of the lock arm 15 biases the lock arm 15 against the latch pln so that it remains hooked onto the latch pin.

It will be apparent that the latch assembly can be closed by a simple downward movement of the latch i handle 18, e.g. by a short downward punch with a closed or open hand. The latch assembly can be closed quickly S 15 and simply, using one hand, e.g. by a person on horseback or on motorbike without dismounting. Yet, when closed, the latch assembly retains the chain securely therein 99 :against even the most determined efforts of livestock.

For added or longterm security, a padlock may be inserted through lock hole 23 in latch plate 11. The S padlock prevents the opening of lock arm To open the latch assembly, the latch handle 18 is simply depressed to pivot lock arm 15 against the bias of its spring-loaded connection. As lock arm 15 pivots outwardly, it releases latch pin 21, and the latch arm 13 may be raised to open the slot 12. Due to the positioning of the latch handle 18 adjacent the latch arm 13, the latch arm can be grabbed by the same hand which depresses the latch handle 18. Thus, the latch assembly can be opened with one hand. The pivot mounting of the latch arm 13 to the latch plate 11 may optionally be spring-loaded so that the latch arm 13 is biased upwardly. In this manner, the latch arm 13 opens automatically on release of lock arm 15 from pin 21.

The latch assembly is of simple construction, and is easily fabricated. All components of the latch assembly can be made from steel or other suitable material.

I Ir II~ The foregoing describes only one embodiment of the invention, and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention.

For example, the latch pin may be provided on the lock arm to engage with a recess on the latch plate.

The latch pin may also be spring-loaded instead of the lock arm.

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Claims (8)

1. 2. A latch assembly as claimed in claim i, wherein :the locking member comprises a lock arm having a first portion which is adapted to engage with a second portion on the base member. S'3. A latch assembly as claimed in claim 2, wherein the lock arm is pivotally connected to the latch arm and is biased relative thereto.
2. 4. A latch assembly as claimed in claim 3, wherein the first portion is a hook-like formation, and the second portion is a projection. A latch assembly as claimed in claim 4, wherein the hook-like portion of the lock arm has an outer cam surface adapted to abut against the projection on the base member, and further wherein the urging of the lock arm towards the base member causes relative movement between the cam surface and the projection such that the lock arm is moved against the bias of its spring loaded connection to cause the hook-like portion to engage the projection in locking relationship.
3. 6. A latch assembly as claimed in any one of claims 2 to 5, wherein the base member is a planar member, and said lock arm is bifurcated into two portions I-- adapted to engage the planar member on opposite sides thereof.
4. 7. A latch assembly as claimed in any preceding claim, wherein the latch handle is positioned adjacent the latch arm such that the two may be grasped w i- one hand.
5. 8. A gate latch comprising a latch plate having a slot open at an end thereof, a latch arm pivotally mounted to the latch plate and movable to a closed position at which it spans across the open end of the slot, the latch arm having locking means for engaging with the latch plate to lock the latch arm in its closed position, characterised in that the locking means locks the latch arm automatically when the latch arm is pushed against the latch plate.
6. 9. A gate latch as claimed in claim 8, wherein the locking means comprises a lock arm pivotal2y connected to the latch arm, the lock arm having a hook-like portion adapted to engage with a projection on the latch plate when the latch arm is pushed closed. A gate latch as claimed in claim 9, wherein the lock arm is biased relative to the latch arm to retain the hook-like portion in engagement with the projection.
7. 11. A gate latch as claimed in claim 9 or wherein the hook-like projection has an outer cam surface which moves relative to the projection when the latch arm is pushed against the latch plate to thereby guide the hook-like portion into locking engagement with the projection.
8. 12. A gate latch substantially as hereinbefore described with reference to the accompanying drawing. DATED this first day of March 1995 GRAHAM WILLIAM STRONG and SHELLEY LORRAINE STRONG By their Patent Attorneys Cullen Co. ~W ABSTRACT A gate latch (10) comprises a latch plate (11) having an open ended slot (12) for receiving a chain. A latch arm (13) is pivotally mounted to the latch plate (11) and is movable between an open position and a closed position whereat it spans across the open end of the slot A locking arm (15) is connected to the latch arm (13) and engages a locking pin (21) on the latch plate The lock arm (15) can be locked in its closed position by pushing the latch arm (13) towards the latch plate (11). A handle (18) is provided on the locking arm (15) to permit the lock arm (15) to be disengaged from the latch plate thereby enabling the latch arm (13) to be opened.