GB2132678A - Spring catch - Google Patents

Abstract

A spring catch, with a safety device which prevents it from opening accidentally in use, comprises a first catch element 1 in the shape of a hook, or ring and a second closing catch element 2 pivoted to the first; one of the catch elements is provided with a manually operable locking device 5a acting to allow and prevent one of the elements of the spring catch from moving with respect to the other. A spring 4 or similar resilient component acts either on the spring catch in order to return the elements thereof to the closed position, or on the locking element. A particular fork-shaped configuration of one of the spring catch elements allows rapid unfastening. <IMAGE>

Description

SPECIFICATION Spring catch with safety device The present invention relates to a spring catch orthe like equipped with a safety device which can be operated manually to lock orto allow the spring catch to open.

There are known spring catches of the type having an element in the shape of a hook, ring orthe like, and a second closing element pivoted to the former and subjected to the action of a resilient return component which tends to maintain the elements ofthe spring catch in the closed position.

The elements ofthe spring catch can assume various shapes and dimensions according to the specific use for which the spring catch is intended. For certain applications or in certain conditions of use of the spring catch, safety devices which prevent it from opening accidentally and which are highly reliable under all conditions of use, have to be employed. At presentthere are some known safety systems applied to spring catches of a particular shape and for particular purposes, which are difficult to adapt to other types of spring catches.Moreover, these devices sometimes require the use of both hands to operate them, which is a further limitation on the use of the safety device, in particular when the spring catch needsto be opened quickly or using only one hand, and moreover they do not allowthe safety device to be applied to spring catches of other types.

Consequently, one object of the present invention is to provide a spring catch ofthetype mentioned that is equipped with a safety device, that is quickly operated, that can be operated with one hand, and that is highly reliable in use.

Afurther object is to provide a spring catch equipped with a universal safety device, or such as can be adapted easily to different types of spring catches.

Yet another object ofthe present invention isto provide a safety spring catch shaped in such a way that it allows rapid unfastening under emergency or special conditions, thus avoiding the possibility of the snap catch accidentally remaining fastened when it has been opened.

According to the invention, a spring catch is provided comprising a first catch element in the shape of a hook, ring orthe like and a second closing catch element pivoted to the first catch element, said catch elements being resiliently urged to close one against the other, and characterised in that it comprises a safety device which can be engaged and disengaged manually, said safety device including a locking member with a cam element pivoted to one ofthe catch elements, said cam element being movable between a first unlocking angular position in which it allows the catch to open and a second locking angular position in which it abuts a contact surface of the other catch elementto prevent the spring catch from opening, and a resilient return component acting either on the elements ofthe spring catch to close them or on the locking member in both its aforementioned angular positions.

These and other characteristics and objects of the spring catch according to the invention will be apparentfrom the following description given with reference to the example of construction shown in the accompanying drawings, wherein: Fig. lisa plan view, from above, of an embodiment of spring catch; Fig. 2 is a longitudinal section along line 2:2 in Fig. 1, with the spring catch closed and with the safety device in the locked state; Fig. 3 is a view similarto that of Fig. 2, but with the safety device in the unlocked state; Fig. 4 is a longitudinal section similar to that of figs. 2 and 3, with the spring catch open.

As shown in the figures, the spring catch generally comprises a first catch element 1 and a second catch element 2 which cooperate with each other, in the closed state, to couple with or hold a link 3' of a chain or collar or part of any other device to which the spring catch is to be fastened. The catch elements 1 and 2, independently of their shape as shown, are pivoted together by a transverse pin 3 and are subjected to the action of a torsion spring 4 or other equivalent resilient component suitable to return and maintain the catch elements 1 and 2 close to each other, in the closed state shown in Figures 2 and 3.

One ofthe catch elements, e.g. the catch element bearing the reference numeral 2, has a safety device comprising a locking cam element 5 pivoting at 6 on the element itself and having an axis of rotation parallel to that of the elements 1 and 2, the cam element 5 being designed to be interposed orto come into contact with a contactsurface7 of the other element 1, as shown in Fig. 2, to prevent relative rotation.

The cam element5 has a knurled top Sawhich partly protrudes from a longitudinal aperture 8 in the element 2, and on the opposite side has a rounded cam tip 5b positioned to come into contact with the inside contactsurface7 ofthe other catch element 1 in orderto prevent rotation andthusopening of the spring catch itself.

The same spring 4 which returns the two catch elements 1 and 2 against each other also maintains the cam element 5 in both its unlocking (Fig. 3) and locking (Fig. 2) operative positions, in the first case preventing unwanted locking of the spring catch and in the second case preventing the spring catch from unlocking accidentally, with serious and uncontrollable consequencies. The fact that the cam element 5 has to be made to rotate forwards, i.e. in the opposite direction to the longitudinal traction which is normally exerted on the spring catch, is in itself a further safety feature inasmuch as the spring catch would tend automatically to put itself in the safety state rather than open itself.

Spring 4 of the spring catch also acts on cam elementS; for this purpose cam element 5 has on one of its sides two contact surfaces arranged at an angle and consisting for example ofthe contiguous side surfaces of a square pin 9, coaxial with the pivot pin of cam element 5, againstwhich bears one of the arms of traction sring 4, while the other arm bears on the other element ofthe spring catch. These side contact surfaces of pin 9 areatan angle of 90" to each other and in general have to form substantially the same angle as there is between the two angular operative positions of cam element 5, so that the arm of spring 4 bears from time to time against one or the other ofthe side surfaces ofthe aforementioned pin.

The construction shown, which makes use of a locking member with a cam and of a single resilient componentforthespring catch and forits safety device is extremely advantageous inasmuch as it simplifies construction and makes the locking device applicable to a large number oftypes of different spring catches. Nevertheless, it is also possible for the locking memberto have its own resilient component serving a similar purpose to the one illustrated. The construction illustrated is extremely reliable, inasmuch as it ensures that the locking cam 5 is stably maintained in both of its operative positions.

The drawings show a type of spring catch whose elements 1 and 2 are shaped in such away as to allow the opening ofthe catch and the unfastening ofthe link 3 even in difficult or emergency conditions, and thus preventing the catch from accidentally remaining fastened.

For this purpose, catch element 1 has a channeled shape with a U-shaped cross-section, i.e. a bottom with contact surface 7 and two side walls 10, each of which has a longitudinal recess 11 opening towards the end ofthe catch to allow the insertion and removal ofthe link 3' or other equivalent elementto which the catch is to be fastened. These recesses 11 have a width which is greater than the thickness of link3' and in any case the width of recess 11 must be such thatthe hook-shaped end 2a of the other catch element 2, in the open state shown in Fig. 4, is substantially on a level with or slightly behind the longitudinal edge of the aforesaid recess 11. This ensures that link 3 comes outofthe catch without being caught or held by the hooked end 2a of element 2.

The operation of the spring catch is briefly as follows: the closed catch with the locking cam 5 in the unlocked position is as shown in Fig. 3; in this state, taking the catch between finger and thumb, it can be opened and closed merely by pressing on it, to insert or remove link3'. Usingthethumbofthesamehand, cam element 5 can be made to rotate backwards, taking it into the locking position shown in Fig. 2. As this is done, spring 4which previously had one arm resting on one ofthe contact surfaces of square pin 9, maintaining the element firmly in the unlocked state, now comes to bear against the other surface of the aforementioned square pin, maintaining element 5 in the locked state. Unlocking can be achieved simply by rotating element Sforwards with the thumb alone, overcoming the reaction of spring 4.

Finally, the drawings show a furtherfeature ofthe catch. The plan view in Fig. 1, in particular, shows the use of a double joint articulated along two axes at right angles to each other, to prevent any possible transmission oftorsion form the catch to the rope, slipknot, or anything else to which the spring catch is attached. Ajoining element 12 is therefore provided in the shape of a fork, which is articulated on the two sides of catch element 1, corresponding to the articulation 3 between catch elements 1 and 2. The fork element 12 of the joint has a rear pin 13 terminating in a head 14 which defines an axis ata right angle to the previously mentioned articulation, on which a ring 15 rotates.

It is therefore evident that the invention provides a spring catch ofnewand original construction equipped with a safety device which prevents it from unfastening accidentally and which is constructed in such a way as to ensure a high degree of reliability during use; the use ofthe said locking device can moreover be extended to othertypesofspring catch, without thereby departing from the present invention as defined in the appended claims.

Claims (10)

1. Aspring catch comprising a first catch element in the shape of a hook, ring orthe like and a second closing catch element pivoted to the first catch element, said catch elements being resiliently urged to close one against the other, characterised in that it comprises a safety device which can be engaged and disengaged manually, said safety device including a locking memberwith a cam element pivoted to one of the catch elements, said cam element being movable between a first unlocking angular position in which it allows the catch to open and a second locking angular position in which it abuts a contact surface ofthe other catch elementto prevent the spring catch from opening, and a resilient return component acting either on the elements ofthe spring catch to close them or on the locking member in both of its aforementioned angular positions.

2. A spring catch, according to claim 1,wherein said locking member is pivoted on one ofthe catch elements about an axis of articulation ofthe catch elements.

3. A spring catch, according to eitherofthe preceding claims, wherein said locking member has portions which contact the resilient return component and which form an angle corresponding to that formed between the angular positions which can be adopted by the locking member.

4. A spring catch, according to claim 3, wherein said portions are defined by side surfaces of a square pin.

5. A spring catch, according to any one of the preceding claims, wherein said resilient component is a torsion spring one ofwhose arms bears against a contactsurface of one ofthe catch elements and whose other arm bears against side surfaces, positioned at an angle of90", of a pin fixed to the locking cam and pivoted on the other catch element.

6. Aspring catch, according to claim 5, wherein said pin is positioned on one side of the locking member, coaxiallywith the pivoting axis ofthe locking member.

7. A spring catch characterised in that it comprises a first catch element shaped as a channel and a second catch element pivoted internally on the first catch elementand urged byatorsion return spring against said first catch element, said first catch element having side walls with a longitudinal recess opening at the end of the spring catch, said second catch element terminating at one of its ends in the shape of a hook which is positioned on a level with or slightly behind one longitudinal edge ofthe recess in the other element, when the aforesaid catch elements are in the open state.

8. A spring catch, according to claim 7, wherein there is provided a safety device comprising a manually operable locking member pivoted to the hook-shaped catch element, said locking member partly protruding from a longitudinal recess in the same hook-shaped catch element and having a pin with flat side contact surfaces abutted by said return spring.

9. Aspring catch, according to claim 7, wherein a double connecting joint is provided and comprises a firstforked element pivoted to the spring catch and a second element, with a ring pivoted to the forked element along an axis at right angles to the axis of articulation oftheforked element to the spring catch.

10. A spring catch substantially as described herein with reference to the accompanying drawings.