IE43140B1 - Latch assemblies - Google Patents

Abstract

1511738 Panic bolts NEWMAN-TONKS Ltd 24 June 1976 [22 July 1975] 30572/75 Heading E2A In a panic bolt, operation of handle 17 lifts lower bolt 12 and plate 22 together, the top of this plate rotating lever 27 to pull down top bolt 13. If lower bolt is raised independently (to pick the fastening), a wedging surface 37 on the top of the bolt jams the end of lever 27 to lock both bolts, the plate 22 dropping down by lost motion 15, 24.

Description

This invention relates to door latch assemblies of the kind comprising a body securable to one side of a door, a manually operable member pivotally mounted on the body, said manually operable member, for example, being connected in use to a bar extending horizontally across the door, and , the body housing a mechanism connected to two latch bolts extending in opposite directions normally upwardly and downwardly out of tho body and being simultaneously retracted or extended with respect to the body by manipulation of the ' I manually operable member, said latch bolts being arranged, ; in use, to engage with respective keepers at the opposite ; edges of the door frame respectively, and the latch bolts being spring loaded towards their extended latching positions respectively. Such an assembly is usually referred to a ί panic bolt assembly and will hereinafter be referred to as being of the kind specified, .

The object of tho present invention is to provide a ’ door latch assembly of the kind specified which prevents unauthorised entry, through the door from the opposite side thereof to that at which the latch assembly is secured, by the lifting of the lower of the two latch bolts out of its keeper.

According to the present invention a door latch assembly of the kind specified is characterised by an element attached to one of said bolts through connecting means permitting a predetermined amount of relative sliding motion between -243140 tho olomont and tho said one of tho bolts, a rotatable member pivotally mounted in the body and engaging the two bolts, said member being contacted by a portion of said element when said manually operable member is operated to retract the bolts from their fully extended positions respectively so as to cause rotation of said rotatable member, and said one of the bolts having a formation which during retraction of the bolts by the manually operable member, is out of contact with said rotatable member, the arrangement being such that during retraction of the bolts by tho manually operable member the element and the said bolt move together, whereas movement of the said bolt independently of the manually operable member causes relative movement between the element and the said bolt with the result that said formation contacts said rotatable member and prevents rotation thereof and hence retraction of the bolts.

The invention will now be described by way of example with reference to the accompanying drawings in which, Figure 1 is a cross-sectional side elevation view of a door latch assembly constructed in accordance with the present invention, and Figure 2 is a plan view thereof with the cover removed.

With reference to Figures 1 and 2, there is shown a door latch assembly comprising a hollow generally rectangular body 10 which is adapted to be secured to one side of a door -343140 and which is also provided with an underneath flat cover plate 11. Slidably mounted within the body 10 are two bolts 12, 13 extending in opposite directions respectively out of the body. In use, connected to these bolts 12 and 13 are respective extension tubes engageable in respective keepers in the door frame at the top and bottom thereof respectively» In the body 10, the bolt 12 has an integral extension 12a which at its extremity is slotted at 14. Intermediate its ends, the bolt 12 has a lateral parallel sided slot 15 with a widened entry 16 to receive one arm of a bell ci’aiik lever 17» The boll crank lever is pivotally mounted at 18 upon a lug formed integrally on the body 10.

The other arm of the bell crank lever 17 is outside the body 10 and has a generally circular hole 19 to accept a bar, (not shown). When the assembly is fitted to a door, this bar extends horizontally across the door, being pivoted at its opposite end on the door. The arrangement is such that the lever 17 can be pivoted between the position shown in the drawings and a further, position for the purpose of opening the door as will be described. Such a mechanism is usually described as a panic bolt assembly» The end of the arm of the bell crank lever 17, received in the slot 15, Is of generally cylindrical form as indicated at 20, and is hold in a socket formed by a pair _ 2, „ of parallel ears 21 turned down from a metal plate 22, this socket being received into the parallel sided portion of the slot 15· 'fhe plate 22 is attached in a slidable manner to the bolt 12 by means of a number of pin like ' projections 23, formed integrally on the bolt 12, which pass through respective elongate slots 24 in tho plate 22, with respective spring fix washers 25 being fitted on the projections to hold the plate on the bolt 12. Each projection 23 is, in tho lengthwise direction of the slot, substantially smaller than the length of the slot, so that relative sliding movement between the plate 22 and the bolt 12 is possible.

Tho distance between the external surfaces of the two ears 21 respectively which form the socket in the plate 22, is less than the width of the portion of the slot 15 in which said socket is received by approximately 0.10 inches, in order to allow the sliding movement referred to above to take place. Accordingly the limit of said movement is thus 0.10 inches.

Connecting the extension 12a of the bolt 12 with a similar but shorter extension 13a of the bolt 13 in which is formed a slot 26 is a member 27 pivotally mounted in the body 10. The member has a pair of generally diametrically opposed arms 28, 23 respectively having respective portions -5 turned down from their extremities to form respective ears , 31, which extend into the slots 14 and 26 respectively in the bolts 12 and 13« -53140 The member 27 is provided with a central non-circular shaped hole 32 for insertion of a tool whereby this member 27 may be rotated. Where provision is made at the side of the door opposite to that at which the assembly is fixed, such door will be provided with a hole aligned with the hole 32 so that a tool can be inserted therein for rotation of the member and thus operation of the latch, assembly.

The extension 13a of the bolt 13 carries a rod 33 surrounded by a compression spring jb. One end of the spring 3^ bears against the end of the extension 13^ and the other end bears upon an abutment 35 formed integrally tilth the bolt 12 and through which the rod 33 can. slide.

The slot 14 comprises an upper surface 36 disposed perpendicularly to the length of the bolt 12, against which surface an upper surface of -the ear 3θ normally bears. The lower portion of the slot, opposite to the surface 36, comprises a generally wedge-shaped abutment 37» Between this abutment and a vertical surface 38 of the slot 14 is defined a recess 39 of a shape substantially to match a lower portion of the ear 3θ· At the extremity of the plate 22 is an integral upturned lug 40. The bottom of the recess 39 lies below the extremity of the lug 40 by a distance slightly more than 0.10 inches, which is the amount of relative sliding movement allowed between the plate 22 and bolt 12. In the normal position of the assembly with the bolts extended, the extension 13a is forced by the spring 3^ to a position in -643140 which the member 27 is rotated so that the lower surface of the ear 30 contacts the lug 40 and in this position the recess 39 in the slot 1k in the extension 12a extends below the lug kO. In such a position, furtliei'more, there is a clearance of 0.10 inches between the external surface of the lower of the two ears 21 and the horizontal surface of the slot 15, us shown best in Figure 1.

In normal operation of the assembly, depression of the cross bar, held in the hole 19, causes the bell crank lover 17 to pivot about the point 18, The cylindrical end of the lever is thereby forced against the interior surface of the upper oar 21 of the plato 22 which in turn forces the bolt 12 artd its extension 12a, and tho plate 22 upwardly. Since in this case tho bolt 12 and plate 22 move together, and Since the lug kO is disposed ahead of the recess 39, the lug kO of the plate contacting the lower surface of the ear 30 causes the member 27 to rotate in an anti-clockwise direction (as viewed in Figure 2) about its pivot. The locus of the ear 3θ is an arc which just clears the adjacent side wall of the body 10. To . this end the outer surface of each ear JO, 31 is of slightly convex form.

As the member 27 rotates, the bolts 12 and 13 are retracted into the body 10, the rod 33 passing through the abutment 35 as tho spring J8 is compressed. Although not shown, means are usually provided fox’ holding the bolts in their retracted positions to stop the lower bolt dragging on -7. the ground when the door is opened. Otherwise the bolts automatically extend once the lever 17 is released.

If, however, the bolts are in their extended positions and an attempt is made to lift the lower extension tube out of its keeper independently of the lever 17, for example for the purpose of obtaining unauthorised entry, the following occurs.

Firstly the lower bolt 12 can be moved relative to the plate 22 by the allowed 0.10 inches of clearance provided between the socket of the plate 22 and the slot of the bolt 12. This causes part of the recess 39 and the abutment 37 of the extension 12a to be raised ahead of the lug 40 of the plate 22. Thus once the bolt has moved by. this 0.10 inches, further upward pressure to lift the bolt 12 causes the lower surface of the slot 15 to bear against the lower of the ears 21 thereby causing the lever 17 to pivot and the bolt 12 and plate 22 to be raised together. However because the 0.10 inch clearance has been taken up by the original movement of the bolt 12, the ear 3θ, which is disposed at an acute angle to the length of the body 10, is thus received into the recess 39 as the bolt 12 is lifted, and before rotation of the member 27 can occur, the abutment 37 wedges between the outer surface of the ear 30 and the side wall of the body 10. Further lifting of the bolt is thus prevented by this wedging action and since the bolts cannot thus be retracted, entry cannot be gained. -8.

To re-set the assembly for normal operation the extension tube of the bolt 12 is fully replaced in its keeper, thereby restoring the 0.10 inch cleai’ance, so that upon subsequent depression of the lever 17, the lug kO in contact with the ear 30 causes rotation of the member 27 as the bolt 12 and plate 22 are raised.

Claims (6)

1. lo A door latch assembly of the kind specified characterised by an element attached to one of said holts through connecting means permitting a predetermined amount of relative sliding motion between the element and the said one of the bolts, a rotatable member pivotally mounted in tho body and engaging the tiro bolts, said member being contacted hy a portion of said element when said manually operable member is operated to retract the bolts from their fully extended positions respectively so as to cause rdtation of Said rotatable member, and said one of the bolts having a formation which during retraction of the bolts by the manually operable member, is out of contact with said rotatable member, the arrangement being such that during retraction of tho bolts by tho manually oporable member the clement and tho said bolt move togethor, whereas movomont of the said bolt independently of tho manually operable member' causes relative movement between the element and the said bolt with the result that said formation contacts said rotatable member and prevents rotation thereof and hence retraction of the bolts,

2. A door latch assembly as claimed in claim 1 in which said element is a plate and tho portion thereof which contacts said rotatable member is a lug disposed at one end of said plate,, -1043140

3. Λ door latch assembly as claimed in claim 2 in which a portion of said manually operable member is held in a socket provided by said plate, the socket being received in a slot in said one of said bolts which is 5 larger than said socket and theroby allows said predetermined amount of relative sliding motion between said plate and said one of the bolts.

4. A door latch assembly as claimed in claim 3 in which said rotatable member has a pair of oppositely directed 10 arms extending therefrom, each arm having an ear at its free end, said ears engaging in respective slots at the ends of tho bolts. -114 31 40

5. » A door latch assembly as claimed in claim 4 in which . the slot at the end of said one of the bolts in which said ear of the rotatable member engages is provided with said formation in the form of a wedge shaped abutment, which abutment defines a recess between it and a surface of said slot, the recess being disposed behind said lug of the plate by an amount substantially equal to the predetermined amount of relative sliding motion permitted between said plate and said one of the bolts during retraction of the 0 bolts by the manually operable member, whereas movement of said one of the bolts independently of the manually operable member causes said bolt to move relatively to said plate so that said abutment is moved ahead of said lug and contacts a surface of the ear of tho rotatable 5 member in said slot at the end of said one bolt, said abutment thereby wedging between said surface of the ear and a portion of the body of tho latch assembly to prevent rotation of the rotatable member and hence retraction of the bolts.

6. A door latch assembly substantially as hereinbefore described with reference to and as shown in the accompanying drawings.