Latch operating mechanism

A latch operating mechanism comprises a body part (10) for mounting on the frame of an openable glazed panel, a rotary handle (13) mounted on the body part by a spindle (28) a rack member (33) slidably mounted with respect to the body part and driven by a gear (30) within the housing which gear operably is connected to said handle. The rack member has a part (34) projecting from said body part for insertion through a slot in the frame and adapted to engage a part of an espanulette. The body part includes primary attachment locations (11) by which it is adapted to be secured to said frame, in which at least one primary attachment location is provided adjacent each end of the path of movement of the rack member.

This invention relates to latch operating mechanisms suitable for use on 
openable glazed panels, e.g hinged windows. 
Window frames are known which have, within the thickness of one side of the 
frame, a longitudinally movable slide bar or espanulette having at, or 
adjacent, each end thereof latching projections. The latching projections 
extend through slots in the wall of the frame to engage cooperating 
abutments on the fixed window surround, in the latched condition, to hold 
the window closed. Movement of the espanulette from the latched condition 
disengages the latching projections from the fixed abutments allowing the 
window to be opened. A conventional latch operating mechanism comprises a 
body part for securing to the window frame, a slidable member mounted on 
the body part and projecting through a slot in the frame to engage a part 
of the espanulette to control the movement of the espanulette, and a 
handle on the body part for operating the aforesaid slidable member. In 
such mechanism the handle has a spindle extending into the body part on 
which a spur gear is mounted. The aforesaid slidable member is provided 
with rack teeth engaged with the spur gear such that rotation of the 
handle and therefore of the spur gear causes sliding movement of the 
aforesaid slidable member and, in turn, longitudinal movement of the 
espanulette between its latched and unlatched position. 
However, in prior constructions the relative positioning of the slidable 
member and the fixing locations by which the body part is secured to the 
window frame is such that conventional latch operating mechanisms are 
unsuitable for use on narrow window frames, particularly those made of 
plastic material, since they are too broad. 
The invention is concerned with providing a latch operating mechanism 
suitable for use on relatively narrow framed windows for the type having 
internal slide bars with latching projections (espanulettes). 
According to the present invention there is provided a latch operating 
mechanism comprising a body part for mounting on the frame of an openable 
glazed panel, a rotary handle mounted on the body part of a spindle, a 
rack member slidably mounted with respect to the body part and means 
driven by a gear within the housing which gear is operably connected to 
said handle, the rack member having a part projecting from said body part 
for insertion through an opening in the aforesaid frame and adapted to 
engage a part of an espanulette mounted therein, the body part having 
primary attachment locations by which it is adapted to be secured to said 
frame, said rack member being mounted for movement in a slot provided in 
said body part characterized in that at least one primary attachment 
location is provided adjacent each end of said slot in that said gear is 
contained within a central portion of the body which projects outwardly 
beyond one side of a part of the body which includes said slot and in that 
a notational plane passing through said primary attachment locations is 
spaced from a substantially parallel notational plane containing the axis 
of said spindle. 
Another aspect of the invention provides an assembly of a latch operating 
mechanism as defined in the immediately preceding paragraph and a frame 
set comprising a fixed frame and a glazed frame which is openable with 
respect to the fixed frame, said central portion of said latch operating 
mechanism being raised and said mechanism being secured to a side face of 
the glazed frame such that said raised central portion of the body part 
extends beyond said side face in a direction which is remote from an 
adjacent part of the fixed frame when the glazed frame is in its closed 
position. 
A mechanism in accordance with either aspect of the invention enables the 
width of the body part to be reduced in relation to the aforesaid 
conventional mechanisms while enabling a sufficient travel of the rack 
member to be achieved for each rotational operation of the handle.

Referring to the drawings, a latch operating mechanism for an openable 
window having a relatively narrow plastics or aluminium frame comprises a 
body part or housing 10 (FIGS. 1 to 3 and 12) having countersunk holes 11 
therethrough for receiving screws for securing the housing of the window 
frame. The housing 10 has a raised central portion 12 on which a handle 13 
(FIGS. 4, 4a, 4b) is rotatably mounted. Side areas 14 of the raised 
central portion 12 are notched out to leave abutments 15 and 16 for 
engagement by a lug 17 on the handle 13 to define the extreme rotational 
positions thereof. 
The housing is formed with a cavity 18 in its lower surface the cavity 
having a wall defined by a circle. A bore 19 extends through the raised 
portion 12 of the housing into the cavity 18 and is coaxial with the 
circle defining the cavity. A shallow blind bore 20 is formed centrally in 
the base of the cavity, for a purpose described below. 
The base of the housing, which has a depending peripheral wall 21, is also 
formed with a longitudinal slot 22 which intersects the cavity 18 along 
one side thereof. The slot 22 is generally L-shaped in cross-section 
having a deep portion 23 adjacent the peripheral wall 21 of the housing 
and a shallow portion 24 extending from the deep portion 23 a short way 
towards the opposite longitudinal edge of the housing. 
The housing 10 is further formed in its bottom surface with a pair of 
threaded bores 25 for receiving fixing screws 26 for securing a bottom 
plate 27 (FIG. 5) to the bottom of the housing. 
The handle 13 has an integral spindle 28 which is rotatably received in the 
bore 19 to mount the handle on the raised central portion 12 of the 
housing. The spindle 28 has a square-sectioned end portion 29 which 
projects into the cavity 18 and on which a spur gear 30, having a 
square-sectioned central aperture is fixedly mounted. The spur-gear 30 is 
formed with five teeth 31 spaced about only a part of its periphery. The 
spur-gear 30 is secured to the spindle 28 by means of an Allen screw 32 
(or other suitable fixing) whose head is received in the blind bore 20. 
Thus the gear is accommodated within the central portion of the housing 
which projects outwardly beyond one side of the part of the body which 
includes the slot 22. 
FIGS. 6 and 7 show a fork plate 33 having a main clevis portion 34 for 
projecting from the housing into a slot in the window frame to which it is 
affixed, to engage and cooperate with a part of a slide bar mounted within 
the frame. The fork plate 33 has an integral mounting rack portion 35, 
which, as seen in FIG. 7 is generally L-shaped in cross-section to conform 
with the L-shaped slot 22 in the housing The transverse part 36 of the 
rack portion 35 engages in the shallow portion 24 of the housing slot 22 
and the flange portion 37 thereof engages in the deep portion 23 of the 
housing slot. The flange portion 37 is formed with a series of racked 
teeth 38 which mesh with the spur gear 30 (as illustrated in FIG. 12) to 
be driven thereby. The mounting rack portion 35 is therefore slidably 
mounted in the L-shaped slot 22 in the housing for movement therealong 
when driven by the spur gear 30. The rack portion is retained in the slot 
22 by the bottom plate 27 (FIG. 5) which is received within the depending 
peripheral wall 21 at the bottom of the housing and secured thereto by 
screws 26. The clevis portion 34 of the fork plate projects from the 
bottom of the housing through a slot 39 defined by the bottom plate 27 and 
an adjacent part of the housing. 
Thus, it will be seen that the countersunk holes 11 to receive fixing 
screws of the mechanism are located adjacent the ends of the housing slot 
22. Indeed, the fixing holes 11 are positioned such that the planes 
containing the clevis portion 34 of the fork plate 33 substantially passes 
through the fixing holes. 
The first embodiment of the invention (FIG. 12) the bottom plate 27 is 
provided with a pair of flanges 27a, 27b, respectively, at its opposite 
ends each of which project outwardly at 90.degree. to the plane of the 
plate. These flanges include apertures a.sup.1, a.sup.2 to receive 
suitable fasteners and provide secondary attachments by which the 
mechanism can be attached to the surface of the window frame which is 
normal to that on which the body part is mounted. This combined attachment 
arrangement provides a more secure mounting of the mechanism on the window 
frame. However, the flanges 27a, 27b may be omitted as in the mechanism of 
the assembly shown in FIG. 11. 
In operation, the handle is rotated from one extreme position to the other, 
defined by the engagement of the lug 17 on the handle with the abutments 
15 and 16 defined on the raised central portion 12 of the housing. This 
causes rotation of the spur gear 30 thereby moving the fork plate 33 along 
the slot 22 in the housing, through the rack teeth 38 meshed with the spur 
gear 30. 
A mechanism in accordance with the invention achieves a reduction in the 
overall width of the housing while providing a sufficient stroke of the 
fork plate. 
Locking means may be provided for locking the handle in one or both of its 
extreme positions of rotational movement. One such means includes a pair 
of dimples or partspherical depressions 40 (FIGS. 1 and 3) formed in the 
raised portion 12 of the housing to receive an end portion of a securing 
screw which can be located in a bore provide through the handle which is 
brought into alignment with each depression 40 when the handle is moved to 
its respective extreme position. Another such means is a key operated 
barrel lock provided in an aperture 41 FIG. 12 in the handle. 
FIG. 10 shows, in cross-section an assembly of a latching mechanism secured 
to an openable window frame and which incorporates the fork plate 33 
illustrated in FIGS. 6 and 7. 
The openable frame 42 of a frame set `S` includes a horizontal section 43 
in which one edge portion of a double glazed panel is accommodated. The 
double glazed panel comprises spaced glass plates 44 and 45 separated by 
an air gap as is well known. Opposite the double glazed panel the 
horizontal section 43 houses an espanulette 46 having an upstanding pin 47 
which is engaged by the clevis portion 34 of the fork plate 33. The 
upstanding pin is connected to a latching projection 48 which engages a 
keeper or striker 49 provided by a fixed frame 50 in order to lock the 
openable frame to the fixed frame. 
The housing 10 is secured to one side wall 51 of the openable frame by 
fixing screws passing through primary attachment locations (the 
countersunk holes 11) such that the raised central portion 12 extends 
beyond the upper surface of the openable frame remote from an adjacent 
part of the fixed frame. This construction permits the housing 10 to be 
secured to the limited space available on side wall 51 and allow the fork 
plate to pass through the openable frame for engagment with the 
espanulette. 
The assembly shown in FIG. 10 is particularly suitable for a plastics frame 
construction. 
FIG. 11 shows an assembly which incorporates aluminium frame component and 
a latching mechanism which is similar to that previously described. Like 
parts are designated like reference numerals with the addition of suffix 
`a` However, in this modified arrangement the clevis portion 34a of the 
fork plate 33a is cranked towards the fixed frame 50a in order to clear 
the lower edge of the double glazed panel. Thus, clevis portion 34a 
includes a cranked portion 34b which is adjacent, but extends away from 
the bottom plate 27a. 
It will be appreciated that in the constructions described, the transverse 
part 36, 36a of the fork plate 33, 33a is slidably supported between the 
bottom plate 27, 27a and shallow portion 24, 24a of the housing slot.