US3897092A

US3897092A - Lever operated door latch opener

Info

Publication number: US3897092A
Application number: US433355A
Authority: US
Inventors: Norman C Atkins
Original assignee: Citation Companies Inc
Current assignee: Von Duprin LLC
Priority date: 1974-01-14
Filing date: 1974-01-14
Publication date: 1975-07-29
Anticipated expiration: 1992-07-29
Also published as: CA1014190A

Abstract

A lever operated door latch opener adapted for use on a conventional door having a conventional door latch mechanism comprises a cam mechanism that is mounted on the door over the spindle of the door latch mechanism and a hollow casing that fits over the cam mechanism. A lever arm having a cam actuating finger on one end is pivotably mounted in the casing such that the finger engages the cam and rotates the spindle when the arm is pivoted. The arm may be connected to a panic bar handle extending across the door, or it may be used as a lever type of handle. The cam mechanism comprises a cam rotatably mounted in an opening on a flat cam plate, with an axial spindle opening being formed in the cam such that the cam fits non-rotatably over the spindle. The cam is formed with symmetrical upper and lower cam surfaces and may be placed in a number of positions on the door latch spindle, so that the cam mechanism may be used on either side of the door and with either type of handle and with the handle in an upward or downward position.

Description

United States Patent [191 Atkins [451 July 29, 1975 LEVER OPERATED DOOR LATCH OPENER Norman C. Atkins, Franklin Park, 111.

[75] Inventor:

[73] Assignee: The Citation Companies, Inc.,

Grand Rapids, Mich.

[22] Filed: Jan. 14, 1974 [21] Appl. No.: 433,355

[52] U.S. Cl 292/92; 292/3363 [51] Int. Cl. E05c 9/00 [58] Field of Search 292/21, 92, 165, 173, 232,

[57] ABSTRACT A lever operated door latch opener adaptedfor use on a conventional door having a conventional door latch mechanism comprises a cam mechanism that is mounted on the door over the spindle of the door latch mechanism and a hollow casing that fits over the cam mechanism. A lever arm having a cam actuating finger on one end is pivotably mounted in the casing such that the finger engages the cam and rotates the spindle when the arm is pivoted. The arm may be connected to a panic bar handle extending across the door, or it may be used as a lever type of handle. The cam mechanism comprises a cam rotatably mounted in an opening on a flat cam plate, with an axial spindle opening being formed in the cam such that the cam fits non-rotatably over the spindle. The cam is formed with symmetrical upper and lower cam surfaces and may be placed in a number of positions on the door latch spindle, so that the cam mechanism may be used on either side of the door and with either type of handle and with the handle in an upward or downward position.

4 Claims, 10 Drawing Figures Jllllllllllllllllll PATENTEDJULZQIQYS v 3.897. 092

FIG. 6 89 FIG. 5

SHEET PATENTED JUL 2 9 I975 FIG. 8

LEVER OPERATED DOOR LATCH OPENER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to door latch openers and more particularly to a panic bar assembly that fits on an ordinary door latch mechanism without any modification in the door latch mechanism or in the door itself.

2. Description of the Prior Art Panic bar door latch openers are well known and comprise a lever-operated door latch opener that is actuated by depressing a horizontal bar that extends across the width of the door. Such door latch openers are useful in public places wherein it is desirable that in emergency or panic situations the door can be opened easily by pushing the panic bar.

I-Ieretofore, one of the principal deficiencies with such panic bar door latch openers is that each such assembly requires its own special type of door latch. Further, intricate cam and lever mechanisms are required in order to actuate the latch. In some cases, special modifications or mortises must be made in the door itself in order to accommodate the panic door hardware or like lever operated systems.

SUMMARY OF THE INVENTION The present invention provides a simple lever operated door latch opener that may be mounted on a conventional door in a number of positions, without modification of either the door or the conventional door latch mechanism, and that may be used with a number of different types of actuating handles.

In accordance with the present invention, a lever operated door latch opener adapted for use with a conventional door latch mechanism comprises a cam mechanism that fits over the spindle of the door latch mechanism and a hollow casing that fits over the cam mechanism. A lever arm having a cam actuating finger on one end thereof is pivotably mounted in the casing such that the cam actuating finger engages the cam mechanism and rotates the spindle when the handle is pivoted from a deactuated to an actuated position.

The cam mechanism of the present invention includes a flat cam plate that is fastened to the surface of the door by screws or the like, with a cam opening being formed in the cam plate over the spindle of the door latch mechanism. A cam is rotatably mounted on the outside of the cam plate by means of a flared collar that fits in the cam opening in the cam plate, and a square spindle opening formed in the cam at its axis of rotation non-rotatably fits over the spindle of the door latch. Hence, rotation of the cam causes the rotation of the door latch spindle and the opening of the door.

The cam mechanism is enclosed by a hollow casing that fits over the cam mechanism. A lever arm is pivotably mounted in the casing about an axis perpendicular to the spindle, and a cam actuating finger extending from an inner end of the lever arm engages and rotates the cam when the arm is pivoted. A spring biasing means resiliently holds the lever in a deactuated position.

When the door handle employed in the mechanism in the present invention is a panic bar, the lever arm is pivoted abouta horizontal axis and a corresponding casing and lever arm are spaced a pre-determined distance across the width of the door. A horizontal panic bar is then mounted between the outer ends of the two arms.

Another type of door handle that may be used in connection with the present invention is a simple lever type of door handle. This type of door handle may be used on the other side of the door from which a panic bar door handle is placed. In such a case, the panic bar door handle assembly is securely fastened to the door by employing long machine screws that extend from the casing of the panic door hardware all the way through the door and screw into threaded receptacles in the casing of the lever handle door latch opener on the other side of the door. This provides a secure mounting that resists torsional stresses placed on the door handles by the lever type of operation.

One of the important features of the present invention is that the cam mechanism is simple and inexpensive but is extremely versatile. The cam mechanism may be used interchangably on either side of the door with either type of handle and may be used whether the handle is mounted so that the door is opened by an upward movement of the lever arm or downward movement of the lever arm. In order to accomplish this end, the cam mechanism comprises a radially extending arm having symmetrical upper and lower cam surfaces on the upper and lower surfaces of the arm. The sides of the cam to which the arm is connected are beveled away from the arm so that the cam does not engage the sides of the cam actuating finger when the cam is rotated. Since the spindle opening in the cam is square the cam may be positioned at four different angular positions on the spindle, each position being apart.

These and other advantages of the present invention will hereinafter appear and, for purposes of illustration, but not of limitation, a preferred embodiment of the present invention is described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a door having a conventional latch mechanism and employing the panic bar door latch opener of the present invention.

FIG. 2 is an exploded view showing the manner in which the various components of the panic bar door latch opener are mounted on a conventional door latch mechanism.

FIG. 3 is a view taken along line 33 of FIG. 1, with the cam plate being removed in order to show the interaction between the lever arm and the cam.

FIG. 4 is a sectional side view taken along lines 4-4 of FIG. 1.

FIG. 5 is a perspective view showing the opposite side of the door shown in FIG. 1, employing a lever type of handle instead of the panic bar handle.

FIG. 6 is a broken edge view of a door showing a panic bar handle on one side and a lever handle on the other side.

FIG. 7 is a perspective view of the panic bar door latch opener of the present invention.

FIG. 8 is a view of the interior of the casing employed with the lever type of handle of the present invention.

FIG. 9 is a perspective view of the lever handle of the present invention.

FIG. 10 is a perspective view of the cam mechanism of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a convention door employing a conventional door latch mechanism 12 is shown employing the lever operated door latch opener 14 of the present invention in FIG. 1. In this figure the door latch opener employs a panic bar handle 16. The other side of the same door is shown in FIG. 5, wherein a lever handle 18 is employed instead of the panic bar handle.

The conventional door on which the door latch opener 14 of the present invention is employed is shown in more detail in FIG. 2. Conventional door latch mechanism 12 comprises a plate 20 that is fastened to the edge of the door by fasteners 22 and a beveled latch 24 that is reciprocably mounted to move into and out of the edge of the door through an opening in plate 20. Beveled latch 24 is retracted into the edge of the door by rotation of a square spindle 26 that extends through the door and protrudes outwardly from each side thereof for engagement with a door latch opening mechanism. The latch 24 is biased in its outward position. Typically, such a door latch opening mechanism would comprise a doorknob that fits over the spindle and is held in place on the spindle by means of a set screw.

In order to employ the lever operated door latch opener of the present invention with a conventional door and conventional door latch mechanism, it is only necessary to remove the doorknob on one or both sides of the door and fit the desired door latch opener of the present invention over the spindle in place of the doorknob. Simple screws may be used in order to retain the door latch opener in place on the surface of the door.

As shown in FIG. 2, the lever operated door latch opener of the present invention comprises a cam mechanism 28 that fits over spindle 26 and a hollow casing 30 that fits over the cam mechanism. Cam mechanism 28 is mounted on the door by a pair of screw fasteners 31, and casing 30 is mounted on the door by four fasteners 33. A lever arm for opening and closing the door latch is pivotably mounted in an opening in the casing by means of a pin.

Cam mechanism 28 comprises a cam plate 36 formed of a flat metal, such as steel or the like, and an eccentric cam 38 pivotably mounted on the outer side of the plate for rotation about an axis perpendicular to the plate. Cam 38 includes a cylindrical collar 40 that protrudes from a flat inner surface 41 of the cam and attends through a circular cam opening 42 in the cam plate. A flared flange 44 on the inside of the cam plate holds the cam on the cam plate.

Cam 38 has parallel flat inner and

outer surfaces

41 and 43, respectively, and comprises a body 46 rotatably mounted on spindle 26 and a cam engaging arm 48 that extends radially outwardly from the body. Body 46 is roughly square in shape and comprises an outer or back portion 50 and symmetrically inclined or beveled inner sides or surfaces 52 and 54 that converge inwardly to arm 48.

Sides

52 and 54 are inclined at an angle such that when the cam is pivoted a sufficient distance to open the door, the inclined surface adjacent the cam actuating finger of the lever arm moves to a generally vertical position, so that the body of the cam does not engage the cam actuating finger. Back portion 50 has converging beveled sides in the embodiment shown herein, but the shape of the back portion is not critical. For example, the back portion could be rounded or curved instead of beveled.

Arm 48 has symmetrical upper and lower cam surfaces 55 and 56, respectively. These cam surfaces make it possible for a door to be opened by pivoting the cam in either a clockwise or counterclockwise direction by means of a cam actuating finger engaging either the upper or lower cam surface. This adds versatility to the door handle mechanism.

Cam 38 further comprises a square spindle opening 45 therein at the axis of rotation of the cam with respect to the cam plate. Spindle opening 45 extends all the way through the cam and the collar and is formed so that the cam mechanism fits non-rotatably over the spindle when the cam mechanism is mounted on the door. Thus, rotation of the cam rotates the spindle. Also, because the spindle opening is square it is possible to position cam 38 in any one of four positions on spindle 26 (i.e., extending upwardly, downwardly, to the right, and to the left, according to FIG. 10 orientation). Thus, it is theoretically possible to mount the door latch opener in any of four different radial positions on the door.

Cam plate 36 is rectangular in shape and comprises a pair of openings 60 for screws 31. Square notches 58 are formed in each corner of the cam plate, so that fasteners 33 may pass from the casing past the cam plate and into the door. Cam plate 36 also has a pair of perpendicular tabs 62 extending away from the door. These tabs engage the inside surfaces of the casing 30 and assist in the alignment of the cam mechanism in the casing.

Casing 38 comprises a flat open bottom 65 that is mounted flush against the door and two side walls 66 and an end wall 68 extending perpendicularly away from the bottom. The tops of side walls 66 are tapered so that the side walls form a peak at the center of the top thereof, and a curved top section 70 encloses the top of the casing. Top section 70 comprises a rectangular central handle opening 72 for the lever arm and four comer openings 73 for fasteners 33. Openings 75 are formed through top 70 and the side walls 66 for pin 34, on which lever arm 32 is mounted.

Lever arm 32 (as used in a panic bar handle) comprises a flat arm 74 having an outer end 76 extending away from the casing and having a rounded inner end 78 pivotably mounted in the casing by means of pin 34. A cam actuating finger 80 fits in a recess 82 formed in the side of inner end 78 of the arm, and a screw 91 or other suitable fastener holds the finger in place on the handle. Finger 80 is flat and fits non-rotatably into recess 82 and extends inwardly away from end 78 into engagement with either the upper or lower cam surface of cam 38. Preferably, finger 80 is formed of bronze or other tough, durable metal.

In the present drawings, for purposes of illustration, the handle is shown extending downwardly from the casing and the finger 80 is shown engaging the lower cam engaging surface of the cam. However, it would be equally possible to mount the casing upside down and have the handle extending upwardly from the casing, so that the finger engages the upper side of the cam. In reversing the elements to accomplish this purpose, it should be noted that cam 38 can be positioned with the cam arm extending to the right as opposed to the left (FIG. 3 orientation), so that the lever arm may be changed from downward. rotation to upward rotation simply, by turning the casing and attached handle fupside down and by changing thepositionof the cam arm to the opposite direction.

Casing is mountedon the door by means of four fasteners 33 that extendthrough the casing, through the notches in the corners of thecam plate and into the door. These fasteners may be screws or the likeor, if another lever operated door latch opener is used on the other side of the door (as shown in FIG, 6 it is possible to mount the casing to the door by using long machine screws that pass through the door and screw into the casing on the other side of the door. This provides a more secure mounting meansfor mounting the door latch openers on the door andprovides important reinforcement in resisting any torsional forces placed on the-casing by-the lever handle.

-As shown in FIG. 8, when two lever operated door latch openers are fastened together on opposite sides of a'door, the screws are received in threaded openings 79 formed in special mountingmembers 81 mounted on the upper and lower sides of the interior of one casing. Mounting members 81 are spaced slightly away from, top 70 of the casing (the reason-for which is stated below) andzare provided with central slots ,83 adjacent the end walls of the casing,.in orderto accomodate tabs 62 on the cam plate. w

Arm 32 is maintained .in a deactuated or ready position by means of a springor other resilient biasing means 82- that fits in a slot orgroove 86 out below pin 34 in the inner end 78 of the-handle and wraps around pin 34. The spring has a short end 88 that engages the handle and urges it to a deactuated position, and has a long end 90 that is anchored in place in the casing. Typically, end 90 fits-under either around retaining bar 92 (as shown in FIG. 3) that extends between side walls 66 of the casing. Alternatively,-when the latch openers are fastened together on botl'rsides of a door by means of long screws 33 and mounting members 81 are employed in one of the casings, the spring may be fitted under the mounting member 8l-(as shown in FIG. 8), rather that providing a'separate retaining' bar 92 for that purpose. In any case the spring biasing means resili'ently holds the handle in its deactuated-position until it is pivoted manually to its actuated position, wherein it turns the spindle in the door latchfThereafter, the spring biasing means returns the door handle to its deactuated position.

As stated above, the lever operated door latch opener of the present invention may be operated with a panic bar handle 16 (as shoyvr'i in FIG. 1) or with a lever handle 18 (as shown in FIG. 5). In either case the cam mechanism is identical and the casing is substantially'the same, exceptas noted below.

When a panic' bar handle is employed lever arrri 32 is used merely as a lever and not'zi hand grip, so lever arm 32 is a flat and relatively narrow arm 74, and the arm is mounted in a narrow $16185 inthe casing that extends lesstha'n half of the width of the casing An identical casing is spaced horizontally apart from the first casing on the door, and a bar 87 is connected between the outer ends of the arms by; screws 89 or similar fasteners. j i

The casings and arms employed at both ends of the panic bar handle are identical except thattypically a cam actuating finger will not be mounted on both arms.

If one desired, however, the panic bar latch opener could be mounted upside down simply by fitting a cam actuating finger on the other arm and mounting the bar upside do wn on the door, reversing the position of the cam.

When a lever handle 18 is employed with the latch opener of the present invention, the cam mechanism and easing are the same as the elements employed with a panic bar handle, except that the lever handle 18 is wider than arm 74, so a wider opening 93 (FIG. 8) is formed in the casing to accommodate the handle. Also, in the illustrative embodiment shown herein, the latch opener with the lever handle is attached directly to the latch opener with the panic bar handle, and the casing for the lever handle includes mounting members 81, which are adapted to receive fasteners 33. In all other respects, however, the casing and cam mechanism are the same for both types of handles.

Similarly, except for the shape of the hand grip 94 of the lever handle (which is broad and fiat and formed at a slight angle) lever handle 18 is substantially the same as arm 74 in the panic bar handle. For convenience, in describing handle 18, the same reference numerals used for the panic bar handle will be used where the parts are substantially the same, except that the numerals will be primed.

Lever handle 18, as shown in FIGS. 8 and 9, comprises hand grip 94 on an outer end and a rounded inner end 78 pivotably mounted in the casing by pin 34'. A rounded collar 96 at the inner end of hand grip 94 engages the outside'of the casing. The rounded end 78' also includes a groove 86' for a spring 84' and a recess 82 in which a cam actuating finger is mounted by means of a screw 91'. The lever handle functions in the same manner as the panic bar handle in opening the door and, like the panic bar handle, may be mounted with the handle extending upwardly or downwardly simply by turning the casing over arid reversing the direction of the cam.

It should be understood that the embodiments described herein are merely exemplary of the preferred practice of the present invention and that various changes, modifications, and variations may be made in the arrangements, operations, and details of construction of the elements disclosed herein without departing from the spirit and scope of the present invention.

The embodiments of the invention in which an exclusive property or priviledge is claimed are defined as follows:

1. In a door latch mechanism, wherein a door latch is actuated by the rotation of a spindle extending out of a door, a lever operated door latch opener comprising:

a cam mechanism comprisingz a cam plate having a circular cam opening formed in the middle thereof, said cam plate being mounted as a separate unit against the door, with the cam opening fitting over the spindle; and

' a cam rotatably attached to the cam plate for rotation about an axis perpendicular to the cam plate, said cam including a body that engages an outer side of the cam plate and a cylindrical collar extending from the body that fits through said cam opening, said cam including means on the inner side of the cam plate for holding the collar in the cam opening, said cam having an axial spindle opening formed therein that nonrotatably fits over the door latch spindle such that rotation of the cam rotates the door latch spindle, said cam further having a lever engaging arm having symmetrical upper and lower cam surfaces facing away from the lever engaging arm, said cam surfaces permitting engagementof the earn from the top or bottom of the cam;

a hollow casing separately mounted on the door over the cam mechanism, said casing having a handle opening therein; and

a lever arm pivotably mounted in the apparatus at an inner end extending through the handle opening of the casing, said lever arm having an outer end extending out of the casing, said inner end having cam actuating finger means thereon adapted to engage and rotate the one of the cam surfaces on the cam sufiiciently to open the door latch when the lever arm is pivoted from a deactuated to an actuated position.

2. A lever operated door latch as claimed in claim 1 wherein:

the body of the cam comprises beveled sides that converge symmetrically inwardly to the arm of the cam; and

the arm of the cam is rectangular in crosssection and extends radially outwardly from the point of convergence of the sides of the body.

3. In a door latch mechanism, wherein a door latch is actuated by the rotation of a spindle extending out of a door, a lever operated door latch opener comprising:

a cam mechanism comprising:

a cam plate having a cam opening formed therein, said cam plate fitting against the door, with the cam opening fitting over the spindle; and

a cam rotatably mounted on the cam plate for rotation about an axis perpendicular to the cam plate, said cam having an axial spindle opening formed therein that non-rotatably fits over the door latch spindle such that rotation of the cam rotates the door latch spindle;

a hollow casing mounted on the door over the cam mechanism, said casing having a rectangular handle opening therein; lever arm having an inner end pivotably mounted in the handle opening of the casing and an outer end extending out of the casing, said inner end having cam actuating finger means thereon adapted to engage and rotate the cam sufficiently to open latch when the lever arm is pivoted from a deactuated to an actuated position; the inner end of the lever arm being mounted in the handle opening by means of a pin extending through the casing and the lever arm in a direction perpendicular to the plane of rotation of the lever arm, with the pin being removably mounted in the casing by means of a pressure fit;

the inner end of the lever arm being rounded and comprising a radial slot that is cut to a depth below the pin passing through the lever arm, said inner end further having a flat recess formed on one side thereof;

the cam actuating finger fitting in the recess and being held non-rotatably in place by a screw extending through the cam actuating finger into the lever arm; and

spring biasing means mounted inside the casing and adapted to resiliently urge the lever arm to a deactuated position out of contact with the cam, said is actuated by the rotation of a square spindle extending out of a door, a lever operated door latch opener 10 comprising:

cam mechanism comprising:

a flat, rectangular cam plate having a circular cam opening formed therein having a diameter greater than the spindle of the door latch, said cam plate also having fastener openings therein for mounting the cam plate to the door, said cam plate further having notches formed in the corners thereof and having a pair or tabs extending outwardly from opposite edges of the cam plate in a direction perpendicular to the cam plate, said cam plate being mounted to the door by means of screws that fit through the fastener openings, with the cam opening fitting over the spindle; and

a cam rotatably mounted on the cam plate for rotation about an axis perpendicular to the cam plate, said cam being mounted on the cam plate by means of a cylindrical collar that fits through the cam opening in the cam plate, said cylindrical collar having a flange on the end thereof that is flared outwardly on the other side of the cam plate so as to hold the cam on the cam plate for rotation with respect to the cam plate, said cam having a square spindle opening therethrough that non-rotatably fits over the door latch spindle in any one of four positions separated radially by a angle, said cam comprising a body having tapered sides that converge symmetrically inwardly toward a common point, said cam further having a rectangular arm extending outwardly from the tapered sides of the body adjacent the point of convergence, said arm having symmetrical upper and lower cam surfaces thereon, said arm being positioned so that when the cam is placed on the spindle, the arm will be extending in a horizontal direction;

hollow casing having a rectangular cross section mounted on the door over the cam mechanism,

said casing having a rectangular handle opening therein, and having a transverse pin opening that extends horizontally through the casing at the middle of the rectangular handle opening;

a cylindrical pin that fits in the pin opening by means of a pressure fit;

lever arm having a rounded inner end pivotably mounted for rotation in a vertical plane in the handle opening of the casing by means of the pin extending through the pin opening, said pin also extending through a corresponding mating opening in the inner end of the lever arm, said inner end having a slot formed internally therein that extends below the point where the pin passes through the lever arm, said inner end further comprising a recess formed on one side thereof;

cam actuating finger nomrotatably fitting into the recess in the side of the inner end of the lever arm, said cam actuating finger being mounted to the spring biasing means mounted in the casing and adapted to resiliently urge the lever arm to its deactuated position, said spring biasing means comprising a spring steel wire having a central portion coiled about the portion of the pin that extends through the slot in the inner end of the lever arm and having two free ends, one end bearing against the handle and the other end bearing against the casing, such that the handle is resiliently urged by the spring wire towards its deactuated position;

fastening means at each corner of the casing adapted to hold the casing to the door over the cam mechanism, said fastening means comprising threaded fasteners that pass through openings in the exterior of the casing in a direction perpendicular to the plane of the door, said fasteners extending through the notches in the corners of the cam plate and into the door;

a separate casing and pivotably mounted lever arm spaced horizontally apart from the first casing a predetermined distance across the door, with the lever arm of the second casing being positioned for rotation in a vertical plane in the same direction as the lever arm of the first casing; and

a panic bar handle extending between the outer end of the lever arms of the two casings.

Claims

1. In a door latch mechanism, wherein a door latch is actuated by the rotation of a spindle extending out of a door, a lever operated door latch opener comprising: a cam mechanism comprising: a cam plate having a circular cam opening formed in the middle thereof, said cam plate being mounted as a separate unit against the door, with the cam opening fitting over the spindle; and a cam rotatably attached to the cam plate for rotation about an axis perpendicular to the cam plate, said cam including a body that engages an outer side of the cam plate and a cylindrical collar extending from the body that fits through said cam opening, said cam including means on the inner side of the cam plate for holding the collar in the cam opening, said cam having an axial spindle opening formed therein that nonrotatably fits over the door latch spindle such that rotation of the cam rotates the door latch spindle, said cam further having a lever engaging arm having symmetrical upper and lower cam surfaces facing away from the lever engaging arm, said cam surfaces permitting engagement of the cam from the top or bottom of the cam; a hollow casing separately mounted on the door over the cam mechanism, said casing having a handle opening therein; and a lever arm pivotably mounted in the apparatus at an inner end extending through the handle opening of the casing, said lever arm having an outer end extending out of the casing, said inner end having cam actuating finger means thereon adapted to engage and rotate the one of the cam surfaces on the cam sufficiently to open the door latch when the lever arm is pivoted from a deactuated to an actuated position.

2. A lever operated door latch as claimed in claim 1 wherein: the body of the cam comprises beveled sides that converge symmetrically inwardly to the arm of the cam; and the arm of the cam is rectangular in crosssection and extends radially outwardly from the point of convergence of the sides of the body.

3. In a door latch mechanism, wherein a door latch is actuated by the rotation of a spindle extending out of a door, a lever operated door latch opener comprising: a cam mechanism comprising: a cam plate having a cam opening formed therein, said cam plate fitting against the door, with the cam opening fitting over the spindle; and a cam rotatably mounted on the cam plate for rotation about an axis perpendicular to the cam plate, said cam having an axial spindle opening formed therein that non-rotatably fits over the door latch spindle such that rotation of the cam rotates the door latch spindle; a hollow casing mounted on the door over the cam mechanism, said casing having a rectangular handle opening therein; a lever arm having an inner end pivotably mounted in the handle opening of the casing and an outer end extending out of the casing, said inner end having cam actuating finger means thereon adapted to engage and rotate the cam sufficiently to open latch when the lever arm is pivoted from a deactuated to an actuated position; the inner end of the lever arm being mounted in the handle opening by means of a pin extending through the casing and the lever arm in a direction perpendicular to the plane of rotation of the lever arm, with the pin being removably mounted in the casing by means Of a pressure fit; the inner end of the lever arm being rounded and comprising a radial slot that is cut to a depth below the pin passing through the lever arm, said inner end further having a flat recess formed on one side thereof; the cam actuating finger fitting in the recess and being held non-rotatably in place by a screw extending through the cam actuating finger into the lever arm; and spring biasing means mounted inside the casing and adapted to resiliently urge the lever arm to a deactuated position out of contact with the cam, said spring biasing means comprising an elongated spring steel wire coiled around the pin in the slot, said wire having two free ends, one end bearing against the lever arm inside the slot and a second end bearing against the casing such that the lever arm is urged toward its deactuated position.

4. In a door latch mechanism, wherein a door latch is actuated by the rotation of a square spindle extending out of a door, a lever operated door latch opener comprising: a cam mechanism comprising: a flat, rectangular cam plate having a circular cam opening formed therein having a diameter greater than the spindle of the door latch, said cam plate also having fastener openings therein for mounting the cam plate to the door, said cam plate further having notches formed in the corners thereof and having a pair or tabs extending outwardly from opposite edges of the cam plate in a direction perpendicular to the cam plate, said cam plate being mounted to the door by means of screws that fit through the fastener openings, with the cam opening fitting over the spindle; and a cam rotatably mounted on the cam plate for rotation about an axis perpendicular to the cam plate, said cam being mounted on the cam plate by means of a cylindrical collar that fits through the cam opening in the cam plate, said cylindrical collar having a flange on the end thereof that is flared outwardly on the other side of the cam plate so as to hold the cam on the cam plate for rotation with respect to the cam plate, said cam having a square spindle opening therethrough that non-rotatably fits over the door latch spindle in any one of four positions separated radially by a 90* angle, said cam comprising a body having tapered sides that converge symmetrically inwardly toward a common point, said cam further having a rectangular arm extending outwardly from the tapered sides of the body adjacent the point of convergence, said arm having symmetrical upper and lower cam surfaces thereon, said arm being positioned so that when the cam is placed on the spindle, the arm will be extending in a horizontal direction; a hollow casing having a rectangular cross section mounted on the door over the cam mechanism, said casing having a rectangular handle opening therein, and having a transverse pin opening that extends horizontally through the casing at the middle of the rectangular handle opening; a cylindrical pin that fits in the pin opening by means of a pressure fit; a lever arm having a rounded inner end pivotably mounted for rotation in a vertical plane in the handle opening of the casing by means of the pin extending through the pin opening, said pin also extending through a corresponding mating opening in the inner end of the lever arm, said inner end having a slot formed internally therein that extends below the point where the pin passes through the lever arm, said inner end further comprising a recess formed on one side thereof; a cam actuating finger non-rotatably fitting into the recess in the side of the inner end of the lever arm, said cam actuating finger being mounted to the inner end of the lever arm by means of a screw that fits through an opening in the cam actuating finger and into an internally threaded opening in the lever arm, said cam actuating finger being positioned so that it is in alignment with a cam surface on the cam, such that rotation of the lever arm from a deactuated position to an actuated positiOn causes the cam actuating finger to engage a cam surface on the cam and rotate the spindle sufficiently to open the door latch; spring biasing means mounted in the casing and adapted to resiliently urge the lever arm to its deactuated position, said spring biasing means comprising a spring steel wire having a central portion coiled about the portion of the pin that extends through the slot in the inner end of the lever arm and having two free ends, one end bearing against the handle and the other end bearing against the casing, such that the handle is resiliently urged by the spring wire towards its deactuated position; fastening means at each corner of the casing adapted to hold the casing to the door over the cam mechanism, said fastening means comprising threaded fasteners that pass through openings in the exterior of the casing in a direction perpendicular to the plane of the door, said fasteners extending through the notches in the corners of the cam plate and into the door; a separate casing and pivotably mounted lever arm spaced horizontally apart from the first casing a predetermined distance across the door, with the lever arm of the second casing being positioned for rotation in a vertical plane in the same direction as the lever arm of the first casing; and a panic bar handle extending between the outer end of the lever arms of the two casings.