US2242647A

US2242647A - Door opening mechanism

Info

Publication number: US2242647A
Application number: US239525A
Authority: US
Inventors: Haslam Robert
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-11-08
Filing date: 1938-11-08
Publication date: 1941-05-20
Anticipated expiration: 1958-05-20

Description

May 20, 1941. HASLAM 2,242,647

DOOR OPENING MECHANI SM Filed No a, 1938 s Sheets-Sheet i I 1N VENTOR. ROBERT IVA-SLAM ATTORNEYS.

May 20, 1941.

R. HAsLAM DOOR OPENING MECHANISM 6 Sheets-Sheet 2 Filed Nov. 8, 1958 INVENTOR ROBERT HASLAM ATTORNEYS.

May 20, 1941.

R. HASLAM DOOR OPENING MECHANISM Filed Nov. 8, 1958 6 Sheets-Sheet '3 ATTORNEYS.

May 20, 1941. R. HAs'LAM noon OPENING MECHANISM Filed Nov. 8, 1938 6 Sheets-Sheet 4 INVENTOR. X03512? HAsLAM ATTORNEYS;

May 20, 1941. R HASLAM noon OPENING MECHANISM 6 Sheets-Sheet 5 Filed Nov. 8

INVENTOR. HAsLAM 7 ATTORNEYS.-

May20, 1941. R. HASLAM DOOR OPENING MECHANISM 6 Sheets-Sheet 6 Filed Nov. 8, 1938 1 w A m T m Camp m Mme Patented May 26, 1941 UNETED STATES FATE.

orrics 12 Claims.

This invention relates. to door opening mechanisms. It has for its objects the production of a device of this class which will be positive in its operation both in opening and closing the door and which will nevertheless be comparatively sim le in structure.

For the purpose of illustrating my invention, I have disclosed in the drawings which form a part hereof, and will now describe two of the many possible embodiments of my invention.

In said drawings,

Figure 1 is a perspective view of my novel structure attached to a door. A portion of the tread-plate 6 has been broken away for the purpose of showing otherwise hidden parts. The full lines show the position of the respective elements when the door is closed and the dot and dash lines show the position of the arm and cable when the door is opened.

Figure 2 is a. plan view of the door actuating portion of my novel mechanism with the casing removed, taken along the lines 2-2 of Figure 1.

Figure 3 is a front View of the disclosure in Figure 2.

Figure 4 is an end View of the disclosure in Figure 2 taken along the line 44 of said figure.

Figure 5 is a plan View of the tread portion of my mechanism.

Figure 6 is a section taken along the line 6--6 of Figure 5.

Figure '7 is a section taken along the line 7-1 of Figure 5.

Figure 8 is a section of a fragment taken along the line 8-8 of Figure 5.

Figure 9 is a section of a fragment taken along the line 99 of Figure 5.

Figure 10 is a section of a fragment taken along the line |0|9 of Figure 5.

Figure 11 is a section of a fragment taken along the line I Il l of Figure 5.

Figures 12 and 13 are schematic plan views of the door actuating portion of the mechanism taken along the line 2-2 of Figure 1. The full and dotted lines in Figure 12 show the respective positions of the respective elements when the door is closed, while the dot and dash lines in this figure show the positions to which these elements have moved just after a person has stepped upon the tread-plate.

The full and dotted lines in Figure 13 show the positions of the respective elements of the door actuating mechanism when the door is fully opened, and the dot and dash lines in Figure 13 show the positions to which these elements have moved just after a person has stepped ofi" the tread-plate. A portion of the door intermediate its ends has been broken away to permit the showing of the remaining parts on as large a scale as possible.

Figure 14 is a plan view of a modification of the door actuating portion of my mechanism with the casing removed.

Figure 15 is a front View taken along the line l5l5 of Figure 14:.

Figure 16 (see Sheet 2 of the drawings) is a section taken along the line i6l6 of Figure 2.

Figure 17 (see Sheet 4 of the drawings) is an enlarged section of a fragment taken along the line I'i-ll of Figure 5. The full lines show the positions which the pin and tread-plate occupy before the tread-plate has been adjusted, and the dot and dash lines show the position which each of these elements assumes after the treadplate has been adjusted.

Referring more particularly to the drawings wherein similar reference numerals denote similar parts, reference numeral I denotes my door opening device as a unit. The unit I consists of the tread portion 2, the transmitting portion 3, and the door actuating portion 4.

The tread portion 2 consists of a frame 5, a tread-plate 6 pivoted with reference to said frame at I, and an arm 8 which is actuated in a horizontal plane about a pivot 9 by the movement of said tread-plate 6.

The frame 5 is rectangular in shape and comprises the walls If], H, l2, and I3. The walls Ii), ll, l2, and I3 have, respectively, the sloping outer surfaces l4, I5, I6, and. IT and the vertical surfaces [8, I9, 20, and 2i. The walls In, H, l2, and I3 have formed therein the apertures 22 through which extend suitable bolts 23 which fasten the frame 5 to the floor 24.

Each of the walls H and i3 (see Figures 5 and 1'7) has formed therein an internally threaded aperture 26 which receives a suitably threaded pin 2?. Each pin 21 terminates in a nonthreaded portion 28 which extends into and is received in a suitable bore 30 formed in the boss 29 which is formed on the tread-plate 6. Each threaded pin 21 has mounted thereon near the outer end thereof the washer 25 and the locknut 31. The non-threaded portion 28 of the pin 21 serves as a pivot 1 for the tread-plate 6. The

threaded pins 21 also serve as a means for laterally adjusting the tread-plate 6. The locknut 3| serves to lock the threaded pin 21 in any desired position.

A shoe 32 is formed in each of the front corners of the frame 5. Each shoe 32 has a recess 33 formed therein which serves as a seat for the lower end 38 of the spring 34. The upper end 55 of the spring contacts the inner surface 31 of the tread-plate 5 and serves to keep the treadplate in the raised or normal position shown in the drawings.

The wall I2 has a cut-out 88 formed therein centrally thereof which receives the arms 48 of the bearing plate 39. Each of the arms 48 has suitable apertures formed therein through each of J which a screw 4I extends. This screw 4I attaches the arms 48 of the bearing plate 39 to the wall i2 of the frame 5.

The bearing plate 99 has formed therein the cut-out 42 through which a portion of the wedge 83 may extend when the tread-plate 6 moves downwardly. A roller 44 is carried by the bearing plate 39 and is positioned for contacting the surface of the wedge 43. The surface 48 of the wedge 43 contacts a roller 41 which is suitably positioned in the arm 8. The arm 8 also carries a roller 28 which is suitably positioned for contacting the surface 58 of the wedge 49 which extends downwardly from the under surface 31 of the tread-plate 6. The

wedges

43 and 49 act as a couple to cause the arm 8 to rotate about its ivot 9 from its full line position shown in Figure 1 towards its dot and dash line position in said figure whenever force is exerted upon the tread-plate 6 in the direction indicated by the arrow A in Figure 7.

The bearing plate 38 has attached thereto by means of suitable screws the bar I39, the lower surface of which rests upon the floor 24 thereby furnishing additional support to the outer end of II the bearing plate 89. This construction permits the plate 39 to be raised a distance above the floor 24 sufficient to permit the

wedges

43 and 49 to be depressed to their lowest respective points without touching the floor. It therefore becomes unnecessary to either make depressions in or to out holes in the floor 29.

The bearing plate 59 has attached thereto by means of suitable rivets the arm I48 which in turn has threadably mounted therein the bolt 5I.

The end 52 of the bolt 5! contacts the face 53 of the arm 8 and acts as a stop to limit the motion of the arm 8 in the direction of the arrow B in Figure 1.

The arm 8 has formed therein a series of 5;

threaded apertures 54 any one of which receives the bolt 55 which extends through a suitable eye formed in the lower end of the cable 58 and serves to attach the cable 58 to said arm 8.

The cable 59 extends from the arm 8 through T a suitable aperture 51 formed in the wall I8 of the frame 5, around a pulley 58 mounted in the lower end of the hollow standard 59, up through the standard 59, around a pulley 58 mounted in the upper end of the standard 59 and is con- The bracket 84 not only serves as a point of attachment for the strap 83 but it also serves as a support for one of the ends 58 of the plate 85 which serves as the bearing member of the door actuating portion 4. plate 55 is attached to a bracket 68 which in The other end 61 of the turn has attached thereto one of the ends 18 of a turnbuckle cable 69. The other end H of the turnbuckle cable 89 is attached to a suitable hook 12 imbedded in the lintel 13. The turnbuckle cable 59 makes it possible to readily level off the door actuating portion 4 and to compensate for sagging which may occur from time to time either in the door frame or other elements of the building to which the door opening device may be attached.

The other of the ends 16 of the lever arm 14 is fixedly attached to the shaft 11 which is carried by the bearing plate 65. The shaft 11 also has fixedly attached thereto the gear 18 which meshes with a gear 19 fixedly attached to the shaft 8| which is also carried by the bearing plate 65. The shaft 8| has fixedly attached thereto the gear 88 which is positioned below the gear 19. The gear 88 meshes with the rack 82. The rack 82 is carried by an arm 83 which in turn is fixedly attached to one of the ends 85 of the cam band 84. The other of the ends 85 of the cam band 84 is pivoted on a shaft 81 which is carried by the bearing plate 55. The cam band 84 passes between the rollers 9| and 92 carried by the

arms

89 and 98 of the lever 88. The lever 88 is pivoted on a suitable shaft 93 carried by the bearing plate 65 and, in addition to the

arms

89 and 98, also has the arm 94 which terminates in a socket member 95. This socket member 95 has formed therein a suitable bore which receives the pin 98 which extends downwardly from the collar 91. The collar 91 encompasses the arm 99 of the lever 98 and is slidable thereon. The lever 98 is pivoted at one of its ends I98 upon the shaft I8I carried by the plate 85 and has depending therefrom near the other of its ends I82 the socket pin I84. The end I82 of the lever 98 is forked and has mounted therein the roller I83. The socket pin I84 has a suitable bore formed therein which receives the pin I86 which extends upwardly from the collar I85 which is slidably mounted on the bar I81. The bar I81 is attached at its ends I88 and I89 to the door H8 which is to be actuated. The bar I81 has fixedly attached thereto near its end I89 the collar III. This collar serves as a bearing surface for one of the ends H3 of the spring I I2 which is also mounted on the bar I81. The other end I I4 of the spring I I2 is attached to the collar I I5 which is slidably mounted on the bar I81. The collar I85 contacts the collar H5 at a certain point in the swing of the door from its closed to its open position causing said collar to move and compress the spring l I2. This in turn serves as a retarder and shock absorber with reference to the movement of the door to said position.

The free end of the arm 98 of the lever 88 has attached thereto one of the ends I I1 of the shock absorbing unit H8. The other end II8 of the unit I I6 is pivoted on the pin H9 carried by the plate 65.

The cam band 84 has extending therefrom the arm I28, the hook I2I of which serves as a point of attachment for the end I23 of the spring I22. The other end I24 of the spring I22 is attached to a hook I21 extending from a post I28 carried by the tensioning block I25. The tensioning block I25 is mounted in suitable channels formed in the angles I28--I28 attached to the .plate 65 for movement in a horizontal plane. The tensioning block I25 is held in any desired position in the slideway I29 by the pressure of the bolt I38 which is rotatably mounted in a suitable box I3I carried by the plate 65. The strength of the sprin I22 is such that it will overcome the inertia of the door Ill) against movement, the frictional force of the door III] upon its hinges and the frictional forces in the door actuating mechanisms 4, so that in the absence of a counter-acting force or forces which may be exerted upon the door H as a result of a pull upon the cable 56 the force of the spring I 22 will be sufiicient to cause the door III] to close and keep it closed. Whenever it is desired to increase the force exerted by the spring I22 on the arm I20 it is only necessary to advance the bolt I30 in the direction of the arrow Z in Figure 4.

It is to be noted that the first act in mounting the tread-plate in the frame 5 is the positioning of said tread-plate upon its pivots "I. When this is accomplished it often happens that the wedge 43 is not in the position shown in Figures 5 and 6 where the face 45 of said wedge contacts the roller 44. Instead, this face is at a point either to the right or left of said roller. To properly position said wedge it is only necessary to advance the pins II in the direction and through the distance which the wedge 43 must be moved in order to bring it to the position shown in Figures 5 and 6. In the course of this motion one of said pins will move outwardly, thereby removing its shoulder 545 as a barrier to the motion of said treadplate; and the shoulder I45 of the other of said pins will contact that face I55 of the tread-plate E which is contiguous thereto, thereby pushing said tread plate 6 before it. In the course of said motion the tread-plate 6 carries with it the wedge 43 which is finally caused to assume the position shown in Figures 5 and 6. The full and dot and dash lines in Figure 17 portray the respective movements of one of the pins and of the treadplate in the making of such an adjustment.

In this case the wedge 43 fell between the rollers 14 and ll with the face 45 out of contact and to the right of the roller 44. To secure such contact it was therefore necessary to move the wedge towards the left. The threaded pin ll at the left side of the tread portion 2 was therefore screwed outwardly (toward the left) and moved from its full line position shown in Figure 17 to its dot and dash line position in said figure. Thereafter, the threaded pin IT at the right side of the tread portion 2 was screwed inwardly (toward the left) a distance equal to that which the pin on the left side was moved outwardly. In the course of this motion, the shoulder I45 of the right hand pin contacted the face I55 of the tread-plate 6 which was contiguous thereto and pushed the plate 6 toward the left from its position designated by the full lines of the fragment shown in Figure 17 to that shown by the dot and dash lines in said figure. When the tread-plate reached the position designated by the dot and dash lines in Figure 17 the wall contacted the roller 45.

It is further to be noted that the cable may develop some slackness in use. Such slack is readily eliminated by advancing the bolt 5| the necessary distance.

It is further to be noted that in assembling the the tube I46 which telescopes over the upper end of the shaft I45, and the tube Ml which telescopes over the lower end of the shaft I45. The tubes I55 and MI are each laterally movable upon said shaft I45 and are also rotatable thereon. The tube I 36 carries the pulley 60 and is locked in the desired position upon the shaft I45 by means of the set screw M8. The tube I47 carries the pulley 53 and is locked. in the desired position by the set screw I49.

Although the operation of my device is believed to be obvious from the drawings and foregoing description, yet to obviate any possibility of a misiuiderstanding the following detailed description is here given.

Let it be assumed that the door III) is closed and that a person is desirous of causing the same to open. As he moves toward the door I III he steps upon the tread-plate 5. His weight exerts a force upon the tread-plate 6 in the direction of the arrow A in Figure 7, which is greater than the force exerted by the spring I22 upon the cam band 84. As a result, the tread-plate 5'. moves downwardly about its pivots l and carries the wedges 13 and G9 downwardly with it. In the downward motion of the wedge 43 its surface 45 contacts and exerts pressure upon the roller 41 and in the downward motion of the wedge 49 its surface 50 contacts the roller 58. This results in the action of a couple upon the arm 8 causing it to move from its full line position in Figure 1 to its dot and dash line position in said figure. This results in the movement of the cable 56 which in turn causes the lever arm 15 to move in the direction of the arrow C in Figures 2 and 12. This results in the movement of the gear 18 in the direction of. the arrow D, of the gear IS in the direction of the arrow E, of the gear in the direction of the arrow F, of the rack 82 in the direction of the arrow G, of the band 84 in the direction of the arrow H. At the beginning of this motion, the rack 82 and the cam band 34 move from their respective full and dotted line positions in Figure 12 to their respective dot and dash line positions in said figure. When the cam band 84 reaches its dot and dash line position in Figure 12, its surface I32 contacts and exerts pressure upon the roller 92 carried by the lever arm 95 urging the lever arm 98 of the lever 88 in the direction of the arrow I. This results in the rotation of the lever 88 about its pivot 53 in the direction of the arrow J This results in the movement of. the arm 94 of the lever 83 in the direction of the arrow K. This motion is communicated to the collar 91 through the socket 95 and the pin 96. This results in a contact between the side I35 of the lever arm 99 with that surface of the collar 91 adjacent to said side. This results in a pressure upon the lever arm 99 in the direction of the arrow L. This causes the rotation of the lever 38 about its pivot IIFI in the direction of the arrow M. In moving in the direction of the arrow L, the arm 99 carries with it the socket pin I64. The socket pin I 04 communicates this motion to the collar I05 through the pin I86. This causes the collar I05 to exert pressure upon the side I36 of the bar I01 in the direction of the arrow N. This in turn causes the door I III to open by rotating in the direction of the arrow 0 about its hinges I38. As the door IIB continues to open, the collar I05 contacts the collar H5 and causes it to move in the direction of the arrow P which in turn causes the spring II 2 to become compressed. The spring IIZ acts as a shock absorber and also as a retarder to slow down and limit the motion of the door IIU.

When the person steps off the tread-plate 6, the force which he exerted in the direction of the arrow A (Figure 7) is removed. The pull of the extended spring I22 then becomes the strongest force in the door actuating mechanism 4. As a result, all of the movements hereinabove specified are reversed and the door I I8 caused to close. In doing so, the cam band 84 and its associated elements move from their respective full line positions shown in Figure 13 to their respective full line positions shown in Figure 12, and the cable 55 and arm 8 move from their respective dot and dash line positions in Figure 1 to their respective full line positions in said figure. This permits the springs to force the tread-plate 6 to rotate about its hinges I and rise from its depressed position to its normal position shown in Figures 1 and '7 of the drawings.

In the first phase of the movements aforesaid, the cam band 84 moves from its full line position shown in Figure 13 to its dot and dash line position in said Figure 6. In doing so, the outer face I32 of the cam band 84 ceases to contact the roller 92 carried on the lever arm 95 while the inner face I33 of said cam band 84 comes into contact with the roller 9! carried by the lever arm 89. This removes the pressure on the lever 88 causing it to rotate in the direction of the arrow J in Figure 2 and results in a pressure upon the lever 88 causing it to rotate in the direction of the arrow Q in Figure 13. This in turn results in the movement of the lever arm 94 in the direction opposite to the arrow K.

This motion is communicated to the collar 91 and results in a contact between the side I35 of the lever arm 39 and that surface of the collar 32' adjacent to said face. This results in a pressure upon the lever arm 99 in a direction opposite to the arrow L. This causes the rotation of the lever 98 about its pivot IIlI in the direction of the arrow R in Figure 13. In the course of this rotation, the lever arm Q9 carries with it the socket pin Hi4 which communicates its motion to the collar H15. This causes the collar I05 to exert pressure upon the side I3! of the bar II)? in a direction opposite to the arrow N. This in turn causes the door I iii to close by moving about its hinges I353 in the direction opposite to the arrow 0. It is to be noted that at certain points during the opening and closing of the door IIB, the roller I83 comes into a position where it contacts the door I III. During the motion of closing the door, this contact produces a force on the door I ID in the direction of the arrow N. In the act of closing the door I I0, this contact does not result in any appreciable force which retards the motion of the door I I8 to its closed position. This is because the lever 99 is constantly being urged in the direction opposite to the arrow N during the time that the door I I9 is being closed.

While the cam band 84 is exerting the pressure upon the roller 9! which results in the closing of the door IIfl, the rack 83 moves in the direction of the arrow S shown in Figure 13. This results in motions in the gears 80, I9, and I8 in the lever I l, and in the cable 56 in the direction of the arrows T, U, V, W, and X, respectively. This results in a pull upon the arm 9 causing it to move from its dot and dash line position to that shown by the full lines in said figure. This is readily accomplished because the springs 3 have already caused the tread-plate 6 to return from the depressed position to its normal position.

The door actuating portion I4I shown in Figures 14 and 15 difiers from the door actuating mechanism 4 shown in Figures 1 to land 12, 13 and 16 only in the following particulars:

(1) The gears 19 and have been eliminated.

(2) The rack I42 has been substituted for its equivalent, 83. I

(3) The rack I42 meshes directly with the gear I43 which otherwise is the equivalent of the gear I8.

(4) The lever I44 has been substituted for its equivalent, the lever 14.

(5) The tube I46 of the hollow standard 59 has been rotated from the position shown in Figures 1 and 2 to that shown in Figure 14. In the course of this rotation, the tube I46 has carried the pulley 60 from its position shown in Figures 1 and 2 to that shown in Figure 14.

The door actuating portion I4I may be substituted in my novel mechanism for the door actuating portion 4, particularly in cases where the door III) is comparatively light. With the exception of the fact that there is a direct contact between the rack I42 and the gear I43 and therefore a direct transfer of force from each of said elements to the other, the unit which has a door actuating portion I4I as a component part functions exactly in the, same manner as the unit which has a door actuating portion 4 as a component part.

The foregoing description is to be understood as being by the way of illustration only and not by the way of limitation since many changes may be made in the disclosure here made without departing from the spirit of my invention. These changes may include, among other things, changes in the shape and size of the various component elements of my mechanism and changes in the material of which said elements are made.

Having described my invention, what I claim as new and useful is:

1. A door opening device consisting of a base member; a tread-plate pivotally mounted in said base member; a door actuating portion positioned for operative contact with the door which is to be opened by said door opening device, said door actuating portion comprising a bar carried by said door, sliding means mounted for movement upon said bar, an arm. pivoted near one of its ends and attached to said sliding means near the other of its ends, sliding means mounted for .movement upon said arm, a second arm pivoted by said second arm, a cam band pivoted near one of its ends and positioned for contacting one of said cam contacting surfaces and exerting a force upon said bar mounted sliding means in the direction necessary to open said door when a person steps upon said tread-plate, and for contacting the other of said cam contacting surfaces and exerting a force upon said bar mounted sliding means in the direction necessary to close said door when said person steps off said tread-plate; and means operatively connecting said cam band with said tread-plate.

2. A door opening device consisting of a base member; a tread-plate pivotally mounted in said base member; a door actuating portion positioned for operative contact with the door which is to be opened by said door opening device, said door actuating portion comprising a bar carried by said door, sliding means mounted for movement upon said bar, an arm pivoted near one of its ends and attached to said bar mounted sliding means at the other of its ends, sliding means mounted for movement upon said arm, a second arm pivoted intermediate its ends and attached to said arm mounted sliding means near one of its ends, two spaced apart cam contacting surfaces positioned upon said second arm intermediate its pivot point and its free end, a cam band pivoted near one of its ends and positioned intermediate said cam contacting surfaces for contacting one of said cam contacting surfaces and exerting a force upon said bar mounted sliding means in the direction necessary to open said door when a person steps upon said tread-plate and for exerting a force upon said bar mounted sliding means in the direction necessary to close said door when said person steps off said treadplate; and means operatively connecting said cam band with said tread-plate.

3. A door opening device consisting of a base member; a tread-plate pivotally mounted in said base member and movable therein to assume either a raised or a lowered position; an arm mounted for movement beneath said tread-plate; means carried by said tread-plate and positioned for contacting said arm and exerting a force on said arm when said tread-plate is being moved toward its lowered position; a door actuating portion positioned for operative contact with the door which is to be opened by said door opening device, said door actuating portion comprising a bar carried by said door, sliding means mounted for movement upon said bar, an arm pivoted near one of its ends and attached to said bar mounted sliding means at the other of its ends, sliding means mounted for movement upon said arm, a second arm pivoted intermediate its ends and attached near one of its ends to said arm mounted sliding means, two spaced apart cam contacting surfaces positioned upon said second 'arm intermediate its pivot point and its free end,

said tread-plate and for exerting a force upon plate with said cam band.

4. A door opening device consisting of a base member; a tread-plate mounted in said base member and movable therein to either a raised or lowered position; resilient means positioned in said base member, contacting said tread-plate and exerting a force on said tread-plate sufficient to hold said tread-plate in its raised posi tion; an arm pivoted intermediate its ends and positioned beneath said tread-plate; a Wedge carried by said tread-plate and positioned for contacting one of the faces of said arm; a second wedge carried by said tread-plate and positioned for contacting that face of said arm opposite to that which is contacted by the first of said wedges and on that side of the pivot point which is opposite to that which is contacted by the first of said wedges; a door actuating portion positioned for operative contact with the door which is to be opened by said door opening device, said door actuating portion comprising a bar carried by said door, sliding means mounted for movement upon said bar, a base plate, an arm pivoted near one of its ends in said base plate and attached to said bar mounted sliding means at the other of its ends, sliding means mounted for movement upon said arm, a second arm pivoted intermediate its ends in said base plate and attached near one of its ends to said arm mounted sliding means, two spaced apart cam contacting surfaces positioned upon said second arm intermediate its pivot point and its free end, a cam band pivoted near one of its ends and positioned intermediate said cam contacting surfaces for alternately contacting each of said cam contacting surfaces, means attached to said cam band for exerting a force on said cam band in the direction necessary to cause said cam band to contact one of said cam contacting surfaces and to exert a force upon said bar mounted sliding means in the direction necessary to close said door, and a second means operatively connecting said cam band with said arm positioned beneath said tread-plate for exerting a force on said cam band in the direction necessary to cause said cam band to contact the other of said cam contacting surfaces and exert a pressure upon said bar mounted sliding means in the direction necessary to open said door when a person steps upon said tread-plate.

5. A door opening device comprising means mounted for sliding movement upon the door which is to be opened; an arm pivoted at a point intermediate its ends; means operatively connecting' said pivoted arm with said sliding means; a pair of spaced apart cam contacting surfaces pivotally mounted on said arm; a cam band pivoted near one of its ends and extending between said cam contacting surfaces; cam band actuating means operatively connected with said cam band for exerting a force upon said cam band in the direction necessary to cause said cam band to contact one of said cam contacting surfaces and exert a force upon said door mounted sliding means in the direction necessary to open said door; and a second cam band actuating means operatively connected with said cam band and exerting a force upon said cam band in the direction necessary to cause said cam band to contact the other of said cam contacting surfaces and exert a force upon said door mounted sliding means in the direction necessary to close said door.

6. A door opening device comprising a bar carried by the door which is to be opened; sliding means mounted for movement upon said bar; a supporting member; an arm pivoted near one of its ends in said supporting member and attached to said sliding means near the other of its ends; sliding means mounted for movement upon said arm; a second arm pivoted intermediate its ends in said supporting member and attached to said arm carried sliding means near one of its ends; a pair of spaced apart cam contacting members carried by said second arm; a cam band pivotally mounted in said supporting member and extending between said cam contacting surfaces; cam band actuating means operatively. connected with said cam band for exerting a force upon said cam band in the direction necessary to cause said cam band to contact one of said cam contacting surfaces and exert a force upon said door mounted sliding means in the direction neces-- sary to open said door; and a second cam band actuating means operatively connected with said cam band and exerting a force upon said cam band in the direction necessary to cause said cam band to contact the other of said cam contacting surfaces and exert a force upon said door mounted sliding means in the direction necessary to close said door.

'7. A door opening device: comprising means mounted upon the door which is to be opened for alternately exerting a force upon said door either in the direction necessary to open or in the direction necessary to close said door; an arm pivoted at a point intermediate its ends; means operatively connecting said ivoted arm with said door mounted means; a pair of spaced apart cam contacting surfaces pivotally mounted on said arm; a pivotally mounted cam band extending between said cam contacting surfaces; cam band actuating means operatively connected with said cam band for exerting a force upon said cam band in the direction necessary to cause said cam band to contact one of said cam contacting surfaces and exert a force upon said door mounted means in the direction necessary to open said door; and a second cam band actuating means operatively connected with said cam band and exerting a force upon said cam band in the direction necessary to cause said cam band to contact the other of said cam contacting surfaces and exert a force upon said door mounted means in the direction necessary to close said door.

8. An element of an automatic door opening device, said element comprising sliding means which is attached to the door which is to be opened; a supporting member; an arm pivoted near one of its ends in said supporting member and attached to said sliding means near the other of its ends; sliding means mounted for movement upon said arm; a second arm pivoted intermediate its ends in said supporting member and attached to said arm carried sliding means near one of its ends; a pair of spaced apart cam contacting members carried by said second arm; a cam band pivotally mounted in said supporting member and extending between said cam contacting surfaces; cam band actuating means operatively connected with said cam band and exerting a force upon said cam band in the direction necessary to cause said cam band to contact one of said cam contacting surfaces and exert a force upon said sliding means in the direction necessary to close said door; and means operatively connected to said cam band for connecting said cam band to a source of power.

9. A door opening device comprising a base member; a tread plate pivotally mounted in said base member; a door actuating portion positioned for operative contact with the door which is to be opened by said door opening device, said door actuating portion comprising a bar which is connected to said door, sliding means mounted upon said bar, a pair of spaced apart cam contacting members operatively connected to said sliding means, a cam band extending between said cam contacting members and positioned for contacting one of said cam contacting members and exerting a force upon said sliding means and cause said sliding means to mov in the direction necessary to open said door when a person steps upon said tread plate and for exerting a force upon said sliding means and cause said sliding means to move in the direction necessary to close said door when said person steps off said tread plate; and means operatively connecting said cam band with said tread plate.

10. A door opening device comprising a base member; a tread plate movably mounted in said base member; a door actuating portion positioned for operative contact with the door which is to be opened by said door opening device, said door actuating portion comprising a bar which is connected to said door, sliding means mounted upon said bar, an arm operatively connected to said sliding means, a second arm operatively connected to said first arm, a pair of spaced apart cam contacting members carried by said second arm, a cam band extending between said cam contacting members and positioned for contacting one of said cam contacting members and exerting ;a force upon said sliding means through said second and first arms and cause said sliding means to move in the direction necessary to open said door when a person steps upon said tread plate, and for contacting the other of said cam contacting members and exerting a force upon said sliding means through said second and first arms and cause said sliding means to move in the direction necessary to close said. door when a person steps off said tread plate; and means operatively connecting said cam band with said tread plate.

11. An element of an automatic door opening device, said element comprising sliding means which is attached to the door which is to be opened; a supporting member; an arm pivoted in said supporting member at a point intermediate its ends; a pair of spaced apart cam contacting members pivotally mounted in said arm; means operatively connecting said arm with said sliding means; a cam band pivotally mounted in said supporting member and extending between said cam contacting surfaces; cam band actuating means operatively connected with said cam band and exerting a force upon said cam band in the direction necessary to cause said cam band to contact one of said cam contacting surfaces and exert a force upon said sliding means in the direction necessary to close said door; and means operatively connected to said cam band for connecting said cam band to a sourc of power.

12. An element of an automatic door opening device, said element comprising means mounted upon the door which is to be opened for alternately exerting a force upon said door either in the direction necessary to open or in the direction necessary to close said door; a supporting member; an arm pivoted in said supporting memher at a point intermediate its ends; apair of spaced apart cam contacting members pivotally mounted in said arm; means operatively connecting said arm with said door mounted means; a cam band pivotally mounted in said supporting member and extending between said cam contacting surfaces; cam band actuating means operatively connected with said cam band and exerting a force upon said cam band in the direction necessary to cause said cam band to contact one of said cam contacting surfaces and exert a force upon said door mounted means in the direction necessary to close said door; and means operatively connected to said cam band for connecting said cam band to a source of power.

ROBERT HASLAM.