US3468060A - Closure member operating mechanism - Google Patents

Description

Sept. 23, 1969 R. c. MuRslNNA CLOSURE MEMBER OPERATING MECHANISM Filed June 20. 1967 5 Sheets-Sheet 1 ^\l AHA A A I /N vE/v rol? R/cHA/w c. MURS/MVA M Mmm A 7' T ORA/f YS Sept. 23, 1969 R. c. MURSINNA CLOSURE MEMBER OPERATING MECHANISM 5 Sheets-Sheet 2 Filed June 20, 196'? INVENTOR RICHARD C. MURS/NNI! Arron/v5 vys Sept. 23, 1969 R. c. MuRslNNA 3,468,060

CLOSURE MEMBER OPERATING MECHANISM Filed June 20, 1967 5 Sheets-Sheet 5 44\ u F/G. 5

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OUTSIDE GARAGE /NvE/vron R/cHARa c. MURS/MVA Arron/VHS CLOSURE MEMBER OPERATING MECHANISM Richard C. Mursinna, San Diego, Calif., assignor, by

mesne assignments, to Ametek, Inc., New York,

NX., a corporation of Delaware Filed `Iune 20, 1967, Ser. No. 647,456 Int. Cl. 1505i /00 U.S. Cl. 49-200 14 Claims ABSTRACT OF THE DISCLOSURE Operating mechanism for closure members Such as garage doors and the like including a spring arrangement for biasing the door from one to the other of two positions and a hydraulic type operating mechanism for moving the door from the second to the first of these positions and for maintaining it in the first position. Two actuators are preferably provided so that the hydraulic mechanism can be actuated from inside or outside the structure with which the closure member is associated.

BACKGROUND, SUMMARY, AND OBIECTS OF THE INVENTION This invention relates to operating mechanism for closure members and, more specifically, to hydraulic operating mechanism for closure members such as garage doors and the like.

The novel operating mechanism of the present invention is intended to be used in conjunction with standard four-bar, manual type door operating mechanism with the springs of the manual mechanism being retuned to bias the door to either its open or closed position, and the hydraulic mechanism being utilized to move the door to and maintain it in the other of these positions.

Generally speaking, the hydraulic operating mechanism includes a hydraulic motor and a motion transmitting linkage for connecting the hydraulic motor to the manual door operating mechanism. Water may be employed as the hydraulic fluid and a three-way solenoid valve is utilized to either admit water to or permit it to discharge from the hydraulic motor, which respec-tively effects movement of the door in one direction by the hydraulic motor or frees it for movement in the opposite direction by the springs of the manual door operating mechanism.

Operation of the solenoid valve is preferably controlled by a system including a pneumatic actuator located outside of the structure from which the door is supported and a second actuator located inside the structure so that the door may be opened and closed from both inside and outside of the structure.

A number of hydraulic closure operating systems have heretofore been proposed. Among these are the systems disclosed in U.S. Patents Nos. 2,260,080 to Lane, 2,293,462 te Haynes, 2,321,079 to Greenwald, 2,440,561 to Wilder, 2,533,423 to Bunch, 2,625,390 to McFadden, 2,641,467 to Reed, and 2,929,623 to Marmont. However, all of these, like others heretofore known, have important drawbacks such as complexity, high production, operating, and maintenance costs, lack of reliability, inecient operation, and lack of compatibility with the hardware of existing installations.

One of the important advantages of the present invention over heretofore available hydraulic door operating mechanisms is its simplicity, which makes it inexpensive to produce and maintain. Other advantages are the ease with which it can be added to existing manually operated installations and the lack of overhead hardware, which eliminates the ceiling clutter associated with heretofore commercially available, power-operated door open- States Patent O 3,468,060 Patented Sept. 23, 1969 icc ing mechanisms. Still other advantages of the present invention are its capabity of operating on water as a hydraulic fluid, the absence of any electrical wiring outside of the structure with which the operating mechanism is associated, maximum utilization of off-the-shelf components, land low operating cost.

From the foregoing it will be apparent that one important and primary object of the present invention resides in the provision of novel, improved hydraulic operating mechanisms for closure members such as garage doors and the like.

Other related and important but more specific objects of the present invention reside in the provision 0f hydraulic operating mechanisms in accord with the preceding object:

(l) Which are compatible with conventional, manual door operating mechanisms and can accordingly be added to existing installations at relatively low cost.

(2) Are simple and have a small number of components and, accordingly, are inexpensive to manufacture and maintain.

(3) In conjunction with the preceding object, make maximum utilization of off-the-shelf commercial components.

(4) In conjunction with object (2), make use of the components of existing manually operated door mechanisms to perform part of the closure opening and closing function to minimize the number of additional components required.

(5) Are inexpensive to operate and are extremely quiet.

(6) Do not have voverhead components and accordingly do not clutter the ceilings of structures in which they are employed.

(7) Can be actuated from either inside or outside the structure in which they are incorporated.

Other important objects, further novel features, and additional advantages of the present invention will become more apparent from the appended claims and as the ensuing detailed description and discussion proceeds in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIGURE 1 is a schematic illustration of a structure having a door equipped with a hydraulic operating mechanism constructed in accord with the principles of the present invention the door being shown in the closed position;

FIGURE 2 is a view similar to FIGURE 1 but with the door in the open position;

FIGURE 3 is an exploded view of the door-attached components of the hydraulic operating mechanism;

FIGURE 4 is a partial side view of the door and the door-attached components of the operating mechanism;

FIGURE 5 is an end view of the mechanism shown in FIGURE 4; and

FIGURE 6 is a partly schematic illustration of the components provided for actuating the hydraulic control mechanism.

DETAILED DESCRIPTION OF AN EXEMPLARY PREFERRED EMBODIMENT Referring now to the drawing, FIGURES 1 and 2 depict a structure 10 having a door 12 adapted to cover an opening 14 in the structure. Door 12 is supported from structure 10 by a pair of four-bar type, manual door operators 16 and is adapted to be moved between the closed position of FIGURE 1 and the open position of FIGURE 2 by springs 18 incorporated in door operators 16 and by a hydraulic door operating mechanism 20 constructed in accord with the principles of the present invention.

Referring now to FIGURE 3, the illustrated door operators 16 are of ythe conventional, commercially available Holmes type, and their details are not part of the present invention. Accordingly, it is not considered necessary to describe them in detail herein. Briefly speaking, however, each of the door operators 16 includes a support plate 22 bol-ted or otherwise fixed to structure 10 adjacent door 12. Mounted on plate 22 by a pivot member 24 is a door supporting crank member or master arm 26, the lower end of which is fixed by pivot member 28 to a vertically extending channel 30 mounted on the edge of door 12.

Also pivotally fixed to support plate 22 is an elongated, depending link 32. The lower end of link 32 is fixed as by pivot member 34 -to a bracket 36 mounted on channel 30.

The remaining major component of each door operator 16 is the tension spring 18 mentioned above. This spring is connected at its lower end through a turnbuckle 40 to structure 10. The upper end of each spring 18 is connected by a tension adjusting bracket 42 to the upper part 44 of master arm 26.

Exertion of an outward and upwardly directed force of the lower part of door 12 will cause door operators 16 to swing the door outwardly and upwardly from the vertical position shown in FIGURE 1 to the open position of FIGURE 2 in which the garage door is at the top of opening 14 and parallel to the ceiling (not shown) in structure 10. To close the door, an outward and then downwardly directed force is exerted on the door, and the process is reversed.

In the manner in which door operators 16 are conventionally employed, springs 18 are tuned to assist in moving door 12 from both the closed to the open and the open to the closed positions, reducing the effort required to open and close the door. For the purposes of the present invention, the springs 18 are retuned by adjustment of brackets 42 and turnbuckle 40 so tha-t they will continuously bias door 12 toward its open, FIGURE 2 position. Thus, absent a restraining force acting in the opposite direction, springs 18 will move door 12 to and maintain it in its open position.

Referring now to FIGURES l-6, the novel hydraulic door operating mechanism 20 of the present invention is employed to provide the oppositely acting force just mentioned; i.e., to move door 12 to and maintain it in its closed, FIGURE 1 position. The major components of operating mechanism 20 are a hydraulic motor 46 associated with each door operator 16, a motion transmitting assembly 48 for connecting the hydraulic motor to the associated manual door operator, a fluid flow system 50 including a solenoid valve 52 for controlling the dlow of hydraulic fluid to and the discharge of the fluid from hydraulic motors 46, and a control system including an electrical switch 54 for energizing and dta-energizing the solenoid valve.

Referring now specifically to FIGURES 1-3, hydraulic motors 46 are of conventional construction, including a cylinder 56 typically having a 2 or 21/2 inch diameter depending on the pressure of the hydraulic fluid and provided with a drip-air vent 57, a piston 58, and a connecting rod 60 fixed to the piston and extending through one end of the hydraulic cylinder. The cylinders 56 of the hydraulic motors are attached to door supporting structure at each side of door 12 by turnbuckles 262 and lag screws 64 or other fasteners.

The connecting rods 60 of the hydraulic motors are connected to door operators 16 by the motion transmitting assemblies 48 mentioned briefly above. As best shown in FIGURE 3, each ofthe assemblies 48 includes a sprocket 66 and a flexible, link-type belt 68. The sprocket 66 is fixed to a Z-shaped mounting bracket 70 by bolts 72 and 74, and bracket 70 is in turn bolted to the upper part 44 of the master arm 26 of the associated door operator 16. An L-shaped bracket 76 bolted to Z-shaped bracket 70 limits rotational movement of the latter relative to master arm 26.

The upper end of flexible chain 68 is fixed to sprocket 66 by a link 78. The lower end of the chain is similarly fixed to the connecting rod 60 of the associated hydraulic motor by a link 80.

Referring now specifically to FIGURES 4 and 5, the center S2 of each sprocket 66 lies approximately 1/z inch aboxe the axis 84 about which the associated master arm 26 pivots; and the point at which flexible chain 68 is attached to the sprocket lies to the left of pivot axis 84. Accordingly, downward forces on chains 68 will rotate master arms 26 (and, accordingly, door 12) in a counterclockwise direction (as shown in FIGURE 4), moving door 12 from the open to the closed position.

Referring now to FIGURES 1 and 2, the downward force on each motion transmitting flexible link 68 is produced by admitting a hydraulic fluid under pressure to the interior 86 of the associated hydraulic motor 46 above piston 58. This moves the piston and connecting rod 60 downwardly in cylinder 56, producing a downward force on link 68 to move door 12 to the closed posi-tion. When the door reaches the closed position, it will engage an appropriate stop (not shown) to prevent further movement. The door is maintained in this position by the continued presence of operating fluid under pressure on the top side of each hydraulic motor piston 58.

To open the door, the admission of pressurized operating fluid to the hydraulic motors is terminated; and the interiors 86 of the motors are connected to a drain, freeing pistons 58 for upward movement in cylinders 46. The springs 18 in door operators 16 accordingly drag the pistons upward in cylinders 56 and, in doing so, move door 12 to and maintain it in its open position.

Referring now to FIGURES 1 and 2, the admission of operating fluid to and the discharge of the fluid from hydraulic motors 46 is controlled by the three-way solenoid valve 52 mentioned above which, when de-energized, assumes the configuration shown in FIGURE 1 in which it provides fluid communication between hydraulic lines 88 and 90. Hydraulic line 80 communicates through T- fitting 92 and branch hydraulic lines 94 with the interiors 86 of hydraulic motors 46 above pistons 58. Line 90 is connected through a manual valve 96 to a source of hydraulic fluid (not shown), which is preferably the city water or other water supply. Hydraulic motors 46 of the type described will typically require `a 40-125 p.s.i.g. source, and any source providing water at such pressures can be used. Accordingly, with solenoid valve 52 de-energized, the pressurized water supply is connected to and supplies water under pressure to the interiors of the motors. Therefore, when solenoid valve 52 is de-energized, door 12 is moved to the closed position of FIGURE 1 and thereafter maintained in this position as explained above.

When solenoid valve 52 is energized, the connection between branch conduits 94 and supply conduit 90 is interrupted; `and the hydraulic motors are connected through the branch conduits, T 92, conduit 88, and the solenoid valve to drain conduit 97. This relieves the pressure on pistons 58 and permits springs 18 to move door 12 to its open position as described above.

Referring now to FIGURES l and 2, solenoid valve 52 is energized and de-energized by respectively closing and opening switch 54, which is connected in series between the solenoid Valve and a source 98 of operating voltage (typically volt A.C.) by leads L100 and L101. Switch 54 is of the push-on, push-off type and can be opened and closed by an actuator 102 located within structure 10 or a remote actuator 103 located outside of the structure.

As shown in FIGURE 6, switch 54 is supported from any convenient part of structure 10 by a bracket 104 to which a housing 106 providing a pressure chamber 108 is also attached. Mounted within housing 106 is a conventional pressure diaphragm 110.

The contactor 112 of switch 54 extends through housing 106 into engagement with diaphragm 110 so that successive displacements of diaphragm 110 to the left as shown in FIGURE 6 alternately close and open the switch. The switch operating displacement of diaphragm 110 can be effected by either of the two actuators 102 and 103 mentioned above.

Actuator 102 includes a plunger 114 extending through housing 106 into engagement with the side of the diaphragm opposite switch contactor 112. A compression spring 116 surrounding the stem of the plunger outside of the housing maintains it in the inoperative position shown in FIGURE 6; and a flexible dust cover 118 protects the actuator mechanism against debris from the ambient surroundings and provides a pneumatic seal against pressure generated when actuator 120 is depressed.

Movement of plunger 114 to the left as shown in FIG- URE 6 effects -a corresponding displacement of diaphragm 110. As mentioned above, this is effective to first close and then open the contacts of switch 54.

Referring still to FIGURE 6, remote actuator 103 includes a squeeze bulb (typically having a four ounce or similar capacity) 120 connected through fitting 122, pneumatic line 124 (which will typically be 3716 inch O.D. plastic tubing buried up to several inches in the ground to protect it from damage) and tting 126 with the pressure chamber 108 in housing 106. When bulb 120 is squeezed or depressed the pressure in the bulb and, accordingly, that in connecting line 124 and pressure charnber 108 increases. The increase in pressure displaces diaphragm 110 to the left as shown in FIGURE 6 with the results described above. Since squeeze bulb 120 is normally located in an out-of-door location (it may be up to 60 feet away from the switch), it is preferably surrounded by a housing 128 provided with a door 130 and lock 132. This limits access to the squeeze bulb and to the structure with which it is associated. Where added expense is acceptable, the remote actuator just described can be replaced with a radio transmitter-receiver or similar arrangement so that the garage door can be opened and closed without leaving the automobile.

From the foregoing, it will be apparent that the novel hydraulic operating mechanism of the present invention has very few components, due in part to its utilization of existing hardware, and that these components are, almost without exception, standard oi-the-shelf hardware. For example, hydraulic motors of the type described above are readily available components as are solenoid valve 52 and on-oi switch 54. Similarly, pressure chamber providing housing 106 together with actuator 102 can be readily fabricated by minor modifications to a conventional vacuum advance control from an automobile ignition system such as that manufactured by Vulcan Motor Products, Inc.

Furthermore, it will be readily apparent that the novel hydraulic operating hystem of the present invention can be readily added to existing installations since the doorassociated components simply bolt on to the existing door operating mechanism. The remaining components of the system may be installed with similar facility.

In conjunction with the foregoing, the only control component located outside the structure is remote actuator 103; and this component is connected to the remainder of the control system solely by a pneumatic line. This eliminates the necessity of running electrical leads outside of the structure with which the system is employed, eliminating a source of considerable expense and the necessity of employing a specialist to make the installation.

A further important advantage of the invention, mentioned briey above, is its operating economy. Since the only electrical power consumed is in operating solenoid valve 52 (which will typically consume no more power than a 16 watt light bulb and that only for short periods of time) and as the system is otherwise operated by water from a city water supply or other source, operating costs are minimal.

Also, there is no need to employ expensive safety devices such as limit switches or override clutches in the hydraulic door operating mechanisms described herein. Because of the small forces exerted by the hydraulic motors, the door can be stopped in the closed position by a simple mechanical stop. For the same reason, the door can be stopped in any position during closing movement by the application of a small force to it to stall the hydraulic motor, which is a significant safety feature.

Another feature of the invention is that, with the exception of the control components, those added in accord with the present invention are located solely along the edges of the door with which they are associated. Accordingly, in contrast to conventional power operated mechanisms for swing out type doors, no ceiling-mounted components are added with the addition of the power operated system. This is particularly important where the garage or similar structure doubles as living quarters.

Although the present invention has been described primarily in relation to its application to garage doors, it will be apparent to those skilled in the arts to which the present invention pertains that it is by no means limited to this one application. Accordingly, insofar as adaptations of the principles of the present invention to other applications are not expressly excluded from the appended claims, they are fully intended to be covered therein.

The invention may be embodied in other specic forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrated and not restrictive. the scope of the invention vbeing indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. The combination of a structure having an opening therein; a closure member yfor covering said opening; means supporting the closure member from said structure for movement between open and closed positions with respect to said opening; means exerting a continuous force biasing the closure member toward the open position; means including at least one hydraulic motor operatively connected to said closure member and capable upon the admission of operating fluid thereto of moving said closure member from said open position to said closed position and for thereafter maintaining said member in said closed position against the force exerted by said biasing means; and selectively operable, biconfigurational fluid supply, discharge, and iiow controlling means capable in one configuration of effecting an admission of operating iiuid to said motor whereby said motor will move said closure member to and maintain it in said closed position, said selectively operable means being capable in the other configuration thereof of permitting a discharge of the operating iiuid from the hydraulic motor and thereby -freeing said closure member lfor movement to said open position by said biasing means.

2. The combination of claim 1, wherein said iiow controlling means includes a solenoid type valve for admitting operating fluid to said hydraulic motor to effect closure moving operation of said hydraulic motor; circuit means including an electrical switch capable when said switch is closed of energizing said solenoid valve to a configuration in which said valve will admit operating fluid to said hydraulic motor; and means for closing said switch including a pneumatic type remote actuator adapted to be located without the structure and fluid conduit means operatively connecting said remote actuator to said switch.

3. The combination of claim 2, wherein said switch closing means comprises a second actuator located in the structure, whereby movement of the closure member can be initiated from both inside and outside of the structure.

4. The combination of claim 2, wherein said pneumatic actuator is located outside the structure and including a housing surrounding said actuator and means for locking said housing and thereby limiting access to said actuator.

5. The combination of a structure having an opening therein; a closure member for covering said opening; means supporting the closure member from said structure for movement between open and closed positions with respect to said opening including first supporting members pivotally fixed at one end to said structure adjacent opposite sides of the closure member, means pivotally fixing said first supporting members at the opposite end thereof to said closure member at opposite sides thereof, and a second supporting member associated with each first supporting member and pivotally fixed at one end to said associated member intermediate the ends thereof, said second members being pivotally fixed at their opposite ends to said closure member; means biasing the closure member toward one of said positions `comprising a tension spring associated with each of the pairs of pivotally connected door supporting members, one end of each spring being fixed to the structure below the point of pivotal connection of the associated second supporting member thereto, and the opposite end thereof being fixed to the associated first supporting member above the connection between said first member and the associated second member; means including a hydraulic motor including piston and cylinder components operatively associated with each pair of supporting members and capable upon the admission of operating fiuid thereto of moving said closure member from said one position thereof to the other position thereof and for thereafter maintaining said member in said other position against the force exerted by said biasing means, one of the aforesaid components of each motor being fixed to said structure; a motion transmitting linkage connecting the other of the aforesaid components of each hydraulic motor to the closure supporting member; and selectively operable, biconfigurational fluid supply, discharge, and iiow controlling means capable in one configuration of effecting an admission of operating fluid to said motor whereby said motor will move said closure member to and maintain it in said other position, said selectively operable means being capable in the other configuration thereof of permitting a discharge of the operating fluid from the hydraulic motor and thereby freeing said closure member for movement to said one position by said biasing means.

6. The combination of claim 5, wherein the motion transmitting linkages each include a motion transmitting member, means fixing said member to the associated first closure supporting member for rotation therewith about the pivot axis of the member relative to the structure and a fiexible link adapted to wrap around the periphery of the motion transmitting member, said flexible link being connected at one end to said motion transmitting member and at the other end to one of the components of the associated hydraulic motor.

7. The combination of a closure member supporting linkage .for moving a closure member supported thereby between open and closed positions, said linkage including an elongated, closure supporting member adapted to have the closure member fixed thereto; a first operating member pivotally fixed at one end to said supporting member intermediate the ends thereof; means for pivotally fixing said first operating member to the structure with which the closure member is associated; a second operating member pivotally fixed at one end to said supporting member in spaced relation to said one end of said first operating member, the other end of said second operating member being pivotally xed to said second operating member intermediate the ends thereof and means for converting said closure member supporting linkage for hydraulic operation from one to the other of said open and closed positions including a third operating member fixed to said rst operating member for rotation about the axis about which said first operating member pivots with respect to the structure with which the closure member is associated; a hydraulic motor including a cylinder component and a piston component slidable in said cylinder component; a iiexible belt member connected at one end to said third operating member and at the other end to one of the aforesaid components of the hydraulic motor; link means for attaching the other of the component of the hydraulic motor to the structure with which the closure member operating mechanism is associated; and means for moving said closure member from said other position to said one position including spring means connected at one end to said first operating member and means for connecting the other end of said spring means to the structure with which the closure member is associated.

8. The combination of claim 7, together with means including a solenoid type valve for admitting operating fluid to said hydraulic motor to effect closure moving operation of said motor; circuit means including an electrical switch capable when the switch is closed of energizing said solenoid valve to a configuration in which said valve will admit operating fluid to said hydraulic motor; and means for closing said switch means including a pneumatic type remote switch actuator and fluid conduit means connecting said remote actuator to said switch.

9. The mechanism of claim 8, wherein said motion transmitting member comprises a sprocket and said connecting means is a flexible belt member connected at one end to said sprocket and at the other to the piston of the hydraulic motor.

10. The combination of claim 8, together with fiuid discharge means connectable to the interior of said hydraulic motor by the de-energization of said solenoid valve whereby, when said switch is opened to de-energize said solenoid valve, the closure member with which the hydraulic operating mechanism is associated is freed for movement by other means.

11. Mechanism for converting a manual type closure member operating linkage including a pivotally mounted closure supporting member to hydraulic operation comprising a motion transmitting member adapted to be fixed to said closure supporting member for rotating said member about its pivot axis; a hydraulic motor; means so connecting said motor to said motion transmitting member that operation of said motor will effect closure moving motion of the motion transmitting member; a solenoid type valve for admitting operating fiuid to said motor to operate the motor; means including an electrical switch capable when said switch is closed of energizing said solenoid valve to a configuration in which said valve will admit operating fiuid to said motor; and means for closing said switch including a housing having a diaphragm therein, said switch having a contactor extending through said housing into operative relationship with said diaphragm; a pneumatic type remote actuator; means providing fluid communication between said pneumatic actuator and the interior of said housing, whereby operation of said actuator creates a pressure in said housing effective to displace said diaphragm and effect a switch closing movement of the switch contactor; and a second mechanical switch actuator extending through said housing into diaphragm displacing relationship with said diaphragm, whereby the closing of said switch may be effected from rst and second separated locations.

12. Mechanism for converting a manual type closure member operating linkage including a pivotally mounted closure supporting member to hydraulic operation comprising a rotatable member adapted to be fixed to said closure supporting member for rotating said member about its pivot axis; a hydraulic motor including a cylinder cornponent and a piston component slidable in said cylinder component; a flexible belt member connected at one end to said rotatable member and at the other to the piston component of the hydraulic motor; link means for attaching the cylinder component of the hydraulic motor to the structure with which the closure member operating mechanism is associated; a solenoid type valve for admitting operating uid to said motor to operate the motor; means including an electrical switch capable when said switch is closed of energizing said solenoid valve to a configuration in which said valve will admit operating fluid to said motor; and means including a remote actuator for closing said switch.

13. The mechanism of claim 12, wherein said switch closing means includes a housing having a diaphragm therein, wherein said switch has a contactor extending through said housing into operative relationship with said diaphragm, and including means providing fluid communication between said pneumatic actuator and the interior 15 housing into diaphragm displacing relationship with said diaphragm, whereby the closing of said switch may be effected from rst and second separated locations.

References Cited UNITED STATES PATENTS 1,421,002 6/ 1922 Hagen 49-200 1,941,574 1/1934 Nichols 49-200 2,330,006 9/1943 Odenthal 49-199 X 2,344,276 3/1944 Thompson 49-265 X 2,624,569 1/ 1953 Peterson 49-265 X 2,663,047 12/1953 Grenzeback 49-l97 X FOREIGN PATENTS 973,596 10/1964 Great Britain.

DENNIS L. TAYLOR, Primary Examiner U.S. Cl. XR.

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