US2077659A

US2077659A - Door operating mechanism

Info

Publication number: US2077659A
Application number: US63153A
Authority: US
Inventors: James E Bancroft
Original assignee: RICHMOND FIREPROOF DOOR COMPAN
Current assignee: RICHMOND FIREPROOF DOOR Co; RICHMOND FIREPROOF DOOR COMPAN
Priority date: 1936-02-10
Filing date: 1936-02-10
Publication date: 1937-04-20
Anticipated expiration: 1954-04-20

Description

April 20, 1937. J. E. BANCROFT 2,077,659

DOOR OPERATING MECHANISM A.

(Ittorneg April 20, 1937. J. E. BANcRoFT DOOR OPERATING MECHANISM Filed Feb. 10, `l956 6 Sheets-Sheet 2 17/ @1 Amddw (Ittorneg April 20, 1937. J. E, BANCROFT 2,077,659

DOOR OPERATING MECHANISM I Filed Feb. 1o, 195e e sheets-sheet 4 Slwentor;

J. E. BANCROFT DOOR OPERATING MECHANISM April 20,1937.

Filed Feb. lO, 1956 e sheets-sheet 5 Snventor:

. 'BHC/EM (Ittorneg April 20,V 1937. J. E. BANcRoFT DOOR OPERATING MECHANISM Filed Feb. l0, 1936 6 Sheets-Sheet 6 Cttomeg Patented Apr. 20, 1937 UNITED STATES PATENT OFFHQE DOOR OPERATING MECHANISM Application February 10, 1936, Serial No. 63,153

8 Claims.

This invention relates to an operating mechanism which is applicable to sliding doors, such as for instance,rdoors located on elevator cars and at floor landing openings to'elevator hatches.

An object of the invention is the provision of an operating mechanism which will operate two units of doors simultaneously.

Another object of the invention is to provide a clutch mechanism which, when operated in 1o connection with an operating mechanism, will operate a second unit of doors and thereby eliminate the necessity of providing a separate operating unit for each unit of doors to be operated.

Still another object of the invention is the prol5 vision of a dual operator which is eliicient in its operation, which is simple of construction and operation, and which is economical to manufacture and to maintain in operative condition.

Other objects and advantages of the invention will suggest themselves in the course of the following description, and that which is new will be correlated in the appended claims.

The most satisfactory manner of carrying out Y the principles of the invention in a practical, economical, and efficient manner is shown in the accompanying six sheets of drawings, in which- Figure 1 is an exterior or shaft side elevation of an elevator car having horizontally sliding doors suspended thereon, with the operating mechanism for the doors being secured on the top of the elevator car, and with the operating arms extending from the operating mechanism to the doors, and with the doors being shown lin closed position.

Figure 2 is an enlarged detail showing the break joint formed between the arm members lli and i6.

Figure 3 is a shaft side elevation of a pair of horizontally sliding floor landing doors, the same being equipped with operating arms and with an engaging n attached to the operating arms, and with the doors being shown in closed position.

Figure 4 is an enlarged detail showing the break joint formed between the

arm members

40 and 44.

Figure 5 is an elevation of the operating mechanisrn shown with the clutch mechanism in normally disengaged position.

igure 6 is an elevation of the operating mechfr) anism in the position which is assumed when the sii) normally engaged position.

Figure 7 is a top plan View of the clutch mechanism with the same being in normally disengaged position.

doors are in open position, and with the clutch in4 Fig. 8 is a side elevation of the clutch mechanism, taken from line 8--8 of Figure '7.

Figure 9 is a rear side elevation of the clutch mechanism, taken from line 9,-9 of Figure 8.

Figure 10 is a top plan view of the clutch mechanism in normally engaged position.

Figure 1l is a side elevation of the clutch mechanism, taken from line l l-ll of Figure 10.

Figure 12 is a front elevation of the clutch mechanism, taken from line l2-i2 of Figure 10.

Figure 13 is a detail cross section through the air check cylinder, taken on line [3 13 of Figure 11.

Figure 14 is a detail longitudinal vertical section through the clutch mechanism with the same being shown in engaged position, taken on line Ill- I4 of Figure 12.

Figure 15 is a top plan view ofthe yoke and bracket members and the engaging rollers, taken from line l5-I5 of Figure 11. f

yFigure 16 is a detail longitudinal section through one of the yoke arms, taken on line lli- I6 of Figure 15.

one of the bracket members and a roller, taken on line l'l-I'l of Figure 15.

Figure 18 is a detail longitudinalvertical section through the clutch mechanism with the same being shown in disengaged position, taken on line |8-I8 of Figure 9.

Figure 19 is a detail section through one of the air check valves, taken on line E53-i9 of Figure '7.

Figure 20 is a detail isometric view of the clutch-carrying bar and the associated members thereof.

Similar characters designate like parts throughout the several views.

In order that the construction. the operation, and the advantages of the invention may be more fully understood and appreciated, I will now take up a detailed description thereof, in which the same will be more fully and comprehensively set forth.

In the drawings, A designates the elevator car on which the doors B and B are slidably suspended by means of the rollers C mounted on the track D. I designates the operating unit which is rigidly secured on the top of the elevator car by means of the bolts 2. 3 designates the crank arm which is secured to the projecting end portion of the operator shaft i. l designates a mounting angle which is rigidly secured to the top of the elevator car, the same having the upwardly extending end bracket 4 and the brace member 4 rigidly secured thereto. The operating Figure 17 is aidetail vertical section through arm 5 is pivotally secured to the mounting angle 4 by means of the bolt 6, and the lower portion of the operating arm 5 is slidably secured to one edge of the door B by means of the bolt 'I extending through the slotted bracket 8, with the bracket 8 being rigidly secured on the edge of the door B by means of the cap screws 8. The arm 9 extends horizontally from the arm 5, and is pivotally secured thereto by means of a cap screw I which is located midway between the bolts 6 and I. The opposite end of the arm 9 is pivotally secured to the angle bracket II by means of the cap screw I2, the angle bracket II is rigidly secured on the edge of the door B by means of the cap screws I I.

The angular-shaped lever I3 is pivotally secured thro-ugh the arm 5 and the mounting angle 4 by means oi the bolt 6. The arm I4 is pivotally secured to the lower end of the lever I3 by means of the cap screw I5, and is pivotally secured, at its lower portion, by the cap screw I1 to the bar I6 which is slidably secured to the edge portion of the door B by means of the bolt '1, with the bar I6 then extending across the door and providing a handle for manual operation of the doors. A break joint is formed between the bars I4 and I 5 as more clearly shown in Figure 2. The bar I6 has the projecting pin I8 rigidly secured thereto, the same registers with the notch I4 which is formed in one edge of the bar I4. The cap screw I9 is threaded into the bar I4 with the end of the cap screw being convex and registering with the concave aperture I6' which is formed in the surface of the bar I 6. By the above-described arrangement, when the power supply is broken fro-m the doors, the doors may be manually operated without removing any of the operating arms or the connections thereof.

The connecting arm extends from the crank arm 3 to the upper end of the lever I3, the same being pivotally secured to the crank arm by means of the cap screw 3' and is pivotally secured to the upper end of the lever I3 by means of the cap screw 2 I. of two separate pieces of bar which are adjustably secured together by means4 of the cap screw or bolt 22, which allows the arm 20 to be adjusted for any variations which might occur in the other members of the operating arms.

An air check assembly 23 is pivotally secured, at one end, to the upwardly extending bracket 4', and is pivotally secured, at the opposite end thereof, to the connecting arm 2D by means of the bolt 24, and provides a cushioning means for the operating arms during the operation thereof.

The bar 25 is pivotally secured to the upper end of the operating arm 5 by means of the bolt 26 and extends horizontally therefrom, as shown in Figures l, 5, and 6. The arm 2l is pivotally secured to the mounting angle 4 by means of the bolt 28 and extends upwardly therefrom, and is pivotally secured, at its upper end, to the bar 25 by means of the cap screw 2S. It will be noted that the arm .Z'l is parallel with relation to the operating arm 5, and that the distance between the cap screw 6 and the bolt 25 is the same as the distance between the bclt 28 and the cap screw 29, thereby maintaining the arm 2l and the operating arm 5 in parallel relation with each other at all times.

Referring now to Figure 3, E and E designate the horizontally slidable floor landing doors which are suspended on the rollers F positioned on the tracks G. The tracks G are rigidly secured to the usual hanger plate which is anchored into The connecting arm is comprised the wall above the door opening in the usual manner. 30 designates the bracket members which are rigidly secured, at their lower portions, to the hanger plate in any well-known manner. The arm 3| is pivotally secured,l at its upper end. to one of the bracket members 3l! by means of the cap screw 32, and is slidably secured, at its lower end, through an elongated aperture formed through the bracket 34 by means of the bolt 33. The bracket 34 is rigidly secured on the edge of the door E by means of the cap screws 34.

The bar 35 extends horizontally from the arm 3| at a point located midway between the cap screw 32 and the bolt 33, and is pivotally secured to the arm 3! by means of the cap screw 36, and is pivotally secured at the opposite end thereof, to the angle bracket 31 by means of the bolt 33. The angle bracket 3l' is rigidly secured on the edge of the door E by means of the strap 39 and the cap screws 39. The arm 40 is pivotally secured to a second bracket member 38 by means of the cap screw 4I with the upper end portion thereof being pivotally secured to one end of the horizontally positioned bar 42 by means of the bolt 43. Near the lower end of the arm 4) the same is pivotally secured to the upper end of the bar 44 by means of the cap screw 45. The projecting pin 46 is rigidly secured to the face of the arm 45 and is located between the cap screw 45 and the extreme lower end of the arm 4U. A notch 44 is formed in one edge of the bar 44 and is adapted to receive the pin 43. The break joint formed by the arm 4U and the bar 44, which allows manual operation of the doors E and E', is clearly illustrated in broken position in Figure 4. The bar 44 is pivotally secured to the arm 3l by means of the cap screw 4S, and a handle member 41 is rigidly secured to the lower end por-- tion of the bar 44 by means of the rivets 4l. The bar member 48 is pivotally secured, at its lower end, to a third bracket member 35 by means of the cap screw 49, and with the upper end thereof being pivotally secured to the central portion of the iin member 59. The n member 56 is positioned vertically and has the central portion 50 which is rigidly secured through the end portion of the bar member 42 by means of the bolts 5l. 52 designates an electrical Contact switch which is connected in series with the elevator control circuit. 'Ihe electrical contact switch 52 has a contact pin extending outwardly therefrom, with the contact pin being in contactable relation with the end portion of the base 5 I. The electrical contact switch 52 is rigidly secured to the structural angle member 53 by means of the bolts 52.

Referring now to the clutch mechanism and the associated parts thereof in detail, thev plate 25 is rigidly secured to the upper surface of the bar 25. The member 54 is rigidly secured to the face of the plate 25 and extends upwardly therefrom. The upward extension 54 has the horizontal portion 55 formed at right angles thereto and is formed integral therewith, the same having the apertures 55 formed therethrough near the end thereof and through which the cap screws 56 extend. The cap screws 56 are threaded into the upper portion of the forward end cap member 5"! of the air check assembly. 53 refers to the rear end cap member of the air check assembly. The cylinder is positioned between the

end cap members

57 and 58 with the gaskets 6I] and 6I placed at the ends of the cylinder. The forward end cap member 5l has a centrally located aperture formed therethrough for the reception of the piston rod 62. The inner or rear end of the piston rod 62 has the turned portion 62 and the threaded portion 62 formed thereon with the ilat washers 63 and the cup washers 64 being secured on the turned portion 62 by means of the nut 65 which is threaded onto the threaded portion 62". The forward end portion of the piston rod has an aperture formed therethrough for the reception of the connecting pin 08. The

end cap members

51 and 58 are rigidly secured on the ends of the cylinder by means of the bolts 66 extending through apertures 51 and 58' respectively, and are rigidly secured by means of the nuts 51. The block member 68 is rigidly secured to the face of the plate 25' and projects forwardly therefrom. The block member 68 has the two apertures 68 formed vertically therethrough which provide for the reception of the pivot pins 69 and 10. The

-roller brackets 1| and 12 each have upper and lower arms formed thereon and through which apertures are formed vertically. The roller brackets 1| and 12 are pivotally secured to the block member 88 by means of the pivot pins 09 and 10 respectively extending vertically therethrough. The pivot pins 59 and 10 are prevented from moving vertically by the cotters G9 and 10 respectively which extend through apertures formed through the pivot pins near each end thereof. Thc roller brackets 1| and 12 have the

rearwardly extending arms

13 and 14 respectively formed integral therewith, and with the same forming the U-shaped channels and 15 respectively. The

shafts

11 and 13 are formed integral with the lower portions of the roller brackets 1| and 12 respectively. The rollers 19, together with their bearings 80, are revolvably secured on the

shafts

11 and 18 by means of the washers 8| and the pins 82.

The yoke shaft 83 has the threaded portion 84 formed on the forward end portion thereof and forming the shoulder 85. The threaded portion 84 is threaded into a threaded aperture 54' which is formed horizontally through the members 25' and 54 with the shoulder 85 being tightcned against the rear side of the member 25. The yoke member 85 has an aperture formed longitudinally through the central portion thereof, and through which the yoke shaft 83 extends. The upwardly projecting arm 81 is formed integrally with the body portion of the yoke member 85, and has a channeled slot 81' formedin the upper end portion thereof with apertures formed horizontally through the upwardly projecting sides of the channeled slot. The pin 88 pivotally secures the upper end of the arm 81. to the forward end portion of the piston rod 62, as shown in Figures 14 and 18. Extending outwardly from the forward end portion of the body of the yoke member are the

arms

89 and 90 having the forwardly projecting forks 9| and 92 respectively formed integrally therewith. The forks 9| and 92 each have apertures formed vertically therethrough near the forward ends thereof for the reception of the respective bearing pins 93. A roller 94 is positioned on each of the bearing pins 93 and is located between the upper and the lower portions of each of the forks 9| and 92, and a cotter 93 is secured through the lower end portion of each of the pins 93. The rollers 94 are thereby positioned in the U-shaped channels which are formed in the roller brackets 1l and 12 by the

rearwardly extending arms

13 and 14 respectively. The external threads 95 are formed integrally with the rear portion of the body of the yoke member 80.

The sheave 96 has the hub portion 91 formed integrally therewith, and into which the internally threaded collar member 98 is rigidly secured by means of the set screw 99. The unit cornprised of the sheave 96, the hub 91, and the set screw 99 is threaded onto the threaded portion 95 of the yoke member 86. The sheave 90 is provided with the bearing |00 Secured in place by means of the retaining plate |0| and the threaded screws |02. The bearing |00 is secured on the portion 83 of the yoke shaft 83 by means of the bushing |03 and the nut |04 which is threaded onto the threaded portion 83 of the shaft 83, with .the nut |04 being rigidly secured on the threaded portion 83 by means of the pin 55 which extends through both the nut |94 and the threaded portion 83, as shown in Figures 14 and 18. The'sheave 95 has the groove 95 formed in the periphery thereof for the reception of the belt |06.

The electric motor |01 is rigidly supported by the base member |08, the same being secured to the top of the elevator car A by means of the cap screws |09. The motor |01 has an extended shaft on which the sheave ||0 is rigidly secured, and the sheave ||0 has a groove formed in the periphery thereof for the reception of the belt |06.

The .arm 90 of the yoke member has the con tact arm rigidly secured to the rear side thereof by means of the cap screws |l2. The electrical contact switch ||3 is rigidly secured onto the upper surface of the angle mounting bracket ||4, and the angle mounting bracket ||4 is rigidly secured on the forward face of the bar member 25 by means of the threaded screws ||5. The contact switch ||3 has the projecting contact pin ||3 which extends rearwardly therefrom, the same making contact, within the case H3, and completing an electrical circuit through the wires- K and K when the contact pin H3 is pressed by the contact arm A second contact arm ||6 is rigidly secured to the forward face of the bar member 25 by means of the threaded screws ||1, and extends downwardly therefrom with the foot portion H6 turned at a right angle with relation to the major portion of the arm IIB. The contact pin H8 is threaded vertically through the foot portion I6 and is adjustably locked in position by means oi the lock nut H9. The electrical contact switch is rigidly secured on the rear side of the mounting angle 4 by means of the threaded screws |2I, the same being threaded into the case of the contact switch |20. The contact switch |20 has the contact lever |20 which is hingedly secured at one end thereof, and which makes electrical contact within the case |20 when pressure is applied by the lower end of the contact pin I0, and thereby making an electrical circuit through the wires L and L when the lever |29 is carried thereon by the bar member 25.

The air check valves |22 are connected to their respective end cap members 51 .and 58 by means of the threaded conduits |23. The conduits |23 are threaded, at one end thereof, into threaded

apertures

51 and 58 of the cap members 5l and 58 respectively, and at the opposite ends thereof, into threaded apertures formed in the members |22, as shown in Figure 19. A T-shaped aperture is formed in each of the members |22, as shown in Figure 19, with one terminal or the aperture being formed comparatively smaller than the major portion of the same, and thereby forming a seat against which the ball |21 is forced. A plug |24 is threaded into one terminal of the aperture and a threaded aperture is formed vertically through the plug l for the reception of the threaded screw |25. A lock nut tt is tightened against the top portion of the plug to prevent the screw |25 from being accidentally turned. The screw |25 has the slot E25 formed in one side thereof, the same being for the purpose of allowing air to escape from the valve, and permitting a means for controlling the quantity of air drawn into or forced out ci the air check cylinder by the piston.

The operation of the mechanism comprising the invention is substantially as follows:

Electricity, for the operation of the electric motor, which is contained within the operator housing i, and for the clutch motor |07, is obtained from a panel board (not shown) which is located .at a convenient position with relation to the elevator hoisting mechanism. A reversing switch (not shown) is mounted on or near the panel board, from which electric wires are eX- tended to the operator motor, and to oor selector push buttons which are located within the elevator car.

Figure 1 illustrates the position of the operating mechanism, the clutch, and the operating arms with the car doors B and B shown in closed position. Figure 3 illustrates the iioor landing doors in closed position with the operating arms therefor being sho-wn in corresponding relation thereto, and with the n member in position to be engaged by the wheels 19 of the clutch mechanism.

' The arrangement, as shown, is designed to be used in connection with what is known as automatic elevators in which floor selector push buttons are located in the elevator cars. When the floor selector button is pushed for any desired iioor, the elevator car is controlled by means of automatic electrical devices, and is automatically stopped at the pre-selected oor level. It is to be understood that the mechanism herein shown and described, may be used with equal advantage in connection with any type of electric elevator.

As the elevator car travels to within a predetermined distance of the selected oor (approximately six or eight inches), the clutch motor is automatically energized and rotates the interthreaded collar 93 by means of the drive belt :10% running over the motor sheave il!! and the sheave Qt, the latter being rigidly secured to the collar by means of the hub 97 and the set screw When the collar S8 is rotated, the same advances the yoke member 85 by reason of the threaded portion 05 being in mesh with the internal 'threads of the collar 98. As the yoke member advances from the position as shown in Figure 'l to the position as shown in Figure 10, the same causes the arms 'i3 and le, carrying wheels 53, to be rotated and bringing the wheels 'iii into engagement with the iin member of the iloor landing door mechanism. When wheels 'i9 engage the iin member 50, the electrical circuit to the clutch motor |0'l is automatically broken through the contact switch i2@ by reason of the contact pin H8 being carried by the contact arm l iii and allowing the electrical contacts within the switch case to separate and thereby breaking the electrical circuit to the motor When the yoke arms have moved forwardly (as shown in Figure 1G) the contact arm Eil, which is carried by the arm 00, presses against the contact pin l 3 of the contact switch i it with the same forcing the Contact points (enclosed within the case l I3) together and making an electrical circuit through the motor |01. The last mentioned circuit to the motor is not operatively completed until it is desired to start the elevator car, and a button has been pushed to start the car, after which the motor |01 rotates in a reverse direction and causes the motor sheave i l0, the belt |06, the sheave 96 together with the hub Si and the collar 9B to be rotated reversely and thereby causes the yoke member 86 with the arms 9! and 92 to be moved rearwardly. As the yoke arms 0| and 92 'move rearwardly, the rollers Sli cause the roller brackets 'H and 'I2 to swing from the position as shown in Figures l0 and 15 to the position as shown in Figure 7, and thereby disengaging the rollers 19 from the 1in member after which the elevator car may be moved upwardly or downwardly in the elevator hatch.

An instant after the clutch motor |01 is energized, the motor (contained within the operator i) is also automatically energized, and rotates the crank arm, through reducing gears, in the direction as indicated by the arrow in Figure 5, to the position as shown in Figure 6. As the crank arm 3 is rotated one-half revolution, the mechanism comprising the operating arms, together with the bar and the clutch mechanism is moved from the position as shown in Figure 5 to the position as shown in Figure 6. As the arm t and the lever I3 are pivotally secured to the mounting angle 4, the same open the car doors B and B as the crank arm 3 rotates. The clutch mechanism, being secured on the bar member 25, is carried thereby, and with the wheels iii being engaged with the iin member 5@ as described above, the iin member 50 is moved thereby, and the iloor landing doors are opened by means of the operating

arms

42, 40, 3|, and 35. As the nn member moves away from the position as shown in Figure 3, the electrical circuit, for the operation of the elevator car hoisting mechanism, is broken through wires extending into the contact switch 52. The electrical contact is broken by reason of the pressure being released from the contact pin by the base portion 50 of the iin member 50.

When it is desired to move the elevator car from a floor landing, a push button is pressed which automatically reverses the current through reversing switches (not shown), to the operator motor and the clutch motor, and the operation of the operating mechanism is consequently reversed, and thereby reversing the movements of the operating arms and the clutch mechanism from that described above, thereby closing the doors on the elevator car and the iioor landing doors simultaneously, and also causes the elevator car to move away from the iioor landing to another ilocr which has been selected.

rIhe air check assembly, which is mounted above the yoke member, provides a means for cushioning the travel'of the yoke member together with the arms 7l and 72 and the rollers 'i9 which engage the iin member 50. The upwardly extending arm 8l ci the yoke member 06 is pivotally secured to the forwardly projecting end portion of the piston rod 02, and as the yoke member St is moved endwise on the shaft 83, the piston is moved correspondingly within the cylinder 59. The air check valves |22 are provided with the balis i2? which are forced downwardly seal the apertures E22, or are drawn upwardly by the action of the piston within the cylinder. The desired degree of cushioning is obtained by adjusting the threaded screws E25 upwardly or downwardly in their respective threaded apertures n the plugs |24. By turning the adjusting screws outwardly, with relation to the respective plugs |24, a larger opening is obtained, due to the shape of the slots |25', for the escape of air. By turning the adjusting screws |25 inwardly, with relation to the respective plugs |24, a smaller opening is obtained for the escape of air. Thus it is evident that a very fine adjustment for the expelled air can be obtained for cushioning the travel of the yoke member 86, the roller brackets 1| and l2, and the rollers '19, which allows the rollers 79 to quietly but positively engage the fin member 5U.

I desire that it be understood that minor changes may be made in the several details, and in the arrangement of the parts herein shown and described, so far as they may fall within the scope of the appended claims.

Having now fully shown and described the invention, what I claim and desire to secure by Letters Patent of the United States, is:

1. In a door operating mechanism, a clutch supported and carried by said operating mechanism and having pivotally positioned roller brackets, a roller rotatably secured to each of said roller brackets, and means for pivotally swinging said roller brackets and rollers toward each other simultaneously and into engaging relation with a iin member of a second door operating mechamsm.

2. In combination with a door operating mechanism, a clutch secured to and carried by a bar member of the operating mechanism, said clutch comprising a pair of swingable roller brackets, a roller rotatably secured to each of said roller brackets, means for swinging said roller brackets toward and away from each other simultaneously and bringing said rollers into and out of engagement with a fin member of a second door operating mechanism.

3. A door operating mechanism comprising a plurality of operating arms pivotally secured at the upper portions thereof to stationary members and slidably secured at their lower ends to slidable doors, a single n member pivotally secured to and carried by one of the operating arms, and a pair of actuated rollers engaging said n member and transmitting motion through the fin member and the operating arms to the slidable doors.

4. In a door operating clutch mechanism, an internally threaded collar member rotatably positioned on a shaft, a yoke member having one end portion thereof externally threaded with the same being threaded into the internally threaded collar, arms formed at the opposite end of said yoke member, means for rotating said collar member about the shaft and providing longitudinal movement of the yoke member and the arms.

5. In combination with a door operating mechanism, a clutch mechanism having a horizontally positioned slidable yoke member, an arm member formed integrally with said yoke member and projecting upwardly therefrom, a cylinder rigidly mounted above and positioned parallel with relation to said yoke member, a piston slidably positioned within said cylinder with the piston rod thereof extending through one end of said cylinder with the extending end portion thereof being pivotally secured to the upper end of the upwardly projecting arm member, and means secured adjacent to and interconnected with said cylinder for pneumatically cushioning the travel of the piston at the ends of its travel within the cylinder.

6. A clutch mechanism, comprising in combination, a central shaft rigidly secured at one end thereof and with the opposite end thereof being free, a yoke member slidably positioned on said central shaft, oppositely disposed arms formed integral with one end of said yoke member, external threads formed on the opposite end of said yoke member, a sheave wheel rotatably secured on the free end of said central shaft, an extended hub portion formed integral with one side of said sheave wheel, an internally threaded collar member rigidly secured in said extended hub, with the internal threads of the collar member meshing with the external threads of the yoke member, means for rotating said sheave and collar members and transmitting a longitudinal movement to said yoke member, and means for cushioning the movements of said yoke member at the ends of its longitudinal travel.

7. In combination with a door operating mechanism having a clutch mechanism in connection therewith, a mounting means for said clutch mechanism comprising a bar member having a block rigidly secured thereto, an angular-shaped member extending upwardly from said bar member and said block member with apertures formed through the end portion thereof and providing means for securing an air check assembly thereto, a threaded aperture formed through the vertical leg of the angular-shaped member and providing means for securing a central shaft thereto, and said block member having apertures formed vertically therethrough and providing means for swingably securing roller brackets thereto.

8. A door operating mechanism comprising in combination, a power unit having a rotatable shaft extending therefrom with a crank arm secured thereon, a bar member pivotally secured to the crank arm, a door operating arm pivotally secured through a mounting angle and having the lower end thereof slidably secured to the edge of a slidable door and with the upper end thereof projecting upwardly, an angular-shaped lever pivotally secured through the vertex thereof to the mounting angle with one end of the lever being pivotally secured to one end of the arm member and with the opposite end thereof being pivotally secured to the upper end of a second door operating arm, said second door operating arm having a break joint formed in the length thereof with the lower end of said second door operating arm being slidably secured to the edge of a slidable door, a horizontally positioned arm member pivotally secured through the upper end of the rst mentioned door operating arm and supported at the opposite end thereof by means of another bar member, and means rigidly secured to and carried by the horizontally positioned bar member for simultaneously operating a second set of slidable doors.

JAMES E. BANCROFT.