US2298542A

US2298542A - Door operator

Info

Publication number: US2298542A
Application number: US328622A
Authority: US
Inventors: Robert S Potter; Maurice D Bennett
Original assignee: Yale and Towne Manufacturing Co
Current assignee: Yale and Towne Manufacturing Co
Priority date: 1940-04-09
Filing date: 1940-04-09
Publication date: 1942-10-13
Anticipated expiration: 1959-10-13

Description

fj'UNITED. 'STATES PATENT .OFFICE I y e v, 2,298,542

DOOR OPERATOR Manufacturing Company, Stamford, Conn., a=

corporation of Connecticut Application April 9, 1940, Serial No. 328,622

17 Claims.

This invention relates to a door, opening and closing mechanism forming an improvement of the door opening and closing mechanism shown inYour application Serial No. 188,512, filed in the United States Patent Oflice on February 3, 1938.

As in the said application, the important feature of: our invention is the utilization of a commercial form of door closer such as is shown in the Potter Patent No. 1,926,554 and in the Norton Patent No. 1,152,339, to open the door to which the closer is attached through the application of nuid pressure to the checking piston. The application of this fluid pressure will reverse the usual action of the closer and cause it to open the door through the same means as are normally used for closing the door. It is a further feature of our invention that should the fluid pressure source cease to function, the door maybe opened and closed in the same manner as though it were controlled by the usual type of commercial door closer.

The several features so far discussed by us are inherent in the construction shown in our application supra, vthe invention in this application being a modification whereby we simplify the valve and control mechanism of the door closer and opener so that it will better perform its operations.

We shall now describe the drawing wherein our invention is shown generally in a diagrammatic form. We have preferred to show the invention in diagrammatic form because the door closer is well known in the art, while the pumping mechanism is of a type which anyone skilled in the art couldassemble quite readily. In addition, both the door closer and the pumping mechanism are more particularly described in our earlier application. We do show in considerable detail the actual structure of a valve body which forms an important part of our invention.

Referring nowmore particularly to the drawing, Fig. 1 is a diagrammatic view of our door closing and opening mechanism applied to a door. Fig. 2 is a diagrammatic view of the parts of Fig. 1 with certain of those parts enlarged to more accurately show their operation. Fig. 3 is a view of the valve body shown in Fig. 2, but with certain parts thereof in a different position. Fig. 4 is a -section along lines 4-4 of Fig. 3.

Referring now more particularly to the drawing, reference numeral III designates a door which is mounted for opening and closing movement relatively to a frame'l I. A door closer I2 of ,the

type disclosed in our earlier application and 55 shown more particularly in the Norton and Potter patents supra, is secured through a bracket I3 to the door frame. It is connected through an arm I4, pivoted at I5 to an arm Ii, to the door II, all in a manner which is well known in the art. As a matter of fact, the door closer I2 may be secured to the door, and be connected by the arms I4 and I6 to the door frame. 'I'hose skilled in the art will fully appreciate the several different types of installations possible.

The door closer I2 is connected through the intermediary of a valve body designated by the reference letter V, to a source of fluid pressure, designated generally by the reference letter P, it being understood that when fluid under pressure is transmitted from the fluid pressure source P through the valve body V to the door closer I2, the door is opened through a reversal of the operation of the door closer.

The operation of the fluid pressure source P is controlled by suitable photo-electric equipment, designated by reference letters L and L'. Those skilled in the art will appreciate that with the provision of suitable electric circuits, shown in our earlier application, the interception of the light beams B and B' will bring about the actuation of the fluid pressure source P to force fluid under pressure into the door closer to open the door.

We shall now refer to Figs. 2, 3 and 4, where our invention is shown in greater detail and will be more readily understood. In Fig. 2, the door closer I2 is shown equipped with brackets II and I8 whereby it is readily secured to the main bracket I3. A checking piston I5 equipped with heads 20 and 2l slides in the cylinder 22 of the door closer, and has a. rack portion 23 in engagement with a pinion 24 secured to the main shaft 25 of the closer. The shaft 25 is urged toward closed position by the usual spring 25, it being understood that upon opening of the door, the arms I l and I6 act to wind the spring through the shaft 25 and to move the piston I9 to its extreme left hand position, which movement is substantially unopposed, since the liquid of the door closer will flow in the cylinder 22 from one side of the piston to the other through

valve passages

21 and 29, and past the ball valve 2l carried by the piston head 20.

In the usual type of door closer, such as shown in the Potter and Norton patents, the right hand end of the closer is equipped as is the left hand end shown in Fig. 2; that is. there are present the passages 2l and 29, and a -valve adjusting screw 30.' Our door closer is modied by the of the cylinder 22.

It is apparent, therefore, that unless means are provided for allowing the escape of fluid between the piston head 26 and the cap 3l at the high pressure end of the cylinder 22, the door will be incapable of closing under the iniiuence of the closer spring 26. We shall now describe the means whereby the said iluid may be moved by the piston head 26 relatively to the pressure end of the cylinder 22 to the low pressure end of the cylinder incidental to the closing oi' the door. In

- this same connection, we shall describe the means whereby the door closer action 'is reversed by the application of fluid against the piston head 26.

In Fig. 2, we have shown the source of fluid pressure P as including a motor M, which through a suitable coupling 32 drives a pump 33, `whose supply line 34 extends from a tank 35. The pressure line of the pump is designated by reference numeral 36 and extends through a nipple 31 into the valve body V. Formed in this valve body is a passage 38 communicating with a further passage 39 which is in further communication 'with a passage 46. The passage 46 in turn leads to a nipple 4I which is connected to a pipe 42. 'I'he pipe 42 in turn leads through a nipple 43 into the cap 3l, forming the pressure end oi.' the door closer cylinder 22. In considering our invention, it will be well to note that the pipe 36, nipple 31,

passages

38, 39, 46, nipple 4I, pipe 42, and nipple 43, form what we call the pressure line leading from the pump to the door closer.

A nipple 44 is secured to the door closer, as shown in Fig. 2, on the low pressure side of the door closer piston, and is connected through the pipe 45 and nipple 46 with the passage 41 of the valve body V. In turn, the passage 41 is connected through nipple 48 and pipe 4'6 back to the tank 35 of the fluid pressure source P. Nipple 44, pipe 45, nipple 46, passage 41, nipple 48 and pipe 49 form what we term the exhaust` line leading from the low pressure side of the door closer piston chamber to the iluid pressure source P.

A relief line 34a extends from the pressure line to the pressure relief valve 35a, so that the pressur@ of the fluid made available to the closer I2 may be controlled.

Mounted in the passage 38 is a piston 56 spring pressed by a spring I against a pin 52 so as to shut olf all communication between

passages

36 and 36 of the valve body. It will `be noted that the spring 5I is supported and maintained in position by a pin 53 forming part of a screw plug 54 which closes the upper end of the passage 38. It will further be noted that leading from the passage 46 is a Toy-,pass passage 55 which extends into the passage 38 and through said passage 38 communicates with a further by-pass passage 55a released, it will be closed by the spring." The piston head 26 of piston I3 will move against the fluid and force it out of the pressure end of the chamber 22 through the pressure line into the leading to the passage 41. An adjusting valve for varying the size of the passage 55 is designated by reference numeral 56. Functionally, we consider the passages 55 and 55a as forming with the passages 46 and 41, a by-pass passage around the fluid pressure source P.

In the position of the parts in Fig. 2, the piston 56 is spring pressed against the pin 52 so that while it shuts of! communication between

passages

38 and 39, it opens and allows full communication from the pressure line to the exhaust line through the by-pass passages 55 and 56a.. Because of this relation ofthe parts, should the door have been opened manually and the spring wound as already described, if the door be then valve body V, thence through by-pass passages 55 and 55a to the exhaust line and back through the nipple 44 into the low pressure end of the closer. The speed of movement of the fluid will of course depend upon the setting of the valve 56, and thereby the speed of closing of the door may be readily determined and adiusted.

We believe it will now be clear to those skilled in the art that the door Il may readily be opened manually with practically no resistance of the fluid, due to the fact that the fluid will flow freely past passage 21 and past ball valve 28 in a manner well known in the art. It will -be further appreciated that the door is closed in the usual way, but that the fluid instead of being forced through the usual valve passages such as 21 and 23 under the control of a screw valve' 36, will be forced instead through the, by-pass passage of the valve body V as controlled by the adjusting valve 56.

Fig. 3 shows the position of the parts in the valve body when fluid under pressure is applied from the fluid pressure source to the door closer through the intermediary of the valve body V. In that case, the control piston 56 is moved against the pressure of spring 5I into an upper position in which it shuts oil the by-pass passage and opens up the pressure line through opening up communication between the

passages

38 and 38. Pressure is then applied to the end of the piston head 26 which moves to the left in Fig. 2 to open the door and to wind the spring 26.

Incidentally, it will be interesting to note that in the ilnal opening movement of the door, the piston head 2| will shut oil passage 21, and thereafter, all uid between the piston head 2l and the end cap 58 must escape through the passage 29 as controlled by the screwvalve 36. By a proper setting of the screw valve 36, the movement of the piston I8 may be snubbed or checked so as to cushion the nal opening action of the door.

As soon as pressure in the pressure line is relieved by the shutting oli of the pressure from the fluid pressure source, the control valve piston 56 will move back to the position of Fig. 2, and the piston I8 will move toward the right in Fig. 2 under the influence of spring 26, causing the piston head 26 to move toward the pressure end cap 2l of the cylinder. 'I'his movement forces the liquid out through the pressure line and through the now open by-pass passages 55 and 56a past the adjusting valve 5l and through the exhaust line back to the low pressure side of the door closer chamber 22, bringing the door into closed position. It will be appreciated that this closing movement of the door takes place under exactly the same conditions as when the door is opened manually and released for closing.

Referring to Fig. 4, we show the adjusting valve 56 and the manner in which it is set by rotation of the screw head 51, all as is well understood by those skilled in the art.

While we have thusdescribed a particular detailed form in which our invention is preferably embodied, it will naturally be understood that those skilled in the art may embody our invention in other forms while still 'utilizing our contribution to the art.

We now4 claim: Y

l. In a combination of the class described. a

door closer having a cylinder. a piston movable in said cylinder, a iluid pressure source, a valve body, a pressure line leading from said'fluld pressure source to said valve body and from said valve body to the high pressure end of said cylinder, an exhaust line leading from the low pressure end of said cylinder to the iluid pressure source, a pressure e in said valve body forming a functional part of said pressure line, a by-pass passage in said valve body leading from the pressure passage to the exhaust line, means movable incidentally to the ilow of iluld under pressure from said iiuid pressure source to said pressure passage for the flow of fluid therethrough into said cylinder, whereby 'saidiluid acts against the piston to reverse the normal action of the door closer, said means moving to open said by-pass passage and to shut oil said pressure passage incidental to the stoppage ofthe flow of fluid under pressure from said fluid pressure source, whereupon said piston forces said iluid from the high pressure end of said cylinder through said by-pass passage toward the low pressure end of said cylinder.

2. In a combination of the class described, a door closer having a cylinder, a piston movable in said cylinder, a iluid pressure source, a valve body, a pressure line leading from said duid pressure source to said valve body and from said valve body to the high'pressure end of said cylinder, an exhaust line leading from the low pressure end of said cylinder to the fluid pressure source, a pressure passage in said valve body forming a functional part of said pressure line, a by-pass passage in said valve body leading from the pressure passage to the exhaust line, a regulating valve for adjusting the effective size of said passage, a valve piston in said valve body movable upon flow of fluid under pressure from said iluid pressure source to obstruct said by-pass e while opening up said pressure passage for the ilow of fluid therethrough into said cylinder. whereby said iluid acts against the door closer piston to reverse the normal action of the door closer, said valve piston moving to open said bypass passage and to shut oiI said pressure passage incidental to the stoppage of the ilow of iluid under pressure from said fluid pressure source. whereupon said piston forces said iluid from the high pressure end of 4said cylinder through said by-pass passage toward the low pressure end of said cylinder.

3. In a combination of the class described, a door closer having a cylinder, a piston movable in said cylinder, a iluid pressure source, a valvek body, a pressure line leading from said fluid pressure source to said valve body and from said valve body to the high pressure end of said cylinder, an exhaust line leading from the low pressure end of said cylinder to said valve body and from said valve body to the fluid pressure source, a pressure passage in said valve body forming a functional part of said pressure line, an exhaust passage in said valve body forming a functional part of said exhaust line, a by-pass passage in said valve body leading from the pressure passage to the exhaust passage, a regulating valve for adjusting the edective size of said passage, a valve piston in said valve body spring pressed into position to shut od said pressure passage and movable upon ilow of iluid under pressure from said fluid pressure source to obstruct said by-pass passage while opening up said pressure passage for obstruct said by-pass passage while opening up cylinder, whereby to reverse the normal action of the door closer, said valve piston moving into position to block `said pressure passage upon the stoppage of the ilow of duid under pressure from said. duid pressure source through into said while opening said by-pass passage, and means for moving the door closer piston to force the fluid out of the high pressure end of the cylinder through said pressure line and by-pass passage and through the exhaust line to` the low pressure end of the cylinder.

4. In a combination of the dass described, a

leading from said fluid pressure source to said leading from the the iluow of fluid therepressure source,

valve body and from said valve body to the high pressure end of said cylinder, an exhaust line leading from the low der to said valve body and from said valve body to the iluid pressurel source, a pressure passage in said valve body forming a functional part of said pressure line, an exhaust passage in said valve body forming a functional part of said exhaust line, a by-pass passage in said valve body pressure passage to the exhaust passage, a regulating valve for adjusting the effectivesize of said by-pass passage, a valve piston in said valve body spring pressed into position to shut oil said pressure passage and movable upon ilow of iluid under pressure from said uid pressure source to obstruct said by-pass passage while opening said pressure passage for the flow of fluid therethrough into said cylinder, whereby to reverse the normal action of the door closer to open the door, said valve piston moving into position to block said pressure passage upon the stoppage of the ilow of fluid under pressure from said iluid pressure source while opening said by-pass passage, whereupon the said door closer will act to close the door with the door closer piston forcing the iluid out of the high pressure end of the cylinder through said pressure line and by-pass e and through the exhaust line to the low pressure end of the cylinder, and means whereby fluid flows freely from the low pressure side of the door closer piston to the high pressure side thereof to permit easy manual opening of the door to which the door closer is applied.

5. In a combination of the class described, a door closer having in said cylinder, a spring adapted to close the door to which the closer is secured while said piston serves to slowdown the closing action, a iiuid pressure source, a prsure line connecting said tluid pressure source with the pressure end of said cylinder, an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source, and a by-pass passage for said iluid pressure source leading from said high pressure line to said low pressure line whereby when said spring closes the door, fluid is forced by said piston out of the pressure` end of the cylinder and through said by-pass passage toward the low pressure end of said cylinder.

6. In a combination of the class described, a door closer having a cylinder, a piston movable in said cylinder, a spring adapted to close the door to which the closer is secured while said piston serves to slow check valve in said piston to permit free passage of uid when the door is opened manually, a fluid a pressure line connecting said pressure end of said cylina cylinder, a piston movable down the closing action, a

fluid pressure source with the pressure end of said cylinder, an exhaust line connecting the low pressure end of said cylinder with the nuid pressure source, a by-pass passage for said fluid pressure source leading from said high pressure line to said low pressure line, a regulating valve in said by-pass passage, means normally maintaining said by-pass passage open while maintaining closed said pressure line to said fluid pressure source, whereby said piston forces the fluid from the'pressure end of the cylinder through said bypass passage and regulating valve toward the low pressure end of the cylinder and in by-passing relation to said fluid pressure source during the closing movement of the door by said spring.

'1. In a combination of the class described, a door closer having a cylinder, a piston movable in said cylinder, a spring adapted to close the door to which the closer is secured while said piston serves to slow down the closing action, a fluid pressure source, a pressure line connecting said fluid pressure source with the pressure end of said cylinder, an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source, means for initiating the application of fluid from said fluid pressure source against said piston to reverse the action of the closer and to open the door, a by-pass passage for said fluid pressure source leading from said high pressure line to said exhaust line, a regulating valve in said passage, means normally maintaining said bypass passage open while maintaining closed said pressure-line to said fluid pressure source, whereby said piston forces the fluid from the Pressure end of the cylinder through said by-pass passage and regulating valve toward the low pressure end of the cylinder during the closing movement of the door by said spring after the door has been opened by the application of fluid from said fluid pressure source against said piston, and means whereby fluid flows freely from the low pressure side of the door closer piston to the high pressure side thereof to permit easy manual opening of the door to which the door closer is applied.

8. In a combination of the class described, a door closer having a cylinder, a piston movable in said cylinder, a spring adapted to close the door to which the closer is secured while said piston serves to slow down the closing action, a'fluid pressure source, a pressure line connecting said fluid pressure source with the pressure end of I said cylinder, an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source, a by-pass passage for said fluid pressure source leading from said high pressure line to said low pressure line, a regulating valve in said passage, a spring pressed valve piston normally maintaining said by-pass passage open while maintaining closed said pressure line to said fluid pressure source, whereby said lines and passage will act to control the closing of the door through the forcing of fluid by the door closer piston from the pressure end of thev cylinder through said by-pass passage and regulating valve to the low pressure end of the cylinder, said valve piston being movable upon the application of uid under pressure from said uid pressure source to open the pressure line while shutting oif the by-pass passage whereby fluid under pressure will be admitted to said cylinder against the door closer piston to reverse the normal action of the door closer and to open the door.

9. In a combination of the class described, a door closer having a cylinder, a piston movable in said cylinder, a spring adapted to close the door to which the closer is secured while piston serves to slow down the closing action, l. fluid pressure source, a pressure line connecting said fluid pressure source with the pressure endA of said cylinder, an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source, a by'pass passage for said fluid pressure source leading from said high pressure line to said low pressure line, a regulating valve in said passage, a spring pressed valve piston normally maintaining said by-pass passage open while maintaining closed said pressure line to 'said fluid pressure source, whereby said lines and passage will act to control the closing of the door through the forcing of fluid from the pressure end of the cylinder through said by-pass e and regulating valve to the low pressure end of the cylinder, said valve piston being movable upon the application of fluid under pressure from said fluid pressure source to open the pressure line while shutting off the by-pass passage wherebyfluid under pressure will be admitted to said cylinder against said door closer piston to reverse the normal action of the door closer to openthe door, and means whereby iiuid flows freely from the low pressure side of the door closer piston to the high pressure side thereof to permit easy manual opening of the door to which the door closer is applied.

l0. In a combination of the class described, a door closer having a cylinder, a piston movable in said cylinder, a spring adapted to close the door to which the closer is secured while said piston serves to slow down the closing action, a fluid pressure source, a pressure line connecting said ud pressure source with the pressure end of said cylinder, an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source, a by-pass passage for said fluid pressure source leading from said high pressure line to said low pressure line, a regulating valve in said passage, means normally .maintaining said by-pass passage open while maintaining closed said pressure line to said iluid pressure source, whereby said lines and passage will act to control the closing of the door through the forcing of fluid from the pressure end of the cylinder through said by-pass passage and regulating valve to the low pressure end ofthe cylinder, said means being movable upon the application of fluid underpressure from said fluid pressure source to open the pressure line while shutting olf the by-pass passage whereby fluid under pressure will be admitted to said cylinder against said door closer piston to reverse the normal action of thedoor closer to open the door, and means whereby fluid flows freely from the low pressure side of the door closer piston to the high pressure side thereof to permit easy manual opening of the door to which the door closer is applied.

11. In a combination of the class described, a

Y door closer having a cylinder, a piston movable in said cylinder, a spring adapted to close the door to which the closer is secured while said pis-` ton serves to slow down the closing action, a fluid pressure source, a pressure line connecting said fluid pressure source with the pressure end of said cylinder, an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source, a by-pass passage for said fluid pressure source leading from said high pressure line to said low pressure line, a regulating valve in said passage, a spring pressed valve piston nor-v mally maintaining said by-pass passage open while maintaining closed said presure line to said duid pressure source, whereby said lines and passage will act to control the closing of the door through the forcing of iiuid from the pressure end of the cylinder through said by-pass passage and regulating valve to the low pressure end of the cylinder, said valve piston being movable upon the application of iluid under pressure from said fluid pressure source to open the pressureA line while shutting oil' the by-pass passage whereby fluid under pressure will be admitted to said cylinder to reverse the normal `action of the door closer to open the door, the said spring pressed valve piston moving back to its saidnor mal position upon stoppage of the dow of fluid under pressure from said fluid pressure source,

whereupon the said door closer will act to close the door with the door closer piston forcing the fluid out of the high pressure end of the cylinder through said pressure line and by-pass passage and through the exhaust line to the low pressure end of the cylinder.

12. In a combination of the class described, a door closer having a cylinder, a piston movable in said cylinder, a spring adapted to close the door to which the closer is secured while said piston serves to slow down the closing action, a uid pressure source, a pressure line connecting said fluid pressure source with the pressure end of said cylinder, an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source, a lay-pass passage for said iluid pressure source leading from said high pressure line to said low pressure line, a regulating valve in said passage, a spring pressed valve piston normally maintaining said lby-pass passage open while maintaining closed said pressure line to said iluid pressure source, whereby said lines and passage will a-ct to control the closing of the door through the forcing of fluid by the door closer piston from the pressure end of the cylinder through said by-pass passage and regulating valve to the low pressure end of the cylinder, said valve piston being movable upon the application of fluid under pressure from said fluid pressure source to open the pressure line while shutting oi! the by-pass passage whereby uid under pressure will be admitted to said cylinder to reverse the normal action of the door closer to open the door, the said spring pressed valve piston moving back to its said normal position upon stoppage of the ilow of iluid under pressure from said uid pressure source, whereupon the said door closer spring will close the door with the door closer piston forcing the fluid out of the high pressure end of the cylinder through said pressure line and bypass passage and through the exhaust line to the low pressure end of the cylinder, and means whereby fluid ows freely from the low pressure side of the door closer piston to the high pressure side thereof to permit easy manual opening of the door to which the door closer is applied.

13. In a combination of the class described, a door closer having a cylinder formed with a high pressure end and a low pressureend, a piston movablein said cylinder from the high pressure end to the low pressure end during opening movement of thedoor to which the closer is attached, and then to the high pressure end as the door closes, a spring adapted. to close the' door to which the closer is secured while said pistonserves to slow down the closing action, a uid pressure source, a pressure line connecting said fluid pressure source with the pressure end of said cylinder, an exhaust line connecting the low pressure haust line, and means for directing the flow of fluid under the pressure of the piston from the pressure end of the cylinder through said bypass passage and exhaust line to the low pressure end of the cylinder when said spring moves said door to closed position.

14. In a combination of the class described, a door closer having a cylinder formed with a high pressure end and a low pressure end, a piston movable in said cylinder from the high pressure end to the low pressure end during opening movement of the door to which the closer is attached, and then to the high pressure end as the door closes, a spring adapted to close the door to which the closer is secured while said piston serves to slow down the closing action, a uuid pressure source, a pressure line connecting said iiuid pressure source with the pressure end of said cylinder, 'an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source. a by-pass passage for said fluid pressure source leading from said high pressure line to said exhaust line, a regulating valve in said by-pass passage, and means for directing the flow of fluid under the pressure of the piston from the pressure end of the cylinder through said by-pass pmage and exhaust line to the low pressure end of the cylinder when said spring moves said door to closed position.

15. In a combination of the class described, a door closer having a cylinder, a piston movable in said cylinder, a spring adapted to close the door to which the closer is secured while said Ipiston serves to slow down the closing action, a fluid pressure source, a pressure line connecting said uid pressure source with the pressure end of said cylinder, an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source, a by-pass passage for said fluid pressure source leading from said high pressure line to said low pressure line, a regulating valve in said passage, means normally maintaining said whereby said lines and passage will act to control the closing of the door through the forcing of fluid by the door closer piston from the pressure end of the cylinder through said by-pass passage and regulating valve to the low pressure end of the cylinder, said means being movable upon the application of fluid under pressure from said iluid pressure source to open the pressure line while shutting off the by-pass passage whereby fluid under pressure will be admitted to said cylinder against the said piston to reverse the normal action of the door closer and to open the door.

16. In a combination of the class described', a door closer having a cylinder, a piston movable in said cylinder, a spring adapted to close the door to which the closer is secured while said piston serves to slow down the closing action, a fluid pressure source, a pressure line connecting said fluid pressure source with the pressure end of said cylinder, an exhaust line connecting the low pressure end of said cylinder with the fluid pressure source, a by-pass passage for said fluid pressure ingoithedoorthroughtheioreingoimxidbythe doorcloserpistontromthe pressureendofthe cylinder through said by-pass passage and regulating valve to the inder, said means being movable upon the application o! iluid under pressure from 'saidiluid pressuresource toopenthepressurelinewhileshutting oi! the byfpass passage whereby nuid under pressuremllbe admitt'edtnsaideylinderagainst' the said piston to reverse the normal actiun ot the dnor closer and to open they door, and means whereby iluid flows freely from the low pressure sideofthedoorcloserpiswntothehlhpres- -suresidethereoi'tepermlteasymanualopening man low pressure end ot the cylthecioserissemredwhilesaidplstcnm slow down the closing aetlen. a iluid souree,apressurelineeonneetingsaidmiidpres suresoureewlththepressureend-otsaid der. an exhaustlineeonneeting'theluw'prelure endofsaideylinderwlththemlidpresnnesmnee.

Y @en said door, means for shutting said ivy-pase passage incidental to the said application o! :lluid against saidpiston and for opening said thereafter to permit the piston to tores from the pressure end of the cylinder said by-pass passage and exhaust line to pressure end of the moves said door to closed position.

s ROBERT BL POTTER.

' MAURICE D.' m11.