US3508361A

US3508361A - Sliding door assembly

Info

Publication number: US3508361A
Application number: US779772A
Authority: US
Inventors: James Paul Ryder
Original assignee: Ardco Inc
Current assignee: Ardco Inc
Priority date: 1968-11-29
Filing date: 1968-11-29
Publication date: 1970-04-28
Anticipated expiration: 1987-04-28

Description

- April 2s, 1910 1P. YD'ER `3,L=.o,;fs1

I SLIDING DoR ASSEMBLY 4 Sheets-Shee'L 2 y Filled Nov. 29, 196e QHG'.y

y April 281, 1970 I P.IRYDER SLDING DOOR ASSEMBLY 4` sheets-sheet s Filed Nov. 29. 1968' APYil 28 1970 v.1. P. RYDER 3,508,361

v V.SLID'ING DOOR ASSEMBLY 4 sheets-sheet 4 Filed Nov. '29, 196s] United States Patent C) 3,508,361 SLIDING DOOR ASSEMBLY James Paul Ryder, Hacienda Heights, Calif., assignor t Ardco, Inc., Chicago, Ill., a corporation of Illinois Filed Nov. 29, 1968, Ser. No. 779,772 Int. Cl. E061: 7/ 12 U.S. Cl. 49-70 6 Claims ABSTRACT OF THE DISCLOSURE A pair of sliding doors are mounted in a rectangular door frame having top, bottom and side members. Each door is supported by a pair of grooved rollers which ride along a ange or track projecting upwardly from the bottom member of the frame. Each roller has a shaft with an eccentric mounting stud which can be turned to adjust the elevation of the roller, so that the doors can be aligned with the frame. Each door has a closure spring which is mounted vertically along one of the side members and is connected to the door by a cable which is Wrapped around a pulley. The spring and the vertical portion of the cable are enclosed by a removable channel shaped strip which is mounted in the side member of the frame. Each door contains a heater which is supplied with electrical current by a cord connected between the door and the frame. The cord is formed into a U- shape with upper and lower'horizontal legs. Horizontal channel members are provided on the frame and the door to retain and conceal the upper and lower legs of the cord so that the cord will be kept out of the way and out of view.

This invention relates to sliding doors, particularly those of the type frequently employed in connection with refrigerated display cabinets or compartments, used to hold dairy products and other items requiring refrigeration, in food stores and the like.

Typically, such display doors are made of ,metal and are tted with glass panels so that the merchandise in the display cabinet will be clearly visible to the customers. In doors of this type, it is common practice to provide heaters within the metal door frames to prevent moisture from condensing upon the outer surface of the doors. AIn the absence of such heaters, the door frames become cold enough to cause such condensation, particularly when the atmospheric temperature and humidity are high.

The electrical current to energize the heater is commonly supplied to a door of this kind by meansof a exible electric cord connected between the door andv the frame. In sliding doors, such cords are quite long to provide for the full sliding movement of the door. In prior doors, such cords have hung down to an objectionable extent, where they are in the way of the customers, so that the cords impede access to the merchandise in the display cabinets. Moreover, the prior cords have been unsightly and subject to frequent breakage, due to the accessibility of the cords to the customers.

One object of the present invention is to provide a sliding door in which the electrical cord is fully concealed and completely out of the way, so that the cord does not obstruct the access to the merchandise displayed behind the door.

To this end, the present invention provides a sliding door assembly in which the flexible electrical cord is formed into a U-shape with legs extending parallel to the direction of movement of the door. Channel members are provided on the door and the stationary frame to retain and conceal the legs of the U-shaped cord. As

3,508,361 Patented Apr. 28, 1970 ICE the door is moved in one direction, the cord is fed from the channel member on the door to the channel member on the frame. The opposite action occurs when the door is moved in the opposite direction.

VOne of the prevalent disadvantages of prior sliding doors resides in the fact that the doors are often left open by the customers. While door closers have sometimes been employed, these have been cumbersome and unsightly.

Another object of the present invention is to provide a sliding door assembly having a spring closer in which the spring itself is completely enclosed, and in which the other elements of the closer are concealed or very nconspicuous.

In this regard, the present invention preferably comprises a closer spring which is mounted along one side member of the stationary frame. One end of the spring is anchored to the frame. A tension member is connected between the door and the other end of the spring. The tension member is Wrapped around a corner member, preferably in the form of a pulley which is rotatably mounted on the frame. A closure member is removably mounted on the frame to close and conceal the spring and the Vertical portion of the tension member.

Prior doors have sometimes -been mounted on antifriction rollers, but such rollers have generally been mounted on the upper end of the door, with an arrange- -ment whereby the rollers are hung upon an overhead rail. With such arrangements, it has been diicult to maintain accurate alignment between the door and the stationary frame.

Another object of the present invention is to provide a sliding door assembly in Iwhich the anti-friction rollers are mounted on the lower end of the door and are adjustable in elevation so that the alignment of the door can readily be adjusted.

In this regard, the present invention preferably comprises a pair of grooved rollers, mounted on the lower portion of the door and adapted to ride along a flange projecting upwardly from the lower member'of the sta tionary frame. Each roller is preferably provided with a shaft having an eccentric mounting element which can be turned to adjust the elevation of the roller. In this Way, the alignment of the door can be adjusted.

Further objects, advantages and features of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. l is a perspective view of a display cabinet or compartment, equipped with sliding door assemblies which exemplify the present invention.

FIG. 2 is a diagrammatic horizontal section taken through the sliding door assemblies of FIG. l.

b FIG. 3 is a front elevation of one of the door assemlies.

FIG. 4 is a fragmentary vertical section, taken generally along the line 4-4 in FIG. 3 to show the arrangement of the rollers which support the sliding doors.

' FIG. 5 is a fragmentary enlarged elevation, partly in section, corresponding to the lower right-hand portion of FIG. 3.

FIG. 6 is a fragmentary vertical section, taken generally along the line 6-6 in FIG. 3.

FIG. 7 is a fragmentary enlarged elevation, partly in section, corresponding to the upper right-hand portion of FIG. 3.

FIG. 8 is a fragmentary enlarged elevation, partly in section, corresponding to the upper central portion of FIG. 3.

FIG. 9 is an upwardly directed view showing the underside of the upper stationary frame member, partly in section along the line 9 9 in FIG. 3.

FIG. 1-0 is a fragmentary horizontal section, taken generally along the line lll-10 in FIG. 3.

FIG. 1l is a fragmentary enlarged horizontal section taken generally along the line 11-11 in FIG. 3.

FIG. 12 is a fragmentary enlarged horizontal section taken generally along the line 12-12 in FIG. 3.

It will be seen that FIG. 1 illustrates a refrigerated display cabinet or compartment incorporating two sliding door assemblies 12 which are of identical construction. The sliding door assemblies 12 are mounted side by side in the display cabinet 10 to provide a large area for the display of merchandise.

Each sliding door assembly 12 comprises a stationary mounting frame 14 having two sliding

doors

16a and 16b mounted therein. The

doors

16a and 16b are of similar construction, except that the door 16a opens to the right, while the door 16b opens to the left. The two doors 16a and b are adapted to close the opening in the stationary frame 14.

It will be seen that the stationary frame 14 is generally rectangular in shape. Thus, the frame 14 comprises an upper horizontal member 18, a lower horizontal member 20, and left and hight-

hand side members

22 and 24.

Each of the illustrated doors 16a and b is of the type comprising a metal border frame 26 in kwhich a transparentpanel 28 is mounted, so that the merchandise in the cabinet 10 will be clearly visible to the customers. However, the invention is also applicable to doors of other types.

Typically, the transparent panel 28 is made of glass. Thus, as shown to best advantage in FIG. l2, each of the illustrated transparent panels 28 comprises two

parallel glass panes

30 and 32 with a dead air space 34 therebetween. A spacer 36 is provided between the edge portions of the

panes

30 and 32. With this construction, the transparent panel 28 provides a high degree of heat insulation. It will be understood that more than two spaced panes may be employed, if desired The metal border frame 26 is generally channel shaped in cross section, with front and rear anges 38 and 40 between which the transparent panel 28 is mounted. A gasket 42 is preferably interposed between the glass panel 28 and the metal border frame 26. As shown, the gasket 42 is U-shaped in cross section and is wrapped around the edge portions of the transparent panel 28, so that portions of the gasket 42 are between the panel 28 and both

flanges

38 and 40.

FIGS. 4 and 5 show the manner in which each of the doors 16a and b is supported by a plurality of antifriction rollers 44. In the illustrated construction, two such rollers are mounted on the lower portion of each door. The rollers 44 are arranged to ride along tracks 46a and b for the left and right-hand doors. Each of the illustrated tracks 46a and b is in the form of an upright flange pro jecting upwardly from the lower member 20` of the stationary frame 14. Each roller 44 is formed with a peripheral groove or channel 48, adapted to retain the rollers on the tracks or rails 46a and b.

Provision is made for adjusting the elevation of the rollers 44 so that the doors 16a and b can lbe levelled and brought into alignment with the stationary frame. 14. In the illustrated construction, each roller 44 is rotatably mounted on a shaft 50 having an eccentric mounting element 52, illustrated as being a threaded stud. The border frames 26 of the doors 16a and b comprise lower members 54 on which the rollers 44 are mounted. As shown, the eccentric studs 52 extend through appropriate openings in rear flange portions 56 of the lower members 54. A clamping nut 58 is screwed onto each stud 52 to secure the stud to the ilange portion 56.

The elevation of each roller 44 can be adjusted by loosening the nut 58 and turning the threaded stud 52. Due to the eccentricity between the shaft 50 and the stud 52, the elevation of the roller 44 is thus effectively changed.

The tracks 46a and b project into channels 60 formed along the lower side of the lower member 54 on each border frame 26. The walls of the channel 60 are cut away locally to provide space to accommodate the rollers 44.

In addition to the lower member 54, each border frame 26 comprises an upper member 62 and two

side members

64 and 66. As shown to best advantage in FIG. 6, the upper members 62 of the two doors 46a and b are preferably formed with guide channels 68, adapted to receive guide iianges 70a and b, projecting downwardly from the upper member 18 of the stationary frame 14. As shown, one or more U-shaped anti-friction strips or guides 72 are mounted in each of the channels 68, for smooth sliding engagement with the anges 70a and b. The guides 72 may be made of nylon or some other suitable material.

A sealing arrangement is provided between one side member of each door and the stationary frame. This side member is the one previously designated 64 in FIG. 3. As shown to best advantage in FIG. ll, the side member 64 is formed with a laterally facing channel 74 a-dapted to receive a flange 76 projecting laterally from the stationary frame 14. A U-shaped sealing strip or gasket 78 is mounted in the channel 74. The strip 78 may be made of vinyl or some other suitable material. As shown to best advantage in FIG. 12, the other side member 66 of each door is formed with a channel 79 in which a similar U-shaped strip 80 is mounted.

The doors 16a and b are provided with handles 82a and b which are mounted on the side members 64. The handles 82a and b are similar in construction, but the handle 82a is of greater depth to allow for the fact that the door 16a is movable behind the door 16b.

The door assembly is provided with means for automatically closing each of the doors 16a and b so that they will not stand open if left in an open position. As shown to best advantage in FIGS. 7 and 10, each of the

doors

16a and 16b is provided with a closer mechanismk 84, preferably comprising a spring 86 adapted to exert a closing force on the door. As shown, the spring l86 is of the coiled extension type and is mounted in a vertical posltion adjacent one of the

side members

22 and 24 of the stationary frame 14. In this case, the lower end of the spring 86 for the left-hand door 16a is anchored to the side member 22, while the lower end of the spring for the right-hand door 16b is anchored to the other side member 24. As shown in FIG. 5, the lower end of the spring may be formed with a hook 88, adapted to be retained in an opening 90 formed in the

corresponding side member

22 or 24.

Means are provided to connect the upper end of the spring 36 to the

corresponding door

16a or 16b. As shown, a flexible tension member 92 is connected to the upper end of the spring 86. The tension member 92 extends upwardly and is flexed at approximately 90 around a guide element 94. The tension member 92 then extends horizontally to a pin or other anchoring device 96 whereby the tension element is connected to the upper frame member 62 of the door 16a or 16h. The guide element 94 is preferably in the form of a pulley, rotatably mounted on the stationary frame 14. The tension member 92 is preferably in the form of a flexible cable. The illustrated pulley 94 is formed with a peripheral groove 98 to retain the cable 92.

Means are provided to conceal and enclose the spring `86 and the vertical portion of the cable 92. These elements are in close proximity to the

side member

22 and 24 of the stationary frame 14 and are partially enclosed by the side members. Thus, as shown to best advantage in FIG. 1l, the

side members

22 and 24 are generally channel shaped in cross section. The channel is formed by front and

rear flanges

100 and 102 with a web 10'4 extending therebetween. The spring '86 is between the

flanges

100 and 102 and opposite the

corresponding door

16a or 16b. The anchoring hole 90 for the lower end of the spring is formed in the web 2.

To complete the enclosure of the spring 86, a closure member or strip 106 is preferably mounted in each of the channel shaped

side members

22 and 24. As shown to best advantage in FIG. 11, the closure strip 106 is generally channel shaped in cross section and is made of a soft resilient material such as vinyl or some other suitable plastic. The illustrated strip 106 has front and rear flanges 108 and 110' with a curved web 112 extending therebetween. The front and

rear flanges

108 and 110 are adapted to engage the front and

rear flanges

100 and 102 of the

corresponding side member

22 or 24. Flexible sealing lips or flaps 114 are preferably formed on the

flanges

108 and 110` to engage the

flanges

100 and 102 with a spring pressure, so that the strip 106 will be securely retained. However, the strip 106 may readily be removed, when necessary, by pulling the web 112 away from the

side member

22 or 24.

'I'he closure strip 106 extends for nearly the entire length of the

corresponding side member

22 or 24, leaving clearance for the pulley 94 and the horizontal portion of the cable 92. The spring -86 and the vertical portion of the cable 92 are fully enclosed between the strip 106 and the

corresponding side member

22 or 24.

If desired, several of the spring anchoring holes 90 may be distributed along each of the

side members

22 and 24 so that tension in the spring 86 can be adjusted by changing the anchoring point of the spring.

The horizontal portion of the cable 92 is disposed in the narrow space between the upper member 1-8 of the stationary frame 14 and the upper member 62 of the corresponding door 16a or b. Thus, the cable is in a very inconspicuous position. Moreover, it is completely out of the way.

The doors 16a and b preferably are equipped with one or more elements which require energization with electrical power. As shown to best advantage in FIGS. 6, ll and 12, the illustrated doors 16a and b are equipped with electrical heater elements 116, which serve the purpose of warming the

metal frame members

54, 62, 64 and 66 of the doors, so as to prevent the condensation of moisture on the frame members. In s-ome cases, the transparent'panel 28 may incorporate an electrical heating condensation of moisture on the panel. Thus, the transparent panel 28 may incorporate an electrical heating element, usually in the form of an electrically conductive coating on one of the inaccessible surfaces of-the

transparent panes

30 and 32. The illustrated heating elements 116 are in the form of cables, concealed within the metal border frame 26. As shown, the cables 116 are mounted in channels or grooves 118 which open into the

larger channels

68, 74 and 78. The heating cables 116 are retained in the channels 118 by the

gaskets

72 and 78, and by the bumper strip '80.

To energize the heating cables 116, it is preferred to connect an electrical cord or cable 120 between each

door

16a or 16b and the stationary frame 14. The electrical cord 120 is arranged so that it is completely out of the way and fully concealed. Thus, as shown to best advantage in FIGS. 6, 8 and 9, each cord 120 is flexed into a U-shape, so as to have upper and lower horizontal legs 122 and 124, with a semicircular portion 126 extending therebetween. Movement of the door 16a or b in one direction causes the cord 120 to be fed between the legs 122 and 124, while the semicircular portion 126 travels in the same direction as the door is moved. Thus, in FIG. 8, the righthand door 16b is shown in its closed position. As the door 16b is opened, it is moved to the left. The electrical cord 120y is fed from the lower leg 124 to the upper leg 122, while the semicircular portion 126 is translated to the left, but at a speed only about half that of the door.

The upper and lower legs 122 and 124 of the electrical cord 120 are retained and controlled by channel members 128a and b and '130. The channel members 128a and b are on the upper member 18 of the stationary frame 14, While the channel members 130 are on the upper members 62 of the doors 16a and b. As shown to best advantage in FIG. 6, the channel member 128b is preferably formed by a pair of

flanges

132 and 134, projecting downwardly from a horizontal wall portion 136 of the stationary frame 14. The upper leg 122 of the cable 120 is guided between the

flanges

132 and 134. The channel mem-ber 128 is -secured to the upper member of the stationary frame 14 and is formed with

ilanges

138 and 140 projecting downwardly from a horizontal wall portion 142. The flange is considerably deeper than the flange 138, to provide full concealment of the rear cord 120, while also insuring that the cord will not be displaced accidentally from the channel member 128a. The member 128a has another ilange 141 which provides a wiring raceway 141a. Lighting fixtures may be mounted on the race- Way, if desired. l

On the doors 16a and b, the channel members 130 take the form of L-shaped flanges projecting rearwardly and then upwardly from the rear side of the upper door member 62. Thus, each channel member 130 has a horizontal leg 143 and an upwardly projecting vertical leg 144.

It will be evident that the cord-s 120 are completely enclosed and concealed by the upper frame member 62 of the doors 16a and b, the guide flanges 70a and b on the outer frame 14, and the channel members 128a and b and 130.

Each of the cords 120 is preferably provided with

separable connector elements

146 and 148, whereby the cord can readily be disconnected from the stationary frame 14. Such disconnection is necessary when one of the doors is to be removed from the frame 14, for the replacement of glass or any other reason. The illustrated connector 146 is in the form of a plug on the end of the electrical cord 120, while the connector 148 takes the form of a receptacle 148, mounted on the stationary frame 14. A clamp 150 is preferably provided to hold the cord 120 against the stationary frame 14, at a point near the plug 146, so as to prevent any accidental disconnection of the plug 146. The illustrated clamp 150 is secured to the frame 14 by a screw 152. Separable connectors 153a and b are also preferably provided between each cord 120 and the corresponding door 116a or b.

As shown to best advantage in FIG. ll, the stationary frame 14 is also preferably provided with electrical heating cables 154 to prevent condensation of moisture on the frame. As shown, the cables 154 are received in channels 156 formed in the frame 14.

The stationary frame 14 is adapted to be tted into an opening 158 formed by structural members 160 made of wood or the like. Screws 162 or other suitable fasteners may be employed to secure the frame 14 to the structural members 160. As shown to best advantage in FIG. 11, the screws 162 extend through appropriate openings in the web portion 104 of the frame 14.

To cover the opening 158, the stationary frame 14 has outwardly projecting flanges 164, at the front portion of the frame 14. Gasket strips 166 are preferably employed between the frame 14 and the structural members 160. Each gasket strip 166 is illustrated as being generally in the shape of a Z, having a front flange 168 disposed between the flange 164 and the structural members 160, a web portion 170 extending along the web portion 104 of the frame 14, and a rear leg 172, extending behind the rear surface of the lframe 14. For initial protection of the flange `164 during shipment and installation, the gasket strip 166 may comprise an additional leg or flap 174, adapted to be ripped away from the front leg 168 as one of the final steps in the installation of the frame 14.

As shown to best advantage in FIG. 12, a sealing strip 7 are closed. The illustrated strip 176 is mounted on the front or right-hand door 16b and is formed with a rearwardly projecting flange or ap 178 which is engageable with the metal side member 66 of the left-hand door 16u. The sealing strip 176 is preferably made of a flexible resilient material, Isuch as vinyl or some other suitable plastic. The illustrated strip 176 is secured to the door 16b by means of a forwardly projecting flange 180 which is force-fitted into a channel 182 formed in the metal border frame 26.

One or more stops 183 are preferably mounted on the rear side of the front door 16b to limit the opening Vmovement of both doors 16a and b, while also preventing engagement between the front door 16b and the handle 82a of the rear door 16a. Two such stops 182 are preferably provided, near the top and bottom of the door 16b. Each stop is preferably in the form of an L-shaped bracket, having one or more Ibumpers 184, made of rubber or some other soft, resilient material.

In the normal operation of the door assembly 12, the doors 16a and b are kept closed initially by the closer springs 86. Each of the doors 16b and b can be opened by sliding or translating it along the stationary frame 14. The anti-friction rollers 44 ride along the guide rails or llanges 46a and b. The peripheral grooves 48 in the rollers 44 retain the rollers on the bange 46a and b. If it is necessary to level or align the doors 16a and b, the elevation of the rollers 44 can be changed by loosening the nuts 58 and turning the eccentric shafts 50 of the rollers.

When either door 16a or b is opened and released, it is automatically closed by the corresponding spring 86, which pulls downwardly on the cable 92, so that the horizontal portion of the cable pulls the door towards its closed position. The cable 92 moves smoothly around the guide pulley 94. The spring 86 and the vertical portion of the cable 92 are enclosed and concealed by the plastic closure strip 106, which can readily be removed if it is desired to adjust the tension in the spring 86.

The electrical power to energize the heaters 116 in the doors 16a and b is ybrought to the doors by the ilexible electrical cords 120, which are fully concealed and completely out of the way. The upper and lower legs 122 and 124 of each U-shaped cord 120 are guided and retained by the channel members 128a or b and 130. When either door 16a or b is opened, the cord 120 is fed from the lower leg 124 of the U-shaped cord to the upper leg 122. The reverse action occurs when the door is closed.

With this cord arrangement, the electrical cords never get in the way of the customers. Moreover, it is practically impossible for the cords to become damaged or disconnected accidentally.

When a door is to be removed, the cord 120y can be disconnected by removing the plug 146 from the receptacle 148. Moreover, the plastic strip 106 can readily -be removed so that the spring 86 can be unhooked from the cable 92. The door is removed by lifting it bodily to disengage the rollers 44 from the flange or rail 46a or b. The door is lifted sufficiently to enable the lower member 54 of the door to clear the rail 46a or b, whereupon the lower portion of the door can be swung outwardly, to clear the front portion of the stationary frame 14. The door is then moved downwardly to disengage the rupper member 62 of the door from the guide flange 70a or b. During normal operation the guide ange 70a or b is received in the channel 68, with the gasket 72 between the guide flange and the inside of the channel;

The channel `68 is `deep enough and wide enough, in relation to the size of the ange 70a or b, to provide the clearance necessary to permit the upward lifting movement of the door when it is being removed from the stationary frame 14. The cable 92 can readily be unhooked from the anchor 96.

. 8 It will be evident that the door assemblyis smooth and eicient in operation, yet easy to maintain. The doors are closed automatically when they are not held open by a customer. In this way, the load on the refrigeration equipment is minimized. The electrical cords to the door heaters are completely invisible and out of the way.

Various other modiiications, alternative constructions and equivalents may be employed, as will be understood by those skilled in the art.

I claim: 1. A door assembly, f comprising the combination of a stationary door frame, a movable door mounted in said frame, means supporting said door for translatory movement in said frame, an element on said door requiring electrical energization, a tiexible electrical cord connected to said element and extending between said door and said frame, said cord being llexed into a U-shape with legs eX- tending parallel to the direction of movement of said door in said frame,

and rst and second guide means on said frame and said door and extending parallel to the direction of movement of said door for retaining the corresponding legs of said cord as the length of said legs is changed by the movement of said door in said frame.

2. A door assembly according to claim 1,

`in which said -irst and second guide means comprise opposed channel members on said frame and said door for receiving and retaining the legs of said cord.

3. A door assembly according to claim 1,

in which said irst guide means comprise a channel member on said frame for receiving the corresponding leg of said cord,

said second guide means comprising a channel member disposed on the rear side of said door and opposite said channel member on said frame for receiving and retaining the corresponding leg of said cord.

4. A door assembly. according to claim 1,

- in which said irst guide means comprise a ange member on said frame for receiving and retaining the corresponding leg of said cord,

said second guide means comprising a flange member on said door for receiving and retaining the corresponding leg of said cord.

5. A door assembly according to claim 1,

i in which said first guide means comprise a pair of anges on said frame for receiving the corresponding leg of said cord therebetween,

said second guide means comprising an L-shaped tlange on the rear side of said door for retaining the corresponding leg of said cord.

`6. A door assembly according to claim 1,

including rst and second separable connectors on said frame and said corwd for disconnecting said cord.

References Cited UNITED STATES PATENTS 2,762,675 9/1956 Janows 49-475 XR 2,858,408 10/1958 Barroero 49-70 2,912,714 11/1959 Rich 49-425 XR 2,962,773 12/1960 Heuer 49-425 I3,177,989 4/1965 Dichiaro 49-425 KENNETH DoWNEY, Primary Examiner Us. c1. X.R.

PMU-1U UNITED STATES PATENT OFFICE 6) CERTIFICATE 0E CORRECTION Patent NC 3.508J 361 Dated ADril 28. 1970 Inventor(s) J.P. Ryder It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 3, line 23, change "hight-hand" to "right-hand".

Col. 5, line 44, delete "may incorporate an electrical heating" and substitute "is also electrically heated to prevent any".

Col. 7, line 22 change 16h to 16a.

Col. 7, line 26, change "bange" to "flange".

SiNED AND QEALED Eamall'lewhnlr o umm x. n. L Amtlng ber miam or Pam