US2856836A

US2856836A - Blower construction

Info

Publication number: US2856836A
Application number: US447586A
Authority: US
Inventors: Walter A Spear
Original assignee: Nutone Inc
Current assignee: Nutone Inc
Priority date: 1954-08-03
Filing date: 1954-08-03
Publication date: 1958-10-21
Anticipated expiration: 1975-10-21

Description

Oct. 21, 1958 w. A. SPEAR 2,856,836J

BLOWER CONSTRUCTION Filed Aug. 5, 1954 5 Sheets-Sheet 1 IN V EN TOR.

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Oct. 21, 1958 w. A. SPEAR 2,856,836

BLOWER CONSTRUCTION Filed Aug. 5, 1954 5 Sheets-Sheet 2 4 JNVENTOR.

BY flwwfim ATTORNEYS.

Oct. 21, 1958 r w, sp 2,856,836

BLOWER CONSTRUCTION Filed Aug. 3, 1954 5 Sheets-Sheet I5 INVENTOR.

W J WJQ ATTORNEYS.

Oct. 21, 1958 w. A. SPEAR BLOWER CONSTRUCTION 5 Sheets-Sheet 4 Filed Aug. 3, 1954 BY 2 I aI'NVENTOR.

ATTORNEXS.

Oct. 21, 1958 w. A. SPEAR 2,856,835

BLOWER CONSTRUCTION Filed Aug. 5, 1954 5 Sheets-Sheet 5 BYMiVENTOR. I

lh'romvsys United States Patent ELQWER CONSTRUCTION Walter A. Spear, Cincinnati, Ohio, assignor to Nutone, Inn, Cincinnati, Glue, a corporation of New York Application August 3, 1954, Serial No. 447,586

7 tllaims. (Cl. 98-43) This invention relates to blowers of the type exemplified by U. S. Patent No. 2,349,668. This type of blower is one which is adapted to be recessed in a ceiling, or in a wall, or in cabinet structure, to exhaust air from a room, such as a kitchen, and deliver it to the outside atmosphere through a duct which may be enclosed within the walls or ceiling of the building structure.

More specifically, the present invention is directed to improvements in the construction of a blower of the type set forth, which improvements greatly simplify installation and maintenance. 7

One of the problems which arise in making a blower installation, particularly in an old building structure, is to arrange the duct so that it follows as straight a path as possible from the place of installation to an exhaust outlet. Turns in the duct not only increase the cost r of the installation, because of the special fittings required,

but they also reduce substantially the efiiciency of the blower due to the increase in resistance to the flow of air through a tortuous duct. Therefore, to be commercially practical, and to avoid the use of special fittings, a blower must be adaptable for connection to an exhaust duct which may lead from the point of installation in any one of a number of different directions. With this in mind, it is one of the objectives of the invention to provide a blower construction which may be altered in a matter of minutes and Without'the use of special too-ls to change the exhaust and intake sides thereof as demanded by diiferent installation conditions.

in the preferred embodiment of the invention, I provide a casing to house the blower which has two fixed end walls and two fixed side walls which are permanently joined to one another. One of the fixed side walls has a duct fitting or connector secured thereto. The other two sides of the casing are each adapted to receive a transposable side Wall or a shiftable air intake grill. By chang ing the relative positions of the shiftable grill and the transposable side wall it is found that the blower casing can be made to accommodate substantially all duct conditions likely to be found in ordinary building structures. The simple expedient of interchanging the positions of the transposable side wall and the intake grill makes it possible to have horizontal intake and discharge, vertical intake and discharge, horizontal intake with vertical discharge, and vertical intake with horizontal discharge. These arrangements of the intake and discharge sides of the blower will accommodate duct work leading from the place of installation at any one of the four sides thereof or leading from it in direct alignment with the opening into the blower recess whether the opening be in a ceiling, or in a wall, or whether it is built into cabinet structure.

Another objective of the invention is to provide a blower construction of the type set forth which may be disassembled easily and quickly by an unskilled person for cleaning purposes without the use of tools. This is an exceedingly important feature, particularly in a kitchen installation where the blower parts become loaded, from time to time, with an accumulation of greasy dirt-the 2,856,836 Patented Get. 21, 1958 result of air which is laden with cooking greases, along with the usual dust, passing through the blower.v The blower wheels which move the air, the electric motor which drives the blower wheels, and involute housings provided to enclose the blower wheels in the present construction are adapted to be removed from the casing through the intake grill side thereof as a unit. This is possible irregardless of the position of the blower casing within a recess. to latch the blower unit in position within the casing so that it is properly aligned with the duct connector irregardless of the position of the casing within a recess. Otherwise expressed, the blower and motor unit may be removed and replaced, latched and unlatched from the grill side of the casing, which side may be the one opposite to the duct connector or one adjacent to it because of the shiftable nature of the grill. In the preferred embodiment the latch comprises a bail shaped element which is disposed at to the sides of the casing. In this angular relationship it is adapted to function as efiectively in either one of the two positions of the grill.

In addition, novel means are provided for removably fastening the involute blower wheel housings to the blower unit so that they may be removed for cleaning. This too is an exceedingly important feature because most of the dirt which accumulates inside of a blower is found on the inside of the blower wheel housings.

A further objective of the invention is to provide novel means to mount the shiftable grill so that it may be changed from one side of the casing to the other without removing it from the casing. Furthermore, the means provided are arranged so that the grill may be swung down and removed from the casing in an installation to provide adequate room for disengaging and removing the blower unit. This is made possible by means of a novel, pivotable mount which operates in conjunction with one or more coil spring to provide a toggle action which is effective in both positions of the grill to hold the grill in tightly closed position and to hold the grill mounting means in fully opened position.

Other objectives, features and advantages of the present invention will be readily apparent to those skilled in the art from the following detailed description of the drawings in which:

Figure l is a diagrammatic view showing a typical ceiling installation of a blower incorporating the principles of the present invention in which air is discharged through a duct which extends horizontally from a side of the blower casing.

Figure 2 is a View similar to Figure l in which the duct is shown leading vertically upwardly from the blower casing.

Figure 3 is a view of the underside of the blower casing in which certain parts have been broken away to illustrate details of construction.

Figure 4 is a cross sectional view taken on the line d4 of Figure 3.

Figure. 5' is a view similar to Figure 3 in which parts are broken away to illustrate the details of the means provided to secure the motor-blower unit in place.

Figure 6 is a cross sectional view taken on the line 6--6 of Figure 5. in this view the parts are arranged for discharging air horizontally from a side of the blower casing.

Figure 7 is a View similar to Figure 6 in which the parts are arranged to discharge air upwardly vertically from the blower casing.

Figure 8 is a cross sectional view taken on the line 3-8 of Figure 4.

Figure 9 is an enlarged cross sectional view taken on the line 9-9 of Figure 4.

For purposes of this disclosure, the blower, which. is designated generally by the numeral 10, is shown in- Furthermore, novel means is provided stalled in a ceiling. In Figure 1 it is shown between floors, for example, in a two story house. In an installation of this type, it is usually necessary to run a duct, such as that shown fragmentarily only at 11, horizontal- 1y from a side of the blower in the spaces between joists to an exhaust outlet at the outside of the building structure. In an installation such as that shown in Figure 2, the duct 11 extends from the top of the casing. This type installation may be used in a one floor plan building structure, or in other places where conditions require. The two installations shown are intended to be representative only. It is believed that it will be obvious to those skilled in the art that the blower construction is adaptable to many other types of installations such as, by way of example only, an installation in an overhead storage cabinet of the type used in kitchens, an installation in a stove ventilator hood, an installation in a wall between studs, and an installation in the space provided by a dropped ceiling.

The blower is housed within a rectangular, sheet metal casing which is designated generally by the numeral 12. The casing, it will be noted, is square in lateral cross section. The casing includes two end walls which are indicated at 13 and 14 respectively and a side Wall 15 which, in the present instance, are formed from one piece of sheet metal bent at right angles at the respective opposite ends of side wall 15. The three sided construction thus provided is permanently affixed to another side wall which is designated 16. Three sides of wall 16 at the top and two ends thereof are flanged as at 17 to provide a means for attaching this wall to the three sided construction comprising

end walls

13 and 14 and side wall 15. It

is preferred that the flanges 17 be spot Welded to

walls

13, 14 and 15 so as to provide a rigid, four sided, selfsustaining structure. openings 1818 therein adjacent to the edge thereof which joins side wall 15. These openings constitute the exhaust outlets for the blower and they open into a rectangular duct fitting or connector, designated 19, which is permanently afiixed in place. Right angular flanges 20 at three sides of the duct fitting are spot welded to wall 16 and an extension 21 at the top of the duct, as viewed in Figure 8, overlaps the marginal edge of side wall 15 and is also spot welded in place. The lower edges of the two

end walls

13 and 14, the lower edge of side wall 16, and the side edges of the

respective end walls

13 and 14, as viewed in Figure 8, are configurated to provide strengthening ribs 22 which extend along these walls adjacent to their free edges.

The other two sides of the casing 12 are adapted to receive, interchangeably, either a transposable side wall 23 or a shiftable grill 24. It is the interchangeability of wall 23 with grill 24 which makes the present construction adaptable to accommodate substantially all duct conditions likely to be found in ordinary building structures.

Transposable side wall 23 has a flange 25 turned over at right angles at three edges thereof. The flanges are adapted to engage and embrace the outer marginal edges of the two end walls of the casing and the outer marginal edge of a side wall. The flanged longitudinal side edge of the transposable wall 23 has three tabs thereon like the one shown at 26 in cross section in Figure 6. These tabs, although parallel to the plane of the flanged edge of transposable wal 23, are oflset from it by one thickness of sheet metal, and are adapted to be engaged in complementary slots 27 which are provided along the edge of side wall 15 or in slots 28 which are provided along the edge of wall 16. In addition, transposable wall 23 has a tab on each one of the flanges at the ends thereof. The latter tabs are designated 29 and are adapted to be engaged underneath of or through bands 3030 which are lanced from the

respective end walls

13 and 14 at the side thereof opposite side wall 16, or in the bands 3131 which are lanced from the respective end walls at the edge thereof which is opposite to side The wall 16 has two rectangular wall 15. To change the transposable side wall 23 from one position to the other it may be disengaged from slots 27 and bands 3030, for example, and re-engaged in slots 28 and bands 31. In order to make the change the end wall must be turned end for end. To fasten the transposable wall permanently in place the tabs 29 may be bent back around the bands, either those designated 3030 or those designated 31--31 so as to lock the wall against removal from the casing. Preferably, the free edge of. the transposable wall is headed or ribbed as shown at 32 to strengthen it.

As will be seen from Figures 1 and 2 the casing 12 of the blower is dimensioned to fit between joists that are spaced on standard 16 inch centers. The

respective end walls

13 and 14 of the casing are pierced as shown in Figures 1 and 2 to provide holes 33 for nails which may be used to fasten the casing to the joists, or to wall studding, or to support members in cabinet structure.

The grill 24 in the present embodiment is fabricated from a single piece of sheet metal. The grill includes a marginal frame 34, which may be substantially rectangular in shape with rounded corners, a plurality of grid members or bars 35 which extend longitudinal of the frame, and an upstanding peripheral flange 36 which is turned outwardly at its upper edge. As will be seen in Figure 6 the outwardly turned rim of flange 36 makes contact with the plaster. surrounding the recess in which the blower is situated in a ceiling installation.

At'the respective opposite ends of the grill, and on the longitudinal center line thereof, a pair of mount brackets 37 are secured by means of rivets to the inner face of frame 34. With the grill in place as shown in Figure 6 the respective mount brackets extend into the casing adjacent to the opposite end Walls thereof. Each mount bracket has a pivot pin 38 secured therein which extends at right angles from a side thereof in axial alignment with the longitudinal center line of the grill. Each pin is rotatably engaged in an aperture which is provided in the end of a link designated 39. The other endof each link is pipoted upon means such as a rivet which is secured to the end wall in the corner thereof which is opposite to

side walls

15 and 16. Furthermore, the point of pivot is on one of the diagonal lines of the end wall so that it is symmetrically placed with respect to the two sides of the casing which the shiftable grill is adapted to enclose. Substantially mid-way between the pivot pin 38 and the point at which the link is pivoted to the end wall a small hole 40 is provided in link 39, which hole provides a means of attaching one end of an elongated coil spring 41. The other end of the coil spring may be secured to an angle bracket 42 or an angle bracket 43. These two brackets are substantially identical in construction and each 'may comprise a triangular metal plate which is flanged and spot welded to the fixed walls of the casing.

The means which are provided to mount the grill 24 performs several functions. The link permits the grill to be shifted from one side of the casing to the other side of the casing in order to change the direction and position of the duct fitting. The coil spring 41 in conjunction with the link 39 provides a toggle action which holds the grill tightly against the plaster line when it is in closed position, but, which in addition, serves to hold the grill links in open position when swung down as shown by the dot-dash lines of Figure 6. In the latter position, it will be noted that the spring is moved over center with respect to the point of pivot for the link 39 so that the grill is stable when open.

A comparison of Figures 6 and 7 will show how simple it is to change the relative position of the grill. In Figure 6 the grill is shown with the duct extending from a side of the casing. To change it to the condition shown in Figure 7 all that it is necessary to do is to move the upper end of the coil spring 41 from bracket 42 over to bracket 43. This change, of course, can be made without the use of special tools. At the same time, of course, the transposable wall 23 of the casing is moved as described above.

The blower unit which is used to move the air in the present construction comprises a pair of centrifugal type, squirrel cage blower wheels 44-44 which are keyed to the opposite ends of the shaft of a double ended electric motor 45. The blower Wheels may follow conventional design, but it is preferred that they are made of steel in order that they may be sufiiciently rigid to keep them from becoming bent out of line during cleaning. The motor 45 is enclosed within a cylindrical jacket 46 which has a pair of blower housing mounting rings 4747 affixed to its opposite ends. Involute housings 48-48 for the blower wheels are removably secured to the respective mounting rings 47-47 by means to be described below.

The motor and the blower wheels, the jacket for the motor and the two blower wheel housings comprise a structural unit which is adapted to be readily removed from and replaced in the casing 12 through the grill side thereof as will be explained below.

As may be seen in Figure 9, the cylindrical jacket 46 for the motor is open at one side thereof to an air intake duct 4-9. This duct is made of sheet metal which is formed into a box-like structure open at both ends. The duct 49 is permanently secured to the jacket 46 by a pair of flanges 5t which are turned outwardly from the jacket and which are spot welded to the duct. Duct 49 is located just below duct fitting 19 and is open to the outside of the casing through louvers 51 which are cut into the wall 16 of the blower casing. Cooling air is induced to flow into jacket 46 through louvers 51 by the spinning blower wheels. The two wheels pull the air through a plurality of openings 52 in the mounting rings 47 which are secured to the opposite ends of the jacket. The louvers 51, it will be noted, open into the recess in which the casing is mounted so that the air used to cool the motor is not that which is drawn through the grill. In this way, an accumulation of greasy dirt in the jacket is avoided. Both ends of jacket 46 are flanged as at 53, the flanges extending outwardly at right angles to the Walls of the jacket. it is preferred that one of the flanges 53 be spot welded to one of the mounting rings. To facilitate assembly, the other flange is bolted to the other one of the two mounting rings.

The mounting rings also serve to mount the motor 45. The central area of each ring 47 has a circular opening therein in which is mounted a rubber grommet 54, the grommet having an annular groove extending around the circumference thereof which seats the marginal edge of the ring 47 in the area thereof immediately surrounding the opening. The end caps for the motor bearings may seat directly in the respective grommets. Each mounting ring, in addition, has an annular, peripheral flange 55 thereon which is oifset inwardly from the opposite ends of the motor jacket. It is these flanges which mount the involute blower wheel housings. Each blower wheel housing is secured to flange 4;7' by means of spring urged bayonet pin devices which are designated generally at 56. Each device includes a pair of large headed pins 57--57 and a stiff coil spring 58. The heads on the pins, it will be noted from Figure 4, taper outwardly as at 59 from the shank portion thereof. The two pins of each device 56 are slidably mounted in apertures in the respective annular flanges 47-- l7 opposite one another at points which are aligned parallel with the motor axis. The shanks of the heads point toward one another and each has a transverse hole therethrough which receives the hook end of spring 58. The spring is under considerable tension, thus the heads of the two pins seat firmly against the apertures in the respective annular flanges.

In the instance shown, three bayonet pin devices 56 are employed, being located at substantially equally spaced points around the blower jacket. Each involute housing 48 has three bayonet slots 60 in a wall thereof which are spaced in accordance with the locations of pins 57. Thus, to remove and replace the blower wheel housings, each housing is twisted with respect to the motor jacket to align the large openings in the bayonet slot with the heads of the pins. With the heads of the large openings lined up, the housing may be pulled straight off the end of the blower wheel.

The two blower wheel housings, other than having the bayonet slots in them, may follow substantially conventional construction. In the present instance each housing comprises an inner wall 61 having a circular opening 62 therein to seat upon a shoulder 63 which is provided where the annular flange 55 is turned outwardly from the mounting ring. The opposite or outer wall 64 of the blower housing has a large central opening 65 therein, the marginal edge of which may be turned in as at 66 to provide an air intake passageway which is in communication with the area inside of the blower wheel. Two side walls 61 and 64- are enclosed by a continuous wraparound wall 67, the opposite side edges of which are flanged as at 68 to seat the peripheral edges: of the respective side walls.

The motor blower unit is adapted to be fastened inside of the casing by means of a bail shaped latch indicated generally at 69. This latch is pivoted at its opposite ends in brackets 70.-7tl which may be spot welded or riveted to the opposite end walls of the casing. The pivotal axis of the bail shaped latch extends longitudinally of the casing in the quadrant thereof which is adjacent to the duct fitting. The bail shaped latch, when it is in blower unit locking position, extends from the pivot points at approximately 45 to the longitudinal axis of the casing to engage in detent grooves Til-71 which are formed by punching outwardly the metal of the respective wraparound walls 67 of the two blower wheel housings. These detents are located at places opposite the air outlets of the housings at approximately 45 to a plane passing vertically through the motor axis.

In the present construction, the whole blower casing is turned through to shift from side discharge to vertical discharge. The blower motor unit is also turned in such movement inasmuch as the discharge openings from the blower wheel housing must remain aligned with the permanently affixed duct fitting. Witlrthe duct fitting 19 extending from a side of the casing as viewed in Figure 9, the bail shaped latch 69 may be swung up along the side of the blower motor unit which is opposite to the duct fitting to free the unit for removal through the opening provided by swinging the grill down into the position shown in Figure 6. With the discharge duct extending upwardly, the bail bar may be swung up to release the unit at the side thereof which is toward the duct fitting. In either instance, the swing is in the direction of the transposable side wall 23 of the casing.

The electric motor 45 is powered through Wiring 7?. which passes through a grommet '73 seated in a hole in the motor jacket 4-6. A male plug 74- is provided at the end of the wiring which plug is adapted to be engaged into a socket mounted within a wiring box 75. Preferably, the wiring box is in one of the corners of the casing which is adjacent to a duct fitting. Thus located, it serves, with a rib 76, to position the unit so that the openings 1818 are aligned correctly with the blower wheel housings.

It will be noted that the present blower unit is virtually free of vibration due to the fact that all mounting components are either fastened by springs or held in place by spring members. The motor itself is seated within the rubber grommets 54, the housings for the blower wheels are secured by the spring urged bayonet pin devices 56 and bail latch 69 employed to secure the motor blower unit in place also has a certain amount of springiness, and in addition, the grill is held in place by the springs 41-41.

For the initial shipment of the blower, the transposable side wall may be taped or otherwise temporarily affixed to one of the sides of the casing. At the point of installation the transposable wall and shiftable grill may be arranged as conditions dictate. Then, with the motorblower unit out, the casing may be fastened into place by nails or screws which pass through the holes provided in the two end walls. In an installation in a new building structure, the casing may be put in place before plastering so that the plaster line may come right up to the casing walls. In an installation in an old building, if care is exercised in cutting the hole through the plaster, it is not necessary to plaster in the areas immediately surrounding the casing, because the substantially wide frame on the grill will hide the broken edges of the old plaster.

To clean the unit the grill may be swung down into open position, and then disengaged from the links which remain in down position due to the toggle action provided by the springs 4141. The bail then may be disengaged and the motor-blower unit removed from the casing. Any dust or dirt at the inside of the casing then may be cleaned out. The blower wheel housings may be removed from the motor jacket by turning to release the bayonet pins. Thehousings, after removal, may be washed in the sink, if desired. The blower wheels may be brushed to remove any accumulation of dust or dirt from the blades. It is preferred that appropriate markings made on the two blower wheel housings and on the motor jacket to serve as a guide to assist in the reassembling of the motor-blower unitso that the housings are correctly related to one another and to the motor. With the motor-blower unit assembled it may be reinstalled in the casing by swinging the bail latch to one side and then re-engaging it in the detents once the unit is properly seated.

Having described my invention I claim:

1. A blower casing for installation in a recess, said blower casing being rectangular and comprising end walls and two adjacent side walls permanently joined to one another, a transposable side wall, a grill, means to receive said transposable side wall at either one of the two sides of the casing opposite to the first mentioned side walls, means to mount said grill for selective shifting movement between positions in which it is disposed at either one of the two sides of the casing opposite to the first mentioned side walls, and a duct fitting afiixed to one of the permanent side walls, adjacent to the juncture of said side walls.

2. A blower casing adapted to be mounted within a recess, said blower casing being rectangular and comprising two end walls and two side walls permanently open sides of said four-sided construction, a grill, means removably fastening said grill to the respective end walls of the casing for shifting movement between positions in which it may enclose either one of the two sides of the four-sided construction not enclosed by said transposable wall, and a duct opening in one of the permanent side walls of said four-sided construction.

3. A blower adapted to be mounted in a recess, said blower comprising a rectangular casing having two side walls and two end Walls which are permanently joined, a duct fitting associated with one of said side walls, a transposable side wall, means for afiixing said transposable side wall to either one of the two sides of the casing opposite said permanently joined side walls, a grill, means aflixing the grill to the casing to enclose the fourth side of said casing, a motor-blower unit including a pair of blower wheel housings disposed at the opposite ends thereof, a bail shaped latch, means pivotally mounting the opposite ends of said bail shaped latch at the inner sides of the respective end walls of the casing, and said bail shaped latch adapted to engage said blower wheel housings to removably secure said motor-blower unit in said casing.

4. A casing for a motor-blower unit adapted to be installed in a recess in a ceiling or the like, said casing comprising a pair of end walls and a pair of side walls permanently afiixed to one another to provide a foursided, box-like construction, said side walls being disposed adjacent to one another, a duct fitting permanently affixed to one of said side walls, a transposable side wall, means to accommodate said side wall selectively at either one of the two sides of said four-sided construction opposite to one of the permanent side walls thereof, a shiftable grill, and spring urged means linking said shiftable grill to said casing to permit said grill to be moved from one of the sidesthereof to the other one of the sides thereof opposite to said permanently aflixed side walls.

5. A casing construction for a motor-blower unit adapted to be installed in a recess in a ceiling or the like, said casing construction comprising a pair of end walls and two side walls which are permanently affixed to one another to provide a four-sided, box-like construction, a duct fitting permanently affixed to one of said side walls adjacent to its juncture with the other one of said side Walls,'a transposable side wall, means to affix said transposable side wall selectively to either one of the two sides of the casing construction opposite to the permanent side walls thereof, a grill, linking means for securing said grill to said casing for swinging movement from a position opposite one of the permanent side walls of the casing to a position opposite to the other one of the permanent side walls of the casing, and spring means associated with said linking means and adapted to re siliently hold said grill in either one of its said positions.

6. A blower comprising a casing having two end walls and two side walls, said side walls being permanently joined to one another and to the end walls, a transposable side wall, a grill, means to mount said transposable side wall selectively at either one of the two open sides of said casing, means to mount said grill at the same two sides of the casing but alternately with said transposable wall, the latter named means comprising links arranged to permit shifting of the grill from one side of the casing to the other, and spring means associated with said links arranged normally to hold said grill against a side of said casing but adapted upon the swinging of the grill into an open position to hold said grill in said open position.

7. A casing construction for a motor-blower unit adapted to be installed in a recess in a ceiling or the like, said casing construction comprising a pair of end walls and two side walls which are permanently ailixed to said end walls and to each other, a duct fitting permanently afiixed to one of said side walls adjacent to its juncture with the other one of said side walls, a transposable side wall, means to aflix said transposable side wall selectively to either one of the two sides of the casing construction opposite to the permanent side walls thereof, a grill, means linking said grill to said casing for swinging movement from a position opposite one of the permanent side walls of the casing to a position opposite to the other one of the permanent side walls of the casing, and the latter named means including a spring arranged to urge said grill toward engagement with the casing but also permit said grill to be swung into an open position.

References Cited in the file of this patent UNITED STATES PATENTS 2,014,507 Price Sept. 17, 1935 2,134,142 Orear Oct. 25, 1938 2,349,668 Marker et a1 May 23, 1944 2,661,894 Stevenson Dec. 8, 1953 2,686,630 Burrowes Aug. 17, 1954