US2076561A

US2076561A - Portable resistance unit

Info

Publication number: US2076561A
Application number: US19094A
Authority: US
Inventors: Hanna Fry
Original assignee: Guyan Machinery Co
Current assignee: Guyan Machinery Co
Priority date: 1935-04-30
Filing date: 1935-04-30
Publication date: 1937-04-13
Anticipated expiration: 1954-04-13

Description

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April 13, 1937. F. HANNA PORTABLE RESISTANCE UNIT Filed April 50, 1935 Inventor Cttorncus 2......2222 w v. 3. .w V .w

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2 Claims.

This invention relates to electrical resistance units and particularly to the structural details of such a unit which make it rugged, durable, easily accessible for inspection and repair, and well ventilated.

In the prior art it has been difiicult to obtain a resistance unit which was sufficiently rugged and free from failures to make it suitable for use in rail bonding and mine repair work where available voltages usually exceed those to be used in Welding or other repairing. Work of this character is very frequently carried on under severe atmospheric conditions where the air contains a large percentage of moisture, and hence the majority of the electrical failures have been due to grounding of the resistance coils or of the connections to them. Consequently, the object of this invention is to provide a rugged resistance unit which will be durable and will have an unprecedented freedom from grounding failures.

Briefly stated, the invention consists in a resistance unit having a plurality of resistance coils carried between spaced insulating supports and supported at intermediate points by perforated sheets of moisture resisting pressed insulating material which is entirely free from any metallic content. The unit so constructed is covered over by an apertured casing which permits free flow of air over and about the resistance coils and at the same time leaves all of the resistance coils open for inspection and repair without requiring difficult dismantling operations.

Other objects and advantages of the invention will be apparent from the following specification when read in conjunction with the accompanying drawing in which:

Figure 1 is a side view of one form of electrical resistance unit embodying this invention, certain parts of the unit being shown in section.

Figure 2 is a partial section on line 2-2 of Figure 1; and

Figure 3 is a detail view of one of the resistance coils removed from the unit so as to illustrate the manner of mounting the coils.

The resistance unit shown in the drawing comprises a substantially flat metallic base 5 having upstanding lateral flanges 6 and reentrant end flanges 1 contacting with the ends of the unit. The base 5 is covered by a sheet of insulating 50 material 8 extending throughout its length and contacting with the inner face of each of two spaced end members I 2 projecting upwardly from the base and attached to it by means of angle members 9, bolts II, and rivets l0.

Covering the outer face of each of the end members i2 is an insulating plate l3 held in position by the reentrant end flanges l at the bottom, and adapted to cover up and protect the metallic supports for the resistance coils.

The end members [2 are connected at the top by a perforated sheet metal plate l4 secured to these end members by angle plates I5 and bolts l6. The lateral sides of the plate [4 are bent down over reticulated side shields l1 composed preferably of expanded metal. The top [4 is secured to the side shields by bolts I8 which serve the purpose, not only of holding the parts of the casing together, but supporting in spaced relation certain elements later to be described. The lower edges of the side shields I! are secured to the lateral flanges 6 of base 5 by means of bolts l9. Angle plates 2| cover the exposed ends of the side shields l1 and these plates are secured to the end members by screws 23. Inasmuch as the unit is constructed for portable use, it may carry handles 20 secured to the top l4, these handles being of any suitable form.

It will be understood from the preceding description that the end members in conjunction with the base, the perforated top, and the re-' ticulated side screens, form an enclosing casing which permits free flow of air therethrough. Mounted within this casing are a plurality of electrical resistance coils 24 composed preferably of non-oxidizing material and each having substantially the form indicated in Figure 3 of the drawing. Each of these coils 24 is connected to both of the end members I2, and each coil is provided for this purpose with a hook portion 25 terminating in an eye which may receive a bolt 26 for securing it either to the eye of an adjacent coil or to a terminal connection. The hook portions 25 are attached to hooks 21, each having a threaded shank 28 passing through openings in the end members l2 and secured by nuts 29. Each of these shanks preferably carries an enlarged collar to limit the entrance of the shank into the end members.

As shown in Figure 1, the resistance coils are arranged in vertical rows, each row containing five of the coils, four of these being paired and the remaining one having a free end attached to a hook 3| terminating in an eye and secured to the eye of the resistance coil by a bolt 32. An angle piece 33 is also secured by the bolt 32 and forms an electrical connection between the top coil 24, and a terminal bolt 34 passing through the end member I! so as to clamp the end member l2, the facing plate l3, and the angle member 33 in fixed relation. This bolt also serves as a means of obtaining electrical connection to the resistance coil without the use of switches or plugs.

The resistance coils 24 are supported at intermediate points between the end members l2 by supports 36, each composed of insulating material such as compressed asbestos lumber perforated at 31 to permit the coils to pass through them. As shown in Figure 1, the unit has three of these supports 36, each resting upon the insulating lining 8 and held in spaced relation by deflected portions 38 of the lateral flanges 6, and between clips 39 and nuts 4| associated with bolts l8. The insulating supports 38 are consequently held in permanent fixed spaced relation by the deflected portions 38 at both sides of the bottom of the casing and by two of the clips 39 adjacent the top of the casing.

These supports being composed entirely of insulating material, prevent sagging of the resistance coils and there is no possibility of breakage, causing failure of the unit. Additional connections may be made to the resistance coils 24 by means of the terminals 35 carried by the right hand end member shown in Fig. 1. Inasmuch as these connections will be similar to those indicated in connection with the terminal 34, a detail description will not be necessary.

It will be apparent from the preceding description that this unit comprises a simple sturdy frame in which the resistance coils are mounted and in which all of the electrical connections are visible for inspection. Each of the resistance coils can be removed readily in case of breakage, since the various coils are not embedded. This complete exposure also facilitates flow of air in and about the coils so that they may operate efiiciently and without overheating. The fact that no conductor passes through metal, renders grounding possible only by a long surface leak. While only three of the supports 36 are indicated, it will be obvious that more of these supports may be employed when the resistance coils 24 are made of light material, and in this way all possibility of two adjacent coils coming into contact can be avoided.

Although only one embodiment of the invention has been described, it will be obvious that various changes may be made in the details of the construction within the scope of the claims,

without departing from the spirit of the invention.

What I claim is:

1. An electrical resistance unit comprising a flat metal supporting base adapted to rest directly on the surface of the ground and having upstanding lateral and end flanges, said end flanges forming surfaces inclined to the ground and adapted to ride over small obstructions; an up standing end member of insulation at each end of said base engaging said end flanges; a perforated metal top sheet connecting said end members together; a plurality of insulating supports of compressed material, said supports having spaced openings therein; deflected tangs on said lateral flanges for holding said supports in fixed relation to said base; clamps on said topfor holding said supports; a plurality of resistance coils slung between said end members and passing through and positioned by the openings in said supports; means on one of said end members for supporting said coils and insulating them against contact with objects outside of the unit; means on the other end member for making electrical connections to said coils, and side screens of expanded metal cooperating with said end members, said base and said top to form a ventilated enclosing casing.

2. An electrical resistance unit comprising a flat insulated metallic base having upstanding lateral flanges with spaced deflected portions thereon, and reentrant end flanges; upstanding end members of insulation secured on said base and engaging said reentrant end flanges, said base being adapted to rest directly upon the ground and said reentrant flanges permitting the base to slide over small obstructions; a plurality of perforated spaced supports made up entirely of insulation and held in spaced relation by engagement with the deflected portions of said base; coil supporting means on each of said end members; a plurality of resistance coils slung between the means on said end members and passing through the perforations in said spaced supports; a metal plate on one of said end members for enclosing the coil supporting means and insulated from it; terminal means on the other end member and connected to said coils; and a perforated cage-like cover secured to said end members and said spaced supports.

FRY HANNA.

CERTIFICATE or CORRECTION.

Patent No. 2,076,561. April 13, 1957.

FRY HANNA.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2,

second column, claim 2, lines 54 to 37, strike out the comma and phrase said base being; adapted to rest directly upon the ground and said reentrant flanges permitting the base to slide over small obstructions" and insert the same after the Word flanges before the semi-colon in line 32, of said claim; and that the said Letters Patent should be read with this correction therein that the same conform to the record of the case in the Patent Office.

Signed and sealed this 8th day of June, A. D. 1957.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 2,076,561.

FRY HANNA.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, claim 2, lines 54 to 57, strike out the comma and phrase said. base being adapted to rest directly upon the ground and said reentrant flanges permitting the base to slide over small obstructions" and insert the same after the Word flanges and before the semi-colon in line 32, of said claim; and. that the said. Letters Patent should be read. with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 8th day of June, A. D. 1957.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

April 13, 1957.