US 3161085 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Patent O 3,161,085 FUSE FULLER llames T. Pratt, 10506 W. Villard Ave., Milwaukee, Wis. Filed `lan. 25, 1963, Ser. No. 253,896 2 Claims. (Cl. gli-3.8)
This invention relates to improvements in tools for removing or pulling electric fuses from r placing such fuses in their mounting cli-ps or their sockets, and which are usually called fuse pullers.
Electricians and electrical maintenance men and the like, desire a single ltool with which to remove and to replace in their mountings, such diverse electric fuses as the cartridge type fuses ranging in size from la diameter (for 2 amperes) to 11/2" (for 250 amperes) and the plug type fuses screwed into sockets and which generally have the same dimensions but different electrical rating.
Fuse removal or replacement is generally done while the circuit is energized up to the fuse clip or socket so that there is danger of arcing, or short-circuiting or of electrical shock to the operator unless the fuse is handled by an electrically insulated tool. Heretofore, tongs-like tools made of pressed paper or synthetic resins such as nylon and with jaws of a size to grip either the large paper tube enclosed, or the small glass tube enclosed cartridge type fuses, were used so that two separate tools were required `to handle the total range of fuse sizes.
Recently many electrical installations and particularly those on naval ships, have employed cartridge type fuses in which the mounting clips havel been made of relatively heavy spring steel to retain the fuses in fully seated position even when the installation is subject to heavy shocks. Consequently `a fuse puller to be used under such conditions must be capable of providing enough gripping action to overcome the resistance of such clips. Heavy duty fuse pullers of resilient insulating material such as nylon must be designed to concentrate the pressure on the fuse and the ends of the tongs members should have surfaces designedto limit the pressure on and iiexure of the fuse puller to that which can be resisted by the pivot pin and by other small parts or" the fuse puller. The ilexure limiting surfaces must be suiiciently large to avoid excessive stress concentration anywhere in the tongs and the members must be so made that both the large and the small pairs of jaws are fully opposed and cannot ex laterally to slip off the fuse or to twist the fuse as it is being inserted.
The present construction provides a molded synthetic and elastic electrical insulating fuse puller of generally tongs-like form and with jaws at one end of a size and shape to grip a range of sizes of the large paper wrapped cartridge fuses. The large jaws are relatively short from the pivot joining the two members and the handle portion is made relatively long to give an adequate grip and to be able to apply suicient pressure for removing or replacing various sizes of fuses. The handle end-s of the fuse puller are formed to bring such ends close together when the large jaws approach closed position and such ends are reduced to relatively small finger-like portions -to reach around the glass tube type of fuse of smaller sizes and which are generally surrounded by insulation walls closely spaced relative to the fuses. Such small ends are made to interlock when they grip a fuse to prevent spreading of the small jaws when pressure and tension are exerted thereon.
In the drawings:
FIG. 1 isa perspective view of one form of the present fuse puller.
FIG. 2 is a top plan view of the fuse puller with a relatively large size cartridge type fuse gripped thereby.
FIG. 3 is a side elevation of the device shown in FIG. 2.
FIG. 4 is a side elevation of a fragment of the handle portion of the fuse puller with the smaller jaws at the ends thereof closed on a small size cartridge type fuse.
FIG. 5 is a cross section on the line 5-5 of FIG. 3.
FIG. 6 is a cross section on the line 6 6 of FIG. 4, and
smaller jaws, which is produced by particular dimensional relationships ot the tongs parts.
Referring to the drawings by numerals, 1l) and 11 generally designate the two members of a tongs-like tool, which are joined by a pivot 12. The two members 10 and 11 are substantially alike and differ only in having the pivot 12 made integral with part 1t) and in having part 11 provided with ya recess 13 into which a projectionV 14 from therpart 1@ may be received. When jaws 22,
23 receive a fuse 26 (see FIGS. 4 and 6), projection 14 enters recess 13 to aid in keeping the jaws in opposed position and preventing twisting of the jaws and the fuse, but does not seat in the recess. The proportions of the pieces Iii and 11 from the pivot 12 toward the large jaws 1,8 and 19 .and from such pivot toward the other end are such that the handle portions 20 and 21 are relatively long and small jaw parts 22 and 23 at the handle ends are also proportionally longer than the large jaws at the other end of the fuse puller.
law parts i8 and 19 are much wider than jaw parts 22 and 23 so that the relatively narrow areas 25 at the nose of the jaw parts are adequate to act as stop or pressure limiting areas whenthe small jaws 22, 23 are used to grip a fuse as indicated at 26 (see FIG. 4). The mountings for the large fuses 27 are usually such as to allow ample space around the fuse puller for entry of the jaw parts 18 and 19 .to grip the fuse. The jaws 13 and 19 may accordingly take the gener-al shape and proportions of `the jaws of a pliers. However the Vfree space around the smaller fuses 26 islimited so that the jaws 22, 23 must be made as relatively thin and long ngers to enter such spaces. Such jaw parts 22, 23 should be approximately parallel when opened enough to pass around a fuse 26, and are made with opposing plane surfaces 30, 31 which seat when pressure on the handle parts 20, 21 uponrgripping of a fuse 26, causes such jaw parts to approach one another. The fuse pulier thus has only the relatively small stop surfaces 25, 3@ and 31 which may seat when a fuse is gripped by oneor another pair of jaws ,to prevent over-stressing of the jaws.
The recessesfor holding a fuse in the jaw parts, are made with one dimension less than the diameter of the smallest fuse to be handled thereby, Iand accordingly only a limited iiexing of the handle portions 20, 21 is possible before the surfaces 25 or 30, 31 come into contact and the `pivot of the handle portion cannot be overstressed. The two tongs members 10, 11 are however otherwise so dimensioned as to have the handle portions'Zil, 21 in slightly spaced relations when the jaws 1S, 19 bear on one another. The recess 13 in one of the smaller jaws is made deep enough so that the projection 14 on the other of such jaws, cannot seat in the end of the recess to limit the bearing of stop surfaces 30, 31 on one another.
The tongsare preferably made of an overall length of approximately seven and one-half inches to al-low effective gripping by persons with large hands while leaving approXimately two inches from each end of the tongs free for entry around the fuse and for spacing between the fuse and the users hands. A smaller version of the fuse puller, but with the same general proportions as above indicated, has been found satisfactory for use by homeowners, electronics repair men and the like.
Patented Dec. 15, 1964 FIG. 7 is a side elevation to show an effect on the The two parts 10, 11 are so dimensioned that the smaller jaws 22, 23 are spaced as shown in FIG. 7, when the larger jaws 18, 19 have their nose stop surfaces 25 in contact. The opening of jaws 22, 23 are spaced as shown in FIG. 7, when the larger jaws 18, 19 have their nose surfaces 25 in contact, and such opening is less than the diameter of the glass tube cartridge fuse to be gripped. Thus a glass tube type fuse may be within the jaws 22, 23, but the opening of such jaws is larger than the fuse and no pressure is put on such f-use until after the large jaw surfaces 25 are in contact. Thereafter flexing of the handles 20, 21 closes jaws 22, 23 for gripping the fuse. The tongs material has limited flexibility but does ilex enough to bring jaws 22, 23 to fuse-gripping position and to enter the projection 14 into the recess 13. Because the users grip acts against the resilience of the handles andthe small jaws have much less cross sectional area than the handles and flex more readily than the handles, there is no tendency to exert crushing force on the glass tube of the fuses.
It will thus be seen that the present fuse pullerfmay be made from any moderately elastic insulating material because exure limiting surfaces are provided so that neither the pivot pin nor any other portions of the fuse puller will be stressed beyond the elastic limit. Because the relatively small glass cartridge type fuses are frequently enclosed in insulated compartments, the jaws for gripping such fuses are at the ends of the handle portion of the tongs and are made as relatively thin fingers to reach into such compartments. Such ends are likely to be quite flexible and are therefore provided with interlocking parts to prevent relative lateral movement of the jaws. A single tool is accordingly provided with different kinds of pairs of jaws for handling various kinds and sizes of fuses.
1. In a fuse puller of the tongs type made of electrical insulating material of limited flexibility and relatively low elastic limit, a pair of members joined by a pivot intermediate their ends to provide shorter portions extending from one side of the pivot and longer handle portions extending from the other side of the pivot, the shorter portions having opposed nose stop surfaces for bearing on one another to stop pivoting of the members and being larger in cross section than the handle portions for withstanding pressures upon ilexing of the handle portions, jaw parts at the free ends of the handle portions, said jaw parts being smaller in cross section than the handle portions and having adjacent opposing tlat surfaces in spaced substantially parallel relation when the nose stop surfaces are engaged whereby gripping of fuses below a given size by the jaw parts depends upon flexing of the handle portions and thereby limits pressure on the smaller fuses.
2. The structure of claim 1 in which one of the opposing fiat surfaces has a projection extending therefrom and entering into a recess in the other part, the recess being deeper than the height of the projection for avoiding seating thereof in the recess until the jaw parts approach one another closer than the diameter of the smallest size fuses to be handled.
References Cited in the le of this patent UNITED STATES PATENTS 354,313 Galloway Dec. 14, 1886 1,363,515 Knoss Dec. 28, 1920 1,481,517 Kurz Jan. 22, 1924 1,518,251 Carlson Dec. 9, 1924 1,561,082 Jung Nov. 10, 1925 2,236,941 Foley Apr. 1, 1941 2,563,236 Gragg Aug. 7, 1951