US3030545A - Positive carbon holder for arc lamps - Google Patents

Description

Aprxl 17, 1962 J. scHLElFER ETAL 3,030,545

POSITIVE CARBON HOLDER FOR ARC LAMPS Filed Sept. 25, 1959 United States Patent POSITIVE CARBON HOLDER FOR ARC LAMPS Josef Schleifer, Krumbach, Schwaben, and Werner Fleck, Josef Droppa, and Kurt Muller, Stuttgart, Germany, assignors to Eugen Bauer G.m.b.H., Stuttgart- Unterturlrheim, Germany Filed Sept. 25, 1959, Ser. No. 842,351 Claims priority, application Germany Sept. 26, 1958 12 Claims. (Cl. S14- 80) The present invention relates to arcs lamps, particularly of the type used in cinematographic projection.

More particularly, the present invention relates to that part of an arc lamp of the above type which supports and feeds the positive carbon of the arc lamp.

In lamps of this latter type electrically conductive shells press against the positive carbon in order to transfer current thereto with a minimum of resistance, and it is necessary to rotate and feed the positive carbon so that it will move with respect to the electrically conductive shells. However, the elements which engage the carbon to rotate and advance the latter cannot press with too great a force against the carbon since this will result in injury to the exterior surface thereof with resulting poor transfer of electricity and non-uniform burning away of the carbon. At the present time extremely complex structures are used to carry and feed the positive carbon of an arc lamp of the above type, and the conventional lamps of the above type do not operate reliably for the desired long periods of time since the complex structures thereof are subjected to the relatively high temperatures of the arc lamps. Moreover, the conventional structures require an extremely large amount of energy in order to drive all of the complex mechanism.

One of the objects of the present invention is to provide for a lamp of the above type a positive carbon holding and feeding device which is of relatively simple construction and which is capable of being operated with a relatively small amount of energy and which at the same time willreliably feed the carbon without Lany danger of injury to the exterior surface thereof while at the same time feeding the carbon with a force sufficient to move the carbon with respect to the stationary electrically conductive shells which engage the same.

Another object of the present invention is to provide in a structure of the above type a means which will rotate and axially feed the positive carbon and which at the same time can automatically align itself with respect to the carbon so that irrespective of the direction in which the carbon extends, as determined by the electrically conductive shells pressing thereagainst, the structure which rotates and feeds the carbon can align itself with respect thereto so that there is no tendency for the structure which feeds the carbon to tilt the carbon with respect to the electrical conducting structure and to become jammed with respect to the carbon.

A further object of the present invention is to provide a structure wherein the pressure of the rolls which rotate and feed the carbon can be very accurately determined and is uninliuenced by the weight of the structure which carries these rolls. l

An additional object of the present invention is to provide a structure of the above type which can be easily and quickly actuated by the operator for the purpose of exchanging one carbon for another.

With the above objects in view the invention includes in a device for holding and feeding the positive carbon of an arc lamp, a hollow drive gear into which a part of the carbon is adapted to extend. A. first carrier turnably supports this 4hollow drive gear as well as a pair of pinions meshing therewith, and a pairof --rolls which are 3,030,545 Patented Apr. 17,` 1962- respectively fixed coaxially to these pnions are adapted to engage the carbon to participate in the rotation and axial feeding thereof. A second carrier is pivotally carried by the first carrier, and this second carrier carries a third pinion which meshes with the drive gear and to which a third feed roll is coaxially fixed. The first carrier is itself pivotally carried by a stationary support. The connection of the first carrier to the stationary support enables the first carrier and all of the parts carried thereby to automatically align themselves with respect to the carbon, and a spring means between the first carrier and stationary support counterbalances the weight of the first carrier and all of the parts carried thereby. A second spring means cooperates with the first carrier and the second carrier to urge the feed rolls with a predetermined pressure against the carbon.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accomwhich a stationary support 4 is located, a sheet of elec-.

trical insulating material 2 being interposed between the. stationary support 4 and the base 1. A foot portion 3 of the stationary support 4 directly engages the plate 2 of electrical insulating material. The stationary supportv 4 is provided in the vicinity of its rear wall 5 with a pair. of coaxial bearings 6 and 7 which turnably support a'.A

stationary drive shaft 8 which at its lower end is connected with an unillustrated drive and which at its upper end carries a bevel gear 9. The upper part of the sta-vy tionary support 4 is provided with a partly broken away support portion 10, those parts of the support portion 10 which are broken away or removed forming the openings `62 for a purpose described below. The stationary sup-- port 4 further includes `a portion 11 in the form of an upstanding ear.

This upstanding ear or portion 11 of the support 4 is formed with a horizontal bore 12 which extends therethrough (FIG. 2), and an elongated pivot pin 13 extends through the bore 12, this pivot pin 13 having an intermediate portion 14 of elliptical configuration locateddirectly in the bore 12 so that the pin 13 is tiltable with respect to the ear 11. Beyond its elliptical intermediate portion 14, the pin 13 has a pair of cylindrical portions 15 and 16 which are respectively received in mating cylindrical bores of a pair of spaced portions of a carrier 18, this carrier 18 having the bifurcated portion 17 which is formed with the bores which receives the cylindrical portions 15 and 16 of the pin 13. The cylindrical portion 15 is axially split and has sections which define the split and which resiliently move apart from each other beyond the confines of portion 17 of carrier 18 which receive the portion 15 of the pin 13, so that the sections of the part A 15 which define the split therein press against the porate portion 14 of the pin 13 the carrier 18 is connected to the support-4 not only for rotation about the axis of the bore 12 but also for limited turning movement about a vertical axis perpendicular to the horizontal axis of the bore 12, and infact the carrier 18 can tilt in all directions to a limited degree with respect to the ear 11. The cylindrical portion 16 of the pin 13 is located next to an outer free end portion of the pin 13 which is provided with a knurled knob 19 adapted to be grasped by the operator to facilitate the assembly and disassembly of the components.

p A hollow drive gear 21 is supported for rotation about its axis by the support means which is formed by the carrier 18. For this purpose the carrier 18 carries needle bearings 20 which cooperate with a tubular extension 22 of the drive gear 21 to support the latter for rotation about its axis. The tubular extension 22 has a free end portion extending reamward'ly beyond the carrier 18, and a bevel gear 23 is xed to the right free end portion of the tubular extension 22, as viewed in FIG. 1. This bevel gear 23 meshes with the bevel gear 9 in the immediate vicinity of the pivotal connection between the carrier 18 and the stationary support, which is to say the immediate vicinity of the pivot pin 13. The axial thrust ofthe bevel gear 23 with respect to the carrier 18 is absorbed bya thrust bearing 24 located between the carrier 18 and the bevel gear '23. As is apparent from FIG. l, the positive carbon 26 of the lamp is adapted to extend into and through the hollow interior of the gear 21.

The carrier 18 turnably supports at an elevation somewhat lower than the gear 21 a pair of shafts 27 and 27 for respective rotation about their axes, and these shafts respectively fxedly carry at their right ends, as viewed in FIGS. 1 and 2, pinions 29 and 29 which mesh with the drive gear 21, while these shafts iixedly carry at their left' ends, as viewed in FIGS. 1 and 2, feed rolls 28 and 28 which engage the carbon 26 as illustrated in FIGS. 1 and 2 for the purpose of axially advancing and rotating the latter. The axes of the shafts 27 and 27 are slightly skew with respect to the axis of the drive gear 21, so that the feed rolls 28 and 28 will not only rotate the carbon 26 but will in addition axially advance the latter, andy the .pair vof feed rolls 28 and 28' are provided with flutes at their exterior surface, these flutes being somewhat inclined with respect to the axis of the rolls 28 and 28', as illustrated, in order to improve the frictional engagement between the feed rolls and the carbon.

The carrier 18 is provided with a portion 30 formed with a bore which is substantially parallel to the bore 12, and a pivot pin 31 extends through and beyond the bore of the portion 30 into aligned bores of a bifurcated portion '32 of a second carrier 33, so that the second carrier 33 is pivotally supported through the medium of the pivot pin 31 on the first carrier 18` for turning movement with respect to the latter about an axis substantially parallel to the axis of the bore 12 of the ear 11. The carrier 33 is in the form of an elongated tubular sleeve which carries needle bearings 34 in its interior, and these needle bearings 34 serve to support the shaft 35 for rotation about its axis, this shaft 35 tixedly carrying at its right end, as viewed in FIGS. 1 and 2, a pinion 38 and at its left end, as viewed in FIGS. 1 and 2, a feed roll 36 which is xed to the shaft 35 through the medium of a set screw 37. It will be noted that the pivotal connection 31 between the first carrier 18 and the second carrier 33 is located directly adjacent to the place where the pinion 38 meshes with the hollow drive gear 21. The pinion 38 is formed with a recess in which a ball member 39 is freely turnable, and this ball member 39 extends to the right, as viewed in FIGS. l and 2, beyond the pinion 38 into engagement with a surface of the carrier 18 so that the ball 39 acts as a thrust bearing opposing forces which tend to shift the feed roll 36 to the right, as viewed in FlIG. 1, in a direction opposite to the feeding direction of the carbon 26. In thev same way,

21, and the degree of skew is apparent from FIG. 2, the.

shafts 27 and 27' being skew to substantially the same degree. The structure fwhich supports the shafts 27 and 27' is substantially identical with the structure which supports the shaft 35, which is to say that the carrier 18 is provided with needle bearings which support the shafts 27 and 27 for rotation, the main difference between the support of the shafts 27 and 27', on the one hand, and the support of the shaft 35, on the other hand, being that the pinions 29 and 29' cannot move radially with respect to the drive. gear 21 whereas the pinion 38 due to its support by the carrier 33 can move radially with respect to the drive gear 21. rolls enables them to advance the carbon 26 to the left, as viewed in FIGS. l and 2, while rotating carbon 26, and it will be noted that the feed roll 36 is provided at its exterior surface with inclined flutes similar to those of the feed rolls 28 and 28.

Thus, due to its support by the carrier 33, the shaft 35 together with the pinion 38 and feed roll 36 can turn l,

around the axis of the pin 31. During such turning the extent of mesh between the gears 21 and 38 will not change substantially, as long as the angle of turning remains relatively small, and this angle of turning is maintained relatively small. Due to the skew position of the shafts 27, 27', 35 with respect to the axis Vof the drive gear 21, the pinions 29, 29 and 38 will exert an axial thrust to the left, as viewed in FIG. l, on the drive gear 21, and this thrust is absorbed by the thrust bearing 24 described above.

t A plate 40 is fixed to the left end of the tubular carrier 33, as viewed in FIG. 1, and this plate 40 is formed with an opening through which the axis of the drive gear 21 extends and through which the carbon 26 freely extends, as illustrated in FIG. l. Thus the plate 40 has a lower portion located well beneath the axis of the gear 21 and the carbon 26, and a substantially U-shaped member 41 is xed to this lower portion of the plate 40 and extends horizontally so that the member 41 provides the plate 40 with a pair of rearwardly directed upper and lower extensions. A leaf spring 42 which is fixed at its right end to the lower surface of the carrier 18 bears with its left end against the top face of the lower extension provided by the member 41, so that this leaf spring 42 urges the carrier 33 in a counterclockwise direction around the pivot 31. Thus, the spring 42 serves together with the weight of the carrier 33 to urge the roll 36 against the carbon 26.

The carrier 18 carries at its lower portion a cross shaft 43 which is fixed at the exterior of the support 4 to a hand lever 44, and thisshaft 43 fxedly carries an eccentric disc 45 which upon turning of the shaft 43 will engage the upper extension formed by the member 41, so that the parts 43-45 form an operator-actuated means capable of turning the carrier 33 together with the roll 36 inopposition to the spring means 42.

A second spring means in the form of a leaf spring 46 is fixed to the underside of the carrier 18 and bears with its lower left end, asviewed in FIG. 1, against thestationary support 4, this spring means 46 being designed to exert against the carrier 18 an upward force substan` tially equal to the weight of the carrier 18 and parts carried thereby so that the spring means 46 serves to counterbalance the weight of the carrier 18 and the parts carried thereby, and in this way the spring 42 will control the force with which the rolls 28, 28', 36 engage the carbon 26. An adjustable means in the form of a screw 47 threadedly carried by a part of the support portion 10 is directly in engagement with the lower endof the leaf spring 46, so that by changing the vertical position of the screw 47 it is possible to control the force which the The skew position of the feed` springs means 46 exerts on the carrier 18 and thus it is possible to obtain the desired counterbalancing of the carrier 18 and the parts carried thereby. Thus, with this arrangement the rolls 28, 28 and 36 cannot exert any downward force on the carbon 26.

As may be seen from FIG. 1, the carbon 26 is almost entirely surrounded adjacent its left end, as viewed in FIG. l, by a pair of electrically conductive shells 50 and 51 each of which form substantially a half cylinder. The lower electrically conductive shell 51 is carried by a hollow member 49 which is in turn carried by the support 4. The upper shell 50 is carried by the hollow member 48, and this member 48 is connected to a pair of hollow tubes 54 one of which is visible in FIG. 1. These tubes 54 are located at the opposite ends of the member 48 and communicate with the interior of member 48, and the tubes 54 extend downwardly through openings formed in the top wall of the support 4. Adjacent their lower ends the members 54 respectively carry washers 53, and coil springs 52 are respectively coiled about the tubular members 54 with the top ends of the coil springs 52 bearing against the top wall of the support 4 and with the bottom ends of the springs 52 bearing against washers 53, so that the springs 52 urge the hollow member 48 together with the shell 50 downwardly and thus cause the shells 50 and 51 to bear with a predetermined pressure against the carbon so as to provide transfer of electrical current thereto with the minimum amount of resistance. A hollow tube 57 communicates with the interior of the lower hollow member 49, and a pair of flexible hollow metallic tubes 55 and 56 respectively communicate with the tubes 54 and 57, as illustrated in FIG. 1, so that these tubes 55 and 56 on the one hand can conduct cooling fluid to the interior of the hollow members 49 and 48 through the tubes 54 and 57, respectively, and on the other hand the metallic tubes 55 and 56 can serve as electrical conductors participating in the delivery of current to the carbon 26. They consist of an alloy of at least 66% of copper with zinc. The current is derived from a conductor 58 which is connected to both of the metallic tubes 55 and 56. The tubes 55 and 56 shown in FIG. 1 may be used to deliver cooling fluid to the hollow interiors of the members 49 and 48, respectively, and the cooling fluid can be conveyed from these hollow members by corresponding flexible tubes.

The support 4 carries at its upper left end, as viewed in FIG. 1, a shield 59 formed with an opening through which the carbon 26 extends, this shield 59 protecting the structure located to the right of the shield 59 from the heat of the arc. Also, a tube 68 is supported in the manner shown in FIG. l with its upper open end located between the shell holders 48 and 49, on the one hand, and the shield 59, on the other hand, so that cooling air may be blown through the tube 16 in the space between the shield 59 and the shell holders 4S and 49. The base 1 is formed with openings 61 one of which is illustrated in FIG. l, and the upper portion of the support `4 is formed with openings 62, as illustrated in FIG. l.

During operation of the arc lamp of Ithe invention the current flows from the conductor 58 along the tubes 55 and 56 as well as along the tubes 54 and 57 to the holders 48 and 49 and from the latter to the shells 50 and 51 so that the current is in this way delivered to the positive carbon 26, and then the current of course travels over the unillustrated arc to the negative carbon which is not illustrated. The shells 50 and 51 closely surround and press against the carbon 26 so that the current is delivered to the carbon 26 without any resistance which can detract in any way from the operation of the lamp, and simultaneously the shell holders y48 and 49 are cooled in the manner described above.

Also, during operation of the lamp, the shaft 8 rotates and through the gear 9 the drive is transmitted through the gear 23 and to the tubular extension 22 as well as through the drive gear 21, and this latterrdrive gear 6 rotates the pinions 29, 29' and 38, so that the feed rolls 28, 2S and 36 also rotate.

The pair of shells 50 and 51 determine the position of the carbon 26 by pressing thereagainst. The spring 46 raises the feed rolls 28 and 28 so that they engage but do not appreciably press against the carbon 26 at its underside. The spring 42, on the other hand, presses the feed roll 36 against the carbon 26 at its top side, and of 'course the spring 42 also determines the pressure with which the feed rolls 28 and 28 press against the carbon 26, and the spring 42 is designed so that the feed' rolls will engage the carbon with a force sufficient to guarantee the desired rotation and axial feeding of the carbon, this force being suicient to overcome the pressure of the shells 50 and 51 against the carbon so that the carbon 26 can be rotated by the feed rolls with respect to the stationary shells as well as axially advanced with respect to the stationary shells 50 and 51. The carbon 26 is fed in this way axially to the left, as viewed in FIG. l, while simultaneously rotating, and the parts are designed so as to feed the carbon precisely at the rate at which its left end burns ot due to the arcing. The several bearings'6, 7, 2t), 24, 34 and 39 guarantee that all of the elements which participate in the feeding of the carbon operate reliably and with a relatively low friction even though they become so hot that an effective lubrication by the usual lubricating devices is not always assured.

Because of the elliptical configuration of the intermediate portion 14 of the pin 13 it is possible for the entire carrier 18 to tilt and turn in all directions with respect to the upstanding ear 11 of the support 4, and thus the carrier 18 automatically assumes :the position which is determined by the direction in which the carbon 26 extends, this direction being in turn determinedby the shells 5i) and 51 pressing against the carbon 26,V

and thus with this structure the carbon will not be clamped and injured. Although in FIG. 2 the bifurcated end portion 17 of the carrier 18 is shown as having a relatively close tit with respect to the ear 11, it is to be understood that 4there is sucient clearance between the ear 11, on the one hand, and the bifurcated end portion 17 of the carrier 18, on the other hand, to guarantee free turning of the carrier 18 in all directions with respect to the ear 11 within the limits afforded by the elliptical intermediate portion 14 of the pin 13.

In the position of the parts illustrated in FIG. 1, the eccentric 45 does not engage the element 41. When it is desired to replace one carbon 26 with a new carbon 26, then the operator turns the handle '44 so that the eccentric 45 presses against the upper horizontal extension provided by the member 41, and in this way the member 41 together with the plate 40 and carrier 33 arev moved upwardly so that the feed roll 36 is raised upwardly away from the carbon, and then it is a simple matter to remove the remainder of the carbon and replace it with a new carbon. Thereafter, the handle 44 is turned back down to the position thereof shown in FIG. 1, and the frictional engagement rbetween the feed rolls and the carbon is reestablished.

During the operation of the lamp, there is always relatively cool air in the region of the base 1, supplied, for example, by a suitable fan, and this relatively cool air moves automatically up through the openings 61 and 62 along the interior of the support 4 and around the carrier 18 so that in this way a particularly effective cooling of the structure is provided.

It will be understood that each ofthe elements described above, or two or more together, may also find a useful application in other types of lamps differing from the types described above.

While the invention has been illustrated and described as embodied in arc lamps, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal-the gist of the present invention that others can by applying current lknowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of .the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a device for supporting and feeding the positive carbon of an arc lamp, in combination, a hollow drive gear; first support means supporting said gear for rotation about its axis, the positive carbon being adapted to extend into said hollow gear; a plurality of pinions distributed around and meshing with said gear, said first support means also supporting said pinions for rotation about their axes, respectively; a plurality vof driving rolls respectivcly fixed coaxially to said pinions for rotation therewith and adapted to engage the positive carbon to rotate the latter and feed the same axially; and second support means supporting said first support means for movement about a pair of mutually perpendicular axes both of which are perpendicular to the axis of said hollow drive gear so that said first support means can align itself automatically with respect to the positive carbon.

2. In a device for supporting and feeding the positive carbon of an arc lamp, in combination, a hollow drive gear; first support means supporting said gear for rotation about its axis, the positive carbon being adapted to extend into said hollow'gear; a plurality of pinions clistributed around and meshing with said gear, said first support means also supporting said pinions for rotation about their axes, respectively; a plurality of driving rolls respectively fixed coaxially to said pinions for rotation therewith and adapted to engage the positive carbon to rotate the latter and feed the same axially; second support means supporting said first support means for movement about a pair of mutually perpendicular axes both of which are perpendicular. to the axis of said hollow drive gear so that said first support means can align itself automatically with respect to the positive carbon; an elongated tube fixed to and extending coaxially from said drive gear; a first bevel gear fixed to said tube; and a second bevel gear meshing with said first bevel gear, so that a drive can be transmitted through said bevel gears to said drive gear, said frstand second bevel gears meshing with each other in the immediate vicinity of the connection between said first and second support means.

3. In a device for holding and feeding the positive carbon of an arc lamp, in combination, a stationary support having a portion formed with a bore passing therethrough; a carrier having a pair of spaced portions between which said portion of said support is located and said spaced carrier portions being respectively formed with bores which form extensions of said bore of said support portion; an elongated pin having spaced portions respectively located in said bores of said spaced portions of said carrier and having an intermediate substantially elliptical portion located in said bore of said support portion so that said carrier is turnable with respect to said stationary support about the axis of said pin as well as about a second axis perpendicular to said pin axis; a hollow gear turnably carried by said carrier and into which a positive carbon is adapted to extend, said gear lbeing adapted to be driven; a plurality of pinions distributed about and meshing with said gear, said carrier supporting said pinions for respective rotation about their axes; and a plurality of rolls respectively fixed coaxially to said pinions to rotate therewith, said rolls being adapted to engage the carbon for rotating and axially advancing the latter.

4. In a device as recited in claim 3, one of said spaced pin portions being axially split and having sections defining said split and resiliently movableaway from each other beyond the confines of the bore of said carrier portion in which saidV split pin portion is located, so that said split pin portion resiliently presses against said carrier to hold said pin axially.

5. In a device for holding and feeding the positive carbon of an arc lamp, in combination, a hollow drivel gear into which the carbon is adapted to extend; support means supporting said gear for rotation about its axis; a pair of pinions angularly spaced along and meshing with said gear to be driven upon rotation of the latter, said support means supporting said pinions for respective rotation about their axes and preventing radial movement of said pinions with respect to said gear; a pair of rolls fixed coaxially to said pinions to rotate therewith and adapted to engage the positive carbon to participate in the rotation and axial feeding thereof; a third pinion meshing with said gear and a third roll fixed coaxially to said third pinion; and means supporting said third pinion and roll for rotation about their common axis and turnably connected to said support means for turning movement with respect thereto in the immediate vicinity of meshing engagement between said third pinion and gear.

6. In a device for holding and feeding the positive carbon of an arc lamp, in combination, a hollow drive gear into which the carbon is adapted to extend; support` with said gear and a third roll fixed coaxially to said,

third pinion; means supporting said third pinion and roll for rotation about their common axis and turnably connected to said support means for turning movement with respect thereto in the immediate vicinity of meshing engagement between said third pinion and gear; spring means cooperating with said third roll for urgingl the latter toward the axis of said drive gear into engagement with a positive carbon; and operator actuated means cooperating with said third roll for turning the latter away from said drive gear axis in opposition to said spring means.

7. In a device for holding and feeding the positive carbon of an arc lamp, in combination, a lirst carrier; a hollow drive gear rotatably carried by said first carrier; a pair of pinions meshing with said gear and supported for rotation by said first carrier, said first carrier preventing radial movement of said pair of pinions with'respect to said gear; a pair of rolls fixed coaxially of said pinions for rotation therewith and adapted to engage a carbon which is adapted to extend into said hollow drive gear for participating in the rotation and axial feeding of the carbon; a third pinion meshing with said gear and a third roll fixed coaxially to said third pinion, said third roll also being adapted to engage the carbon to participate in the rotation and feeding thereof; an elongated hollow second carrier supporting said third pinion and third roll for rotation, said second carrier being pivotally connected with first carrier for turning movement with respect to the latter in the immediate vicinity of meshing engagement between said third pinion and gear, said gear having a substantially horizontal axis and said second carrier being turnable with respect to said first carrier about a substantially horizontal second axis perpendicular to said gear axis, said third pinion being located over and engaging an upper portion of said drive gear and said pair of pinions both being located at an elevation lower than said third pinion; a hollow plate fixed tosaid secondcarrier bril and formed with an opening through which the axis of said drive gear extends and through which the positive carbon is adapted to freely extend, said plate having a lower portion located beneath said drive gear axis; a pair of extensions located one above the other, fixed to said lower portion of said plate, and extending substantially parallel to the drive gear axis; spring means carried by said first carrier and cooperating with one of said extensions for urging said second carrier downwardly around said second horizontal axis in a direction pressing said third roll against the carbon; and operator actuated eccentric means carried by said first carrier and cooperating with the other of said extensions for raising said plate and second carrier around said second horizontal axis in opposition to said spring means to move said third roll upwardly away from the carbon.

8. In a device for holding and feeding the positive carbon of an arc lamp, in combination, stationary support means; a carrier pivotally carried by said stationary support means; a hollow drive gear into which the positive carbon is adapted to extend, said 'gear being rotatably carried by said carrier; a plurality of pinions rotatably carried by said carrier and meshing with said gear; a plurality of rolls respectively fixed coaxially to said pinions and adapted to engage the carbon for rotating and feeding the latter; and spring means located between and engaging said carrier and said support means for urging said carrier upwardly with a force substantially equal to the weight of said carrier and all of the parts carried thereby.

9. In a device for holding and feeding the positive carbon of an arc lamp, in combination, stationary support means; a carrier pivotally carried by said stationary support means; a hollow drive gear into which the positive carbon is adapted to extend, said gear being rotatably carried by said carrier; a plurality of pinions rotatably carried by said carrier and meshing with said gear; a plurality of rolls respectively fixed coaxially to said pinions and adapted to engage the carbon for rotating and feeding the latter; spring means located between and engaging said carrier and said support means for urging said carrier upwardly with a force substantially equal to the weight of said carrier and all of the parts carried thereby; and adjustable means carried by said support means and engaged by said spring means for adjusting the force of the latter.

10. In a device for holding and feeding the positive carbon of an arc lamp, in combination, a plurality of feed rolls and a plurality of pinions fixed coaxially to said feed rolls; a hollow drive gear surrounded by and meshing with said pinions, the positive carbon being adapted to extend into said drive gear and to be surrounded and engaged by said feed rolls, the common axis of each feed roll and pinion connected therewith being skewed with respect to the axis of said drive gear so that said pinions exert an axial thrust on said drive gear; and thrust bearing means cooperating with said drive gear for absorbing said axial thrust.

11. In a device for holding and feeding the positive carbon of an arc lamp, in combination, stationary support means having an upstanding ear formed with a horizontal 'bore passing therethrough; an elongated pivot pin having an intermediate elliptical portion located in said lbore so that pivot pin is tiltable with respect to said ear; an elongated first carrier having a bifurcated portion receiving said ear and turnably supported by portions of said pin extending beyond said ear; a hollow drive gear turnably carried by said first carrier; a first bevel gear fixed coaxially to said drive gear and located over said ear; a second gevel gear turnably carried by said stationary support means and meshing with said first bevel gear in the immediate vicinity of said pin; a pair of pinions turnably carried by said first carrier and meshing with said gear; a pair of roils fixed coaxially to said pinions and adapted to engage a positive carbon to participate in the rotation and feeding thereof; a second carrier turnably carried by said first carrier for turning movement with respect to the latter about an axis substantially parallel to the axis of said bore of said ear of said stationary support means; a third pinion meshing with said drive gear and turnably carried by said second carrier; and a third roll fixed to said third pinion for rotation therewith and adapted to engage the carbon.

l2. In a device for holding and feeding the positive carbon of an aro lamp, in combination, stationary suppont means having an opstanding ear formed with a horizontal bore passing therethrough; an elongated pivot pin having an intermediate eliiptical portion located in said bore so that pivot pin is tiltable with respect to said ear; an elongated first carrier having a bifurcaited portion receiving said ear `and turnably supported by portions of said pin extending beyond said ear; a hollow drive gear turnably carried by said first carrier; a first bevel gear fixed coaxially to said drive gear and located over said ear, a .second bevel gear turnably carried by said staltionary support means and meshing with said first bevel gear in the immediate vicinity of said pin; a pair of pinions turnably carried by said first carrier and meshing with said gear; a pair of rolls fixed coaxially to said pinions land adapted 4to engage a positive carbon to participate in the rotation and feeding thereof; a second carrier turnably oarried by said first lcarrier for turning movement with respect to the latter about an axis substantially parallel tothe yaxis of said bore of said ear of said stationary support means; a third pinion meshing with said drive `gear and turnably carried by said second carrier; a third roll fixed to said third pinion for rotation therewith and yadapted to engage the carbon; rst spring means cooperating with said first carrier and support means for counterbalanoing the weight of said first carrier and all of the parts carried thereby; and second spring means cooperating with said rst and second carriers for urging said third roll towards said pair of rolls so that the pressure with which said rolls engage the carbon is controlled by said second spring means.

References Cited in the file of this patent UNITED STATES PATENTS 1,282,133 Sperry Oct. 22, 1918 1,460,793 Davis July 3, 1923 1,603,244 Mole Oct. 12, 1926 2,162,524 Brace et al. June 13, 1939 2,788,459 Gretner Apr. 9, 1957

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