US2261587A

US2261587A - Electric tilting furnace

Info

Publication number: US2261587A
Application number: US196268A
Authority: US
Inventors: William E Moore
Original assignee: PITTSBURGH RES CORP
Current assignee: PITTSBURGH RES CORP; PITTSBURGH RESEARCH Corp
Priority date: 1937-03-19
Filing date: 1938-03-16
Publication date: 1941-11-04
Anticipated expiration: 1958-11-04

Description

Nov. 4, 1941. w. E. MOORE ELECTRIC TILTING FURNACE Filed March 16, 1938 5 Sheets-Sheet l Nov. 4, 1941. w. E. MOORE 2,261,587

ELECTRIC T ILIING FURNACE 5 Sheets-Sheet 2 Filed March 16, 1938 Nov; 4, 1941. w. E. MOORE 2,251,537

' ELECTRIC TILTING FURNACE Filed March 16, 1938 5 Sheets-Sheet William E. Moore m (".jg 7ww Nov. 4, 1941. w. E. MOORE I ELECTRIC TILTING FURNACE Filed Ma rn 16, 1958 5 Sheets-Sheet 5 glwumvkvo William EMoore.

W g /W w C 'o'uwn Patented Nov. 4, 1941 UNITED STATES PATENT OFFICE ELECTRIC TILTING FURNACE William E. Moore, Pittsburgh, Pa., assignor to Pittsburgh Research Corporation,. Pittsburgh,

14 Claims.

This invention relates to electric tilting furnaces and more particularly to tilting mechanism for such furnaces.

An important object of this invention is the provision of an electric furnace with hydraulic mechanism for tilting the furnace.

Another object of the invention is to provide a furnace in which the roof is lifted and the crucible tilted by a hydraulic system having means to supply fluid under pressure to the roof lifting mechanism or the furnace tilting mechanism but not to both mechanisms at the same time.

A further object of the invention is to provide a furnace in which the tilting axis is spaced laterally beyond the furnace crucible.

Still another object of the invention is the provision of a furnace of this character which is of simple construction and operation and which may be inexpensively constructed and operated.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings which form a part of this specification and wherein like characters of reference denote like parts throughout,

Figure l is a top plan view of a furnace embodying this invention, parts being broken away.

Figure 2 is a side elevation thereof, parts being broken away and parts being shown in section,

Figure 3 is an elevation at right angles to Figure 2 illustrating the tilted positions of the furnace in broken lines,

Figure 4 is a' verticalsectional view of the roof lifting mechanism,

Figure 5 is a longitudinal sectional view of the swivel joint permitting movement of the tilting cylinders about their pivots,

Figure 6 is a diagrammatic view of the furnace and the roof lifting and furnace tilting control system.

Figure 7 is a side elevation of the furnace showing a slightly modified form of tilting mechanism,

Figure 8 is a top plan view thereof, and,

Figure 9 is a detail sectional view of the piston packing member.

In the drawings, wherein for the purpose of illustration is shown a preferred embodiment of the invention, the numeral I designates a furnace crucible having a removable roof ll. The furnace is illustrated as an arc furnace having electrodes I2 and electrode columns I3 supported 7 by a spectacle casting l4 carried by the roof ring.

than are furnaces, however. The bottoms of furnaces of this type are usually convex as shown.

A pair of spaced metal brackets I are welded or otherwise rigidly secured to the metal shell 5 of the crucible ill, projecting laterally beyond the furnace crucible at either side of the pouring spout l6 and terminating in bearings Ill. The brackets 15 are of stout construction, being widest and thickest at their junctures with the crucible shell and tapering to the bearings l'l'.

A pair of spaced metal supports 18 are bolted or otherwise firmly secured to the concrete foundation and are bifurcated at their upper ends to form bearing ears l9 spaced apart to receive bearings ll. Pivot shafts 20 extend through ears l9 and bearings I! to pivotally secure the brackets l5 to supports 18. It will be seen that the axis of aligned pivot pins 20 is spaced laterally beyond the furnace crucible l0, and is disposed in a 20 horizontal plane passing through the furnace at about the center thereof.

A pit 2! is arranged in the foundation beneath the furnace and a pair of hydraulic cylinders 22 are pivotally secured at their lower ends to spaced brackets 23 secured at the base of the pit in line line, as indicated in Figure 3, and hydraulic pistons 25 have bifurcated ends pivotally secured to these brackets. Brackets 2d are so spaced as to be arranged adjacent the outer wall of the furnace, as seen in Figure 2, so that there will 36 be no tendency on the part of the furnace to twist as it is moved about the pivots 2G.

A pair of spaced depending feet or legs 26 are secured to the bottom of the furnace shell adjacent the side of the furnace opposite the tilting pivot 20 and are adapted to support the furnace in one of two positions. A concrete wall or pillar 2i may be a part of the foundation and. terminates below the lower level of the furnace or the floor level and in line with the legs or feet 26.

Supporting castings 28 are secured to the wall 21' below feet 26 and are each provided on the side farthest from the furnace with a pivot pin 29 to which'apedestal support 30 is pivotally secured. The pedestals 30 normally rest upon the castings 38 and extend vertically upwardly to contact the feet 26 and support the furnace in a level or horizontal position. A projection 3| is secured to the lower end of each pedestal and is curved downwardly to engage the wall 21 when the pedestal The present invention may be applied to other 56 is pivoted about pin 29 to support the pedestal in the broken line position indicated in Figure 3,

out of the path of corresponding foot 26.

When the pedestals are in their broken line or inoperative position the furnace may be tilted back past the horizontal position into slagging or back-tilt position indicated by broken lines 32 in Figure 3. In this position the feet 26 rest upon the immovable pedestal supports 33 which may be an integral part of casting 28, and which are arranged forwardly of pedestals 30. When the pedestals 30 are in operative position, their upper faces and the upper faces of supports 33 are disposed in the arcuate paths through which feet 26 move when the furnace is moved about its tilting pivot 20.

It will be seen that when pistons 25 are force out of cylinders 22, furnace ID will be moved about pivots 26 to the pouring position indicated by broken lines 34 in Figure 3. When pressure is released the furnace will return to the level position with the feet 26 resting on pedestals 36. When it is desired to move the furnace to its back-tilt or slagging position 32, th furnace is raised slightly so that pedestals 30 may be swung out of the way and the furnace may then be lowered into contact with supports 33 by releasing the pressure in cylinders 22. Bylocating the brackets 24 adjacent the center line of the furnace, an even pivoting is obtained with no detrimental thrusts on pivot pins 26 and bearings I7 and I9 and without the use of exceptionally long cylinders. While the furnace may be tilted by one cylinder centrally arranged, and supported by one foot and pedestal also centrally arranged, the use of pairs of these elements, spaced as shown, produces a much smoother action without danger of twists and strains.

Any suitable hydraulic system may be employed tooperate the pistons '25 butit is preferred to use that illustrated, in which a pipe or conduit 35 connects the two cylinders 22 at their lower ends. It will be seen that as the pistons 25 are operated to tilt the furnace, the brackets 24 will move through an are about tilting pivot 26, and that hydraulic cylinders 22 and pistons 25 will consequently move about the pivotal connection at the lower brackets 23. As conduit 35 is spaced from the bracket pivot, it will also move in an are about the pivot. In order to avoid a flexible conduit connection, a swivel joint illustrated in detail in Figure is provided to permit movement of the conduit 35. Due to the proximity of the conduit to the pivot axis, no great movement of the conduit takes place, so that only slight freedom of motion in the swivel joint is required. The swivel comprises a pipe socket section 36 and a pipe swivel section 31 telescoping therewith and forming a longitudinal continuation thereof. The sections 36 and 31 are screw-threadedly connected and a packing collar 38 surrounds the swivel section 31, being bolted to section 36 to force the packing 33 against the two sections and prevent leakage between the sections. The threads 46 fit loosely together to pernecessary to remove the furnace roof to give access to the crucible for charging or other purposes. This operation may be conveniently accomplished by means of a hydraulic ram arranged to raise the roof and swing it way from the crucible. The ram may be supported by the foundation and arranged to engage and disengage the roof, but it is preferred to mount the ram on the furnace shell to move therewith and dispense with the necessity of disengaging the ram from the roof. The ram cylinder 43, shown in detail in Figure 4, is rigidly secured to the furnace shell l0 and is provided with a piston 44 connected to piston rod 45 by means of roller bearing 46 which permits free rotation of rod 45 with respect to piston 44. The upper end of piston rod 45 is rigidly secured to one end of spectacle casting l4 by means of bolts, and a bushing 41 in the top of cylinder 43 serves to guide the rod in its movement relative to the cylinders.

A cam slot 48 is disposed in the wall of cylinder 43 adjacent the upper end thereof and a roller 43 is secured to piston rod 45 and disposed in slot 48. Fluid under pressure is forced into the lower end of cylinder 43 through conduit 50. Suitable packing 5| on the piston prevents escape of the fluid past the piston while an overflow conduit 52 is arranged at a point spaced above the bottom of the cylinder. When the piston 44 is forced upwardly, roller 49 moves upwardly in the vertical portion of the cam slot 48 and the roof is raised vertically. When the roller reaches the inclined portion of the cam slot the roof will have cleared the top of th crucible, and further upward movement of piston 44 serves to rotate the piston rod and swing the roof |l horizontally away from the furnace crucible. If the piston rises above the conduit 52 the fluid will leak out through the overflow conduit and return to the reservoir, thus preventing excessive upward movement of the piston and roof.

An important feature of the present invention is the control system for the hydraulic roof lifting mechanism and the hydraulic furnace tilting mechanism. In Figure 6 the furnace roof lifting mechanism, tilting mechanism and the hydraulic system are illustrated diagrammatically. The fluid pump 53 is driven by suitable means such as an electric motor 54 and is connected by conduit 55 with the fluid reservoir 56. A conduit 51 connects the delivery end of pump 53 to a three way valve 58. An impulse neutralizer 59 may be disposed in conduit 51 between the pump and three-way valve. A four-way tilt control valve 66 is connected by conduit 6| to threeway valve 56 and by conduit 62 to the reservoir 56. A fourway roof control valve 63 is connected by conduit 64 to three-way valve 56 and by conduit 65 to reservoir 56. Suitable check valves 66 are arranged in conduits 6| and 64. Tilt control valve 60 is connected by conduit 42 to the swivel joint section 36 while roof control valve 63 is connected by conduit 61 to the inlet 56 of roof lifting ram 43.

A return conduit 66 connects valves 66 and 63 to the reservoir 56. Conduit 52 connects the overflow port of ram cylinder 43 to return conduit 66, a check valve 63 being interposed in this overflow conduit, and a conduit 10 connects conduit 52 to conduit 4| of the tilting mechanism. A tilt limit valve TI is arranged in conduit 16 and operated by a flexible member such as a chain 12 connected to the underside of the furnace crucible.

The three positions of the tilt control valve 66 and roof control valve 63 are indicated in Figure 6. Considering the middle or neutral position, fluid is pumped directly through the valve, returning to the reservoir. When the valve lever is moved to its left hand position to tilt the furnace, fluid under pressure is delivered to the cylinders 22 through the swivel joint which permits pivoting of the cylinders, and the movement of pistons 25 tilts furnace l8 about its pivots 28. If the furnace passes its limit of movement, chain 12 opens limit valve H which vents the fluid back to the reservoir and prevents damage due to overtilting. If the valve 68 is then moved to its middle or neutral position, the furnace will be held in its tilted position. When the valve 60 is moved to its right hand position in Figure 6 to lower the furnace, fluid drains out of the cylinders 22 back to the reservoir.

It is to be understood that fluid from pump 53 is supplied to valve 60 or to valve 63 by threeway valve 58. In operation it is first necessary to set valve 58 and then operate the control valves 68 or 63. When it is desired to lift and swing the furnace roof, the three-way valve 58 is moved to supply fluid to the roof control valve 63, and with the control valve in its middle or neutral position, fluid will be pumped through the valve and back to the reservoir. When the control valve 63 is moved to its right hand position in Figure 6, fluid is pumped through the valve and through conduit 51 into ram cylinder 43. The fluid passing through conduit Bl first passes through check valve 13 and then through flow adjusting valve M set to limit the flow of fluid to the roof cylinder 48 so that the speed of travel and the force applied will not be greater than desired. From the flow adjusting valve M the fluid passes to a swivel joint 15 of any suitable construction to allow for the tilting action of the furnace, and thence into the roof cylinder. As the piston rises in cylinder 43, the cam and roller construction raises the roof and then swings it away from the furnace. If the roof lifting ram rises above the overflow conduit 52, fluid leaks out through the overflow conduit and is returned to the reservoir, thus preventing over-operation of the ram and damage to the mechanism. If the control valve 83 is moved to its neutral position, the roof will be held in its raised position. When it is desired to lower the roof, the control valve is moved to its left hand position in Figure 6 and the fluidis returned through conduit M and by-pass 18 in which flow adjusting valve ll and check valve T8 are arranged, as indicated by the arrows in Figure 6. Flow adjusting valve ll permits re turn of the fluid to the reservoir at a rate fast enough to permit lowering of the roof within the desired time. If the fluid were returned through the how adjusting valve i l, the roof would be lowered too slowly because of the difference in fluid pressure which on the lift would be under pressure from pump 53 but which on the return is only under the pressure of the weight of the roof mechanism supported by the ram.

A relief valve 19 connects conduit 51 with the reservoir 56 to permit a circulation of fluid when the motor and pump are running and the fluid pressure not being utilized, to prevent formation of excessive pressure in the system. The capacity of the motor 54 and pump 53 is such as to supply fluid at sufficient pressure and at a sufficiently fast rate to accomplish the tilting of the furnace in the desired time. This capacity is much greater than required for the roof lifting mechanism. The provision of the flow adjusting valves permits the use of a constant flow pump to supply both of these mechanisms, and obviates the necessity for a variable flow pump.

It will be seen that three-way valve 58 prevents operation of the tilting mechanism and the roof lifting mechanism at the same time, and that tilt limit valve 'li prevents overtilting of the furnace, while conduit 52 prevents over operation of the roof lifting mechanism. In addition to these precautions, electrical means are provided to prevent faulty operation of the control mechanism. An electrical tilt limit switch is secured to one of tilt cylinders 22 and is operated by a rod 8! attached to the piston 25. Switch 88 is normally closed and is in circuit 82 with the pump motor 54. A push button or other suitable control switch 83 in circuit 82 controls motor '54 to tilt the furnace through the operation of the hydraulic system. The length of rod 8i controls the tilt limit and when this limit is reached rod opens switch 80 and stops motor 58. In case of failure of switch 80-8l to function, further tilting of the furnace operates valve ll through the medium of chain 12 to prevent overtilting of the furnace.

A switch 84 is mounted on roof ram 43 and arranged in circuit 82 in series with switch 88. Switch 84 is normally closed by reason of the pressure of the adjacent portion of spectacle casting It on spring pressed lever 85 when the roof is in position on the furnace crucible. When the roof is in raised position, however, the lever 85 operates the switch 84 and opens circuit 82 so that operation of push button switch 83 cannot start the motor 561 to tilt the furnace. By this construction the furnace tilt operation is not only prevented by valve 58 when the roof is off the furnace but is also prevented by switch 84 in motor circuit 82.

A switch. 86 is disposed in proximity to tilting bracket i5 or other suitable portion of the furnace and has a spring pressed lever 8'! normally engaged by bracket 15 to maintain switch 88 in closed position. A push button or other suitable motor control switch 89 is arranged in a second motor control circuit 88 in series with switch 86 and is operated to start the motor for the roof lifting operation.

If the furnace is in its tilted position, operation of the roof lifting mechanism. is not only prevented by three way valve 58 but also by switch 86 which will open the control circuit 88 so that operation of control switch 89 will not start motor 5d.

It will be seen that the roof lifting mechanism and furnace tilting mechanism are interlocked by the valve 53 in the hydraulic system and by the

switches

86 and 88 in the electrical control system to prevent simultaneousoperation of the two mechanisms, and that over-operation of the mechanisms is prevented by switch 80, valve ll and overflow conduit 52.

The control valves 58 and 53, three-way valve 58 and motor control switches 83 and 89 may be arranged together ona control platform for convenient operation. I

In Figures 2, 3, and 6 the piston 25 is shown as connected to the furnace and the cylinder ,22'is shown as connected to the foundation brackets 23. Obviously the positions of the piston and cylinder may be reversed without affecting the tilting operation or the operation of the furnace. In Figures 7, 8 and 9 the piston and cylinder are shown in their reversed positions which in many instances is preferred. The cylinders 22' are pivotally attached to brackets 24 on the furnace bottom and pistons 25' are pivotally connected to base plates 23. Suitable packing such as the "chevron packing members 90 engaged by a follower 9| are forced into engagement with the piston 25' by means of suitable bolts 92 engaging a flange 93 on the lower end of the cylinder, as seen in Figures 7 and 9.

The base plates 23 are surrounded by suitable upstanding flange 94 to provide a receptacle to catch any leakage of the operating fluid which escapes through drain 95. With this arrangement of the pistons and cylinders any leakage of the operating fluid past the packing 90 will serve to wash away dust or dirt on the polished surface of the piston, and can be caught at drain 95 for reuse. Either arrangement of the pistons and cylinders may be used with good results. When the form shown in Figure '7 is employed, fluid is passed through conduit 96 and through the piston to the cylinder. A flexible supply connection to the conduit 96 may be made, or the conduit 96 may be passed out through the pivot connection with base plate 23 if desired.

The pedestals 30 are preferably connected, in practice, by means of a rod 91 and may be operated by a suitable hand lever 98 extending beyond the side of the furnace, as indicated in Figure 8.

The disposition of the tilting rams adjacent the sides of the furnace notonly insures a smooth tilting action but are in 'a position where they are least likely to be damaged by hot metal in the event of a cut-through of the furnace bottom by the liquid metal. So emcient is the tilting operation that no counterbalancing of the furnace is necessary.

The pouring spout l6 terminates at a point adjacent the pivot axis 20 so that pouring is greatly simplified. The spout may terminate in line with the furnace pivot axis 20 or may extend a slight distance therebeyond, as indicated in Figures 3 and 7.

The present tilting and control mechanism may be applied to the types of furnaces herein illustrated or to any other type of furnaces.

While I have shown and described the preferred embodiment of the invention, it is to be understood that various changes in size, shape and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention what I desire to claim and protect by Letters Patent is:

1. In an electric furnace, a furnace crucible, a bracket secured to the furnace crucible and projecting laterally therefrom, a support spaced from the crucible and pivotally engaging the bracket, a tilting mechanism engaging the cmcible and adapted to move it about its pivotal connection with the support, and a pedestal disposed beneath a portion of said crucible and adapted to engage and support the crucible, said pedestal being movable to permit back-tilting of the furnace.

2. In an electric furnace, a furnace crucible, a bracket secured to the furnace crucible and projecting laterally therefrom, a support spaced from the crucible and pivotally engaging the bracket, a tilting mechanism engaging the crucible and adapted to move it about its pivotal connection with the support, a pedestal disposed beneath a portion of said crucible and adapted to engage and support the crucible, said pedestal being movable to permit back-tilting of the furnace, and a'second supporting pedestal arranged beneath the crucible and adapted to engage and support the crucible in its back tilt position.

3. In an electric furnace, a furnace crucible, a bracket secured to the furnace crucible and projecting laterally therebeyond, a support spaced from the crucible and pivotally connected to said bracket, a supporting bracket spaced from the crucible, a hydraulic cylinder and piston tilting mechanism pivotally connecting the supporting bracket and crucible 'to move the crucible about its pivotal connection with the support, and a movable pedestal arranged beneath a portion of the crucible and adapted to engage and support the crucible in its level position.

4. In an electric furnace, a furnace crucible, a bracket secured to the furnace crucible and projecting laterally therefrom, a' support spaced from the crucible and pivotally connected to said bracket, a supporting bracket arranged beneath said furnace, a hydraulic piston and cylinder mechanism pivotally connecting the supporting bracket with the furnace crucible adjacent the center line of said crucible to move the furnace about its pivotal connection with the support, a depending leg member carried by said crucible, and a movable pedestal normally disposed in the path of said leg member to engage the leg member in the level position of the crucible to support the crucible.

5. In an electric furnace, a furnace crucible, a bracket secured to the furnace crucible and projecting laterally therefrom, a support spaced from the crucible and pivotally connected to said bracket, a supporting bracket arranged beneath said furnace, a hydraulic piston and cylinder mechanism pivotally connecting said supporting bracket with the furnace crucible adjacent the center line of said crucible to move the furnace crucible about its pivotal connection with the support, a depending leg member carried by said crucible, a pedestal pivotally secured beneath the furnace and normally disposed in the path of the leg member to engage the leg and support the furnace crucible in its level position, and a second supporting pedestal arranged adjacent the base of the pivoted pedestal and adapted to engage the leg and support the furnace when the pivoted pedestal is moved out of the furnace path and the m furnace moved to its back-tilt position.

a means to engage and raise the furnace roof, a

support pivotally engaging the crucible, hydraulic tilting mechanism engaging the furnace crucible and adapted to tilt the crucible about its pivotal connection withthe support, means to deliver fluid under pressure to the roof lifting .ram or to the tilting mechanism, and means preventing delivery of fluid under pressure to said lifting ram and tilting mechanism simultaneously.

7. In an electric furnace, a furnace crucible having a removable roof, a hydraulic ram mechanism associated with the furnace and hav means to engage and raise the furnace roof, a support pivotally engaging the crucible, hydraulic tilting mechanism engaging the furnace crucible and adapted to tilt the crucible about its pivotal connection with the support, means to deliver fiuid under pressure to the roof lifting ram or to the tilting mechanism, said means comprising a source of fluid supply, a motor driven pump connected to the source of fluid supply, a pair of control valves connected one to the lifting ram and the other to the tilting mechanism, and means to deliver fluid from said pump to either of said control valves,

8. In an electric furnace, a furnace crucible having a removable roof, a hydraulic ram mechanism' associated with the furnace and having means to engage and raise the furnace roof, 2. support pivotally engaging the crucible, hydraulic tilting mechanism engaging the furnace crucible and adapted to tilt the crucible about its pivotal connection with the support, means to deliver fluid under pressure to the roof lifting ram or to the tilting mechanism, said means comprising a source of fluid supply, a motor driven pumpconnected to the source of fluid supply, a pair of control valves connected one to the lifting ram and the other to the tilting mechanism, means to deliver fluid from said pump to either of said control valves, and means to render the tilting mechanism inoperative when the furnace is moved to a predetermined angle of tilt. I

, 9. In an electric furnace, a furnace crucible having a removable roof, a hydraulic ram mechanism associated with the furnace and having means to engage and raise the furnace roof, :3. support pivotally engaging the crucible, hydraulic'tilting mechanism engaging the furnace crucible and adapted to tilt the crucible 'about' projecting laterallytherefrom, a support spaced from the crucible and pivotally engaging the bracket, a supporting bracket spaced from the furnace crucible, a hydraulic cylinder and piston mechanism pivotally connected to the crucible and to the supporting bracket, a swivel joint operdeliver fluid under pressure to the roof lifting ram or to the tilting mechanism, said means comprising a source of fluid supply, a pair of control valvesconnected one to the lifting ram and the otherto the tilting mechanism, means to deliver fluid from said pump to either of said control valves, and control mechanism for the pump motor comprising a tilting switch in circuit with the pump motor, means operated by removal of the-"furnace roof to open the tilting switch circuit, a roof lifting switch in circuit with atively connected to the hydraulic cylinder and disposed in axial alignment with the pivotal connection between the hydraulic cylinder and piston mechanism and the supporting bracket, and a source of fluid supply connected to said swivel joint.

12. In an electric furnace, a furnace crucible, a bracket secured to the furnace crucible and projecting laterally therefrom, a support spaced from the crucible and pivotally engaging the bracket, a supporting bracket spaced from the furnace crucible, a hydraulic cylinder and piston mechanlsm'pivotally connected to the crucible and to the supporting bracket, a swivel joint operatively connected to the hydraulic cylinder and disposed in axial alignment with the pivotal connection between the hydraulic cylinder and piston mechanism and the supporting bracket, a source of fluid supply connected to said swivel joint, a relief valve arranged in the connection between the swivel joint and hydraulic cylinder, and means operated by overtilting of the furnace crucibleto open said valve. v

13. In an electric furnace, a furnace crucible, a bracket secured to the furnace crucible and projecting laterally therefrom, a support spaced from the crucible and pivotally engaging the bracket, a supporting bracket spaced from the the pump motor, and means operated by tilting of the furnace to open thereof lifting switch circuit.

support pivotally engaging the crucible, hydraulictilting mechanism engaging the furnace crucible furnace crucible, a hydraulic cylinder and piston mechanism pivotally connected to the crucible and" to the supporting bracket, a swivel joint opjoint, a relief valve arranged in the connection and adapted to tilt the crucible about its pivotal connection with the support, means to deliver fluid under pressure to the roof lifting ram or to the tilting mechanism, said means comprisa source of fluid supp1y,a motor driven constant flow pump connected to the source of fluid supply, a pair of control valves connected one to roof lifting ram ,and its control valve.

11. In an electric furnace, a furnace crucible,

a bracket' secured to the furnace crucible and .valve arranged in the connection between the 1 between the swivel joint and hydraulic cylinder,

means-operated by overtilting of the furnace crucible to open said valve, and a pedestal arranged bracket, a supporting bracket arranged beneath the furnace, a hydraulic cylinder and piston mechanism pivotally connecting the supporting bracket with the furnace crucible adjacent the N center thereof to move the furnace crucible about. its pivotal connection with the support, and

means independent of said" cylinder and piston mechanism to engage the furnace crucible at a point opposite to the furnace bracket and support the furnace cruciblein level or tilted position.

WILLIAM E. MOORE;