US2772006A - Cupola stock line indicator - Google Patents

Description

Nov. 27, 1956 L. A. GIONET CUPOLA STOCK LINE INDICATOR 4 Sheets-Sheet 1 Filed March 11, 1953 INVENTOR.

ATTORNEYS Nov. 27, 1956 L. A. GIONET 2,772,006

CUPOLA STOCK LINE INDICATOR Filed March 11, 1953 4 Sheets-Sheet 3 FIGB.

IN V EN TOR.

ATTORNEYS Nov. 27, 1956 GIONET 2,772,006

' CUPOLA STOCK LINE INDICATOR Filed March I1, 1953 4 Sheets-Sheet 4 INVENTOR.

A ATTORNEYS United States Patent CUPOLA srocrr LINE rNnicA'roa Leo A. Gionet, Port Washington, Wis., assignor to Modern Equipment Company, Port Washington, Was, a corporation of Wisconsin Application March 11, 1953, Serial No. 341,674

11 Claims. (Cl. 214-182) This invention relates to improvements in cupola stock line indicators.

During cupola operation it is essential that the level of the stock in the cupola be maintained within predetermined limits for maximum elficiency. In addition, in conventional open type cupolas where there is a side charging opening, it the level of the stock is too high it may be dificult to withdraw the charging bucket from the cupola. In the closed type cupola of more recent design, the stock is likely to obstruct the exhaust gas bustle ports when the level is too high.

It is a general object of the present invention to provide an improved cupola stock line indicator which is adapted for use on either open or closed type cupolas and which is operable to indicate to the skip operator whether or not there is room in the cupola for another bucket full of charge within the predetermined limits of proper stock line height.

A further object of the invention is to provide an improved cupola stock line indicator of the class described wherein there is an electrical circuit interlocked with the power circuit of the skip hoist to prevent movement of the skip to charging position when the stock line is above a predetermined height.

A more specific object of the invention is to provide an improved cupola stock line indicator which includes a pair of inclined, fluid pressure operated pistons mounted on opposite sides of the cupola and having normally retracted piston rods movable to projected positions within the cupola, said pistons being so arranged that the piston rods can be moved to their maximum inwardly projected positions without obstruction from the stock when there is sufiicient room in the cupola for another bucketful of charge.

A more specific object of the invention is to provide an improved cupola stock line indicator of the class described wherein the pistons are connected to a fluid pressure system including pressure switches and an electrically-opera-ted control valve, said switches and valve being connected with an electrical circuit which includes a push button switch and an indicating light, depression of said push button switch causing successive projection and retraction of said piston rods, and any obstruction for the projecting movement of the piston rods, due to contact with the stock, causing illumination of the indicating lamp.

A further object of the invention is to provide an improved cupola stock line indicator of the class described which is automatic and eficient in operation and which can be installed either on cupolas now in use or as a part of original equipment.

With the above and other objects in view, the invention consists of the improved cupola stock line indicator, and all of its parts and combinations, as set forth in the claims, and all equivalents thereof.

In the drawings accompanying and forming a part of this specification, wherein one complete embodiment of "the the preferred form of the invention is shown, and wherein like characters of reference indicate the same parts in all or" the views:

Fig. 1 is a side elevational view of a cupola equipped with the improved stock line indicator showing the cupola charging apparatus as well as the location of the actuatbutton and indicating light at the skip operators station;

Fig. 2 is a fragmentary, enlarged semi-diagrammatic transverse sectional view looking down on a portion of the cupola and showing one of the fluid pressure operated pistons of Fig. 1, together with the fluid pressure system for said piston;

Fig. 3 is a wiring diagram showing the electrical circuit for the improved cupola stock line indicator; and

Fi 4 is a view similar to Fig. 2 showing a modification wherein there are mechanical actuators for the micro switches rather than the pressure actuators used at 39 and in the construction of Fig. 2.

Referring more particularly to Fig. l of the drawing, the numeral 5 indicates a cupola of any suitable type, the cupola illustrated being of the sealed type having an open top, normally sealed by movable doors (not shown). The cupola is charged by a charging bucket 6 carried by the usual wheeled skip carriage 7 which carriage travels along an inclined track 8. A cable 9 is connected to the skip carriage 7 and to an electric motor-driven hoisting drumit't, said cable passing over suitable pulleys i1, 12 and 13. Rotation of the drum 10 in one direction moves the skip carriage 7 and bucket 6 from the solid line loading position of Fig. 1 to the dot and dash line charging position at the top of the cupola 5.

Mounted at the loading station within the reach and View of the skip operator, is an indicating light 14, and a push button switch 15, actuation of the latter normally initiating movement of the skip from the loading position toward the charging position.

Mounted preferably on diametrically opposite sides'of the cupola 5 is a pair of inclined fluid pressure operated cylinders 16 and 17 having normally retracted piston rods 38 and 19. The latter are projectable through suitable apertures in the cupola wall to the dot and dash line position shown. The pistons 16 and 17 are'so positioned that whenever the stock line in the cupola is low enough to permit the cupola to safely accommodate another bucketful of charge, the rods 18 and 19 can be projected into the cupola to their full length without having their movement obstructed by the stock. If, on the other hand, the level of the stock is such that a full bucket of charge cannot be safely accommodated in the cupola, projecting movement of the piston rods 18 and 19 to their maximum length is prevented by engagement of said rods with the stock. In Fig. 1 the piston rods are projected to their length without obstruction, and therefore there is room in the cupola 5 for one bucketful of charge when the stock line is as shown. Any higher level of stock, however, would obstruct projecting movement of the piston rods before they reached their maximum projected position.

Referring now to Fig. 2, the cylinder 16 is shown in an enlarged sectional View. The cylinder 17 and its hydraulic circuit, being a substantial duplicate of, that shown in Fig. 1, is not shown or described in detail. in Fig. 3 the parts associated with the cylinder 17 are indicated by primed numerals and the analogous parts associated with the cylinder 16 are indicated by the same numerals unprimed.

The cylinder 16 is mounted coaxially on an annular water-cooled gland 2a which is fixed to the shell of the cupola 5 in registration with an aperture 21 in the wall thereof. The piston rodlii is normally in the retracted position shown, with its outer end positioned within the a suitable source of fluid under pressure.

, and 70, each forming a valve seat.

water-cooled gland 2% so that it is not adversely affected by the heat of the cupola; The cylinder 16 is of the type'commonly considered cushioned at both ends. It has a casing including similaroppositely disposed heads 22' and 23 sealinglyconnected in any suitable manner to the ends of an elongated tube 24...

Apiston 25 is slidably positioned in the sleeve 24 and is fixed to the piston rod 18, as-shown, there being a cylindrical cushioning collar 26 on the piston rod side of the piston 25, and a cylindrical cushion plunger or sleeve 27 on the other side of the piston. A suitable seal 28 is provided in the head 23 to sealingly engage the piston rod 18, as shown; The headZZhas a chamber 29 which opens intothe tube 24 through a bore 39, the

' latter being of a size to sealingly and slidably receive the plunger 27. A passageway 31 also affords comntunicationbetween .thechamber 29 and the interior of the pole, single throw pressure switch 39.

The head 23 has a bore 40 which is slightly larger than the piston rod and which is adapted to sealingly and slidably receive the cushioning collar 26, there beingno need for a larger chamber, such as the chamber '29, in' the head 23. A passageway 41, having a needle valve 42 interposed therein afiords communication be tween the inner end of the bore 40 and the interior of the tube.24. A passageway 43 communicates with the passageway 41 and threadedly, receives a conduit 4-4 fwhich, in turn, atfords communication with a normally open single pole single throw pressure switch 45. A

' larger passage 46 communicates with the inner end of the bore 49 and threadedly receives a fluid conduit 47.

A passage 48, having an inlet check valve 49 therein,

alfords communication between the passage 46 and the interior of the sleeve 24.

A, four-way valve of any suitable type is shown diagrammatically and is indicated by the numeral 56 in V FigJ 2. The conduits 34 and 47 are connected to opposite ports of the valve 50, as shown, there being another pair of opposite ports to which conduits 51 and '52 are connected. The conduit 51 serves as a fluid exhaust conduit, whereas the conduit 52 is connected to The valve 5:) is normally in theposition shown, aflording communication between conduits 47 and 52, as well as between " conduits 34 and 51.

The valve may be provided with an actuating arm 53 to which is connected a tension spring 54 which is suitably anchored, as at 55, and

'which'urg'es said handle toward the position shown. A

solenoid plunger 56 may also be connected to the arm 53, said plunger passing through a solenoid coil 57. When the coil 57 is energized, the plunger 56 and arm '53 are pulled toward the right, as viewed in Fig. 2,

against the action of the spring 54, to thereby move the valve to the dot and dash line position wherein communication is afforded between conduits 34 and 52 as well as between conduits 47 and 51.

The numeral 58' indicates a time delay sequence valve of any suitable construction. In the illustrated valve 58 there is acasing 59 having a cylindrical bore 60 and having spaced, intermediate, internal annular flanges 61 The end wall of the casing 60 which is nearer the flange 7i) is formed with a passage 62 having a needle valve 63 interposed therein to adjustably limit the communication afforded by said passage. A conduit 64 affords communication between the'conduit 34 and the passage 62. A piston 65 is slidably positioned in the bore 64 and is connected by an integral stem 66 to a valve 67 which is normally seated on the opposite side of the annular flange 61. The

valve 67 is smaller in diameter than'the piston 65 and is urged against its seat by'a compression spring 68.

A conduit 69 afiords communication between the conduit 34 and the interior of the casing 59 on the valve side of the flange 61. A conduit 71 atfords communication between a portion of the bore 60 which is intermediate the flanges 61 and 7t) and a normally closed;

single pole gle throw pressure switch 72.

Referring now to the wiring diagram of Fig. 3, the push button'switch 15 has sets of normally closed contacts 15a and 15c, as well'as a set of normally open contacts 1512.

A relay 73 has sets of normally; open contacts 73a,' 73b' and73e, as Well as a'set of normally closed contacts 73d. The relay 73 is also provided with a holding'coil 730,

Similar relays 74, 75 and 76 have sets of'normally open contacts indicated by the relay number plus thecorre spending suffix a, b, or e, and have sets of normally closed contacts 74d, 75d, and 76d respectively, as well as holding coils 7 4c, 7 5c, and 76c respectively. 7

A relay '77 has sets of normally open contacts 77a and 77b, as well as a holding coil 77c. A similar relay 78 has sets of normally open contacts 78a and 78b, as well as a holding coil 780. A relay 79 has a set of normally closed contacts 79a, a set of normally open contacts 7%, and a a holding coil 79c.

A two wire source of electric power is indicated by the numeral 89. A conductor 81 connects one side of the source 39 to one of the contacts of a normally closed interlock switch 82 and to one of the contacts 73b. A conductor 83 connects the other contact of the interlock switch 82 with one side. of the contacts 15a, 15b, and 150" of switch 15, as well as with one side of the contacts 73:: and

74a. A conductor 84 connects the other'side of the source to one side of each of the solenoid coils 57 and 57 to one side of each of the holding coils 73c, 74c, 75c, 76c, 77c, 73c and 79c, and to one sideof the lamp 14;

A conductor'85 connects the other side of each of the solenoid coils 57 and 57' with one of the contacts 74b. A conductor 86 connects the other contact 15a with one of the contacts 74d, and a conductor 87 connects the other contact 15b with one of the contacts 73a, whereas a conductor 88 connects the other contact 150 with one of the contacts 79b and with one of the contacts 740. A conductor 39 connects one of the contacts 73d with the other contact 74a. V

A conductor 90 connects the other contact 73a with the other contact 74a and with one of the contacts 79a.

The other contact. 79a is connected to the other side of A conductor 92 holding coil 74c by a conductor 91. connects the other contact 73b with one side of the contacts 75b, 75d, 76b, 7nd, 77b, and 78a, as well as with one of the contacts of each of switches 45, 45', 39, and 39. ing coil 73c with one of the contacts 76:: and with'one of the contacts of switch'72'; and a conductor 94 connects the other contact 73:! with the other contact 79b and with the other side of holding coil 79c, as well as with the other terminal of the lamp 14. A conductor 95 connects the othercontact 73e with the other contact 74d and with one of the contacts 752, as well as with one of i the contacts of the switch 72. A conductor 96 connects the other contact 74b to the othercontact 76d as well as to the other contact 75d. r

A conductor'97 connects the other contacts of switches 72 and 72' with the other contact 75c, as well as with the other contact 76a. A conductor 98 connects one of the contacts 75:: with the other contact 77b, as well as with the other contact of switch 39,; and a conductor 99 connects the other contact 75a with thecther side of the holding coil 77c. A conductor 100 connects the other side of the holding coil 750 with the'other contact 75b,

as well as with theother contact of the switch45; andja A conductor 93 connects the other side of the holdconductor 101 connects the other contact 7617 with the other side of the holding coil 760, as well as with the other contact of switch 45. A conductor 102 connects one of the contacts 762 with the other contact 78a, as well as with the other contact of switch 39'. A conductor 103 connects the other contact 76:: with the other side of holding coil 78c, and a conductor 164 connects one of the contacts 77a with one of the contacts 7811. A conductor 105 connects the other contact 77a with one terminal 107 of the starting circuit of the motor for the hoist drum 10, and a conductor 1% connects the other contact 78 1; with the other terminal 167 of said starting circuit.

The operation of the improved stock line indicator will now be described with particular reference to the cylinder 16, the operation of the other cylinder 17 being substantially identical. With the valve 50 in the full line position of Fig. 2 there is fluid under pressure in the cylinder 16 at the piston rod side of the piston 25 holding the piston rod 18 in the normal retracted position shown. The fluid under pressure is supplied from the source to the cylinder 16 through conduit 52, valve 50, conduit 47, passage 46, and bore 48. At the same time the interlock switch 82 which is located at the loading station for the skip carriage, is held closed by the skip carriage when the latter is in the lowered position of Fig. 1.

in addition, the holding coil 730 is energized through conductor 81, switch 82, conductor 83, contacts a, conductor -86, contacts 74d, conductor 95, switches 72 and 72, conductor 3, and conductor 84. This closes contacts 73a, 73b, and 73e, while opening contacts 73d. The coil 73: is maintained in energized condition through conductor 83, now closed contacts 732, conductor 95, switches 72 and 72, conductor 33, and conductor 84.

When the skip operator actuates the push button switch 15, contacts 15a and 150 are opened, and contacts 15b are closed. This energizes holding coil 74c through contacts 15b, conductor 37, now closed contacts 73a, conductor 90, contacts 79a, conductor 91, and conductor 84, thereby closing contacts 74a, 74b and 742, while opening contacts 74:]. Holding coil 740 is maintained in energized condition by current flowing through conductor 2'33, contacts 741:, conductor 9:"5, contacts 7%, and conductor 84. Closing contacts 741) energizes the solenoid coils 5'7 and 57' through conductor 8i, now closed contacts 737:, conductor 92, contacts 75d and 76d, conductor 96. now closed contacts 741;, conductor 85, and conductor 34.

Ener ization of solenoid coil 57 moves the parts of valve 59 to the dot and dash line position of Fig. 2, thus supplying fluid under pressure from the source to conduit 34, passages 33 and 3S, and chamber 29. This blows the check valve 36 off its seat, permitting the fluid pressure to act against the left hand face of the piston as well as against the end of the plunger 27. The piston 25 and its rod 13 are moved by said pressure toward the right (in Fig. 2), toward the dot and dash line position of Figs. 1 and 2. Due to the restriction provided by the needle valve 63 in passage 62 of the time delay sequence valve 58, the first shock wave of fluid pressure does not open said valve, and therefore is prevented from actuating the pressure switch 7 i fter the piston and rod have started to move and the inertia forces of starting are gone, the fluid pressure builds up in bore 69 of valve 58, and the piston 65 is moved onto the seat provided by flange '79 as the valve 57 is simultaneously moved off of its seat on flange 61. This exposes the pressure switch 72 to the pressure in conduit 3 if no obstruction is met by the piston rod 13 during its inward travel, the cushion collar 26 enters the bore -3 and limits the exhaust of fluid from the cylinder to that which can iiow through the passage 41 and needle valve 42. Continue inward (projecting) movement of the piston rod 18 builds up fluid pressure on the right hand side of the piston 25, as well as in passages 41 and 43 and conduit 44, and pressure switch 45 is then actuated, closing the contacts thereof. Similar movement of the piston rod 19 of cylinder 17 causes actuation and closing of the contacts of pressure switch 45.

Closing the contacts of switch 45 energizes the holding coil 750 of relay 75, closing contacts 75a, 75b and 75e, while opening contacts 75a. The holding coil 750 is maintained in energized condition by closure of contacts 752;. Similarly, closing the contacts of switch 45' energizes the holding coil 760 of relay 76, closing contacts 76a, 76b, and 7 59, while opening contacts 76d. Holding coil 76c is maintained in energized condition by closure cntacts 55 Thus, even after the contacts of switches as and 45 are subsequently opened, the coils 75c and 76c receive electric current through conductor 81, now closed contacts 7%, conductor 92, contacts 75b and 76b,

conductor 84.

Opening contacts 75d and 76d deenergizes solenoid oils 57 and 57. Referring to Fig. 2, this permits the to return the valve 513 to the solid line position rin own, thereby causing retractile movement of the piston S and its red 18. As the piston plunger 27 enters the bore 39, the exhaust of fluid from the left hand side of the cylinder 16 is limited to that which can flow through the assage 31 and needle valve 32, and pressure sufficient to actuate the pressure switch 39 is built up on the left hand side of the piston 25.

Closure of the contacts of pressure switch 39 energizes the holding coil 77c through conductor 81, now closed contacts 735, conductor 92, switch 39, conductor 98, now closed contacts 75a, conductor 89, and conductor 84. Coil 77c is maintained in energized condition through conductor $2, now closed contacts 77b, conductor 98, now closed contacts 75a, and conductors 9S? and 84. Similarly, closure of contacts of switch 39 as a result of retraction of the piston rod 19 of cylinder 17, energizes the holding coil 780 through switch 39, conductor 102, now closed contacts 76e, and conductors 183 and 84. The coil 76c is maintained in energized condition through conductor 92, now closed contacts 785, conductor 1432, now closed contacts 762, and conductors 1493 and 84.

Closure of contacts 77a and 78b completes the circuit between the terminals 107 of the starting circuit of the skip hoist motor 19, through conductor 105, now closed contacts 77a, conductor 104, now closed contacts 78b, and conductor 106. The ship carriage 7 then starts moving from the loading position of Fig. 1 toward the charging position therein, the power circuit being so arranged that a complete charging cycle is initiated by the momentary closure of contacts 77a and 78b.

Movement of the skip carriage 7 away from loading position causes opening of the contacts of the interlock switch 82, thereby deenergizing all of the holding coils 73c, 74c, 75c, 76c, 77c and 780, and resetting the electrical circuit. When the skip carriage 7 returns to charging position, the interlock switch 82 is closed thereby, and holding coil 73c is again energized through conductor 83, contacts 15a, conductor 86, contacts 74d, conductor 95, switches 72 and 72', and conductors 93 and 84. Coil 730 is maintained in energized condition through conductor 83, now closed contacts 732, conductor 95, switches 72 and 72, and conductors 93 and 84.

If, during projectile movement of the piston rod 18, and after opening of the time delay valve 58, movement of the piston rod 18 is obstructed by engagement with the stock in the cupola, fluid pressure is built up on the left hand side of the piston 25, as well as in the open valve 58, thus actuating pressure switch 72 and opening its contacts. This deenergizes the holding coil 730, returning the contacts of relay 73 to the normal condition shown. The resulting closure of contacts 73d energizes the holding coil 7% of relay 79, as well as the lamp 14, through conductor 83, contacts 150, conductor 88, now closed contacts 74c, conductor 89, contacts 73d, and conductors 94 and 84. Energization of holding coil 79:: opens contacts 79a and closes contacts 79b, said coil and lamp being maintained in energized condition through;

' positions shown.

' conductor 33, contacts c, conductor 88, contacts 79b, and conductors 94 and 84.

-. Opening ofcontacts 79a deenergizes the holding coil 74c and returns the contacts of relay 74 to their'normal. 7 Contacts 74b open as a result, and break the circuit to' the solenoids 57 and 57', deenergizing the latter and permitting the valve (Fig. l) and its counterpart (not shown) to be moved to their normal. I

' collar 153 which is'fiXedto the plunger lsl is normally I positions byth e tension spring 54 and its counterpart (not shown). This valve movement causes retractile movement of the piSIOn rods to their normal retracted 7 positions without actutating switches 45 and 45'. Return of the piston rods without actuating switches 45 and 45" prevents energization ,of holding coils c and 76c, and hence of holding coils 77c and 780, thereby rendering the skip hoist circuit inoperative. The lamp 14 will continue In summary, therefore, when the push button switch is .a'ctuated, the piston rods 18 and 19 'are rapidly pro:

jected into and retracted from the cupola. If neither piston rod meets any obstruction during any portion of its full stroke, the charger hoist motor 10 is energized, and

'the chargingbucket 6 is hoisted to load the cupola in I the normal manner. If, on the other hand, an obstruction stops either piston rod from being projected to its maximum'length into the cupola, the charger hoist motor '10 is rendered inoperative, and the lamp14 is illuminated to alert the hoist operator. At a later interval the oper to burn until the push button switch '15 is again actuated.

ator may again actuate the push button switch 15, cans ing a repetition of the above process. If the cylinders are able to go through their full strokes, the charger motor'isenergized and the cupola is charged in the normal manner. a V

The cylinders 16 and 17 are so positioned that if the stock height in the cupola is just below the reach of the piston rods 18 and 19, the full capacity of the bucket 6 will ,7 not load the 'cupola beyond the desired maximum stock height. V

. In the modification of Fig. 4, mechanically actuated V switches are employed in lieu of the pressure switches '39 and 45 of Fig. 2.- Referring more particularly to Fig. 4' there is a piston rod 118, corresponding to the piston rod 18 of the form of the invention of Fig. 2, which rod is normally in the retracted position indicated by dot and dash'lines at (a), with its outer end within the water cooled gland .20.. .The cylinder 116 includes heads 122 and .123 sealingly connected in any desired manner to the positioned within the tube-124 and is fried to the piston rod 118. There is a cylindrical cushioning collar 126 'on the piston rod side of the piston and the. cy'

lindricalcushioning collar 127 on the other side of the piston. The head 122 has a cup-shaped recess 129 which opens into the tube 124 and is of a size to slidablyrer ceive the collar 1 27. The fluid conduit 34 communicates 7 ends of an elongated tube.124. A'piston 1'25 isslidably with a duet 133 which leads to the chamber 129. Threaded into the. outer end of the head 122 is the casing 130 for an actuator plunger 131. The latter has a collar 132 fixed thereon which is acted onbya spring 135 to normally maintain the plunger 13]: in the position shown in Fig- 4, with its end projecting into the cup-shaped recess. 129, the plunger being longitudinally slidable in the cas-. ing 130 and. in a communicating bore: 136 of the head. The .outer end of "the .plunger coacts with a normally openmicro switch 139, which switch is wired exactly like the switch 39 of Fig. 2. When the; piston is in'the fully retracted position a the collar-end 127 will contact the end of the plunger 131 to close the micro-switch 139.

a .The head 1213 has a couhterborezli) forming a cup-' shaped recess for receiving the cushioning collar 1 26 when V thepistonfrod is in fullyeprojected position; Communicating with said recess 140' is a duct 14,6 which is in com munication withzthe flnid conduitAT i Threaded in a side f; t h ad 1 38 casi 56 w hin hi ra p ung r 15 is sl d b a t a er h ing n e slli abl t ro gh a tion of said electric circuit.

nected between said source and ram,.an electrically 'bper:

ransve s 1 52. o he h d p 'ie t hr h. side wallof thecup-shaped recess 140$ shown in Fig. .4; A

acted upon y a pri .1 to e Plu r the position shown in Fig. 4. The opposite end of'the plunger 151 coacts with .a normally. open microswitch 1 45. .which [corresponds to the switch 45 of the torn-riot the l invention of Fig, 2 and which is wired into thesystern of Fig.3'the sarne asthe switch. 45.; Inoperation ofthe modified formbf the invention shown in Fig. 4, if the piston rod fails to meet any.ob-. struction'during its fullstroke inwardly, the collar 126?. i will engagethe plunger' 151 as at-pos'ition (b) to close the switch to produce, the sameresults as when the switch 45 of the found the invention shown in Fig; 2

plunger (1.11127 will engage theactuator plunger .131.to

close the micro-switch 139 with results which are identical to those previouslydescribed in connection with the for m of the'inv'ention of Fig. .2; If, onthe other hand, anobstruction stops the piston rod from being projected to its maximum length intothe cupola, the charger hoist motor 16' is rendered inoperative and the lamp' is illuminated to alert the hoist operator just as in'the form of the inven tion of Fig. 2. a

'It is to be understood that the same wiring arrangement V of Fig. 3 is employed in connection with the system'of Fig. 4, the switch 139 corresponding to the pressure switch is gel-used. On the return stroke of the piston 125 the 39 of Fig. 3 and the-switch 145 corresponding'to the pressure switch 45 of Fig. 3. It is also to be understood that the fluid conduits 34, 64 and 67 of Fig. 4 are connected to the hydraulic system just as 'is shown'in Fig. 2,

53 being employed together with the single throw'pressure switch 72. 7

' Various changes and modifications may be made without departing from the spirit of'the invention, and all of such changes are contemplated as may come within the scopeof the claims. a

What I' claim is:

to a projected position within .said chamber, a source of fluid under pressure for said ram, a fluid circuit'connecte'd between said source and ram, a valve controlling the direction of the flow of fluid to said ram, means responsive to movement of the plunger to projected position for reversing said valve to cause retraction of the plungenaan electric circuit for .said motor, a switch in saidrci'rcuit, l means responsive to return movement of thepiston to rethe same valve 50 and the same time delay sequence valve 1 tracted position for operating said switch to'render said circuit openativeand means operated in response to ob struction of the plunger as it is being moved toward projected position in said chamber for preventing comple- 2. in a cupola having a stock chamber, means includ-.

ing a skip carriage movable between ia' loadingposition and a position for introducing a charge into said'cham ber, an electric motor for driving'said n1eans,'an electric" circuit for ,said motor, a manualswitch in said,circ uit,:a'

stock height determining member mounted on said cupola having a plunger movable fr'om normally retracted position to a projected positionlwithin said chamber, .azsource" "and-including av double acting fluid pressure operated ram 1 of fluidu'nder pressurefor said ram, a fluid circuit conated valve controlling the flow of fluid to said ram, said electrically operated valve-being in the circuit to'said' ,motor and operable to start projection of said plunger when said manual switch isactuated, means responsive' to m vement o e P n e o P ie t P o or rav n in s e. to ca se retraction of e plung r, a se qns 9. switch in said motor circuit, means responsive to movement of the piston to retracted position for operating said second switch to complete said motor circuit, and means operated in response to obstruction of the plunger as it is being moved toward projected position for preventing completion of said motor circuit.

3. In a cupola having a st ck chamber, means including a skip carriage movable between a loading position and a position for introducing a charge into said chamber, an electric motor for driving said means, an electric circuit for said motor, a manual switch in said circuit, a stock height determining member mounted on said cupola and including a double acting fluid pressure operated ram having a plunger movable from normally retracted position to a projected position within said chamber, a source of fluid under pressure for said ram, a fluid circuit connected between said source and ram, an electrically operated valve controlling the flow of fluid to said ram, said electrically operated valve being in the circuit to said motor and operable to start projection of said plunger when said manual switch is actuated, means responsive to movement of the plunger to projected position for reversing said valve to cause retraction of the plunger, a second switch in said motor circuit, means responsive to movement of the piston to retracted position for operating said second switch to complete said motor circuit, and means operated in response to obstruction of the plunger as it is being moved toward projected position for preventing completion of said motor :circuit, and means including an interlock switch in said motor circuit and engaged by the skip carriage when it is in loading position for preparing said circuit for :a new cycle.

4. In a cupola having a stock chamber, an electrically operated device, a stock height determining member mounted on said cupola and including a double acting fluid pressure operated ram having a plunger movable from normally retracted position to a projected position within said chamber, a source of fluid under pressure for said ram, a fluid circuit connected between said source and ram, a valve controlling the direction of the flow of fluid to said ram, means responsive to movement of the plun er to projected position for reversing said valve to cause retraction of the plunger, an electric circuit for said electrically operated device, a switch in said circuit, and means operated in response to obstruction of the plunger as it is being moved toward projected position in said chamber for operating said switch.

5. in a cupola having a stock chamber, an electrically operated device, an electric circuit for said device, a manual switch in said circuit, a stock height determining member mounted on said cupola and including a double acting fluid pressure operated ram having a plunger movable from normally retracted position to a projected position within said chamber, a source of fluid under pressure for said ram, a fluid circuit connected between said source and ram, an electrically operated valve controlling the flow of fluid to said ram, said electrically operated valve being in the circuit to said electrically operated device and being operable to start projection of said plunger when said manual switch is actuated, means responsive to movement of the plunger to projected position for reversing said valve to cause retraction of the plunger, a second switch in said circuit of said electrically operated device, and means operated in response to obstruction of the plunger as it is being moved toward projected position in said chamber for operating said second switch.

6. In a cupola having a stock chamber, an electrically operated device, a stock height determining member mounted on said cupola and including a double acting fluid pressure operated ram having a plunger normally movable from retracted position to a projected position within said chamber, a source of fluid under pressure for said ram, a fluid circuit between said source and ram, an electrically operated control valve in said fluid circuit for reversing the direction of fluid flow to the ram, means responsive to movement of said plunger to projected position to operate said valve to reverse said flow and cause retraction of the plunger, a fluid pressure operated electric switch, an electric circuit connected to said switch and electrically operated device, means connected between said pressure operated switch and the fluid circuit of said ram for causing operation of said switch when a condition in the cupola obstructs movement of the plunger.

7. In a cupola having a stock chamber, means for introducing a charge into said chamber, an electric motor for driving said means, a stock height determining member mounted on said cupola and including a double acting fluid pressure operated ram having a plunger normally movable from retracted position to a projected position within said chamber, a source of fluid under pressure for said ram, an electrically operated control valve in said fluid circuit for reversing the direction of fluid flow to the ram, means responsive to movement of said plunger to projected position to operate said valve to reverse said flow and cause retraction of the plunger, a fluid pressure operated electric switch, an electric circuit connected to said switch and to said electric motor, and means connected between said pressure operated switch and the fluid circuit of said ram for causing operation of said switch to break the circuit to said motor when a condition in the cupola obstructs movement of the plunger.

8. In a cupola having a stock chamber, an electrically operated device, a stock height determining member mounted on said cupola and including a fluid pressure operated ram having a plunger normally movable from retracted position to a projected position within said chamber, a source of fluid under pressure for said ram, a fluid circuit between said source and ram, 21 fluid pressure operated electric switch, an electric circuit connected to said switch and to said electrically operated device, means connected between said pressure operated switch and the fluid circuit of said ram for causing operation of said switch when a condition in the cupola obstructs movement of the plunger.

9. In a cupola having a stock chamber, an electrically operated device, a stock height determining member mounted on said cupola and including a fluid pressure operated ram having a plunger normally movable from retracted position to a projected position within said chamber, a source of fluid under pressure for said ram, a conduit leading from said source to said ram, a pressure operated valve, a fluid conduit connecting said valve to said first conduit so that said valve is operated by abnormal pressure which develops in the ram when the plunger meets an obstruction during projectile movement, a pressure operated electric switch, an electric circuit connected to said switch and to said electrically operated device, and a fluid line leading from said fluid source to said pressure operated switch through said valve, whereby said pressure operated electric switch is connected directly with said source when said valve is open to operate said electric switch.

10. In a cupola having a stock chamber, means for introducing a charge into said chamber, an electric motor for driving said means, a stock height determining member mounted on said cupola and including a fluid pressure operated ram having a plunger normally movable from retracted position to a projected position within said chamber, a source of fluid under pressure for said ram, a fluid circuit between said source and ram, a fluid pressure operated electric switch, an electric circuit connected to said switch and to said electric motor, means connected between said pressure operated switch and the fluid circuit of said ram for causing operation of said switch so as to break the circuit to said motor when a condition in the cupola obstructs movement of the plunger.

11. In a cupola having a stock chamber, an electrically operated signal, a stock height determining member mounted on said cupola and including a fluid pressure operated ram having a plunger normally movable from retracted position to a projected position within said chame'tated Valve, a flilid conduit connecting said valve to said first: conduit Sb that said Valve is opened by abnormal pfes s'u're which develops in the ram when the plunger 5 V V. meets an bstruction during projectile movement aprey sure operated electric switch, ah electric circuit conne'cted V to said switch and to said electrically operated signal, add

a fluidjin e' leading from said fluid source to said pressure nq a witchihxou a aisl px' s i h e al c,whe eby-said, 'q sq e pera esl we; w ch nn ted directly- With S SW1 2 w gl id a ve s. pen d o u er p: afi na j a s si na q i V 7 References Cited ih t he file of this pate ni UNIIED STATESPATENTS.

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