US2232103A

US2232103A - Press

Info

Publication number: US2232103A
Application number: US149692A
Authority: US
Inventors: Ernst Walter; Leslie S Hubbert
Original assignee: HYDRAULIC PRESS CORP Inc
Current assignee: HYDRAULIC PRESS CORP Inc
Priority date: 1937-06-22
Filing date: 1937-06-22
Publication date: 1941-02-18
Anticipated expiration: 1958-02-18

Description

Feb. 18, 1941. w, ERNST ETAL 2,232,103

' PRESS v Filed June 22, 1937 8 Sheets-Sheet 1 nvwzzvroxs Mun? ERA/57' .ATTORNEYS Feb. 18, W ERNST T PRESS v Filed June 22, 1957 8 Sheets-Sheet 2 11v VENTORS Mob-ER ERA/5T y ussuz: s. h'ueasRr A TTOk/VE Y5 Feb. 18,1941. w ERNST 2,232,103

PRESS I Filed June 22, 1937 8 Sheets-Sheet 3 BMLVWA/ A TTORNE V5 Feb. 18, 1941. w. ERNIST ETAL PRESS Filed June 22, 1937 8 Sheets-Sheet 4 INVENTORS h/dLTEI-K ERA/57' BY LESLIE s. HUBBLLRT A TTORNE V5 PEI-=5 PRESS Filed June 22, 1937 s Sheets-Shet 5 mvsmoks M11152 [Rn/5r BY LESLIE s. Huaamr ATTORN EYS Feb. 18, 1941. w, ERiq T m; 2,232,103

I PRESS I Filed June 22 1937 8 Sheets-Sheet 6 -H 4; v m

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- INVENTORS Mum? ERNST By L sa: 5. Hoaemr ATTORNEYS Feb. 18 1941. w Egus'r ETAL PRESS Filed June 22, 1937 a 'snets-s neet a E mra m H$ V 7 E mu? s M M Y A TTORNEYS Patented Feb. 18, 1941 PATENT OFF-ICE raass Walter Ernst, Edison,

and Leslie S. Hubbert,

Mount Gilead, Ohio, assignors to The Hydraulic Press Corp., Inc., Wilmington, DeL, a corporation of Delaware Application June 22, 1937, SerialNo. 149,692

5 Claims.

This invention relates to hydraulic machinery, and in particular, to electrically controlled hydraulic molding presses.

One object of this invention is to provide a hydraulic molding press having a common electrical control system for selectively molding large or small pieces, the selection being made merely by throwing a switch.

Another object is to provide a hydraulic molding press circuit having an electrical control systern, with means for molding articles semi-automatically. by the automatic performance of a single cycle of operation, or completely automatically by the repeated performance of an indefinite succession of operating cycles.

Another object is to provide a hydraulic molding press having a separable mold with automatic means for moving the mold portions apart from each other, and for causing the press plunger to pass through oneportion in order to eject the work-piece.

Another object is toprovide a hydraulic molding press having a separable mold and die, together with means for raising the mold and moving the die to one side in order to cause a plunger to pass into the mold and eject the work-piece.

Another object is to provide an arrangement as described in the preceding paragraph, wherein automatic means is provided for causing the mold and die to come together again after the election of a work-piece.

Another object is to provide a hydraulic molding press arranged to perform alternate moldin and ejection strokes, with means for automatically causing the plunger to execute a shortened return stroke between the molding and ejection strokes, thereby saving time and pressure fluid by performing a shorter ejection stroke than molding stroke.

Another object is to provide a hydraulic molding press circuit having means automatically responsive to the operation of a starting member, such as a switch, for filling the mold with material, preferably in a predetermined measured quantity, and having time delay means operative to start the molding plunger forward a predetermlned time after the operation of said starting member. 4

Another object is to provide a hydraulic molding press circuitincorporating means responsive to pressure rising in the molding operation to start the plunger on its return stroke, as well as to shift the mold and move the die out from under the mold, preferably having the additional .l'eature of holding the mold in its shifted position while operating the plunger on its ejection stroke, thereby pushing the molded piece out of the mold.

Another object is to provide a hydraulic molding press circuit having means for alternately performing a long molding stroke and a shortened ejection stroke, together with means responsive to the ejection of a molded piece for causing the plunger to execute a full length return stroke.

Another. object islto provide a hydraulic molding press circuit having means responsive to the execution of a return stroke of the press for returning the die and the mold to their closed positions, in readiness for the next molding operation.

Another object is to provide a hydraulic molding press circuit with a control circuit having separable mold portions, and an electrical circuit including means responsive to the arrival of one mold portion at a predetermined position for starting another mold portion upon a path bringing it into engagement with the first-mentioned mold portion.

Another object is to provide a hydraulic molding press having a platen and bed adaptable for making either large or small molded pieces merely by replacing the large mold with a small mold, or a plurality of small molds.

Another object is to provide a hydraulic molding press having means including a charging member, such as a movable box or hopper, for receiving the molding material and transporting it into and out of the charging position, together with means for causing the charging box to execute a forward and return stroke prior to the start of the forward stroke of the molding plunger.

Another object is to provide a hydraulic molding press with a hydraulic circuit for moving one part of the mold into molding and ejection positions, respectively, and for moving the die or other mold-closing portion into and out of its mold-closing position.

Another object is to provide a hydraulic molding press circuit, wherein the press is provided with push-back cylinders and served by low pressure and high pressure pumps, the low pressure pump being provided with a pilot-operated unloading valve to unload the discharge of the low pressure pump in response either to the attainment of a predetermined pressure in the main cylinder or to pressure being applied to the push-back cylinders.

In the drawings:

Figure 1 is a front elevation of a hydraulic press embodying the features of the present invention, employing a single large mold and molding plunger and with material-feeding mechanism omitted for clearness of showing.

Figure 2 is a right-hand side elevation of the press shown in Figure 1.

Figure 3 is a front elevation, partly in section, of a portion of the press shown in Figure 1, but modified slightly to accommodate a multiple molding arrangement together with multiple molding plungers for simultaneously molding a plurality of smaller pieces than in Figure 1.

Figure 415 a side elevation of the portion of the press shown in Figure 3.

Figure is a diagrammatic view of the hydraulic circuit employed in the press of Figures 1 5 and 2 when arranged to mold multiple small pieces, as shown in Figures 3 and 4.

Figure 6 is a diagrammatic view of a portion of the hydraulic circuit of Figure 5 pertaining to the pilot and slippage system.

Figure 7 is a diagrammatic view of another portion of the circuit shown in Figure 5, showing the high and low pressure press-operating circuit.

Figure 8 is a simplified diagram of the electrical control circuit for controlling the various motions of the press elements, and for controlling the distribution of the fluid in the hydraulic circuit in Figure 5.

Figure 9 is a wiring diagram showing the various electrical elements in their proper relative positions, but with the same connections as shown in the simplified diagram of Figure 8.

General construction In general, the hydraulic press and circuit of this invention consists of a vertical molding press having a main molding plunger and a movable mold with a movable die closing the lower part of themold. The mold is movable vertically and the die horizontally so that the main plunger may pass into the mold and elect the molded piece therefrom after the completion of a molding stroke. Electrical control elements and circuits are provided for timing the motions of the main plunger, the mold-raising plungers and the dieshifting plunger so that each will accomplish its motion at the proper relative time. An electrical circuit is provided whereby a single large workpiece or a plurality of small work-pieces may be molded merely by throwing a switch and by replacing the one set of molds and plungers by another. The apparatus for molding a'plurality of small work-pieces is additionally provided with a charger operated by hydraulic plungers and likewise timed by :means of an electrical control cir- 5 cuit to move into engagement with the mold charged with molding material, and return to its starting position before the molding plunger accomplishes its molding stroke.

The electrical circuit is also arranged so that 60 the press may be caused to operate either in a semi-automatic or completely automatic manner. The press operates in a semi-automatic manner when it accomplishes a complete cycle of operations, namely, molding and ejection strokes, and 55 then returns to its starting position where it halts. The press operates in a completely automatic manner when it does not halt at the end of this complete cycle of operations, but continues to perform an indefinite number of such cycles until no halted by the operator. Means is also provided for causing the press to accomplish alternate molding and ejection strokes, wherein the ejection stroke is shorter than the molding stroke.

65 Press arranged for molding single large blocks Referring to the drawings in detail, Figures 1 and 2 show the press 'of this invention as arranged for the molding of single large blocks, blocks of salt being chosen for illustrative pur- 70 poses. This press consists of a base 10 having secured thereto the vertical strain rods ll, asby the nuts [2. The strain rods II at their upper ends are provided with a top member l3, held in place by the nuts l4, and containing the main 75 cylinder l5 surmounted by the surge tank l6.

The main cylinder is is provided with a main plunger H with a platen l6 secured thereto, and having a molding plunger l9 depending therefrom and held in position by the bolts 26, engaging the laterally flanged portion 2|. 5 Arranged opposite the molding plunger [3 is a mold 22 mounted upon a mold holder 23, which is vertically movable and supported upon the rods 24 and coil springs 25. The mold holder 23 is provided with projecting portions 26 adapted 10 to engage guide portions 21 mounted upon the strain rods H and serving to guide the mold holder 23 in its vertical motion. Mounted beneath the mold 22 and mold holder 23 and arranged to close the lower end of the aperture in 15 the mold 22, is a die 28 mounted upon a slide 29, which is slidably mounted upon a bifurcated sup- -port 30 with an extended portion 3| forming a bracket. The latter supports the base portion 32 of the hydraulic cylinder 33 having the plunger 20 34 which moves the die slide 2 9' into and out of 1 position beneath the mold 22. Also secured to the bed I0 is a platform 35 for the operator, and having hand rails 36 rising therefrom. The mold holder 23 is provided with hydraulic cylinders 31 25 having plungers 38 emerging therefrom and engaging the mold holder 23 to raise and lower it. Mounted on the side of thepress in brackets 39 is a vertically movable and rotatable control rod 40 (Figure 2), having adjustable spaced stops so 43 thereon engageable by a platen arm 42 having a projection or shelf thereon. The control rod 40 also is provided with an arm 4| carrying a vertically adjustable threaded stop rod 4la, the

end of which is arranged to be engaged by the 35 shelf of the platen arm 42 when the control rod 40 is rotated by the solenoid 6I,'thereby constituting a mechanical short stop for temporarily halting the main plunger II at an intermediate position upon its return stroke immediately after 60 a working stroke as hereinafter explained. The upper end of the control rod 40 carries a stop 44 engaged by the end of a lever 45 (Fig. 2), pivoted to the top member l3, as at 46. Pivotally attached, as at 41, to the lever 45, is the arma- 45 ture 48 of a solenoid 49. The opposite end of the lever 45 has secured thereto. as at 60, a link 5| pivotally connected to a bellcrank 52 mounted upon the bracket 53, and having a rod 64 connected, as at 55, to the rocking lever 66 supported, as at 51, by the member 58 and having pivotally secured thereto, as at 59, the control rod 60 of the main hydraulic pump 6|. The control rod 66 passes into the servomotor control valve 62 of the pump 6|. This valve-62 serves to control 66 the admission of fluid to the servomotor 63, which shifts the shift ring or flow-control element of the main pump 6| in a manner determined by the position of the valve 62. The main pump 6| is of a reversible variable delivery type, the details 60 of which form no part of the present invention. A pump with a servomotor control system, suit-- able for this purpose, is found in the Ernst Patent No. 2,038,272, issued April 21, 1936.

The main pump 6| is provided with a portion 55 64 having forward and return

connections

66 and 66. The pump 6| is mounted upon an extension bracket 61 having an overhanging portion 66 from whcih the motor 69 is suspended. The motor 69 drives the pump 6| by means of an 70 endless member 10, such as a sprocket chain or belt. The motor 69 is movably mounted and adjustable by means of the-screw shaft H to tighten or loosen the sprocket chain or belt 10. Mounted upon the side of the press are three '16 valves I2, I3 and I4 .(Figure 2) having valve rods I5, I9 and Il operated by rocking levers II, I9 and 30, connected to the armatures 3|, 32 and 33 of solenoids 84, and 06. A solenoid 31 (Figure 2) with an armature 33 shifts a bellcrank 39, which swings an arm to rotate the rod 40 and interpose the stop rod 0. as a mechanical stop in the path of the press mechanism in order to shorten the stroke or the main plunger II upon the return stroke between the molding and ejection strokes.

Mounted upon the support 9| upon the top member l3 of the press is the molding material hopper 92, having a weighing chamber 93 below which is a funnel-shaped portion 94, terminating in a diagonal chute 95. A solenoid 90 is seecured to the hopper 92,'and its armature 91 is connected to the crank arm 98 leading to theinterior of the weighing chamber 93, where it operates a material-releasing device. Thus, when the solenoid 90 is energized the material, such as salt, which has been weighed out in the weighing chamber 93, is released so as to fall by gravity through the funnel-shaped portion 94 into the inclined chute 95.

Press arranged for molding multiple small. blocks The press shown in Figures 3 and 4 is the same as the press shown in Figures 1 and 2, but the arrangements for holding the molds and dies are somewhat different. The molding plunger head 99 carries a plurality of molding plungers I00, beneath which is arranged a mold IOI (Figure 3) having a plurality of apertures I02 lined with sleeves I03. The mold IOI is arranged with a recess I04 within the mold holder I05. The latter in its floating supports and lifting plungers is the same as shown in Figure I. Mounted upon the mold I M are guides I06 serving to receive corresponding ridges I0I upon the charger I08. The latter is provided with apertures I 09 matching the various apertures I02 of the mold IN, and is moved toward and from its charging position by means of hydraulic cylinders IIO, operating plungers III connected to the charger I08. The plungers III are threaded at their outer ends and secured by the nuts II2 to the charger I08 (Figure 4).

Arranged beneath the apertures I02 of the mold W! are corresponding dies I I3 (Figure 3) mounted upon a die carrier I I4 which is, in turn, supported upon a member II5 mounted for reciprocation upon the armsof the bifurcated support 30. Secured to the member II5 is the plunger 34 of the cylinder 33, the latter being supported, as before, upon the base portion 32 of the bracket 3| resting upon the bed I0. The plungers llI pass through the portions III, bolted as at II8, to the member I05.

Hydraulic circuit The press arrangement of this invention includes a hydraulic circuit and an electrical circuit for controlling the actions of the hydraulic circuit. The hydraulic and electrical circuits will be described separately, but their operations will be described simultaneously.

The pump assembly, consisting of the main pump-6| and slippage and pilot pumps H9 and I20, is claimed in the copending application of Ernst, Ser. No. 41,281, filed September 19, 1935.

As shown in Figure 5, the hydraulic circuit includes the previously mentioned main cylinder I5 with its main molding plunger II surmounted by the surge tank I6. Also previously mentioned are the mold-raising cylinders 31 with their plungers 30, as controlled bythe valve I2 'responsive to the action of the solenoid 84. Likewise previouslv mentioned are the die-shifting cylinder 33, with its plunger 34, controlled by the valve I3 responsive to the action of the solenoid 85; and also the charger-shifting cylinders IIO with their plungers III, controlled by the valve I4 responsive to the action of the solenoid 86;

The hydraulic circuit shown in Figure 5 may be said to contain four different hydraulic circuits as regulated by four different pumps. The first circuit is the main or high pressure circuit for operating the main plunger II, supplied with pressure from the main pump iii. The second circuit is a slippage circuit for removing operating fluid which escapes past the various plungers, this being operated by the slippage pump H9. The third circuit is a pilot circuit for supplying fluid pressure to operate the chargershifting plungers III and the mold-shifting plunger 34, as well as the servomotor 63 and control valve 62 of the main pump 6|. Fluid for this pilot circuitis supplied by the pilot pump I20. The fourth and final circuit is a low pressure circuit which operates in cooperation with the high pressure circuit supplied by the main pump GI, this low pressure circuit being supplied with fluid from the low pressure pump I26. The major portions of the pilot and slippage circuits are shown in simplified form in Figure 6, whereas themain portions of the high pressure and low pressure operating circuits are shown in Figure 7.

The main pump 6| in the high pressure circuit has associated therewith a slippage pump H9 and a pilot pump I20, all driven from the same mechanism. The pumps 6|, H9 and I20 are independent of one another, but are merely associated with one another for mechanical con venience. The forward pressure connection 65 of the main pump 6| is connected by the conduit I2I to the main cylinder I5, from which a branch conduit I22 having a shut-off valve I23, leads to a pressure gauge I24 for indicatingthe pressure within the maincylinder I5. Similarly, the return pressure connection 66 is connected by the conduit I25 to the surge I6 by way of certain hydraulic devices shown more in detail in Figure 7.

These hydraulic devices, shown within the surge tank I6 in Figure '7, consist of a main cylinder release and by-pass hydraulic system, together with a surge, valve, as set forth in detail in the Ernst patent, No. 1,956,758, issued May 1, 1934. This system is set forth in detail in the above-mentioned patent and forms no part of the present invention. It consists I Figure 7) of a check valve I2I connected to and opening toward the conduit I25,; a by-pass valve I20 likewise connected to-the line or conduit I25; 2. pressure release valve I29 similarly connected to the conduit I25, and a surge valve I30 which terminates the connection of the conduit I25. The pressure release valve I29 is connected, by the line I3I, to the main cylinder I5. A safety valve I32 is mounted upon a conduit I33 connected to the main cylinder I5 for relieving abnormal pressures within the main cylinder I5. The operation of this pressure release and bypass system'for the main cylinder I5 is set forth in detail inthe above-mentioned patent. The surge valve I30 serves for facilitating the downward descent of the main plunger I6 by admittingfluid freely to the main cylinder I from the surge tank I6, in the manner set forth in detail in the above identified patent, and also in the Ernst patent, No. 1,892,568, issued December 27,1932.- The surge valve I30 is forcibly opened on the return stroke of the press by fluid reaching it through the return line I25.

Also connected to the return connection 66 is a. conduit I34 leading to the pushback cylinders I35, having the push-back plungers I36 therein. These plungers I36 are connected to the platen I8 (Figure 'I) for the purpose of returning the platen I8 and the main plunger I6 to their starting position after a pressing stroke has been made. Beyond the push-back cylinders I35 the line I31 leads to the operating cylinder of a double pilotoperated unloading valve I38, which controls the action of the low pressure circuit which cooperates with the high pressure circuit, and which is supplied with fluid by the low pressure pump I26. The suction line I39 thereof is connected directly to the surge tank I6 by way of the valve I40. The pressure line I4I therefrom is connected to the unloading valve I38, beyond which I the line I42 containing the check valve I43, runs to the main cylinder I5. A line I44 likewise runs from the check valve I43 to the operating cylinder of the pilot-operated unloading valve I38. From the latter the discharge line I45 runs directly to the surge tank I6, and on its end carries the check valve I46.

Connected to the return line I34 at one of the push-back cylinders I35 is a branch line I41 (Figure 5), having therein the check valve I48. The line I41 is connected to the intake I49 of the valve 12, the outlet I50 01 which is connected by the line I5I to the mold-raising cylinders 31. The opposite ends of these cylinders 31 are connected to the branch discharge line I52, runningto the discharge line I53. The latter is connected, through the check valve I54, to the surge tank I6 so as to discharge into the latter, and is likewise connected by the branch line 155 to the safety valve I56, mounted upon the outlet I50 of the valve 12. The discharge line I53 is likewise connected, through the branches I51 and I58, to the valves 13 and 14 and serves to convey fluid therefrom back to the surge tank I6.

The slippage circuit consists of the slippage pump II9, previously mentioned, and having the line I59 running therefrom to the slippage tank I60, from the opposite side of which the line I6I proceeds by the branches I62 and I63 to the opposite ends of the push-back cylinder I35 from their connection with the line I34. In this manner any fluid leaking past the plungers I36 is removed to the slippage tank I60. Similarly,

any fluid escaping past the main plunger I1 isremoved through the branch line I64 connected to the line I59. slippage pump II9 the discharge line I65 returns to the surge tank I6 for discharging the excess fluid resulting from this slippage.

The pilot circuit (Figures 5 and 6) is supplied with fluid from the pilot pump I20, which draws in fluid from. the surge tank I6 by way of the suction line I66 having the valve I61 therein. The pilot pump I20 discharges into the line I68 containing the relief valve I69. The discharge line I16 leads from the latter, through a fluid filter "I, to the cooling coils I12 within the surge tank I6. Leading from the line Iis an push-button type.

From the opposite side of the optional branch line I13 having an optional choke I 14 (Figure 6), and running to the pintle cap I of the pump 6|.

Beyond the relief valve I69 the line I68 continues to the servomotor valve cylinder 62, from which the line I16 returns to the surge tank I6 by way of the check valve I11. In this manner the pilot pump I supplies pressure fluid for controlling the actuation of the servomotor which moves the shift ring of the main pump 6| to vary the discharge thereof by varying the eccentricity between its primary rotor and its secondary rotor as is understood by those skilled in the variable delivery pump art. Beyond the relief valve I69 the branch line I18 runs from the line I68 to the intake I19 of the valve 13, from the outlets I80 and I8I, of which the lines I82 and I83 run, respectively, to the opposite ends of the die-shifting cylinder 33 and its plunger 34 (Figure 5). The line I18 also leads into the intake I84 of the valve 14, the outlets I85 and I86 of which lead through the conduits I81 and I88 to opposite ends of the chargershifting cylinders I I0 and their plungers III.

The four hydraulic circuits thus described are controlled by an electrical system through the actuation of

solenoids

49, 64, 85 and 86, the solenoid 49 controlling the shifting of the valve rod 60 which controls the servomotor 63 of the main pump 6I.

Electrical circuit and elements The electrical circuit which controls the hydraulic circuit, in the manner previously described, is shown in simplified form in Figure 8 and in a rather more elaborate form in Figure 9. The simplified diagram of Figure 8 shows the relative connections. of the various switches onerated by the different relays. The more elaborate circuit of Figure 9, however, shows the relative positions of theswitches operated by the different relays, without the possibility of showing simplified connections between them. For tracing the circuits, therefor, it is convenient to utilize Figure 8, whereas for locating the different interlocks or switch blades operated by the difl'erent relays, it is advisable to consult Figure 9.

The electrical circuit consists mainly of a plurality of relays, limit switches and solenoids, together with a transformer for supplying control current at a reduced voltage, a time delay relay, a rectifier, certain resistances and various manually-operated switches, mostly of the These elements will be first listed for convenience, together with the functions they perform, after which the operation will be set forth in more detail.

The electrical control circuit (Figures 8 and 9) receives power from the power lines I89 and I 90, which run through the control fuses I9I and I92 to the lines I93 and I94, leading to the terminals I95 and I96 of the primary winding of the transformer I91. The latter has terminals I98 and I99 leading from its secondary windingto various parts of the control circuit, as hereinafter described in detail. Also included in the control circuit are eleven control relays in the form of magnetically-operated switches, having switch blades either normally closed or normally opened, and operated magnetically by coils. These control relays are generally designated 20I to H I, inclusive. These control relays are supplied with operating coils 20Ia to 2IIa and with switch blades 20"; to 2Ilb, 20Ic to 2Ilc, 2lId to 2Ild and 20le to 2Ile. Also connected in the circuit is a time relay 2I2 having a coil 2I2a and a switch blade 2I2b. This is connected to a rectifier 2I3 and a resistance 2. Below the rectifier 2I8 is a resistance 2|, a pressure switch 2I9, having a switch blade 2I9a. A second pressure switch 2", having a switch blade 2I1a, is found in the lower right-hand corner of Figure 9.

The control relays 2M to 2, inclusive, are in part controlled by the closing and opening of a pluralityoflimit switches 22I to 229, inclusive, and the circuits to these are under the control of various manually-operated switches of the push-button type. Among these are the oif-on switch 238, the hand automatic switch 23! and the block size selector switch 232. Each of these has switch blades or switch positions, respectively designated a and b, and each is normally open or normally closed, according to.

the positions of the switch blades as shown in Figures 8 and 9. 'A reversing switch 233 is also provided, and includes a forward switch member 234 and a reverse switch member 235.

The actions of the various control relays 2Ill to 2 energize or deenergize the coil windings 241 to 246, respectively, corresponding to the

solenoids

96, 8E, 48, 81, 84 and 85. The wires from the various control relays 281 to 2 are brought out to a plurality of terminals 25! to 21, inclusive. An incandescent light bulb 215 indicates the operating condition of the circuit.

The electrical circuit is roughly divided into two sub-circuits. The power sub-circuit supplies relatively high voltage electricityto the solenoid windings 2M to 246, these being energized from the power lines I89 and I98, through the various relay switch blades shown in Figure 8. The control sub-circuit receives current from the secondary terminals I98 and I99 of the transformer I91, the control current thus being of a lower voltage. From the transformer secondary terminal I99 a line 218 runs to the off-on switch 238, and a branch line 211 runs to the rectifier 2 I 3 by way of the relay switch blade 2112c and the resistor 2 I l, the energlzatlon being completed by the line 218 returning as a branch line of the line 219 leading from the transformer secondary terminal I98. The line 219 energizes one side of all of the relay coils 2810. to 2IIa. The normally closed reverse switch 285 is directly connected to the ofi-on switch 238, and beyond it the line 288 runs downward substantially parallel with the line 219, and energizing the opposite side of the circuit.

Beyond the junction of the line 288 at the reverse switch 235 is connected the normally open forward switch 234, this being bridged by the lines 28I and 282. interconnected by the relay switch blades 202e, 2080 and 2IlIe. Beyond the forward switch 234 is connected the hand automatic switch 23I, having an automatic position 23) and a hand position 28 Ba. Connected to the automatic position 23Ib is the line 283, leading to the relay coil 28Ia. Similarly, from the hand position 23; the line 284 leads back to the line 288 by way of the relay switch blade 28Id. Connected to the line 286 is the limit switch 22I, which is in turn connected through the normally closed relay switch blades 2I8d and 2| Id to the block size selector switch 232. The latter has large block and small block selecting positions 282d or 28217 from the line 219 (Figure 8).

. Summarizing the functions of the various relays, the relay 28I controls the completely automatic or full automatic operation only, and maintains a continuous bridging through the relay switch blade .2lIe, around the forward pushbutton switch 234. The control relay 202 controls the energization of the solenoid winding 24I of the solenoid 98. The relay 283 controls the energlzatlon of the circuit containing the relay coils 204a and 285a for molding small blocks or small work-pieces. The relay 284 controls the energization of the winding 242 of the solenoid 86 for operating the charger mechanism. The relay 205, when energized, deenergizes the relay coil 204a and the solenoid winding 242 of the solenoid 88, and also the relay coil 286a undercertain conditions. The relay 208 controls the ener-- gization of the solenoid winding 243 of the solenoid 49 for starting the main plunger on its forward stroke. The relay 281 controls the energization of the solenoid winding 242 of the solenoid 81 for interposing a mechanical short stop on the return stroke between the molding and ejection strokes of the main plunger. The relay 208 controls the energization of the solenoid winding 245 of the solenoid 84 for urging the mold in an upward direction. The relay 289 controls the energization of the solenoid winding 246 of the solenoid 85 for forcing the die out from under the mold. I The relays 2III and 2i I, both with normally closed switch blades, operate in conjunction with various limit switches to control the sequence of operations of certain other relays, as set forth in more detail below.

The six solenoids have the following functions. The solenoid 96 with winding 2 operates the crankarm 98 for releasing the molding material from the weighing chamber 93 to the conical chutes 94 and 95 (Figure 2). The solenoid 85 with winding 242 shifts the valve 1A for operating the cylinder IIOand plungers III for moving the charger. The solenoid 89 with winding 283 shifts the control of the variable delivery pump 6| through the links and levers, previously described, thereby starting the main plunger B1 on its forward stroke. The solenoid 81 with its winding 244 interposes a mechanical short stop in the path of the main plunger to prevent its making a full return stroke between its molding and ejection strokes. The solenoid 84 with winding 24? shifts the valve 12 for supplying fluid to the plungers 38, urging the mold in the upward direction. The solenoid 85 with winding 2% shifts the valve 19 for supplying fluid to the cylinder 33 and plunger 36 for moving the die inward and outward relative to the mold.

The various limit switches have the following functions. all being normally open excepting limit switch 229, which is normally closed. The limit switch 22 i is closed when the main plunger I1 is in its retracted position, and opens as soon as it starts its forward stroke. The limit switch 222 is closed with the charger I08 out. The limit switch 223 is closed momentarily when the main plunger I1 starts on its forward stroke, and thereby energizes the relay coil 201d. The limit switch 224 is closed with the charger I88 in. The limit switch 228 is closed when the mold I8I is in its raised position. The limit switch 228 closes when the die H3 reaches its outer position, and thereby reenergizes the relay coil 288a to start the main plunger I1 on another forward stroke. The limit switch 221 closes when the molded piece or block is ejected from the mold I9I, and thereby energizes the relay coil 2I9a. The limit switch 228 closes when the die III returns to its normal or inner position, beneath the mold IO I. The

normally closed limit switch 229 opens when the mold IIII starts on its upward travel.

The pressure switches have the following functions. The pressure switch 2I6 is normally opened but closes at. a predetermined low pressure in the fmain cylinder ii, at the end of a forward stroke of themain plunger II. The pressure switch '2II is also normally open, but closes at a predetermined higher pressure at the end of the same forward stroke. The time relay 2| 2 has a normally closed switch blade 2I2b which opens when the time relay coil 2I2a is energized, and closes again a predetermined time thereafter.

The manual switches have'the following functions. The oif-on switch 230 serves to place the entire electrical circuit in and out of operation as a whole. The hand automatic switch 23! controls the circuit,- determining whether the circuit isset for semi-automatic (hand) operation or completely automatic operation. Semiautomatic or handoperation' occurs when the press executes a complete working cycle, molding and ejecting one "work-piece and returning to its retracted position-. The complete or full automatic operation occurs when the press executes an indeflnitenumber of complete working strokes and turns out an indefinite number of molded work-piecjs ;until the entire press is halted by the operator.

The block sizeselector switch 232 controls whether urge or; small blocks or work-pieces are to be molded by determining which of the relay coils 202a or 20341 is to be energized. The forward switch 234 serves to energize the press control circuit for a forward stroke of the main plunger I1, and is normally open. The reverse switch 235 is normally closed, and serves, when operated, to causethe main plunger H to halt instantly and return to its retracted position, thereby serving as an emergency or safety switch.

Operation In the operation of the press the motor 68 for operating the pumps 6|, 9, I20 and I28 is started, thereby causing these pumps to begin operation. It will. first be assumed that the hand automatic switch 23I is set for hand or semi-automatic operation, and that the block size selector switch 232 is set for making large blocks. The off-on switch is, of course, closed in its on" position, and the forward push-button switch 234 is depressed, thereby closing its contacts. When the forward switch 234 is closed the operating cycle will be started by energizing the relay coil 202a from the line 216 from the transformer secondary terminal I99, by way of open limit switch 22I (which is closed in the retracted position .of the, main plunger II), the normally closed relay switch blades 2| 0d and 2| Id and the size selector switch blade 232, now set in its. large-size position 23211., The normally closed switch blade 2I0d indicates that the die occupies its inner position, and the normally closed switch blade 2I|d indicates that the mold is in its lowered position.

When the relay coil 202a is energized, its normally open switch blade 202e bridges the circuit around the forward push-button switch 234 so that the relay coil 202 remains energized, even after the forward push-button switch 234 is released. The energization of the relay coil 202a closes its normally open switch blades 242D and 232d, thereby applying power current to the winding 2 of the solenoid 98. The operation of this solenoid moves the crank arm 38 and permits the molding material, such as salt, to it flow into the mold 22. Atthe same time the-energlzation of the relay coil 202a opens the normally closed switch blade 202e and deenergizes the time relay coil 2I2a by breaking the circuit between the lines 211 and 218'. 10

The deenergization of the time relay 2 I2 opens its normally closed switch blade 2I2b. After the lapse of a definite time interval, such as eight seconds, the time relay switch blade 2 l2b again closes, thereby energizing the relay coil 243a. M This lapse of time permits the filling of the mold in adequate time. The energizationof the relay coil 206a closes its normally open switch blades 20Gb and 206d, thereby energizing the solenoid winding 243 of the solenoid 43 by closing the circuit between thelines I89 and Ill. Thisaction shifts the pump control mechanism through the previously described linkage, and causes the pump ii to discharge pressure fluid into the line I2I leading to the main cylinder ll.

Meanwhile, the low pressure pump I26 has also been discharging pressure fiuidthrough the line I, the pilot-operated unloading valve I33, the check valve I43 and the line I42 into the main cylinder I5. The main plunger Il starts downward, thereby opening the surge valve I34 and drawing in additional fluid from the surge tank I6 (Figure 7); The pressure fluid for shifting the pump control mechanism in response to the action of the solenoid 49 has meanwhile been supplied from the pilot pump I20, through the line I68 and the relief valve I69. The slippage pump II9 has meanwhile been operating to withdraw slippage fluid from the various cylinders.

As soon as the main plunger I1 starts downward the limit switch 22I opens and-deenergizes the relay coil 202a, thereby closing the normally closed switch blade 202e and energizing the time relay coil 2I2a. The normally closed time relay 5 switch blade 2I2b then opens, but this does not deenergize the relay coil 206a because this coil is now held in an energized condition through a holding circuit, by way of the normally closed switch blade 2Ille, the now closed normally open switch blade 208a and the normally closed switch blade 2I'Ia of the pressure switch 2". As the main plunger II moves downward the normally open switch 223 closes and energizes the relay coil 201a through the 'normally open but now closed switch blade 206e. The coil 201a remains energized by a holding circuit bridging the limit switch 223 and the switch blade 2ll6e by way of the normally open but now closed switch blade 201d. The energization of the relay coil 201a closes its normally open switch blades 201b, and energizes the solenoid winding 244 of the solenoid 81 which operates a mechanical short stop to limit the travel on the return stroke of the main plunger I! to a shortened stroke prior to its 0 ejection stroke.

Meanwhile, the main plunger II continues on its downward or forward stroke until it reachw the end of its molding stroke and compresses the molded material within the mold; Atthis point 7 pressure is'bllilt up within the main cylinder I5, and eventually operates the low pressure switch 2I3, closing its normally open switch blade 2I3a. This action energizes the relay coil 203a, the energization being held through a holding circuit 15 by way of the normally open but now closed switch blade 208:! and the normally closed switch blade 2| le. The energization of the relay coil 208a closes its normallyjopen switch blades 208i) and 2080, thereby energizing the winding 245 of the solenoid 84. This shifts the valve 12, thereby admitting pressure fluid from the line l4! to the line |5| (Figure 5) for urging the mold-raising plungers. 38 in an upward direction. The mold 22, however, does not travel upward immediately, due to the high pressure which is being exerted in the opposite direction by the main plunger l1 and molding plunger I9.

As the molding openation continues, the pressure accumulates within the main cylinder 15 to the point where it exceeds the high pressure setting of the high pressure switch 2", thereby opening the normally closedswitch blade 2|la. This action deenergizes the solenoid winding 243 and solenoid 49, thus shifting the control rod of the variable delivery pump 6| into its reverse position and causing pressure fluid to pass through the line I34 into the push-back cylinders I35, actuating the push-back plungers I36 to raise the'platen |8 and the main plunger Il totheir retracted positions.

In the meantime, the low pressure pump I26 has been unloaded and its discharge directed through the line I45 and check valve I46, into the surge tank I6. This action occurs when the pressure within the main cylinder 15 passesthrough the line I44 to the operating cylinder of the unloading valve I38, and operates thevalve to accomplish this action. When the push-back cylinders |35 are operated, pressure fluid also proceeds along the line I31 to the unloading valve |38, and continues to operate this valve to discharge the fiuid of the low pressure pump I26 into the surge tank it by way of the line I45. As pressure has already been applied to the moldraising cylinders 3i, the mold will also travel upward in the same direction as the main plunger ll. The latter is stopped when the platen arm 42 engages the end of the rod 4| of the mechanical short stop interposed by the operation of the solenoid Bl and lifts the press control rod 40 to shift the pump control rod 60 to its neutral position so as to place the pump 6| in a zero delivery condition, and thereby halt the main plunger at an intermediate position upon its return stroke. At this instant the normally open limit switch 225is closed when the mold reaches its raised position.

The closing of limit switch blade 225 energizes the relay coil 209a through the normally closed switch blade 2| 0c. The consequent closing of the normally open switch blades209b and 2090 energizes the winding 24B of the solenoid 85, thereby shifting the valve 13 to cause pressure fluid to be applied through the line I83 to the dieshifting cylinder 33, thereby causing the plunger 34 to withdraw the die from .under the mold. When the die has reached its outer limit of travel, the normally open limit switch 226 is closed, thereby again closing the circuit and again energizing the relay coil 205a and. solenoid 49 to reverse the delivery of the pump 6|, as described above. This action again starts the main plunger H on a downward stroke, this time an ejection stroke. As pressure is still being applied to the mold llll, thereby holding it in its raised position, the molding plunger I9 passes into the mold and forces the molded piece, such as a salt block, out of the mold. When the piece has been ejected from the mold it operates the limit switch 221, the closing 'of which energizes the relay coil 2||la through the normally closed normally open but now closed relay switch blade.

When the relay coil 2||la is thus energized, it opens the normally closed switch blade 2||le in series with the relay coil 206a. deenergizing the winding 243 of the solenoid 49 and reversing the delivery of the pump 6|, thereby starting the main plunger ll on another upward stroke, in the manner previously described. This same operation deenergizes the relay coil 201a, which consequently deenergizes the solenoid winding 244 of the solenoid 81 and removes the mechanical short stop by rotating the press control rod 40, thereby permitting the main plunger I! to return to its starting point without being halted at an intermediate point. The energization of the relay coil 2| ia also opens the circuit to the relay coil 26% by opening the normally closed switch blade 2W0, thereby opening the normally closed switi h blades 2092i and 2090. This action deenergizes the solenoid winding 246 .of the solehold 85 and causes the deenergized solenoid 85 to permit the valve 13 to shift to a position causing the plunger 34 to return the die to its normal position beneath the mold.

When the die has reached its normal or inner position, the normally open limit switch 228 closes, thereby energizing the relay coil 2| la by way of the now closed switch blade 2|llb and the normally closed limit switch 229. The energization of the relay coil 2| |a opens the normally closed switch blade 2| |e in the circuit of the relay coil 208a, thereby opening the normally open switch blades 208b-and 2080. This action deenergizes the winding 245 of the solenoid 84 and permits the shifting of the valve 12 into a position permitting the mold-raising plungers 38 to' move downward, lowering the mold 22 into engagement with the die 28. When the mold reaches its lowered position, it opens the normally closed limit switch 229, thereby deenergizing the relay coils 2|0a and 2| la, which again closes the normally closed switch blades 2|0d and 2||d in series with the relaycoil 202a. This action sets the control circuit in a condition for immediate starting when the operator again closes the forward switch 234 after the main plunger I! has returned to its retracted positionand has closed the limit switch 221.

To operate the press for making small blocks or small molded pieces, the single molding plunger l9 and mold 22 are removed and replaced by the multiple molding plungers I00 and multiple mold I01, together with the charger I08 and its operating plunger Ill and cylinder H0. The press arrangement shown in Figures 1 and 2 is thereby changed to the arrangement shown in Figures 3 and 4. The block size selector switch 232 is shifted from the "large block position to the small block" position opening upon 232a and closing upon 232D. The other selector switches 230 and 23i| remain in the same positions, namely, in the on and hand positions, respectively. The operator now depresses the forward pushbutton switch 234, thereby energizing the coil 203a of the relay 203 through the contacts of the now closed limit switch 221 and the normally closed switch blades 2||ld and 2|'|d of the relays 2| 0 and 2, respectively. The closed positions of these switch blades indicate that the die is 8 in and that the mold is down, respectively. The

energization of the relay coil 203a closes its normally open switch blade 203e, thereby creating a holding circuit around the forward push-button 234 so that the circuit remains energized after the push-button 234 is released.

With the charger I08 in its out position (Figure 4) the i normally open limit switch 222 is closed, As soon as the relay 203 has been energized and its normally open switch blade 203e consequently closed in series with the limit switch 222, the-relay coil 204a is energized therefrom by way of the normally closed switch blade 2052. This action closes the normally open switch blades 2041) and 204d, thereby energizing the solenoid winding 242 of the solenoid 0-6. The latter; thus energized, shifts the valve 14, thereby supplying pressure fluid to the cylinders I'll to cause the plungers III to move the charger I03 inward. The energization of the relay 204 likewise closes its normally open switch blade'204c, thereby setting up a temporary holding circuit for the .relay coil 204a around the limit switch 222, causing the @0011 20411 to remain-energized after the opening ofthis limit switch 222.

' Whenthe charger I08 has traveled its full stroke inward, itengages the normally open limit switch 224, closing it and thereby energizing the relay coil 205a. The energization closes the normally open switch blade 205b, thereby setting up a holding circuit around the limit switch 224 so that the relay coil 205a remains energized after -mally open switch blades 204D and 204d to open and deenergize the solenoid winding 242 of the solenoid 86. This action permits the valve 14 to shift, causing the flow of fluid to the cylinders H0 to be reversed and thereby causing the plungers ill to reverse the charger Hi8 and move it back to its starting position.

When the charger 108 returns to its starting position it again engages and closes the normally open limit switch 222, but the relay coil 204a now remains deenergized since the now energized relay coil 205a holds open its normally closed switch blade 205a in series therewith. The closing of the limit switch 222, however, energizes the relay coil 206a through the normally open but now closed switch blade 205a, and through the normally closed switch blade 204e, The closing of relay 206 closes its normally open switch blades 2061) and 206d, thereby energizing the solenoid winding 243 of the solenoid 49. This action shifts the pump control of the main pump 'E-l to its forward position, thereby supplying pressure fluid through the line l 2l to the main cylinder I5, and causing the main plunger ll to start on its downward or molding stroke. V,

As soon as the main plunger ll starts downward, it releases the limit switch -22| and permits its normally open contacts to open, thereby deenergizing the relay coil 203a. This deenergization now opens the normally open switch blade 203e in series with the relay coil 205a, thereby deenergizing the latter. The opening of the normally open switch blade 2030 also deenerg-izes the relay coil 204a in series therewith, thereby opening the normally open switch bllades '204b and 204d and deenergizing the solenoid winding 242 of the solenoid 86. This actiondeenergizes the charger-operating circuit controlled by the solenoid 36 and the valve 14 controlled thereby.

ance oi the cycle proceeds in the same manner and according tothe same energizations and deenergizations as previously described in connection with the making of largeblocks.

For completely automatic or full automatic operation, whereby the press continues to operate an indefinite number of cycles to produce an indefinite number of molded blocks without requiring the attention of the operator. the hand automatic selector switch 2-3l is set to its automatic position, thereby opening-it upon 231a and closing-it upon Nib. The other selector switches are set in the manner previously described, depending upon whether large blocks or small blocks are to be made.

When the forward push-button switch 234 is now depressed by the operator, the cycle of operations is started in the manner previously described in connection with the semi-automatic or hand operation. In addition to the energizations and deenergizations described in that connection, the operation of the forward push-button 234 now also energizes the relay coil 20la. This action. closes the normally open switch blade 20id, thereby setting up. a holding circuit around the forward push-button 234 and hand automatic selector switch 23L This circuit remains in its holding position until the press is completely halted by the operator by shifting the off-on selector switch 230 or by depressing the reverse switch 23-5. The cycle of operations and the consequent energizations and deenergizations repeat themselves in the manner previously described in connection with the hand or semi-automatic operation, except that the continuously closed switch blade 20I'd continuously maintains the holding or bridging circuit around the forward push-button 234 instead of maintaining it merely temporarily, as is the case with the holding circuits operated by the closing of the normally open switch blades 202a and 2030 between the bridging lines 20l and 202. blades 2020 and 2030 in hand operation are opened at the end of each operating cycle by the deenergization of their relay coils 20212 or 203a by reason of the subsequent energizations of the relay coils 210a and 2lia and the consequent opening of their normally closed switch blades 2I0d and 2| Id in series with the relay coils 202a or 203a, according to the setting of the block size selector switch 232.

As a consequence, at the end of the operating cycle when the positions of the switch blade of the relay 206 indicate that the die is in its inward position, and the normally closed switch blades of relay 20! indicate that the mold is in its downward position, and the normally open limit switch 22i is closed, indicating that the main plunger H is in its upper position, the next work operating cycle will repeat itself automatically. This occurs through the normally open switch blades 20Id and 20 Ie, which remain closed continuously after the forward push-button 234 is once operated. The remainder of the operating circuit occurs as previously described under hand operation;

The normally open switch engageable by said ram means and operatively said electrically operative short-stop-moving' as come within the scope of the claims and the invention.

Having thus fully described our invention, what we claim as new and desire to secure by Letters Patent, is:

1. In an electrical control system for a molding press having hydraulic ram means and a hollow mold with a movable closure, said ram means having connected thereto a pump with a fluid flow-controller movable into forward and return positions for selectively controlling delivery of fluid to respectively advance and retract said ram means, and movable into a neutral position to halt said ram means when said ram means reaches a predetermined position on its return stroke, the combination of a movable short stop connected to said pump flow-controller, electrically operative means for moving said short stop into operative position for actuation by said rain means to shift said flow-controller to its neutral position and halt said ram means at an intermediate point on its return stroke, and means-ineluding an electrical control circuit for controlling the shifting of said flow-controller to its forward and return positions, said control circuit including electrically operative means responsive to the completion of a forward molding stroke of said ram means for shifting said flow-controller to its return position to retract said ram means, electrically operative means for concomitantly moving said mold closure to its mold-opening position, electrically operative means responsive to the opening of said mold by said closure for shifting said flow-controller to its forward position to advance said ram means upon its forward ejection stroke, and electrically operative means responsive to the completion of said ejection stroke for shifting said flow-controller to its return position to retract said ram means.

2. In an electrical control system for a molding press having hydraulic ram means and a hollow mold with a movable closure, said ram means having connected thereto a pump with a fluid flow-controller movable into forward and return positions for selectively controlling delivery of fluid to respectively advance and retract said ram means, and movable into a neutral position to halt said ram means when said ram means reaches a predetermined position on its return stroke, the combination of a movable short stop engageable by said ram means and operatively connected to said pump flow-controller, electrically operative means for moving said short stop into operative position for actuation by said ram means to shift said flow-controller to its neutral position and halt said ram'means at an intermediate point on its return stroke, and means including an electrical control circuit for con-' trolling the shifting of said flow-controller to its forward and return positions, said control circuit including electrically operative means responsive to the completion of a forward molding stroke of said ram means for shifting said flowcontroller to its return position to retract said ram means, electrically operative means for concomitantly moving said mold closure to its moldopening position, electrically operative means responsive to the opening of said mold 'by said closure for shifting said flow-controller to its forward position to advance said ram means upon its forward ejection stroke, and electrically operative means responsive to the completion of said election stroke for shifting said flow-controller to its return position to retract said ram means,

means being responsive to the travel of said ram means upon its forward stroke for placing said short stop in its operative position.

- 3. In an electrical control system for a molding press having hydraulic ram means and a hollowmold with a movable closure, said ram means having connected thereto a pump with a fluid flow-controller movable into forward and return positions for selectively controlling delivery of fluid to respectively advance and retract said ram means, and movable into a neutral position to halt said ram means when said ram means reaches a predetermined position on its return stroke, the combination of a movable short stop engageable by said ram means and operativelyconnected to said pump flow-controller, electrically operative means for moving said short stop into operative position for actuation by said ram means to shift said flow-controller to its neutral position and halt said ram means at an intermediate point on its return stroke, and means including an electrical control circuit for controlling the shifting of said flowcontroller to its forward and return positions, said control circuit including electrically operative means responsive to the completion of a forward molding stroke of said ram means for shiftingv said flow-controller to its return position to retract said ram means, electrically operative means for concomitantly moving said mold closure to its mold-opening position, electrically operative means responsive to the openmg of said mold by said closure for shifting said flow-controller to its forward position to advance said ram means upon its forward ejection stroke, electrically operative means responsive to the completion of said ejection stroke for shifting said flow-controller to its return position to retract said ram means, said electrically operative short-stop-moving means being responsive to the travel of said ram means upon its forward stroke for placing said short stop in its operative position, and electrically operative means responsive to the travel of said ram means to a predetermined position on its return stroke for shifting said flow-controller to its forward position whereby to automatically repeat an indeterminate number of operating cycles of said press system.

4. In an electrical control system for a molding press having hydraulic ram means and a hollow mold with a movable closure, said ram means having connected thereto a pumpwith a fluid flow-controller movable into forward and return positions for selectively controlling delivery of fluidto respectively advance and retract said ram means, and movable into a neutral posltion'to'halt said ram means when said ram means reaches a predetermined position on its return stroke, the combination of a movable short stop engageable by said ram means and operatively connected to said pump flow-controller, electrically operative means for moving said short stop into operative position for actuation of said ram means to shift said flow-controller to its neutral position and halt said ram means at an intermediate point on its return stroke, and means including an electrical control circuit for controlling the shifting of said flow-controller to its forward and return positions, said control circuit including electrically operative means responsive to the completion of a forward molding stroke of said ram means for shifting said flow-controller to its returnposition to retract said ram means, electrically operative means for concomitantly moving said mold closure to its mold-opening position, electrically operative means responsive to the opening of said mold by said closure for shifting said flow-controller to its forward position to advance said ram means upon its forward ejection stroke, electrically opwhereby to automatically repeat an indeter-" minate number of operating cycles of said press system.

5. In an electrical control system for a molding press having hydraulic ram means and a hollow mold with a movable closure, said ram means having connected thereto a pump with a fluid flow-controller movable into forward and return positions for selectively controlling delivery of fluid to respectively advance and retract said ram means, and movable into a neutral position to halt said ram means when said ram means reaches a predetermined position on its return stroke, the combination of a movable short stop engagable by said ram means and operatively connected to said pumpflow-controller, electrically operative means for moving said short stop into operative position for engagement by said ram means to shift said flow-controller to its neutral position and halt said ram means at an intermediate point on its return stroke, and means including an electrical control circuit for controlling the shifting of said flow-controller to its forward and return positions, said control circuit including electrically operative means responsive to the completion of a forward molding stroke of said ram means for shifting said flow-controller to its return position to retract said ram means, electrically operative means for concomitantly moving said mold closure to its mold-opening position, electrically operative means responsive to the openin: of said mold by said closure for shifting said flow-controller to its forward position to advance said ram means upon its forward ejection stroke, electrically operative means responsive to the completion of said ejection stroke for shifting said flow-controller to its return position to retract said ram means, said electrically operative short-stop-moving means being responsive to the travel of said ram means upon its forward stroke for placing said short stop in its operative position, and electrically operative means responsive to the travel of said ram means to a predetermined position on its return stroke for shifting said flow-controller to it's forward position whereby to automatically repeat an indeterminate number of operating cycles of said press system.

' WALTER ERNST.

LESLIE S. HUBBERT.