US1342231A

US1342231A - Grinding apparatus for the manufacture of wood-pulp

Info

Publication number: US1342231A
Application number: US369323A
Authority: US
Inventors: Schaanning Peder Christian
Original assignee: Individual
Current assignee: Individual
Priority date: 1920-03-27
Filing date: 1920-03-27
Publication date: 1920-06-01
Anticipated expiration: 1937-06-01
Also published as: DE379718C

Description

P. C. SCHAANNING. GRINDING APPARATUS FOR THE MANUFACTURE OF WOOD PULP.

. APPLICATION FILED MAR- 27, 1920. 1,342,231.

Patented June 1, 1920.

4 SHEETSSHEET 1.

P. c. SCHAANNING.

GRINDING APPARATUS FOR THE-MANUFACTURE 0F WOOD PULP. APPLICATION FILED MAR. 27, 1920.

1,342,28 1 Patented J ne 1, 1920.

4 SHEETS-SHEET'2. m I I I I. III I P. C. SCHAANNING GRINDING APPARATUS FOR THE MANUFACTURE OF WOOD PULP.

APPLICATION FILED MAR. 27. 1920.

Patented June 1,1920.

4 SHEETSSHEET 3- Q m ms w Z h E 1 A W 3!. 7 \ll m a a & W 6

P. c. SCHAANNING. V GRINDING APPARATUS FOR THE MANUFACTURE OF WOOD PULP.

APPLICATION FILED MAR. Z7, 1920. 1,342,231.

Patented June 1, 1920.

. 4 SHEETS-SHEET 4- owes sTAr S;

airest lorries.

PEDER CHRISTIAN SCI-IAANNIN'G, OF VESTRE 'HOLMEN, NEAR CHRISTIANIA,

ORWAY.

GRINDING APPARATUS Fon THE MANUFACTURE OF wooIi-PULr.

Specification of Letters Patent. Patented J lie 1, 1920. I

Application filed March 27, 1920. Serial No. 369,323.

To all whom it may concern:

Be it known that I, Pnnnn CHRISTIAN SCHAANNING, a subject of the King of Norway, residing at Vestre Holmen, near Christiania, Norway, have invented certain new and useful Improvements in a Grinding A paratus for the Manufacture of Wood ulp; and I do hereby declarethe following to be a full, clear, and exact de-' soription of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, andrto letters or figures of reference marked thereon,which form a part of this specification.

In ordinary grinding apparatus for the 'manufacture of wood' pulp the wooden blocks are forced against the grinding stone by means of forwardly'pressing members acting either upon the end faces ofthe blocks or upon the rear surface of the whole block column. This is true as regards magazine grinding apparatus and also as regards grinding apparatus provided with intermittently operating, separate pressing boxes. An absolutely safely operating and at the same time simple and cheap construction, is unknown and therefore the magazine grinding apparatus have not given satisfactory results. Consequently, the factories have continued to use the much more simple and, safe highly developed pressing box devices in which the grinding within each separate box takes place intermittently, because the box must be placed out of action and be refilled each time a box filling has been ground down. A similar intermittent mode of operation has been present also in known made constructions of magazine grinding apparatus, which during longer or shorter intervals had to be placed out of operation before each beginning of the next grinding period.

It is obvious, however, that the interiu tions of the grinding operations which arise. either during a refilling of a pressing box or when disturbances of some sort are to be removed, are connected with losses of manufacture, and in addition thereto the driviiig plant will be unequally or obliquely loaded, the pressing pistons operate with varying pressures, a non-uniform product is obtained and the several machine parts are strongly stressed and worn. In grindng apparatus having a plurality of pressing boxes arranged around one and the same grinding stone attempts have been made to'obtain a constant total ressure of wood blocks against the stone.

ratus have not given satisfactory results and moreover they have caused considerable complications of the whole driving machinery giving rise to new sources of interruptions of operations.

' According to the'present invention all the, said drawbacks are removed and a simply constructed apparatus is obtained infwhich a practically constant pressure of the wood blocks against the stone is presentat' a'ny time at each pressing place so that the grinding operationcan be continuous. f

In grinding apparatus where, in wellknown'manner,'blocks forminga column are pressed forwardly against the stone by means of forwardly moved members grip,

ping the end faces of the blocks, I arrange the magazine or a supply channel for the blocks in such a manner that the blocks fall in a directionmore orless across to the forward pressing direction down into'the space behind the blocks gripped by the said grippingmembers as the latter travel forward toward the stone, whereby. the said space.

will always remain filled with blocks that form the prolongation of the block column.-

of the blocks from the moment at which the forwardly moved gripping members release uch appa their grip upon the end faces of the'blocks and until the said members have moved back. and obtained a new grip at the rear part of the block column prolongation. This alternateoperation of the two forward pressing members operating in different manner and one; of which duringits work allows new blocks to fall in front of the inopera tive second forward-pressing members permits the grinding operation to take place without any interruption and with always the same grinding pressure.-

A'second main feature, which may advan tageously supplement that mentioned above,

'consists in pressing one of the forward column.

pressing device's, during its forward-forcing action upon the block column, against an abutment by means of an engaging piece. Through this latter the second forwardpressing device, during its period of operation, transmits its pressure to the block 7 A complete automatic. operation will be obtained in this case if the engaging piece pressing against the abutment is subjected ma constant pressure acting in i the forward-pressing direction and being cylinders corresp'ondin to ig. 2. t

Fig. 4: shows a modi ed construction, and

somewhat smallert'han the forward-press- 1ng fo rce of the first forward-presslng dev1ce,the' said constant pressure automatr placesthe second forward-pressing device operation and thus, without any interruption, takes over the forwarddriving, of the block column at the samemoment .an dto the same degree as the operation of the-first device ceases temporarily. f

"AIconstruct ienal form of the invention is illustrated in the accompanying drawing in which Figure 1 shows a-portion of thegrinding apparatus in elevation and vertical section. ig. 2 is a corresponding plan viewshown in section on the line I-I of Fig. 1.

Fig. 3 is an end view of the hydraulic preferably in a horizontal direction from V opposite sides, one pressing devicebeing arrangedat either side. The drawing shows only one of the said pressing devices, 1

As it will be seen, the blocks will fall 'downupon the bottom 3 of the magazine 4:, consequently into the pressing path, accordlng a's'a space is opened for such fallingi down. In. order'that'this may take place the forward-pressing. members 5 grip the end faces of the blocks lying in the pressing path. This feature is formerly known 1 per 86.

' However, if the blocks are pressed forward horizontally or in an inclined direction and 1f the "magaz ne. s simultaneously dise'm'bogu ng into the pressing path at an angle tothe pressing direction, the blocks will be able to sink by their own weight down'into the pressing path behind the blocks which are gripped by the members 5 as the said members move toward: the stone; The press path therefore will always be filled. In accordance with the present invention, I combine with the end or" lateral gripping members 5 a pressing plate 6 which is likewise formerly known per 86 and which can be moved forwardwith nearly the same pressure as the member'e, so that pressing plate 6 reduces the pressing force during the short period in which the gripping members 5 are withdrawn from the blocks, travel back, to take a new grip at the rear end of the pressing path and commence their action anew. By these means the grinding apparatus operates continuously to exert a constant pressure upon the blocks and'consequently maintains a constant load on the stone. But of course, this can only be, obtained if the pressing plate 6 is brought into full action at the same momentand to the same degree as the pressure from the gripping members 5.. ceases 71. 6., inversely to the reduction of 7 pressure by the latter during their releasing operation. This may be obtained by letting the mechanisms which produce the pressure upon the parts 5 and 6 act alternately in dependence upon each other, so that the total pressure of both parts is at any time (3011-, i

sta-nt or nearly so.

. whereas the cylinders 9 are provided with guiding parts 14 trai 'elinglin axial guides 15 at the sides of the cylinder 11 (see Fig. 3).

An accumulator or other source 16 for water mder pressure is through a pipe 17 in constant connection with the inner space of cylinder 11, so that the piston 10 is always subjected to the same forward-pressure.

The source 16 is further connected with the inlet 18 of a reversible cook 19, from which one pipe 20 communicates with an outlet and pipes 21 and 22'co1 nmunicate with top and bottom respectively .of the cylinders 9, forced forward or back according as the cojckarm loaded with ,a weight 23 is in'the position a" or in the position 7 respectively.

The pressing plate 6 is in fixed connection with both cylinders by means of ribs or so that the pistons 8 canbe walls 24, so that the

parts

9, 24, 6, 2 1, 9 form one integral system.

The total "area of the two pistons 8 is slightly larger than the area of the piston 10, so that each of the pistons 8, when water under pressure is supplied through the pipes 21 to the top of the cylinders 9, are pressed forward in the direction of the arrows 25, with for instance 550 kg. (consequently in total 1100 kg), whereas the piston 10 is pressed constantly forward with 1000 kg. Thus it will be seen that the two cylinders 9 together will react backwardly with a force of 1100 kg. and this force is, through the medium of the pressing plate 6 and the engaging piece 12, compensated by 1000 kg. on the piston 10 plus 100 kg. pressure on the cylinder 11 at the contacting surface between the foremost end of this cylinder 11 and the piece 12.

Consequently, the result will be that the cylinders 9 and the pressing plate 6 remain stationary and that the pressure at the said contacting surface will be only 100- kg. Simultaneously the pistons 8 are forced forward, so that the gripping members force the wooden blocks 2 toward the stone with a total pressure of 1100 kg. The pressing plate.6, however, is inoperative.

When the gripping members 5 have arrived at the end of their forward travel towardthe stone, the supply of water under pressure through the pipe 21 is interrupted by reversing the cook 19 into position y, so that the pressure upon the pistons 8 and the gripping members 5 rapidly ceases, and is then reversed. The pressing plates 6 will then automatically enter into operation. As soon as the total forward pressure upon the pistons 8 has been reduced to 1000 kg. it will just balance the forward pressure, upon piston 10. Upon further reduction of the forward pressure of the pistons 8 the pressure of the plate 6 against the blocks 2 will increase to exactly the same degree, so that the total pressure received by the blocks located nearest to the stone from the grip ping members 5 and from-the plate 6 in combination will be constantly 1000 kg. \Vhen the forward pressure upon the pistons 8 has ceased completely, the plate 6 alone presses forward the block column with 1000 kg. and it will continue this operation as long as the gripping members 5 are inoperative during their travel back to the rear end oftheir stroke in order to start again for a new pressing period. When the gripping members 5 again come into operation, they gradually unload the pressing plate until they have again taken over their part completely. The pressing plate, which during this shifting of the position of the grip-v ping members 5 has traveled a short dis tance (about 10 cm.) forward,.is rapidly forced back again until the piece 12 presses tively entering into operation, sothat the against the cylinder. 11' with 100 kg.

In the example described above, the stone 1 is always subjected to practically the same pressure from each pressing device, .viz alternately to 1100 and 1000 kg. Of course it is not necessary that the difference be as high as 100 kg. It might be suflicient to have a difference of 50 or even 25kg, but it will be most practical that the contacting pressure between the

parts

12 and 11 be not too low because the piston 10 should be safely brought to return, after its operating period to its engaging position and because the plate 6 should safely not advance simultaneously with the gripping members 5. The latter would besides be obtained by arranging a releasable stopping device (not shown) for the pressing plate 6. In such case I would obtain a constant pressure of 1100 kg. at any time. A difference of 100 a force 1 of 'kg., however, is without any practical importance, and therefore the arrangement shown in the drawing will be preferable.

It is obvious that just the same operation will be obtained, if the piston '10 (or the plate 6) is under influence of a constant weight or spring pressure of 1000kg.-or if the pistons 8 are under a removable weight or spring pressure of 550 kg.

Further it will be seen that the two cvlinders 9 may be combined into one cylinder, which maybe of annular cross. section or may be arranged behind the cylinder 11. This arrangement, however, would be less suitable.

Finally the connections 24L between the. plate 6 and the cylinders 9 may be removed, but in this case I have to use other arrangements in order to bring about the desired condition of dependence between the pressure upon the pistons 8 and the pressure upon the piston 10. An example of such construction is shown in Fig. 4. The top of the cylinders 9is as before in communication with one side of the cook 19 through a pipe 21, and a pipe 37 conducts from the same pipe 21 to the bottom of the cylinder 11. Further the bottom ofcylinders 9 and the top of cylinder 11 are in communication with the other side of the cook 19 through the

pipes

22 and 17 respectively. .In this manner the pistons 8 will be pressed forward, when the piston-10 is pressed back, and vice versa, dependent upon the position of the cock 19. When the cock is reversed, one of the forward pressing devices 5 or 6 will be set out of operation about simultaneously with the other device 6 or 5 respecblock column atall events only for a short interval (certainly not; more than for 1 second) will be'without any pressure against the stone. By reversing the cock rapidly this interval. can be considerably reduced.

flAlthough it will not be possible in' this construction to prevent a shock in the load upon the stone '1 each time the cock 19 is reversed, the constructlon forms neverthelessa rather nearly perfect solution-of the problem automatic continuous grinding and one which constltutes an essential progress as compared with constructions formerly known, and this construction would in many'cases be'preferred to that shown in Fig. 2 on account of its simple arrangement and cheaper manufacture.

In order that -the gripping members shouldbe safely forced into the end faces of'the blocks 2 and be withdrawn therefrom, the members '5 are mounted on a parallel motion device comprisingtwoparallel links 26, 27 upon a cross head 28; The latter is attached tothe outer end of a piston rod 29, thepiston 30-ofwhich travels in a cylinder 31 withinthefront end of the piston rod 7.

This cylinder isfurther connected by a link 32 to a side arm '33 of the link 27. The two last-named

parts

33 and 27 thus form a bell crank lever. V V Theffront and rear end of-the cylinder 31 i is throughpipes3i and respectively con- 7 cross "head 28.

nected withthe pipes 21 and- 22' respectively, consequently with therear and front ends respectively of the cylinders 9. As soon as the'water under pressure is supplied to the passed'to the rear end of cylinder 31 and thereby forces forward the piston 30 with The knives 5 are thereby withdrawn from'the blocks 2.

In order to prevent the difficulty of maintaining'the connectionto the top and bottom of cylinder 31"through the pipes 34: and 35 notwithstanding the motion of'this cylin- 'der in relation tocylinder 9, the construction'ma'y advantageously be 'madeas shown in Fig. 75, in which the piston rod 7'is made like a'pipe and incloses'the similarly pipe-shaped piston rod 29, so that a suitable intermediate annular space is left between t'he'mq The-piston rod 29 is further extended" rearwardly and projects centrally and easily slidesinto'the bored piston 10. Moreover theipistonfrod7 is provided directly in front of thepiston 10 with a lateral hole 39 an d in front, of piston 580 the piston rod '29 is provided with a similar hole 38,

so that the rear'en d of cylinder 9 is'constahtly. in vcommun icati'on with the front end of cylinder 3l through the piston 'rod '29 and the hole 38, and in similar'mannerthe front end of cylinder 9 is in constant communication with -the rear-end of cylinder 31 (the innerspace of piston rod 7) through the hole 39 notwithstanding the shifting posi tions of the piston rods. 7

In order to obtain a safe withdrawal of the knives 5 from the blocks without influence upon their position and" in order to simultaneously guide the block column and close the magazine at both sides of the pressing path, the side walls of the magaaine is here formed of parallel rods 36 similar :to a grate, and between these rods the gripping members 5 constructed like knifeshaped teeth, project'intothe pressing compartment. Claims: 1. In a grinding apparatus for'the-manufacture of wood pulp, the combination'of a grinding stone,a compaitmentfor receiving wooden blocks tobe ground, saidblocks forming a column'to be pressed against the stone, a reciprocable forward-pressing device operating members gripping the faces of the blocks, and a supplying device or hopper'for effecting refilling of blocks into said compartment and arranged to'feed the;

blocks in a direction more or less across to theforimrdpressing direction into the space behind the blocks of the column gripped by the gripping members and according to the movement of the latter toward the stone,

whereby the said space will remain constantly filled with blocks forming an extension of the 'blockcolumn.

2. In a grinding'apparatus for the 'manu-' facture of wood pulp the combination of a grinding stone, a compartment for receiving wooden blocks to be ground, said blocks forming a column'to be pressed against the stone, a forward'pressing device, gripping members operating upon end faces of the blocks, a normally stationary rear wall of the said-compartment, means for moving said wall or a part thereof, said means cooperating with the means for moving the gripping members'to. start said wall or part to take over the forward-pressing ofthe blocks from the moment the gripping members are withdrawn from the end faces of the blocks and until said members have moved back and taken a new grip at the rear part of the bloc'k'column extension, and a supplying device or hopper for supplying blocks-into said compartment and arranged to permit the blocks to feed in a direction more or less across to the forward-pressing direction behind the blocks of the column gripped by the gripping member and in remain constantly filled with blocks forming an extension of the gripped block 7 column. V

accordance withthe movement toward the stone, whereby-the said compartment will 3. In a grinding apparatus for the manufacture of wood pulp, the comblnatlon of a grinding stone, a compartment for receiving wooden blocks to be round said blocks forming a column to be pressed against the stone, a forward-pressing device, gripping members operating uponend faces of the blocks, a second forward-pressing device acting upon the outer end of the whole wooden block column, and means for placing the two forward-pressing devices into operation alternately.

l. In a grinding apparatus for the manufacture of wood pulp, the combination of a grinding stone, a compartment for receiving wooden blocks to be ground, said blocks forming a column to be pressed against the stone, a forward-pressing device, gripping members operating upon end faces of the blocks, a second forward-pressing device acting upon the outer endof the whole wooden block column, hydraulic cylinders, means for moving the two forward-pressing devices, communications between the top and bottom of said cylinders, and reversible means for controlling the supply of fluid or liquid un der pressure to the cylinders to force one forward-pressing device forwardly when forcing the other device backward, and vice versa.

5. In a grinding apparatus for the manufacture of wood pulp, the combination of a grinding stone, a compartment or space for receiving wooden blocks to be ground, said blocks forming a column to be pressed against the stone, a forward-pressing device, gripping members on said forward-pressing device operating upon end faces of the blocks, a second forward-pressing device acting upon the outer end of the whole wooden block column, hydraulic cylinders, means for moving the said .two forward-pressing devices, communications between top and bottom of said cylinders, and a reversible cock or valve for controlling the supply of V fluid or liquid under pressure to the cylinstone, an abutment, and an engaging piece by means of which one of the said devices re acts against said abutment during the action of one of said devices upon the blocks, and through which piece the second device, during its operating period, transmits its pressure to the block column. v

7. In a grinding apparatus for the manufacture of-wood pulp, the combination of a grinding stone, a compartment or space for receiving wooden blocks to be ground, said blocks forming a column to be pressed against the stone, a forward-pressing device, operating members gripping upon end faces of the blocks, a second forward-pressing device, acting alternately with the gripping members for pressing the blocks against the stone, an abutment, an engaging piece by means of which one of the said devices reacts against said abutment during the action of'said device upon the blocks,and through which piece the second device during its operating period transmits its pressure to the block column, and a supplying device or' facture of wood pulp, the combination of a.

grinding stone, a compartment or space for recelving wooden blocks tobe ground, said blocks forming a column to 'be pressedagainst the stone, a forward-pressing device,

gripping members operating upon end faces.

of the blocks, a second forward-pressing'device acting alternately with the gripping members for pressing the blocks against the stone, said second device consisting of a normally stationary rear wall of the said space, means for moving said wall or a part thereof and cooperating means for moving the gripping members to start said wall or part thereof and take over the forwardpressing of the blocks from the moment the gripping members are withdrawn from the end faces of the blocks and until said members have moved. back and taken anew grip at the rear part of the block columnextension,

an abutment, an engaging piece by means of which one of the said devices react agalnst said abutment during the action of said device upon the blocks, and through which piece the second device, during its operating period, transmits its pressure to the block column and a supplying device or hopper for feeding blocks into said space and arranged to feed the blocks in a direction more or less across to the forward-pressing direction into the space behind the blocks of the column gripped by the gripping members as the latter move forward toward the stone, whereby the said space will remain constantly filled -with blocks forming an extension of the block column.

9. In a grinding apparatus for the manu facture of wood pulp, the combination of a grinding stone, a compartment or space for receiving wooden blocks to'be ground, said V temporarily ceases.

blocks forming a column to be pressed vsureto the blockcoluinn, and means for subjecting'the engagingf piece andthe first forvvard pressin-g device," to pressure in the fbr'i'varcl-pressing direction, said engaging,

piece and said second device being under a constant forward-pressure of a somewhat less amount than the. total forward-pressure upon the first device and places the second device'into operation automatically and simultaneouslytake's' over the forward-press ing of theblocli column andtothe same extent hentheoperation' ofthe first device 10. In a grindingapparatus-for the manufact'iire of Wood pulp,the combination of a grinding stone, a compartment or space for receiving, Wooden blocks to bej ground, .-Lll\ .l..

said blocks forming a column to be pressed against the stone, grippingmembers, a for- Ward-pressing device operating said grip pingfmembers upon end faces of the blocks, a seco'rid" forvvard pres'smg device actmgf alrev-satay with the gripping members for pressing, the blocks against the stone, an abutment, an engaging piece bymeans of 1. i H 3 'l n I which one of the s'aicl clev-icesv reacts against 4 I 1 5 said abutment during. the. action of said de; vice upon the hlocks,; and through Which piece the second' device, diiring its operatin'g period; transmits its pressure to. the blocltcol'umn, and means for subjecting the engagingipiece and the first: forward-press ingr. device to pressures in the forward'ihl'GCtlOIl, 'said' engagingpiece and sa id second device heing under a constant forward-pressure of a somewhat less amount than the total forivarthpressure upon the first device,

whereby this constant pressure places the secoi'id device into operation automatically and v takes over the. forvvard pressing. of the blockcoliunn at. the same momentand to the same extent as'tlie operationeof the first device temporarily ceases, and a supplying device or hopper for efiect'ing refilling of:

blocks into said space and arranged. to feed: the'blochs inadirection more or less across to the. fOIAYELPClflQIBSSIng direction into the space behind. the blocks of the column gripped by the gripping. members as the i latter. move forward: toward the stone,\vhereby the. said; space will remain constantly filled with blocks forming. an extension of the blockzcolu nn 1 In' argr'i dingapparatus for'themane.

ufacture of Wood pulp, the combination of a grinding. stone,--,a compartment; or spacefor receivin Wooden blocks to be ground, I

tiona'ry rear wall of the said space, means for moving said Wall'or a part thereof, and cooperating With means for moving, the grippingmemberto start said iv'all'oii part thereof to takeover the forward pressingv oi the blocks from the moment the gripping members are Withdrawn from the end faces of the blocks and until'saidmembers have.

moved" back and taken a new, grip at the 1 rear part ofthe block" column. extension, .an abutment, an engaging, piece by means of which one of the saididevices. reactsaga'inst saida'but'mentduringthe action ofsaid at vice upon the blocks, and through which piece't'he second device,.duriiig,its operating period, transmits its pressure to'the liloek column, and means for sub ecting. the engaging, piece and the first forward-pressing,

device'topressure in the forward direction, said engagingpiece and said second device being under a constant forward-pressure of a somewhat less amount than thetotal forivard pressure uponthe first device, WllBIC hy-this constant pressure places the second device into operation automatically and takes over the forward pressingof the blockcolumn'atithe same moment and'to the same extent as the operation oftheifirstdevice temporarily ceases, and a su plying device or hopper for effecting. refil ing. of blocks into said space and arranged to feed the hloclr'sin a directionzmore. or less across to the forward-pressing direction into the space behind the blocks of the column gripped by the gripping. members and as the latter move forward toward the stone, whereby the said space Will remain constantly fillBClWlth blocks forming an extension of the'block column.

12. In a grinding apparatus for the manufacture of .wood. pulp, .the. combination of a grinding. stoiie,.a.c0mpartment or space for iteceivingivooclen blocks to be ground, said blocks forming: a column. to be pressed ping members upon end faces of the. block's, hydraulically operated pressing. forward: the gripping.- members,

i (is it a against the stone,.gripping members, a for--. Ward-pressing device operating. said. glJlIilit) mechanisms for a normally stationary. rearv walliof. tlle said space for. the purpose of exerting forwarch pressure upon. the rear end of the Whole block column,v hydraulic means. for moving said Wall or part forwardly; fixed abut ment said Wallv orfpart reacting against saidLfixedlabutment and constantly underv a:-

somewhat lower hydraulic prcssure'than the total forward-pressure acting upon the gripping members and which transmits its pressure inversely to the pressure of the gripping members as they become inoperative.

13. In a grinding apparatus for the manu facture of wood pulp, the combination of a grinding stone, at compartment or space for receiving wooden blocks to be ground, said blocks forming a column to be pressed against the stone, a fl rward pressing device, operating membersgripping upon end faces of the blocks, hydraulically operated mechanisms for pressing forward the gripping iembers, a normally stationary rear wall of the said space for exerting forward-pressure upon the rear end of the whole block column, hyd 'aulic means for moving said wall or part forwardly, an abutment, said wall or part reacting against said abutment and constantly under a somewhat lower hydraulic pressure than the total forwardpressure acting upon the gripping members and which transmits its pressure inversely to the pressure on the gripping members as they become inactive, and a supplying device or hopper for effecting refilling of blocks into said space and arranged to feed the blocks in a direction more or less across to the forward-pressing direction into the space behind the blocks of the column gripped by the gripping members as they move forward toward the stone, whereby the said space will remain constantly filled with blocks forming an extension of the block column.-

' let. In a grinding apparatus for the manufacture of wood pulp, the combination of a grinding stone, a compartment or space for receiving wooden blocks to be ground, said blocks forming a column to be pressed against the stone, a forward-pressing device, operating gripping members upon end faces of the blocks, hydraulic cylinders for transmitting forward-pressure to the gripping members. a normally stationary rear wall of the said space for the purpose of exerting forward-pressure upon the rear end of the whole block column, a hydraulic cylinder for transmitting forward-pressure to said wall, a supply conduit for liquid underpressure, a reversible connection between said conduit and the ends of thefirst-named cylinders, a constant hydraulic connection between said conduit and the cylinder acting upon the said wall, whereby the latter is started and presses the blocks inversely as the gripping members become inactive preparatory to taking a new grip at the rear part of the column extension, and a supplying device or hopper for feeding blocks into said space and arranged to feed the blocks in a direction more or less across to the forward-pressing direction into the space hehind the blocks of the column gripped by the gripping members, whereby the said space will remain constantlyfilled with an extension of the block blocks forming column.

15. In a grinding apparatus for the manufacture of wood pulp, the combination of a grinding stone, a compartment or space for receiving wooden blocks to be ground, said blocks forming a column to be pressed against the stone, a forward-pressing device, gripping members for engaging end faces of the blocks, a hydraulic cylinder, piston and piston rod, said gripping members mounted on, said piston rod, and hy draulic means carried by said piston rod and operating the gripping membersjust before or simultaneously tothe starting of the piston forward, and releasing said members upon a reversal of said piston.

16. In a grinding apparatus for the manufacture of wood pulp, the combination of a grinding stone, a compartment or space for receiving wooden blocks toibe ground, saidblocks forming a column to bepressed against the stone, a forward-pressing device, gripping members for engaging end faces of the blocks, a second forward-press. ing device acting upon the outer end of the whole wooden block column, hydraulic cylinders, pistons and piston rods for moving the said pressing devices, communications between the tops and bottoms of said cylinders, reversible means for controlling the supply of fluid or liquid under pressure to the cylinders to force one forward-pressing device forwardly when forcing the other backward and vice versa, hydraulic means carried by said pistonrods for moving the gripping members, and forcing them into the end faces of the wooden blocks just before or at the beginning of the forcing stroke of said piston, withdrawing them from the. blocks upon the reversal of the piston. 1

17. In a grindingapparatus for themanufacture of wood pulp, the combination of a grinding stone, a compartment or space for, receiving wooden blocks to be'ground, said blocks forming a column to be pressed against the stone, a forward-pressing device, gripping members, a second forwardpre ssing device acting upon the outer end of the whole block column, a hydraulic cylinder, piston and piston rod transmitting forward-pressure; to each gripplng member, the latter being mounted upon sald piston rod, means for placing the sand devices into operation alternately, hydraulic cylinders in mechanical connection with the said piston rods, pistons in the latter cylinders having piston rods, cross heads carried by said latter rods, links pivoted to the cross heads, the gripping members he ing pivoted to the free ends of said links,

lateral anms forming part of: the links, links: formingpivotal connection between said lat-- eral arms andzthe latter; piston rod, and come third forward-pressing device acting upon for receiving Wooden blocks to be ground,

said blocks forming'a columnzto-be pressed against the stone, a. pair of; forward press ing devices including a hydraulic cylinder, piston and piston rod, gripping members. operating upon end: faces of t-heblocks, a

the outer end of the Whole wooden block column, a' hydraulic cylinder,ipistonand? piston'rod, means-for placing; the said=two forward-pressing devices into operation alternately, hydraulic cylinders formedi with in said piston mds, pistons in said cylinders having hollow piston rods projecting slid ably into a bore 1 through the first mentioned pistons, said rods formingan annular chamber between them, said outer piston rod liavinga hole in front ofits'piston, and saidinner piston rod having a hole in front of its piston, a cross head carried by the. latter rod, one or more links pivoted to the cross head, a knife'eshaped gripping member pivoted't'o the free ends of said links, a lateral arm formingpart of one of saidlinks and a link pivotally connecting said lateral am and piston rod. l

19: In a grinding apparatus for the manufacture of W006i pulp, the combination of a grinding: stone, a compartment or space for receiving Wooden'blocks to be ground, saidblocks forming a column tobe pressed against the stone, a forward-pressing device, gripping members operating upon end faces of the blocks, said members-being'constituted by a number'of teeth, spaced parallel stationary grate-like bars forming the side Walls: for the-block column space or compartment and between which the said teeth project into said space, and a supplying device or hopper for feeding blocks into said space and arranged to feed blocks in a direction more or less acrossto the forwardpressing direction into the space behind the blocks of the column gripped by the gripping members asthe latter are moved forward" toward the stone," whereby the said space will remain constantly filled with inder, for said piston maintaining a constant fiuid, a slidable cylinder connected V to saidpiston, a piston therein having a* pistonrod, gripping devices carriedby. said rod, and means to; supply motive fluid to opposite sides of said latter piston.-

21. In a grinding apparatus for th manufacture of: wood pulp, a-compartment or space for receiving the blocks to be ground, a piston behind said'blocks, a-cylinder for said: piston maintaining constant fluid, a slidable cylinder connected to said piston, a pistontherein having: a piston rod,

gripping devices carried by said: I'Od,fa11d means: to: supply motive fluid t0? opposite side of; said latter piston, the-maximum total pressure of? which is greater than that on. i

the first mentioned piston; I

22; In a grinding apparatus for the manufacture of Wood pulp, acompartment or space for receiving. the blocks to be ground, having grid-like sides, gripping fingers, a parallel motion device for operating said fingers, fluid operated means for imparting a: feed movement to said fingers and device, and fluid operated means for operatingsaid'device. V v

23. In a grinding apparatus for the manufacture of Wood pulp, a compartment or space for receiving the blocks to be ground, gripping fingers, a hydraulic cylinder, having a piston and piston rod, a parallel: motion device mounted on said rod and carrying said. fingers, and

v hydraulic means for operating said device.

24; In a grinding apparatus for the Y manufacture of Wood pulp, a compartment or space for receiving blocks to be ground,-

reciprocable means acting on the end: faces of blocks to feed them forward; and separate reciprocal feed means acting behindthe block column. in alternationwith the aforesaid means.

In testimony that I claim the foregoing as my invention, I have signed my name in' presence of two subscribing witnesses.

PEDE-R CHRISTIAN SCHAANNING.

Witnesses: V

EDWARD J OHNSON, NATH. A. HnDENsoI-IoU. Q