the baler illustrated in fig1 - 3 has a pick - up device 1 which picks up leaf - type ( e . g . grass , hay ) or stalk - type ( e . g . wheat stalks , corn stalks ) vegetation from the ground . such devices are known per se and therefore do not require a detailed discussion or illustration . the vegetation picked up by the device 1 is engaged by the , e . g . rake - or comb - shaped element 2 ( also known per se ) and pushed into the precompacting chamber 3 . during this operation the tip 2a of element 2 travels in the broken - line path 2b . in the position shown in fig1 the expelling element 4 has expelled a previously precompacted body of vegetation ( not shown ) from the chamber 3 into the main compacting chamber 5 . it is located in its end position in which it blocks the opening which connects the chambers 3 and 5 with one another . at this time the ram 6 of chamber 5 is advanced in the chamber 5 by operation of its hydraulic cylinder - and - piston unit 7 , to further compress the precompacted body and to push it up against the previously admitted and compressed bodies , which are located in the rear portion 8 of chamber 5 and with which it is to form the final bale . it will be noted that the major drive components , the articulated shaft 33 , transmission 34 , flywheel 35 , hydraulic pumps 36 and others , are mounted in the portion 37 of chamber 5 , i . e . rearwardly of the ram 6 . the drive is transmitted via a mechanical connection to the devices 1 and 2 . the baler has a frame or chassis 9 which carries all the operating components and in turn is supported by the wheels 10 . a pivotable attachment tongue or pole 11 is connectable to a tractor or other vehicle ( not shown ) which moves the baler . as shown in fig2 vegetation v picked up by the arms of the device 1 which rotates about a horizontal axis , is fed into the inlet of a passage p in which the device 2 performs the motion indicated by the broken line . device 2 is driven for this purpose by the illustrated crank arrangement and advances the vegetation through passage p into the precompacting chamber 3 . due to the continuing infeed of further vegetation by the device 2 , the contents of chamber 3 become compressed against the hinged chamber wall 12 . the sensing device 13 senses the degree of such compression as a function of the pressure exerted by the contents upon the wall 12 and , when a preset level is reached , allows the wall 12 to pivot in direction outwardly of the chamber 3 ( arrow a ). an edge of the wall 12 is in engagement with a pivotable switching arm 14 having the illustrated inclined cam surface . thus , when wall 12 pivots in direction of the arrow a , its edge rides up on the cam surface and thereby pivots the arm 14 in the direction of the arrow b . the arm 14 is coupled with the drive 15 for the device 2 and also with a hydraulic switching valve 16 . when it pivots in the direction of arrow b the arm 14 disengages the clutch ( not shown ) of the drive 15 and thus temporarily stops further movement of the device 2 ( and consequently the further infeed of vegetation ). the same movement of arm 14 also switches the hydraulic valve to a position in which it permits the flow of hydraulic fluid to the hydraulic cylinder or cylinders 17 ( two shown ) which abruptly displace the expelling element 4 ( shown in fig2 as being of rake - shaped configuration ) towards the main chamber 5 , so that element 4 expels the precompacted contents of chamber 3 into the chamber 5 . since this expulsion relieves the pressure on wall 12 the same is returned to its starting position by the spring of sensing device 13 and , since in so doing the edge of door 12 moves off the inclined cam face of arm 14 , the arm also returns to its starting position . this causes the clutch of drive 15 to become re - engaged so that the device 2 resumes its movement . the expelling element 4 , however , remains in its expelling position ( fig1 ) until the ram 6 -- which is now activated -- has moved to its forward end position in which it expels the precompacted body ( just received from chamber 3 ) from the chamber 5 ( or rather the part 5 of the main chamber ) into the part 8 of the main chamber , whereupon the ram 6 remains in this forward end position to maintain pressure upon the contents of the chamber part 8 . when ram 6 reaches its forward end position the expelling member 4 is retracted to its starting position ( fig3 ). however , in the meantime the chamber 3 has become partly filled with vegetation by operation of the device 2 . the presence of this vegetation prevents a straight retraction of the element 4 . to avoid this problem the element 4 is tiltably mounted on a carrier 19 on which it is engaged by a spring 18 that biases it to its normal operating position . carrier 19 is guided in rails 20 , 21 located above and below the chamber 3 ; it is moved ( pulled , respectively pushed ) along these rails by arms 22 which are themselves guided for to - and - fro movement in rails 23 and are moved in these by operation of the cylinder - and - piston units 17 , so as to tilt the element 4 about carrier 19 against the action of spring 18 . fig3 shows the element 4 in its starting position and the cylinder - and - piston units 17 in their retracted position . the chamber 3 can now be filled with vegetation by the device 2 . when the vegetation in chamber 3 has been compacted to the desired degree the sensor 13 releases the wall 12 for the previously described movement which operates the clutch of drive 15 and the valve 16 as well as a counter 28 . element 4 expels the precompacted contents of chamber 3 into the part 5 of the main chamber and ram 6 advances to its forward end position , thereby expelling the precompacted contents just received from the chamber 3 into the part 8 of the main chamber . cylinder - and - piston units 17 effect the expelling movement of element 4 by moving the carrier 19 and the element 4 via the arms 22 along the rails 20 . rails 20 have spring - biased switches 24 incorporated in them ( fig1 and 3 ) and during the expelling movement the ends of carrier 19 which are guided in the rails 20 pass these switches 24 . this has the result that during the subsequent retraction of the element 4 the carrier 19 is prevented from entering into the rails 20 and is , instead , diverted into the rails 21 . due to the different path defined by the rails 21 ( see fig1 and 3 ) the element 4 is extracted from the chamber 3 during the return movement and re - enters the chamber 3 only at the end of the return movement , i . e . where the rails 21 merge with the rails 20 . thus , element 4 avoids the newly - introduced vegetation in chamber 3 . in addition , element 4 tilts about the carrier 19 under the force of spring 18 during the retracting movement , so as to still more positively avoid any interference with its retraction by the contents of chamber 3 . as mentioned previously , the ram 6 expels the contents of chamber part 5 with the chamber part 8 before retraction of the element 4 begins . the thus expelled contents are pressed by ram 6 against the already present contents of chamber part 8 . ram 6 remains in this forward end position until chamber 3 is filled again and ready for expulsion of its precompacted contents . above that portion of chamber part 8 where the ram 6 stops in its forward end position , there is mounted a bale - tying apparatus 25 and its container 26 ( both known ) for twine or wire rolls . the counter 28 is operated by the sensing device 13 in a conventional manner known , for example , from the agricultural baler which is available on the market under the name &# 34 ; glass magnum .&# 34 ; it is also known , for example in the above - mentioned agricultural baler , to operate a hydraulic switching valve 27 by the counter 28 . when the counter 28 actuates the switching valve 27 , the latter starts the operation of the apparatus 25 which ties up the bale ( formed of the preselected number of precompressed bodies of vegetation which have been expelled from chamber 3 ) in the main - chamber part 8 . the switch 27 is interconnected with the switch 16 , to assure that the ram 6 can be retracted from its forward end position only after tying of the bale is completed . at the far end of the main - chamber part 8 there is located a braking arrangement ( fig3 ) composed of two pivotable walls 29 , star - wheels 30 ( here three of them ) which penetrate with their teeth into the bale in chamber part 8 , and a hydraulic cylinder - and - piston unit 31 . this arrangement can vary the expulsion resistance of the bales from part 8 and thus adjust the pressure exerted upon the bale in part 8 by the ram 6 . the star - wheels 30 are mounted on a shaft which is engaged with brake drums 32 whose engagement force on the shaft can also be hydraulically varied . thus the walls 29 are pivotable about an axis so as to arrange the star wheels 30 and the brake drums 30 in the chamber part 8 . the star wheels 30 penetrate ( i . e . engage ) with their teeth into the vegetation mass ( i . e . the bales ) so as to vary the density of the latter . while the invention has been illustrated and described as embodied in an agricultural baler , it is not intended to be limited to the details shown , since various modifications and structural changes may be made without departing in any way from the spirit of the present invention . without further analysis , the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that , from the standpoint of prior art , fairly constitute essential characteristics of the generic or specific aspects of this invention .
an agricultural baler has a device for picking up stalk - type and blade - type vegetation . the picked up vegetation is inserted into a precompacting chamber wherein it is subjected to initial compacting . the degree of compaction is sensed and , when it reaches a preselected magnitude , the precompacted body of vegetation is expelled from the precompacting chamber into a main compacting chamber . the precompacted bodies are of identical or substantially identical size and density .