to make the object of the invention more concrete , the invention will be described now in a non restrictive form of embodiment as illustrated in the figures of the drawings . the machine in accordance with the invention includes substantially a fixed bench ( 1 ) or equivalent support means , supported by a framework ( 2 ) on which the monospindle working units ( 3 , 4 , 5 , 6 , 7 ) are mounted in alignment and in a fixed manner , the axes between the spindles being separated by same spacings ( a ) which are very accurate . the monospindle units are generally of uneven number . in the non restrictive example which is illustrated , there are five units for carrying out 3 operational steps , however it will be obvious that this number may be different , 3 , 7 , 9 . . . in accordance with the requirements . the central unit ( 5 ) is equipped for carrying out the third and last operational step on the workpieces , while the lateral units ( 3 , 4 ) and ( 6 , 7 ) are equipped for carrying out in an alternate manner the other operational steps for the machining of the workpiece . in the example shown in the drawings , the machine is designed for performing drillings , tappings , chamberings , bevellings or borings on the end face of a crankshaft . in the case which is illustrated , this machining is comprised of four hole , tapped with an equal spacing ( t1 , t2 , t3 , t4 ), to be made at the end of the crankshaft ( v ), as illustrated in fig6 and 7 . in this case , the central unit ( 5 ) is equipped with a tap ( 5a ) in order to perform the last operational step ( tapping ) while the lateral units ( 3 and 6 ) are equipped with a drilling bit ( 3a and 6a ), and the lateral units ( 4 and 7 ) are equipped with a chambering , bevelling or boring tool ( 4a and 7a ). in front of the monospindle units , and according to a pre - determined plane , the crankshafts ( v ) or other workpieces to be machined , are positioned on a table or plate ( 8 ) which is mounted and equipped with the aid of any well - known means , to be movable in reciprocating translations , according to an axis which is normal to the shifting direction of the spindles . the plate ( 8 ) must be sized in the width so that , in the example illustrated , this plate will be capable of receiving three crankshafts which are interspaced for an accurate spacing ( b ) which is equal to the spacing ( a ) between the spindles , and said plate must be sized in the length so that it will be capable of accommodating crankshafts of substantial length . on the side of the end to be machined , the crankshafts are positioned in abutment by a bearing assembly ( v1 ), within v - shaped supports ( 9 ) or half - rings , and are maintained by any pneumatic or hydraulic clamping means such as the hinged flanges ( 10 ) illustrated in fig4 . in order to prevent the supports from wearing off , an alleviating system by oil film or any other film may be provided during the rotation of the workpieces . on the side opposite , the crankshafts are mounted by means of their plate ( v2 ) within a suitable centering and clamping device , of the type of a chuck ( 11 ) for instance . to perform the operational steps of drilling , chambering and tapping on the four holes , it is necessary to provide rotations in succession of the crankshafts . for this purpose , the chucks ( 11 ) are associated with a three - outlet indexing plate or with indexing plates ( 12 ) to permit a 360 ° 0 rotation , the indexing devices being actuated periodically in accordance with the predetermined cycle . the initial angular positioning , as the case may be , is provided by any well - known means such as collapsible auto - centering jaws . the plate ( 8 ), which is movable in reciprocating translations , must also be indexed securely onto the positions corresponding to a machining ( three positions in the example illustrated ). for this purpose , there is provided for instance a finger ( 13 ) actuated by any desired means to pass from a rearward or collapsed position according to which the plate is free , to a forward or indexing position of the plate through insertion of the finger into one of the corresponding notches ( 8a ) of the plate ( fig1 and 2 ). there is provided moreover a loading and discharging means for the crankshafts when they are placed in front of the central unit ( 5 ). this means has been denoted by pincers ( 14 ) in fig2 and 4 , however , it will be understood that any types of convenient transport and gripping organs may be adapted as desired . in an important manner , it will be pointed out that the number of the monospindle working units is determined by a 2n - 1 ratio , in which n is the number of the operational steps of the same type to be carried out on the workpieces . therefore , an uneven number of working units is used , and there is in any case a central unit performing the last operational step , the same number of working units being disposed on either side of this central unit . it will be moted moreover that the number of workpieces being machined is always equal to the number of the operational steps of the same type to be carried out . it will be well understood that the shiftings in reciprocating translations of the plate ( 8 ), as well as the control of the positions , can be monitored by a digital control , in order to be able to adjust an original offsetting corresponding to the drilling radius and the various strokes in accordance with the working radius . the angular indexing of the workpieces for the machining in a hole by hole manner is also effected by digital control of the indexing plate or plates ( 12 ). likewise , it is also possible to use a digital control of each monospindle working unit , for providing correct working cycles and speeds in the operation of the tools . as an alternative form of embodiment , the machine may be designed with a fictitious central unit . in this case , the position of the workpiece in front of this location serves for loading and discharging only , and the number of units is equal to two times the number of operational steps to be performed . the operational cycle of the machine in accordance with the invention will be described now with reference to fig8 to 13 , in one application , and as an example only , concerning the machining on a crankshaft end face , said machining including drillings , chamberings and tappings of four holes with equal spacing , by means of the five monospindle units ( 3 , 4 , 5 , 6 and 7 ) of the plate ( 8 ) with three positions or stations which will be called ( a , b , c ) hereinafter . the plate ( 8 ) is brought forward and indexed in the position wherein the station ( a ) is situated in front of the central unit ( 5 ), with an offsetting , ( x ) which corresponds to the drilling radius of the holes . a first crankshaft ( va ) is positioned at the station ( a ) and wedged in angularly ( fig8 ). the plate ( 8 ) is moved in the direction of the arrow ( fo ) so that the station ( a ) will be in front of the unit ( 6 ), with the offsetting ( x ). the unit ( 6 ) is actuated to perform , on a first hole , the drilling operation prior to the bevelling and tapping . after the backward motion of the spindle , the crankshaft is moved rotatably for 90 degrees by the indexing device ( 12 ), and the second hole is drilled . the same procedure is repeated for the two remaining holes . on completion of the drilling , a second crankshaft ( vb ) is positioned at the station ( b ) of the plate ( broken lines , fig8 ), and the plate ( 8 ) is moved in the direction of the arrow ( f1 ) to be brought forward and indexed in the position ( with offsetting x ) where the station ( a ) is in front of the unit ( 7 ) and the station ( b ) is in front of the unit ( 6 ). in this position , illustrated in fig9 the units ( 6 and 7 ) are actuated to perform simultaneously the drillings on the crankshaft ( vb ) and the entrance chamberings on the crankshaft ( va ). on completion of the operational step , a third crankshaft ( vc ) is positioned at the station ( c ), then the plate ( 8 ) is moved in the direction of the arrow ( f2 ) to be brought forward and indexed in the position ( with offsetting x ) where the stations ( a , b , c ) are respectively in front of the units ( 5 , 4 and 3 ). in this position illustrated in fig1 , the drillings on the crankshaft ( vc ), the entrance chamberings on the crankshaft ( vb ) and the tappings on the crankshaft ( va ) are performed simultaneously . on completion of the operational step , the crankshaft ( va ) which is completed is removed by the discharging device , and a fourth crankshaft ( vd ) is positioned at the station ( a ). the plate ( 8 ) is then moved to be brought back and indexed in the initial position , arrow ( f3 ), in which the stations ( a , b and c ) are respectively in front ( with offsetting x ) of the units ( 6 , 5 and 4 ). in this position ( fig1 ), the drillings on the crankshaft ( vd ), the tappings on the crankshaft ( vb ) and the chamberings on the crankshaft ( vc ) are performed simultaneously . on completion of the operational step , the second crankshaft ( vb ), also completed , is removed and replaced by a fifth crankshaft ( ve ) and the plate ( 8 ) is moved in the direction of the arrow ( f4 ), fig1 , in oder to be brought forward and indexed in the position according to which the tappings on the crankshaft ( vc ), the drillings on the crankshaft ( ve ) and the chamberings on the crankshaft ( vd ) are performed simultaneously by the units ( 5 ), ( 6 ) and ( 7 ) respectively . on completion of the operational step , the crankshaft ( vc ) is removed and replaced by a sixth crankshaft , the crankshaft ( vf ), then the plate is moved ( according to arrow f5 , fig1 ) for carrying out simultaneously the drillings on ( vf ), the chamberings on ( vc ) and the tappings on ( vd ). the operational cycle is continued further on , until all the workpieces are machined . it will be noted moreover that the duration of the machining is varying in accordance with the units and the work thereof . the periods of time for each operation are based on the longest one . the advantages will be clearly apparent from the description , and the following features will be more particularly pointed out : the cost price of the machine is very substantially cut down as compared with the special multispindle machines and the machining centers ( in a 4 to 1 ratio approximately , for the same efficiency ); the simplicity and the high efficiency of the means which are used , thanks to the use of quick drilling organs ( impossible in the multispindle machines and in the machining centers ), and to the fact that a plurality of worpieces are machined simultaneously ( as many workpieces as operational steps ), with substitution of a completed workpiece , always at the same station , by quick automatic handling ; the easiness in adapting the machine for different operations on various workpieces , without expensive specific tooling . it is merely necessary to change the tools , to interchange the positioning means for the workpieces , and to adjust the digital controls , and as the case may be the working cycles of the units ; the quality of the work , thanks to the use of the synchronized digital controls for the size and the positions of the machinings to be made , the order of the operational steps . it will be noted moreover that the tapped holes can be made either according to a different radius , by modifying the dimension ( x ), or at different angles by modifying the angular adjustments of the indexing device ; these modifications are given by the digital control . the invention is not restricted in any way to the use nor to the form of embodiment of the various parts thereof which have been more particularly described , and any alternative form of embodiment remains within the scope of the invention .