fig1 a - 1d show different variants of a first embodiment according to the invention . as will be explained in further detail in the following , according to this first embodiment of the invention the motorised handpiece is constructed in two parts , a clamping system for a tool which is to be driven by the motorised handpiece being arranged in one handpiece part and a motor being arranged in the other handpiece part . the motor and the clamping mechanism are fitted to the same shaft , which is integrally formed . the clamping mechanism for the tool is more particularly constructed as a control grip rapid clamping system , i . e . a tool introduced into the clamping mechanism is automatically clamped in a force - locking manner by rotating the handpiece part associated with the clamping mechanism relative to the handpiece part associated with the motor , so that the rotary movement of the motor is transmitted via the integral shaft to the clamped tool . fig1 a shows a motorised handpiece 1 which is formed by two handpiece parts 12 and 13 which can be coupled together . arranged in the handpiece part 12 is the already - mentioned motor , which in the illustrated example is constructed in the form of a collector - free d . c . motor with a short - circuit ring 2 made of sheet iron , for example , a stator winding 3 and a rotor magnet 4 . the rotor magnet 4 can be a bipolar diametrally magnetised permanent magnet , for example . like the handpiece part 12 , the short - circuit ring 2 , the stator winding 3 and the rotor magnet 4 are substantially rotationally symmetrical and each have a cylindrical shape . the rotor magnet 4 is fitted in a force - locking manner onto a drive shaft 10 , so that the drive shaft 10 is driven by the rotation of the rotor magnet 4 . the collector - free d . c . motor is supplied with current via a supply line 18 , the supply line 18 being guided through an opening at the supply line end of the motorised handpiece 1 into the interior of the handpiece part 12 . located at the supply line end of the handpiece part 12 is a ball bearing 14 , on which the drive shaft 10 is rotatably mounted . at its supply line end , the handpiece part 12 comprises a removable cover 22 , so that the ball bearing 14 is easily accessible from the supply line end of the motorised handpiece 1 and can therefore be simply replaced in the event of repair . the second handpiece part 13 comprises the already - mentioned clamping mechanism . in the embodiments illustrated in the drawings , this clamping mechanism is constructed as a rapid clamping mechanism as in fig5 a . in other words , also provided in the embodiments described below is a clamping jaw 5 , for example , which upon rotation of the handpiece part 13 relative to the handpiece part 12 can be displaced in the longitudinal direction relative to the outer casing of the shaft 10 , so that a tool 8 , e . g . a dental tool , which is disposed in the clamping jaw 5 , can be clamped in a force - locking manner simply by rotating the handpiece part 13 acting as a rotary knob . as in fig5 a , elastic means 7 , more particularly a spring , is again provided , against whose spring force the clamping jaw 5 is moved into the handpiece part 13 and the tool 8 is clamped . as regards the more detailed method of operation of this clamping mechanism , reference is made at this point to the explanations relating to fig5 a . whilst fig5 a illustrates a partial cross section of this clamping mechanism , fig1 is merely an external view of the drive shaft 10 with the section of the clamping jaw 5 projecting therefrom and the spring 7 . the spring 7 can be constructed , for example , as a cup or helical coiled spring and -- as already explained with the aid of fig5 a -- is coupled to the clamping jaw 5 in such a manner that it is compressed when the clamping jaw 5 is drawn into the handpiece part 13 as a result of a rotation of the handpiece part 13 relative to the handpiece part 12 . as can be seen in fig1 a , the drive shaft 10 is also rotatably mounted in the handpiece part 13 at the tool end thereof by means of a ball bearing 15 . in all , a single shaft system with only two ball bearings 14 , 15 for the entire motorised handpiece 1 is therefore formed , although a rapid tool clamping mechanism ( control grip rapid clamping mechanism ) is again used . the collector - free d . c . motor ( without position indicator ) illustrated in fig1 a is constructed in such a manner that the stator winding 3 is associated with the supply line 18 in a fixed or pluggable manner and the rotor magnet 4 is associated with the drive shaft 10 in a fixed or screwable manner . consequently , a simple division and separation of the entire motor region into the supply line 18 and the motorised handpiece section is possible . overall , optimal minimisation of the external dimensions and weight of the motorised handpiece is attained with the aid of the motorised handpiece according to the invention . in addition , a bearing replacement can be simply effected in situ with the aid of the single shaft system according to the invention . different variants of the motorised handpiece according to the present invention illustrated in fig1 a will be described in the following . in this respect , corresponding components are provided with identical reference numerals . fig1 b shows a first variant of the motorised handpiece illustrated in fig1 a . as in fig1 a , the motor is again accommodated in the handpiece part 12 and the clamping mechanism in the handpiece part 13 , the motor and the clamping mechanism being fitted onto the same shaft . in contrast to fig1 a , however , both ball bearings 14 , 15 are arranged in the handpiece part 13 which is associated with the clamping mechanism . more particularly , the two ball bearings 14 , 15 are arranged at opposite end sections of the handpiece part 13 , the spring of the clamping mechanism being accommodated between the two ball bearings 14 , 15 . the drive shaft with the rotor magnet fitted thereon projects freely into the stator winding of the d . c . motor and according to fig1 b is not supported in the housing part 12 by a further support bearing . fig1 c and 1d show further variants of the first embodiment according to the invention . the motorised handpiece according to fig1 c corresponds to the variant illustrated in fig1 b , although a third ball bearing 16 is additionally provided at the supply line end of the handpiece part 12 . as in fig1 a , the handpiece part 12 again comprises a removable cover , so that the third ball bearing 16 is also easily accessible from the outside . the variant shown in fig1 d is based on the motorised handpiece illustrated in fig1 a , a ball bearing 14 , 15 again being provided in the handpiece part 12 facing the electromotor and the handpiece part 13 associated with the clamping mechanism respectively . whilst the first ball bearing 14 is accommodated at the supply line end of the handpiece part 12 as in fig1 a , the ball bearing 15 is now disposed at the end of the handpiece part 13 lying opposite the handpiece part 12 . also provided in fig1 d is a removable cover 22 , so that the ball bearing 14 can be simply replaced . fig2 a - 2d show different variants of a second embodiment of the invention . this second embodiment essentially corresponds to the first embodiment , although in contrast to fig1 the clamping mechanism or the spring 7 of this clamping mechanism is accommodated in the handpiece part on the supply line side , whilst the collector - free d . c . motor is arranged in the housing part on the tool side . fig2 a shows the embodiment corresponding to the variant illustrated in fig1 d . the handpiece part 13 , in which the clamping mechanism or the spring 7 of the clamping mechanism is accommodated , comprises an opening at one end , into which the supply line 18 projects , which supplies the stator winding 3 of the collector - free d . c . motor with current if the handpiece part 12 is coupled to the handpiece part 13 . the actuating mechanism of the clamping system explained with the aid of fig5 a , which as a result of a rotation of the two housing parts 12 and 13 relative to one another causes the sleeve - shaped , slotted clamping jaw 5 to be displaced into the motorised handpiece 1 and to be correspondingly compressed , is disposed together with the spring 7 in the handpiece part 13 . the clamping mechanism is again connected to the d . c . motor via a single shaft 10 , which is integrally formed and is merely rotatably mounted at two bearing sites 14 , 15 . in this respect , one ball bearing 14 is disposed at the tool end of the handpiece part 12 , whilst the other ball bearing 15 is disposed at the end section of the handpiece part 13 facing the handpiece part 12 . fig2 b shows a variant of the motorised handpiece according to the present invention illustrated in fig2 a , the motorised handpiece illustrated in fig2 b corresponding to the design illustrated in fig1 c , i . e . in addition to the ball bearings 14 , 15 , a third ball bearing 16 is provided for supporting the drive shaft 10 . since the arrangement of the d . c . motor and the clamping mechanism is reversed in the embodiments according to fig2 as compared with the embodiments of fig1 according to fig2 b the third ball bearing 16 is disposed at the tool end of the handpiece part 12 . according to fig2 b , the ball bearing 15 is arranged at the supply line end of the handpiece part 13 . for this reason , the handpiece part 13 comprises a removable cover 22 , so that the ball bearing 15 can be easily accessed and replaced from the supply line side . fig2 c and fig2 d show arrangements of the second embodiment of the motorised handpiece according to the invention which correspond to the arrangements illustrated in fig1 b and 1a respectively , although again the arrangement of the d . c . motor and the clamping mechanism is reversed as compared with fig1 i . e . the clamping mechanism is located in each case in the handpiece part which is connected to the supply line 18 , whilst the d . c . motor is accommodated in the handpiece part in which the tool 8 is clamped . in the variant according to fig2 c , the two ball bearings 14 and 15 are each accommodated in the handpiece part 13 at opposite ends thereof , so that the drive shaft projects freely into the stator winding of the d . c . motor of the handpiece part 12 . in contrast , according to fig2 d , the two ball bearings 14 and 15 are accommodated at the respective outer ends of the handpiece parts 12 and 13 , which results in maximum vibration rigidity of the drive shaft . fig3 a - 3e show different variants of a motorised handpiece according to a third embodiment of the invention . the variants illustrated in fig3 a - 3e essentially correspond to the variants illustrated in fig1 a - 1d , although according to the third embodiment of the invention , in contrast to fig1 the rotor magnet 4 is accommodated in a cavity in the drive shaft 10 . fig3 a shows a first variant of the third embodiment of the present invention in its assembled state , i . e . in a state where the two handpiece parts 12 and 13 are coupled together , for example screwed together , whilst fig3 b shows the corresponding variant with the handpiece parts 12 and 13 separated . it can be seen in particular from fig3 b that the drive shaft 10 projects freely from the handpiece part 13 and is held by two ball bearings 14 and 15 in the handpiece part 13 , the section of the drive shaft 10 in which the rotor magnet 4 is accommodated being introduced into the stator winding 3 of the collector - free d . c . motor by joining the two handpiece parts 12 and 13 . the stator winding 3 is supplied with current via the supply line 18 , so that the rotor magnet 4 , which is accommodated in a force - locking manner within the drive shaft 10 , is set in rotation and the drive shaft 10 is simultaneously driven . the clamping mechanism can be constructed in the same manner as in the motorised handpieces illustrated in fig1 and 5a . fig3 c shows a variant of the third embodiment according to the invention , the two ball bearings 14 and 15 being arranged in the same manner as in fig1 a , i . e . a ball bearing is arranged at the outer ends of the handpiece parts 12 and 13 respectively . as shown in fig3 c , the ball bearing 14 arranged at the supply line end can also be accommodated in the removable cover 22 , so that easy accessibility of the ball bearing 14 is also ensured in this case . fig3 d and 3e show variants of the third embodiment according to the invention , the arrangement of the ball bearings corresponding to the ball bearing arrangement illustrated in fig1 d and 1c respectively . both in fig3 d and in fig3 e , the ball bearing 14 or 16 on the supply line side is accommodated in the removable cover 22 of the handpiece part 12 . whilst only two ball bearings 14 , 15 are used according to the variant illustrated in fig3 d , according to fig3 e the drive shaft is supported by a total of three ball bearings 14 , 15 , 16 . finally , it should be noted that the invention can be applied to both operating handpieces used by dental technicians and treatment handpieces used by dentists . however , treatment handpieces used by dentists are often angled in design , so that the integral construction of the shaft proposed according to the invention is only applicable in this case to the core region of a dental treatment handpiece of this type . fig4 shows an example of a motorised handpiece 1 of this type according to the invention with a first housing section 23 and an angled second housing section 24 . the motor 2 - 4 is accommodated in the first housing section 23 , whilst a coupling mechanism 5 of optional design for receiving a ( dental ) tool is provided in the second housing section 24 . in principle , this coupling mechanism can be formed in a similar manner to the preceding embodiments by a rapid clamping mechanism , it being possible to automatically clamp a tool , for example by rotating the second housing section 24 . as regards further details of the method of operation and / or the design of a rapid clamping mechanism of this type , reference is made at this point to the description of the preceding embodiments . on account of the angled construction of the motorised handpiece shown in fig4 it is necessary to couple a further shaft ( not shown ) to the integrally formed drive shaft arrangement 10 arranged in the straight housing section 23 in the region of the angle , for example by means of a gearing 26 . accordingly , according to the present invention this integrally formed shaft 10 in the core region of the motorised handpiece 1 supports the motor or the rotor magnet 4 thereof on the one hand and the gearing 26 on the other hand and is again mounted in the motorised handpiece 1 via two ball bearings 14 , 15 . the motorised handpiece 1 shown in fig4 preferably comprises separation points such that the two ball bearings 14 , 15 are easily accessible for replacement when the handpiece is divided . as shown in fig4 the motorised handpiece 1 also comprises a duct 25 for dental purposes , in order to supply a treatment site with light , spray air or spray water , for example .