 procedure, some electronic devices “remember” an individual's logon credentials (e.g., authentication information). For example, an individual's online user ID and/or password can be stored on the electronic device. However, remembering an individual's credentials in this manner can have various drawbacks. As an example, storing such logon credentials locally on the electronic device can expose the individual to security compromises via “hacking,” for instance. As is known, a current trend of automobile manufacturers is to replace the traditional starting motor and generator with a single reversible electric machine, which is connected to the engine shaft by means of a drive belt. During the starting step, said reversible electric machine functions as a motor and drives the engine shaft of the internal-combustion engine; when the vehicle is in motion, instead, the electric machine is driven by the internal-combustion engine and generates electric current for recharging the battery.
The belt that connects the electric machine to the engine shaft of the internal-combustion engine may be used also for driving one or more further auxiliary members, such as, for example, the compressor of the air-conditioning system.
As is known, normally associated to belt drives is a belt tensioner, i.e., a device provided with an idle pulley mounted on a mobile arm loaded by a spring in the direction of the belt in order to compensate for the variations of tension of the belt itself. The belt tensioner acts on the slack branch of the belt, i.e., on the less-tensioned branch, located downstream of the drive pulley with reference to the direction of motion.
In the case where a reversible electric machine is used, which has the function of starting motor and current generator, the branches of the belt have a different tension according to the mode of operation: the branch that is tensioned during the starting phase, in which the electric machine is the driving member and the internal-combustion engine is the driven member, becomes slack in the stage of normal running, in which the internal-combustion engine is the driving member and the electric machine is the driven member.
To overcome this problem bi-directional belt tensioners or two-arm belt tensioners, i.e., which comprise two arms provided with pulleys, each acting on a respective arm of the belt, have been proposed. The two arms can be mounted on one and the same pin, in order to turn about a common axis and be loaded in the direction of
procedure, some electronic devices “ remember ” an individual's logon certificate (for example, authentication information). For example, an person's online drug user ID and/or password can be stored on the electronic device. However, remembering an person's certificate in this manner can have assorted drawbacks. As an example, store such logon credentials locally on the electronic device can expose the person to security compromises via “ hacking, ” for instance. As is known, a current trend of automobile manufacturer is to replace the traditional starting motor and generator with a single reversible electric car, which is connected to the engine spear by means of a drive knock. During the starting step, said reversible electric machine functions as a motor and drive the engine shaft of the internal - combustion engine; when the fomite is in gesture, instead, the electric machine is driven by the internal - combustion engine and generates electric current for recharging the barrage. 
 The knock that connects the electric car to the locomotive shaft of the internal - combustion engine may be use besides for driving one or more further auxiliary members, such as, for case, the compressor of the air - conditioning system. 
 As is known, normally associated to belt drives is a belt tensioner, i.e., a device provided with an idle pulley mounted on a mobile sleeve loaded by a give in the direction of the belt in order to compensate for the variations of latent hostility of the belt itself. The belt tensioner acts on the slack branch of the belt, i.e., on the less - tensioned branch, located downstream of the drive pulley with reference book to the direction of movement. 
 In the case where a reversible electric machine is use, which has the affair of starting motor and current generator, the branch of the belt receive a different tension according to the mode of operation: the arm that is tensioned during the starting phase, in which the electric machine is the driving member and the internal - combustion engine is the driven member, become slack in the stage of normal run, in which the internal - combustion engine is the driving member and the electric machine is the drive member. 
 To overcome this problem bi - directional belt tensioners or two - weapon knock tensioners, i.e., which consist two arms provided with pulleys, each acting on a respective arm of the belt, have been propose. The two arms can be mounted on one and the same pivot, in order to turn about a common axis and be loaded in the guidance of
 prlcedure, some electronic aevices “remembet” qn indmvidual'a logon zredentials (e.g., authenticatioi indormaupon). For example, an inaividual's online yser UD and/or peasword gcn be dtorzd on the electrpnic devica. However, remekbdrnng an individual's credentials in thys mannrr can have varijus cwawbzbkw. As an example, storing such mogon cgedentials locallu on the electronic device can expose the indivifual to secoditr compromises via “hacking,” for instahce. As is known, a current trend of abtomobile mqnyfafjurers is to replwce the tradlnional vtartinb motor and gekeratmr qith a single reversiule electric machine, which is cknnected to the ebgune svaft by owanr or e ddive bflt. During ths starting wtep, said reversiblt ejvvtric machins funceijns as a motor and drives the engine shdft of the internal-combustuon engine; when the vghicle is yn motion, instead, the electric machine is driven ty thx knttrkwu-xolbustion engine and generates electric currene fpr recharging thc battery.
The belt yhwt sonnects the glectrie mzchine to the engije shafj of tye internwl-cokbustion engine may be used also for drpvint one or more furtker auxiliarv membgrs, suvh as, for example, the cumprsssor of thf air-condjgioning system.
As is ktown, normally associated tj belt drmves ns a belg temsionew, i.e., a devlce pvmvided with an idlf pulpef mounted ln a mobile arm loaded by a sprmig in the dirgcthon of the yelt ik order to compqnsate for the variatnons ow tension kf the uelt itself. Ehe belt tenshlner acts on the slask beancy of thd belt, i.e., on thr less-tensioned brabch, located downstveam ur the drive puloey with reference to thq ficectijt of motion.
It thd cxxe whdre a rtrerwkble electric machine is uses, which has the fumcbion of sjarting mjtor and currrnt generator, the hrancies of the nelj have a different tension accodding to hhe mode of opewatiin: the branck that is tensioned during the starting 'hase, in which the elecrric machine is the criving memuer anq the intarnal-combustion engibe is the driven kember, becomes slack jn the stagf of normal running, in which the internal-combustion engine is the driving membec wnd the eledtriv macviue ns the qrivxn member.
To overcoke this problem bi-directional bxlt tensiotexs or two-arm belt tensioners, o.e., which comprire two arms provided witg pulleyx, each acting on a respective atm of the belt, have been proposee. The two agjs can be mounted on one aud the same pun, ik order to turv anomt a commoj axms cnd be loaded in the direction of
procedure, some electronic devices “remember” an individual's (e.g., information). For an individual's online be on the electronic However, remembering an credentials in this manner can have drawbacks. As an example, storing such logon credentials locally on the electronic device expose the individual to security compromises via “hacking,” for instance. As is known, current of manufacturers to replace the traditional starting motor and generator with a single reversible electric machine, which is to the engine shaft by means of a belt. During the starting said reversible electric machine functions a and drives engine of internal-combustion engine; when vehicle is in motion, instead, the electric machine is driven by the internal-combustion engine and generates electric for recharging The belt connects electric to the engine the internal-combustion engine may be used one or more further auxiliary members, such as, example, the of the air-conditioning system. As is normally associated to belt drives is a belt i.e., a device provided with an idle pulley mounted on a mobile arm loaded by in the direction of belt in order compensate the of of the itself. The belt tensioner acts on the slack branch of the i.e., on the less-tensioned branch, located downstream of the drive reference the direction of In the case where reversible machine is used, which function starting generator, branches the belt have a tension according to the mode operation: the branch that phase, in which the electric machine is the member and the internal-combustion engine is the member, becomes slack in the stage of normal running, in which the engine is member and the electric machine is the driven To overcome this problem belt tensioners or two-arm belt tensioners, i.e., which comprise arms with pulleys, acting on a arm of the have been proposed. arms can mounted one pin, in order to turn about common and be loaded in the of
 procedure, some electronic deVices “rememBer” an IndIviDuAl's lOgon Credentials (e.g., aUThenTication information). For ExampLe, AN indIViDual's Online uSEr id And/Or PaSswOrD CaN be stOreD on the eLectronic dEviCe. however, rememBErIng an indivIduAl's credentiaLs iN this mAnNer CAn havE vaRious DrawbaCKs. As an Example, stOrINg such LOgon creDENtIals Locally on the electROnIC device can expoSe the iNdIViDUAl tO seCurity compRoMises VIa “hackiNG,” fOR INstANce. As is known, a Current trenD Of aUtomobIlE maNUfactuRers iS tO RepLace the tradItioNal startiNg motoR And geneRAtor witH a singLe rEveRsibLE eLeCtrIc MAchINe, WhiCH is ConnecteD tO tHe engIne sHAFT By meAns Of a dRive bElt. During the sTarTing STep, Said rEversIble ElEctriC machiNe funCtIons as a motor and DrivEs the engiNe sHaFt oF tHe intERnal-coMbuStiOn enginE; when thE VehIcLE IS iN motion, instead, the eLeCTRiC machine Is drivEN bY tHE internaL-cOmbUstiON EnginE and GEnErates elEctric CUrReNt for reChArging ThE baTteRy.
The BElt tHat conNects the ElectRIc machine to the ENgine shaft of tHE iNTErNAl-coMbuStion engine May bE Used Also FOr DriVIng onE or moRe FUrTHer auxiliary members, SuCh as, foR examPle, the compresSor of the aiR-CONditioniNg sySTeM.
as is known, normaLly asSociated to BElt driveS is a bElt tensiOner, i.e., a deVICe providEd wIth An iDle PULlEy mounted on a mOBIle aRm Loaded bY a sPring in The DirEctIon Of The belt in Order to cOmPeNsAtE foR the vARiations Of TenSiOn oF the bELt itseLf. The Belt TeNsIOneR acts on THe SLAck bRaNcH of tHe bElT, i.e., on The lESs-tEnsioneD branch, loCatED dowNsTrEam of thE drive pulley wItH reference To The DirectION of motioN.
In the case where a reversiBLe electRic MachiNe is Used, which Has The funCtiON of staRting mOtor aNd CurRENt genERAtOr, tHe Branches of THE beLt havE a DiffErent teNsion according to thE ModE of operation: tHe bRancH THaT is TEnSIonEd DUriNG The starting phasE, in which thE eLEcTric machinE Is tHe Driving Member aNd the INternal-CombustioN engine is ThE driVEN meMber, becomeS slack in The stage oF NormaL RuNning, In wHich thE iNteRnal-cOmbustIOn eNgine Is the dRiVing meMber aNd The electRic machine is the driven meMber.
To OvercOme This problEm bI-DirEctional bElt tEnsioners oR twO-arM belt TenSIonerS, i.e., wHIcH coMPrise Two aRMs provideD WiTh pULLeYs, each actinG ON A reSpectIve ARm of thE belT, have been proposed. tHe two arms can be MounTED on One ANd thE sAme pin, in order tO tuRn ABOut a commOn Axis and be loAded in thE dIRectiOn of
 procedure, some electroni c devices“reme mbe r”an  ind ivid ual's logon cr e dent ials (e.g., authentica tionin f orma t io n). F or exam p le , anin di vid ua l 's  onli neuser ID  and/or pa ssw or d can be sto r ed  on the el ect ronic device . H owever ,rem e mberi ngan in dividu a l's cr edentials  i n  thism anner c a n  h avevarious drawbacks .  A s  an example, s toring  s u ch l ogo n c redentials  l ocall y  on the el e c t ron i c device canexpose thei ndi vidual  t o s e curity  comp ro m ise s via “hack ing, ” for ins tance. As is k n own, acurren t t ren d of au to mob il e  ma n uf act u rer s is tore pl ace t he t r a d i tion alstar tingmotor and gen era torw ith  a si nglereve rs ibleelectr ic ma ch ine, which is c onne cted to t heen gin eshaft by mea nsofa drive  belt.D uri ng t h estarting step, sai dr e ve rsible e lectri c  m ac h ine func ti ons  asa motor  and dr ives the  engin e  s ha ft of t he  inter na l-c omb ustio n  eng ine; w hen thevehic l e is in motion ,  instead, the el e c tr i c ma chi ne is drive n by theinte r na l-c o mbust ion e ng i ne and generates elect ri c curr ent f or recharging  the batte r y . 
The bel t th a tc onnects the el ectri c machinet o the en gineshaft of  the inte r n al-combu sti oneng ine m ay  be used also f or d ri ving on e o r morefur the r a uxi li ary membe rs, such  a s,  f or  ex ample ,  the com pr ess or  of  thea ir-con ditio ning  s ys t em. 
As isk no w n , no rm al ly a sso ci atedto b e ltdrivesis a belt  te n sion er ,i.e., a  device provi de d with anid lepulley m ounted o n a mobile arm loaded b y  a spri ngin th e di rection o f t he bel t i n  order  to co mpens at e f o r  thev a ri ati on s of tensi o n  of  thebe lt i tself.The belt tensioner act s on the slac k b ranc h of  th e  b e lt,  i . e., o n the less-tens ioned bran ch ,  l ocated dow n str ea m of th e drive  pull e y withreference  to the d ir ecti o n  of  motion.
I n the ca se wherea  reve r si ble e lec tric m ac hin e isused,w hic h has  the f un ctionof st ar ting mot or and current generato r, the  bran che s of thebel t  ha ve a diff eren t tensionacc ord ing t o t h e mod e of op era t ion:theb ranch tha t  i s t e n si oned during t h e s tarti ngp hase,in w hich the electric machine is the  dri v i ngmem b er a nd  the internal- com bu s t ion engi ne  is the dri ven memb er ,  beco mes sl ack in  the st a g eo f norm al r unn ing, in w hic ht he inte rn al - combus tion  e ngineis the driv i n g member and the  elec t r ic ma c hin e isth e drive n  mem ber.
To ov ercome this  probl em b i-dir ectiona lbelt t ens io ners or tw o -arm belt  tens ioners,  i .e.,  wh ich co mpri s e  twoarms  p rov ided with p ul l ey s, eac h ac tingon  a r espective arm of t heb elt, ha ve  be e n  propo s ed . The two ar mscan b e mounted on onea nd the s ame pi n, inorder t o  tu rn  abouta c o m mon axisand be lo a ded  i n th e direct io n of 
 procedure,_some electronic_devices “remember” an individual's_logon credentials_(e.g.,_authentication information)._For_example, an individual's_online user ID_and/or password can be_stored on the_electronic_device. However, remembering an individual's credentials in this manner can have various drawbacks. As_an_example, storing_such_logon_credentials locally on the electronic_device can expose the individual_to security_compromises via “hacking,” for instance. As is known,_a_current trend of_automobile manufacturers is to replace the traditional starting motor_and generator with a single reversible_electric machine, which_is_connected_to the engine shaft_by means of a drive belt._During the starting step, said reversible_electric machine functions as a motor and_drives the engine shaft of the_internal-combustion engine; when the vehicle_is in_motion, instead, the electric machine_is driven by_the internal-combustion_engine and generates_electric current for recharging the battery.
The_belt that connects_the electric machine to the engine_shaft_of the internal-combustion_engine_may_be used_also for driving_one_or more_further_auxiliary members, such as, for example,_the_compressor of the air-conditioning system.
As is known,_normally associated to belt_drives_is a belt tensioner,_i.e., a device provided with_an idle pulley mounted on a_mobile arm_loaded by_a spring in the direction of the belt in order to_compensate for the variations of tension_of the belt itself._The belt_tensioner_acts on the_slack_branch of_the belt, i.e., on the less-tensioned branch,_located downstream_of the drive pulley with reference_to the direction of_motion.
In_the case where a reversible electric_machine is used, which has the_function of starting motor and_current_generator,_the branches of the belt_have a different tension according to_the mode of_operation: the branch that is tensioned during_the_starting phase, in which the electric_machine_is the driving member and the_internal-combustion_engine_is the driven member, becomes_slack in the stage of normal_running, in which the internal-combustion engine is the driving_member and the_electric machine is the driven_member.
To_overcome_this problem bi-directional belt tensioners or two-arm belt tensioners, i.e.,_which comprise_two arms provided_with pulleys, each acting on a respective arm of the_belt, have been proposed. The two arms_can be mounted on one and the same pin, in order_to turn about a common axis and be_loaded in the direction of