1991 ACURA NSX wheel

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ACURA NSX 1991 Service Repair Manual Steering Gearbo x
Motor an d Powe r Assis t Mechanis m
A moto r i s house d insid e th e gearbo x housing . I t consist s o f a yok e wit h a permanen t magne t fixe d i n it , a roto r wit h a
fi

Steering Gearbo x
Motor an d Powe r Assis t Mechanis m
A moto r i s house d insid e th e gearbo x housing . I t consist s o f a yok e wit h a permanen t magne t fixe d i n it , a roto r wit h a
fiel d coil , an d brushe s whic h pas s electricit y t o roto r commutators . Th e moto r i s o n th e rac k shaf t o f th e steerin g gearbox .
Th e driv e curren t fro m th e contro l uni t flow s throug h th e powe r rela y an d fail-saf e rela y t o th e brushe s o f th e motor .
Th e driv e curren t flow s t o roto r commutator s throug h brushes , excitin g th e fiel d coi l o f th e roto r an d rotate s th e roto r wit h
th e magneti c actio n o f th e permanen t magne t insid e th e yoke . Th e roto r rotate s i n th e opposit e directio n whe n th e direc -
tio n o f driv e curren t i s reversed .
The rotatio n torqu e of th e moto r is transmitte d to th e bal l scre w through the helica l gear . The rotatio n torqu e on th e bal l
scre w is converte d int o assis t thrus t i n th e directio n o f steerin g rac k b y th e recirculatin g bal l screw . Th e mechanica l advan -
tag e o f th e recirculatin g bal l screw , compaire d t o a conventiona l rac k an d pinion , act s t o reduc e th e steerin g forc e t o th e
steerin g rac k throug h th e joint , t o lesse n th e steerin g effor t require d a t th e steerin g wheel .
ROTORRACK
RECIRCULATIN GBALL SCRE W
BAL L SCRE W
HELICA L GEA R
Recirculatin g Bal l Scre w
Th e recirculatin g bal l scre w is constructe d s o tha t stee l ball s rol l betwee n th e scre w shaf t an d th e nut , an d thos e comin g
ou t o f th e scre w fac e ente r th e scre w groov e agai n throug h a tub e fo r recirculation . Th e rotatio n torqu e o n th e shaf t i s
converte d int o thrus t i n a n axia l directio n a s th e slop e o f th e scre w shaf t presse s agains t th e nu t throug h th e stee l balls .
Sinc e th e torqu e conversio n i s mad e i n thi s metho d throug h th e scre w shaf t an d th e stee l balls , th e frictio n i s small , hig h
transmissio n efficienc y i s obtaine d fo r bot h th e forwar d an d backwar d directions , an d th e steerin g feel s identica l t o th e
ordinar y manua l steering .
Furthermore , sinc e th e forc e fro m th e backwar d directio n (forc e pressin g th e steerin g rack ) i s converte d int o th e rotatio n
torqu e o f th e scre w shaft , instantaneou s kick-bac k fro m th e roa d surfac e wil l rapidl y rotat e th e motor . I n suc h a rapi d rota -
tion , th e inerti a o f th e moto r increases , whic h act s t o reduc e th e kick-back . An y grea t kick-bac k wil l b e transmitte d fro m th e
steerin g rac k t o th e torqu e senso r o n th e pinion , whic h act s t o twis t th e pinio n shaf t i n th e sam e directio n a s th e inpu t
directio n o f kick-back . A s a result , th e moto r operate s th e kick-bac k to reduc e assis t force .
BALL SCRE W
TUBESTEE L BAL L
NUT
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