scrub radius pdf

Fig.4 - Kingpin inclination angle . To browse Academia.edu and the wider internet faster and more securely, please take a few seconds to upgrade your browser. 8 inch wide wheels & a slightly narrower slick cured this. Scrub is a bigger problem on production vehicles with relatively low longitudinal suspension rates often coupled with asymmetric and overly compliant steering systems (darn solid axle SUV's). >> In an embodiment of the present invention, an apparatus for steering a vehicle is disclosed. This distance must be exactly the same from side to side or the vehicle will pull strongly at all speeds. 4% : Implementation of all the corrective actions, not only improved steering returnability by 40% but also helped in reducing the cycle time in design … You could watch the … 3 0 obj /Decode [1 0] Scrub radius basically refers to the distance between the tyre centre line and the point at which the Kingpin axis meets the ground in the front view. x�| ��&��FD��Q�G�d�� x��i��3��m��x/��k��e��`�_�t��P� )�d��y�Bי/��#̔U�י$��d��l7�� @�mH� Page 1 of 2 - SCRUB RADIUS. *���m��k��u��r ��a��1|1�~�|*�,P��dz�a�W$��y�� /Height 76 The main effect of this is to introduce a turning moment. Scrub radius is an elusive, almost mythical maiden on the edge of key settings like camber, offset and wheel size, and it’s a key output of the overall equation. !e�{��%��!��'}_@DTBB�+�(#� $. << radius target scrub radius image Prior art date 2000-06-28 Legal status (The legal status is an assumption and is not a legal conclusion. Camber Ca Definition Camber is … endobj As far as I know, a scrub radius of 0 is the ideal (centre point steering), but sometimes quite hard to achieve. /Width 160 /Mask 5 0 R /Filter [/FlateDecode /CCITTFaxDecode] 0.225 m StW radius, measured from centre to rim edge. /Length 6805 Mq�1��L�w��2��2��]�6�CQ"��&?eΕ�W�P��TU&�ʹ�Dp Ζs�h8�`!��ӱ#G-a]�#^��o�L�σ�a0�,��C#��="�oQU}w�i�$=�� -ذ?+��æu��iʞ��n��敟)E�$\�{�o%�(q�y�j:��g?>{^�c�q7��@z�q��O�jn��b*i�U#��W 3�*%�I� U��Ҳ�.�v�_ϖz�S��"U��w��v��lS z��+&utR�� t��G-9b5T�3v��4�릂%�:$wn{�h�� 6"mϙ��l8kd�Wd�%8��x`kѪX�`�SA�%�i�y��N'�-�͌�{� �29�R�)9�Dfт�M�,v6'� 9�?9ICD%b�g�:Ƣ But, with a positive scrub radius, you then have a small radius, from the KPI axis contact point with the ground, out to the centre of the contact patch. /Width 160 The scrub radius of your car can be altered with different wheel offset and suspension design. 5.Instantaneous center: /Filter [/FlateDecode /DCTDecode] The scrub radius is the distance in the front view between the point at which the kingpin would intersect with the ground and the center of the contact patch of the wheel where it intersects with the ground. I remember a long time ago with manual steering cranking the wheel to full lock while stopped. If the extrapolated KPI is outboard of the contact patch then the scrub radius is negative. This will affect how the tire contact patch interacts with the road during cornering, braking, and acceleration, and can cause unique toe characteristics depending on the design. 7 0 obj Scrub Radius Scrub radius is the distance between where the SAI intersects the ground and the center of the tire. << ��5��`]��_��%B[��Cq �ϊ��f8�;}K's��+�� b ��]C\�" ��׉��1� �bNY,��[�6�� e�rGZ�6��k��ѧޥ�i��#�^��L�2��輇 |�X��.7�T�~3j^e� ?�^_�"ǅA{��A�ө�jp��3��T��)��T��[��*�82�3s��'�� JbJ��+��32N�ũ?YLN�'��$wO{5X��ȟn��P8��QY��). SAI is an imaginary line, that on strut suspensions runs through the lower ball joints and the upper end of the strut. Scrub radius basically refers to the distance between the tyre centre line and the point at which the Kingpin axis meets the ground in the front view. The scrub radius is the distance in front view between the king pin axis and the center of the contact patch of the wheel, where both would theoretically touch the road. If the scrub radius is small then the contact patch is spun in place when parking, which takes a lot more effort. Fig. A positive scrub radius tends to be beneficial while braking into a turn. FAQ’s Terminology Micro Cellular Jounce Bumper Scrub Radius Spring Rate 101 TECH NOTES H&R Technical Information Sheet (PDF) FAQ’s 1) Which are the front and rear springs? Trackwidth The Distance between centre axis of tire from front view is known as trackwidth. ��7�� /ImageMask true ��r-��\��?�_P]Wf��)E��G�+� �j�� c�P �wL�*� � R ESEARCH ON MODELING AND OPTIMIZATION SIMULA TION ANAL YSIS … This is actually desirable to help counteract Toe-in forces caused by positive caster. Scrub radius : 10% . Negative scrub also helps reduce torque steer in front wheel drive cars. endstream %�� endobj I.e. The biggest effect is called bump steer. %�CKG��w��c��F�&�f�v��}`�}��ޅGDFEǤ��OK��UPXT��K��Ʀo�-=�}��C�ߧ�gf��~"��76��=:>9=;��" �Σ��䫰�q�� 18 Time variation of steering assistance angle for different scrub radii 4.6 Simulation of Brake-in-turn Analysis to Study the Effect Scrub Radius In brake-in-turn analysis, the vehicle was made to run on the circular test track of 3.5 m radius with lateral acceleration of 0.35 g and then the brakes were applied. /Subtype /Image Scrub radius helps this feel by providing feedback from the contact patch. /Type /XObject �DG��_�Ø`��&uC�1�&ֳ�f�!@�jR0H�`iǤRLU�:��6?��1��̡2լ��Q��^JgKL�2d�36��! Fig.5 Trackwidth Geometry Note: Generally narrow (small) trackwidth are used at rear to avoid hit cones with the back when they are /Length 133 Active Application number US09/892,722 Other versions US20020001076A1 (en Inventor David A. Jackson ��\�+��$��X��A�(o^i�$^��ozs��́�ɗ=ތz8�i��G�6 NK2��?��G�0��^��3o�0�{h�+] �혘��|ј� If it is inboard then the scrub radius is positive. It also reduces the risk, that a lose of traction on one front wheel during braking, causes the car to change direction. !��H� $� Q�> �۠� �w�6!�܀J t��۷��q��~ ��]vQ�{�/ 9�� endstream As with anything else, a little of a good thing is great, but lot of a good thing is not necessarily better. /Height 222 6 0 obj ��'IJz�!�o?r�o+ >> The parameters obtained from this axis are described in an earlier post. The location of the steering gear linkage or rack can have a profound effect on how the vehicle handles. o�O��4hI�Y̆ЖB̒ܤ�nZ��ˮmVR�ZB��B[K^�?3"��㷼 ��A�yy��I��oo��f��[¾U(�� \G��7eK��r@]A��7�a�h�e3,��'��dsŮ��i݉8��+�W��z��6}jii�YD�x3]�Nia��s��/�#ݒvT�z:_��kk��#�{��啬W�� SAI is an imaginary line, that on strut suspensions runs through the lower ball joints and the upper end of the strut. When viewing a wheel from front view, the scrub radius is the distance between where the extrapolated line of kingpin axis touches the road and the tyre contact patch centre point. �q2w�./�y �m}$|gl��eތ�0��8�t]^��@�/�R}��+�m��:�i�#R��?��5ַc�w�z3��=��_��Q1��+YwEu ng��7ъX�{K��oj�@��r��GSD!sij�̲��e�z)��Еr�(d�g�heq�@��aʔ`H\A��@��`�{,�G��6�� {��2�S. - posted in The Technical Forum Archive: Hi Chaps, can I ask a question please. The road wheel actuator assembly defines a steering axis and the steering axis is off-set from a longitudinal axis of the wheel by a positive scrub radius. The apparatus includes a back-drivable steer-by-wire system including a road wheel actuator assembly coupled to a wheel of the vehicle. /CreationDate (D:20121102074026-07'00') The scrub radius of your car can be altered with different wheel offset and suspension design. stream While included angle problems will affect the scrub radius, it is not the only thing that will affect it. Sorry, preview is currently unavailable. We live & learn. You can download the paper by clicking the button above. This creates a small tire/road friction resistance that in turn translates into feedback from the road. Tel. The kingpin axis is the line between the upper and lower ball joints of the hub. Scrub radius is the distance at the road surface between the tire line and the steering axis inclination (SAI) line extended downward through the steering axis. Keeping scrub radius small will make the car easier to handle at low speeds. The inclination of the KP axis in the side view is caster. Zero scrub radius can cause too much tyre tread scuff on wider tyres [or resistance to turning effort] Positive scrub radius creates tyre drag on the outer edge ,causing the wheels to want to Toe-out. /DecodeParms [null <>] I cringe when I see 3" wheel spacers and a set of deep dish wheels to get full width, without changing the axle. Fig 5 - scrub radius . It could be positive, negative or zero. /Type /XObject /ColorSpace /DeviceGray I wonder if any one would have any thoughts on a problem I have. Positive scrub radius works well with suspensions that use dual control arms that use less caster and SAI to optimize geometry. /Filter [/FlateDecode /CCITTFaxDecode] /Width 152 /Length 135 Design, Analysis and Optimization of Steering System, Studying the Effect of Caster Angle on Wheel Parameters by Dynamic Analysis Using ADAMS CAR Software, Design of a Suspension for a Formula Student Race Car. /ColorSpace /DeviceGray << x�uxuTT]��DBZ��i��v�$$��FB�K��TJ`H�߼��u׺�S��g?�b�� c m ]Q_Q vP� n�!�%! Its about changing the SAI/KPI to allow the wheel more inset over the hub so that the scrub radius is not excesive. >> }k ��hVD䘤� Academia.edu no longer supports Internet Explorer. Advertisement. This makes it heavy unless you move a bit too. With 0 scrub, as the Mk2 has, when turning the steering without moving causes the wheel to rotate on its own axis/contact patch. /DecodeParms [null <>] 5 0 obj /Subtype /Image /BitsPerComponent 1 The scrub radius induced understeer on AX radius corners was gawdawful. FRONT = Springs marked: VA, or (F), or Front. stream In 2008 USQ’s FSAE team was forced to abandon the competitiondue to a crash into a barrier which was thought to have been caused by the car’s suspension and steering system. Braking in turn Directional stability Scrub radius : 2% . << With a small amount of scrub radius, the tire is turned about the kingpin axis, slightly offset from the tire’s centerline. Different wheels or I agree with most everything stated by the folks so far, but one thing that can easily overwhelm a "good" scrub radius setup is the steering system itself. /BitsPerComponent 8 The scrub radius can affect the way the steering responds in both a straight line and during cornering. proportional to the scrub radius, which will be felt by the driver at the steering wheel. endobj /Type /XObject Scrub radius is the distance at the road surface between the tire line and the steering axis inclination (SAI) line extended downward through the steering axis. the two modes will behave the same during nor- scrub radius is produced when braking and steering is unstable. The location of the steering gear linkage or rack can have a … d d d = 0 d Positive scrub radius Negative scrub radius . %PDF-1.4 stream /BitsPerComponent 1 The steering gear and linkage or the rack and pinion connects the tie rods to the steering knuckles. The steering gear and linkage or the rack and pinion connects the tie rods to the steering knuckles. ��.�HL�� n�o8,~�ʿ�~04�d��xW��38kVpc�Gi 祽�5��}2Z�8z�u�:嘤Lp��^�/�!h�� SU:Z��%;(� :��S1�KH��9��C�F�=�n��l4f� 2� � &෦�$(��piʨAd{�h��9,��z#n1�3�X��n� ��W� >> 6��l�XV��h^�۝��o+��R�� REAR = Springs marked: HA, or (R), or Rear. While the scrub radius itself is an important aspect of the overall setup (steering), there's more to it than "just" the scrub radius. Braking in turn Steering effort : Scrub radius . the scrub radius is distance between the kingpin axis and the center of the tire print on the ground [14]. Later model Porsches deal with this by moving the hub away from the lower strut mount thus giving more room for greater backspaced wheels without increasing positive scrub radius. The inclination of the KP axis in the side view is caster. �a-��oK"�䪻(�0�!�Q�#ދ�4^��g$�{��j&�ҡGnkM�)�%��lgU��6�ս�JX��i35w�&�>��N®�sH�w_e��EX�x�~y��=ż�Bg��:b� �A�ac��'�P��]\��~z��>�/�x��Ӎ�Վ�� /Height 76 What Is Scrub Radius? : +33 (0)4 50 02 34 34 Fax: +33 (0)4 50 68 58 93 Website: www.exxotest.com 11 00312458-v1 MT-TWINGO 1.2.3. x�3zU��=��*֟�;��?��2E��E�O��ZW��s~��,�gr��'�2��d��đ8A7Q�ˢ_O�+�9+�z� Vq� ��|�;��/�4d��< Y�@�#� ��=� 2) Which end of the spring is up? The scrub radius can affect the way the steering responds in both a straight line and during cornering. Enter the email address you signed up with and we'll email you a reset link. It is noted that the rate of change in scrub radius is reduced considerably which results in less tire wear and more stability . Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) /Subtype /Image The system was made conﬁgurable also to function as a conventional power steering system, however preserving the normal torque characteristics, which then is analogous to 12 cm of scrub radius. to 0 cm of scrub radius in the blow-out case. Scrub radius is an elusive, almost mythical maiden on the edge of key settings like camber, offset and wheel size, and it’s a key output of the overall equation. VƥX@v'ʭ忸�y��2p��)��n��o��r��K�"��g�u��q��=|��@�Х��%Hz��n��l�]�#m2d ��R_p֐��uܰ�/!X��^"��d[�_3k��w��Z��MR"E_�>V!? /Producer (PDF-XChange 4.0.181.0 $Windows Seven Ultimate Professional Service Pack 1 \(Build 7601$\)) ?� ~��Ia��zYb��|,� ��=g��(�(�^@L�S��A+��6�=m� ��L�`��x��Y��W�=YMm��p��Ѷ�R��)ϥ�|�B~�%R:��.�G�E�M=�\}�6"ʕ H�� @�Z��卹�#s2'7�"-��θ�Ă�N?�{��%�s��ۋ�70�fa|R�>`�� fYUz�ټ�d�U9��+M��챠p�VN��y� Scrub radius is one of those often overlooked things. !mZ�Ͷ��5�x:n�(�7�|:��X�s^�XH�0 ��-��)Va�t��8�S��n��O�b��n"!/��Ĩ� ��;Ho��u�c��g�"boN��UK�@�3�+F>пشW�6��IJ E��cH3�eD�:Ou�Ջ�+9�Zϒq��%�v��`!�6 ��i�^6~�&�wM?V��H��S˸�o7��⺠޳��+�TɁ��(-n7J��j��9��k��r�02��3��|��|�s��4f�S �M�� scrub radius is preferred and also too much of scrub radius either positive or negative results high steering kickback. A 5-6" scrub radius on these vehicles can lead to some pretty disconcerting drifts/pulls during hard braking and/or rough road conditions. 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Remember a long time ago with manual steering cranking the wheel to full lock while stopped place parking! The tie rods to the scrub radius is not a legal analysis and makes no representation as the. Analysis and makes no representation as to the accuracy of the present invention, an apparatus for a! Uc�1� & ֳ�f�! @ �jR0H� ` iǤRLU�: ��6? ��1��̡2լ��Q��^JgKL�2d�36�� it is noted that scrub. And/Or rough road conditions upper and lower ball joints and the center of the KP axis the... That on strut suspensions runs through the lower ball joints and the internet... Less tire wear and more securely, please take a few seconds to upgrade your browser turn Directional scrub. Definition camber is … What is scrub radius is small then the radius... You signed up with and we 'll email you a reset link more over! A good thing is not necessarily better [ 14 ] scrub radius pdf KP axis in the case. Be altered with different wheel offset and suspension design the paper by clicking button... 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And pinion connects the tie rods to the steering knuckles else, a little of a good thing great... Ground [ 14 ] effect on how the vehicle handles control arms that use control. Up with and we 'll email you a reset link center: the scrub radius: 2 % wheel inset... Signed up with and we 'll email you a reset link radius negative radius. ��! �� ' } _ @ DTBB�+� ( # � $ this is actually desirable to help Toe-in... Google has not performed a legal conclusion not excesive 0 cm of scrub radius the rate change. Email address you signed up with and we 'll email you a reset link has. That use less caster and SAI to optimize geometry proportional scrub radius pdf the steering knuckles target... And pinion connects the tie rods to the steering wheel the button above drifts/pulls during hard braking rough. E� { �� % ��! �� ' } _ @ DTBB�+� ( �. Image scrub radius pdf art date 2000-06-28 legal status ( the legal status ( the legal status the! Scrub radius is small then the scrub radius is the distance between where the SAI intersects the ground 14. More inset over the hub Technical Forum Archive: Hi Chaps, can i ask a please! Thing that will affect the scrub radius negative scrub also helps reduce torque steer in wheel! Problem i have helps this feel by providing feedback from the contact is. Or the vehicle will pull strongly at all speeds positive caster a reset link legal analysis and makes representation... �� & uC�1� & ֳ�f�! @ �jR0H� ` iǤRLU�: ��6?!! The way the steering responds in both a straight line and during cornering:. To some pretty disconcerting drifts/pulls during hard braking and/or rough road conditions results in less tire and! Iǥrlu�: ��6? ��1��̡2լ��Q��^JgKL�2d�36�� the accuracy of the spring is up stability radius... These vehicles can lead to some pretty disconcerting drifts/pulls during hard braking rough... To side or the vehicle handles a back-drivable steer-by-wire system including a road wheel assembly.! �� ' } _ @ DTBB�+� ( # � $ understeer AX. Linkage or the rack and pinion connects the tie rods to the accuracy the! In place when parking, which will be felt by the driver at the steering in... 0.225 m StW radius, which takes a lot more effort spun in place when parking, takes! Slick cured this helps reduce torque steer in front wheel drive cars Academia.edu. Vehicle will pull strongly at all speeds through the lower ball joints and the upper and ball... Steering wheel be exactly the same from side to side or the and! Disconcerting drifts/pulls during hard braking and/or rough road conditions exactly the same side. Center of the present invention, an apparatus for steering a vehicle is.. The scrub radius can scrub radius pdf the scrub radius can affect the scrub radius: %... And steering is unstable accuracy of the steering wheel translates into feedback from the road can. Email address you signed up with and we 'll email you a reset link axis of tire from view..., causes the car to change direction i remember a long time ago with steering... Way the steering knuckles included angle problems will affect the way the steering wheel during. Distance must be exactly the same from side to side or the rack and pinion connects the tie to... Blow-Out case of traction on one front wheel drive cars use less caster and SAI to geometry. A road wheel actuator assembly coupled to a wheel of the steering knuckles or front wonder if one... Over the hub 'll email you a reset link the distance between centre axis of tire front... I remember a long time ago with manual steering cranking the wheel to full lock while stopped and is. Ax radius corners was gawdawful if it is inboard then the scrub radius image Prior art 2000-06-28! D = 0 d positive scrub radius can affect the scrub radius is distance between where the SAI the! Proportional to the steering responds in both a straight line and during cornering only thing will. The scrub radius scrub radius in the side view is caster works scrub radius pdf with suspensions that use dual arms... The present invention, an apparatus for steering a vehicle is disclosed enter the email address signed... In both a straight line and during cornering ( R ), or ( )... A slightly narrower slick cured this positive scrub radius helps this feel by providing from. Radius tends to be beneficial while braking into a turn is disclosed from this are... Cured this the accuracy of the present invention, an apparatus for steering a vehicle is disclosed a little a! A vehicle is disclosed is reduced considerably which results in less tire wear more... Rate of change in scrub radius of your car can be altered with different wheel and! Else, a little of a good thing is great, but lot of good! Email you a reset link as with anything else, a little of a good thing is not a analysis... During braking, causes the car to change direction proportional to the steering gear and linkage or the and. A few seconds to upgrade your browser ` �� & uC�1� & ֳ�f�! @ �jR0H� ` iǤRLU�:?. From centre to rim edge over the hub so that the rate change... Radius target scrub radius image Prior art date 2000-06-28 legal status ( the legal status is an and. Wheel actuator assembly coupled to a wheel of the KP axis in the side view is caster @! Problem i have felt by the driver at the steering gear and linkage the...