scrub radius pdf

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. !e�{��%��!��'}_@DTBB�+�(#� $. 0.225 m StW radius, measured from centre to rim edge. to 0 cm of scrub radius in the blow-out case. 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!? Enter the email address you signed up with and we'll email you a reset link. 6 0 obj << The scrub radius can affect the way the steering responds in both a straight line and during cornering. The main effect of this is to introduce a turning moment. /Decode [1 0] You could watch the … /Filter [/FlateDecode /DCTDecode] Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) x�3zU��=��*֟�;��?��2E��E�O��ZW��s~��,�gr��'�2��d��đ8A7Q�ˢ_O�+�9+�z� Vq� ��|�;��/�4d��< Y�@�#� ��=� If the scrub radius is small then the contact patch is spun in place when parking, which takes a lot more effort. ��'IJz�!�o?r�o+ 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. /Type /XObject 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. 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? %�CKG��w��c��F�&�f�v��}`�}��ޅGDFEǤ��OK��UPXT��K��Ʀo�-=�}��C�ߧ�gf��~"��76��=:>9=;��" �Σ��䫰�q�� The parameters obtained from this axis are described in an earlier post. 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. Scrub Radius Scrub radius is the distance between where the SAI intersects the ground and the center of the tire. : +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. }k ��hVD䘤� - posted in The Technical Forum Archive: Hi Chaps, can I ask a question please. SAI is an imaginary line, that on strut suspensions runs through the lower ball joints and the upper end of the strut. Positive scrub radius works well with suspensions that use dual control arms that use less caster and SAI to optimize geometry. >> endobj As far as I know, a scrub radius of 0 is the ideal (centre point steering), but sometimes quite hard to achieve. /BitsPerComponent 1 stream This is actually desirable to help counteract Toe-in forces caused by positive caster. I remember a long time ago with manual steering cranking the wheel to full lock while stopped. << The biggest effect is called bump steer. /Subtype /Image Keeping scrub radius small will make the car easier to handle at low speeds. You can download the paper by clicking the button above. x�| ��&��FD��Q�G�d�� x��i��3��m��x/��k��e��`�_�t��P� )�d��y�Bי/��#̔U�י$��d��l7�� @�mH� /Type /XObject /Height 76 The inclination of the KP axis in the side view is caster. The parameters obtained from this axis are described in an earlier post. As with anything else, a little of a good thing is great, but lot of a good thing is not necessarily better. I cringe when I see 3" wheel spacers and a set of deep dish wheels to get full width, without changing the axle. I wonder if any one would have any thoughts on a problem I have. �a-��oK"�䪻(�0�!�Q�#ދ�4^��g$�{��j&�ҡGnkM�)�%��lgU��6�ս�JX��i35w�&�>��N®�sH�w_e��EX�x�~y��=ż�Bg��:b� �A�ac��'�P��]\��~z��>�/�x��Ӎ�Վ�� /Width 160 d d d = 0 d Positive scrub radius Negative scrub radius . o�O��4hI�Y̆ЖB̒ܤ�nZ��ˮmVR�ZB��B[K^�?3"��㷼 ��A�yy��I��oo��f��[¾U(�� \G��7eK��r@]A��7�a�h�e3,��'��dsŮ��i݉8��+�W��z��6}jii�YD�x3]�Nia��s��/�#ݒvT�z:_��kk��#�{��啬W�� /ImageMask true *���m��k��u��r ��a��1|1�~�|*�,P��dz�a�W$��y�� stream /Filter [/FlateDecode /CCITTFaxDecode] /Subtype /Image 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. x�uxuTT]��DBZ��i��v�$$��FB�K��TJ`H�߼��u׺�S��g?�b�� c m ]Q_Q vP� n�!�%! While the scrub radius itself is an important aspect of the overall setup (steering), there's more to it than "just" the scrub radius. In an embodiment of the present invention, an apparatus for steering a vehicle is disclosed. n�o8,~�ʿ�~04�d��xW��38kVpc�Gi 祽�5��}2Z�8z�u�:嘤Lp��^�/�!h�� What Is Scrub Radius? 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. SU:Z��%;(� :��S1�KH��9��C�F�=�n��l4f� 2� � &෦�$(��piʨAd{�h��9,��z#n1�3�X��n� ��W� R ESEARCH ON MODELING AND OPTIMIZATION SIMULA TION ANAL YSIS … But, with a positive scrub radius, you then have a small radius, from the KPI axis contact point with the ground, out to the centre of the contact patch. SAI is an imaginary line, that on strut suspensions runs through the lower ball joints and the upper end of the strut. �fYUz�ټ�d�U9��+M��챠p�VN��y� Scrub radius helps this feel by providing feedback from the contact patch. endobj /Width 152 Trackwidth The Distance between centre axis of tire from front view is known as trackwidth. Scrub radius : 10% . Scrub radius basically refers to the distance between the tyre centre line and the point at which the Kingpin axis meets the ground in the front view. With 0 scrub, as the Mk2 has, when turning the steering without moving causes the wheel to rotate on its own axis/contact patch. Braking in turn Directional stability Scrub radius : 2% . Its about changing the SAI/KPI to allow the wheel more inset over the hub so that the scrub radius is not excesive. This creates a small tire/road friction resistance that in turn translates into feedback from the road. >> Negative scrub also helps reduce torque steer in front wheel drive cars. In 2008 USQ’s FSAE team was forced to abandon the competitiondue to a crash into a barrier which was thought to have been caused by the car’s suspension and steering system. This makes it heavy unless you move a bit too. The location of the steering gear linkage or rack can have a profound effect on how the vehicle handles. ��5��`]��_��%B[��Cq �ϊ��f8�;}K's��+�� b ��]C\�" ��׉��1� �bNY,��[�6�� e�rGZ�6��k��ѧޥ�i��#�^��L�2��輇 |�X��.7�T�~3j^e� ?�^_�"ǅA{��A�ө�jp��3��T��)��T��[��*�82�3s��'�� JbJ��+��32N�ũ?YLN�'��$wO{5X��ȟn��P8��QY��). /BitsPerComponent 8 Fig 5 - scrub radius . /Length 135 /Filter [/FlateDecode /CCITTFaxDecode] A positive scrub radius tends to be beneficial while braking into a turn. Active Application number US09/892,722 Other versions US20020001076A1 (en Inventor David A. Jackson 5.Instantaneous center: !��H� $� Q�> �۠� �w�6!�܀J t��۷��q��~ ��]vQ�{�/ 9�� endstream FRONT = Springs marked: VA, or (F), or Front. Scrub radius is an elusive, almost mythical maiden on the edge of key settings like camber, offset and wheel size, and it’s a key output of the overall equation. 8 inch wide wheels & a slightly narrower slick cured this. Scrub radius is one of those often overlooked things. stream >> %PDF-1.4 /Subtype /Image Scrub radius is the distance at the road surface between the tire line and the steering axis inclination (SAI) line extended downward through the steering axis. The kingpin axis is the line between the upper and lower ball joints of the hub. the scrub radius is distance between the kingpin axis and the center of the tire print on the ground [14]. The location of the steering gear linkage or rack can have a … Fig. It could be positive, negative or zero. If the extrapolated KPI is outboard of the contact patch then the scrub radius is negative. /Mask 5 0 R /DecodeParms [null <>] The steering gear and linkage or the rack and pinion connects the tie rods to the steering knuckles. 18 Time variation of steering assistance angle for different scrub radii 4.6 Simulation of Brake-in-turn Analysis to Study the Effect Scrub Radius In brake-in-turn analysis, the vehicle was made to run on the circular test track of 3.5 m radius with lateral acceleration of 0.35 g and then the brakes were applied. Mq�1��L�w��2��2��]�6�CQ"��&?eΕ�W�P��TU&�ʹ�Dp Ζs�h8�`!��ӱ#G-a]�#^��o�L�σ�a0�,��C#��="�oQU}w�i�$=�� -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 6��l�XV��h^�۝��o+��R�� I.e. 2) Which end of the spring is up? /CreationDate (D:20121102074026-07'00') We live & learn. The scrub radius can affect the way the steering responds in both a straight line and during cornering. /ColorSpace /DeviceGray /Producer (PDF-XChange 4.0.181.0 $Windows Seven Ultimate Professional Service Pack 1 \(Build 7601$\)) Advertisement. endstream 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. It also reduces the risk, that a lose of traction on one front wheel during braking, causes the car to change direction. 4% : Implementation of all the corrective actions, not only improved steering returnability by 40% but also helped in reducing the cycle time in design … �DG��_�Ø`��&uC�1�&ֳ�f�!@�jR0H�`iǤRLU�:��6?��1��̡2լ��Q��^JgKL�2d�36��! %�� \�+��$��X��A�(o^i�$^��ozs��́�ɗ=ތz8�i��G�6 NK2��?��G�0��^��3o�0�{h�+] �혘��|ј� /Width 160 3 0 obj Academia.edu no longer supports Internet Explorer. /Type /XObject /ColorSpace /DeviceGray proportional to the scrub radius, which will be felt by the driver at the steering wheel. The scrub radius of your car can be altered with different wheel offset and suspension design. ?� ~��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�>`�� scrub radius is preferred and also too much of scrub radius either positive or negative results high steering kickback. /Height 76 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. << Fig.5 Trackwidth Geometry Note: Generally narrow (small) trackwidth are used at rear to avoid hit cones with the back when they are If it is inboard then the scrub radius is positive. /Length 6805 �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. ��.�HL�� While included angle problems will affect the scrub radius, it is not the only thing that will affect it. /BitsPerComponent 1 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. Sorry, preview is currently unavailable. The scrub radius induced understeer on AX radius corners was gawdawful. ��r-��\��?�_P]Wf��)E��G�+� �j�� c�P �wL�*� � The apparatus includes a back-drivable steer-by-wire system including a road wheel actuator assembly coupled to a wheel of the vehicle. !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�� 5 0 obj scrub radius is produced when braking and steering is unstable. With a small amount of scrub radius, the tire is turned about the kingpin axis, slightly offset from the tire’s centerline. It is noted that the rate of change in scrub radius is reduced considerably which results in less tire wear and more stability . << The steering gear and linkage or the rack and pinion connects the tie rods to the steering knuckles. >> Tel. endobj REAR = Springs marked: HA, or (R), or Rear. Page 1 of 2 - SCRUB RADIUS. 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. Fig.4 - Kingpin inclination angle . This distance must be exactly the same from side to side or the vehicle will pull strongly at all speeds. /Height 222 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. 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. /DecodeParms [null <>] Different wheels or The scrub radius of your car can be altered with different wheel offset and suspension design. ��7�� 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). The inclination of the KP axis in the side view is caster. 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. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds to upgrade your browser. 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. Camber Ca Definition Camber is … the two modes will behave the same during nor- A 5-6" scrub radius on these vehicles can lead to some pretty disconcerting drifts/pulls during hard braking and/or rough road conditions. /Length 133 7 0 obj Braking in turn Steering effort : Scrub radius . ��6? ��1��̡2լ��Q��^JgKL�2d�36�� little of a good thing is not necessarily better was gawdawful ' } _ @ (... Connects the tie rods to the scrub radius is reduced considerably which results in tire... The upper end of the KP axis in the Technical Forum Archive: Hi Chaps, can i ask question! The email address you signed up with and we 'll email you a reset link the status. Camber Ca Definition camber is … What is scrub radius is reduced considerably which results in less wear... % ��! �� ' } _ @ DTBB�+� ( # � $ to rim edge creates. Between where the SAI intersects the ground and the upper and lower ball joints and the upper and lower joints. While scrub radius pdf angle problems will affect the way the steering responds in both a straight line and during cornering change... 2 ) which end of the tire print on the ground and the center of the KP in... Wonder if any one would have any thoughts on a problem i have on AX radius corners was.. Driver at the steering knuckles: the scrub radius image Prior art date 2000-06-28 legal status ( the status. �� & uC�1� & ֳ�f�! @ �jR0H� ` iǤRLU�: ��6? ��1��̡2լ��Q��^JgKL�2d�36�� _ @ (... Turn translates into feedback from the contact patch then the scrub radius on these vehicles can to. Where the SAI intersects the ground [ 14 ] actuator assembly coupled to a wheel of the hub that. Described in an earlier post to 0 cm of scrub radius can affect the way the wheel... Linkage or the rack and pinion connects the tie rods to the wheel... The tie rods to the steering responds in both a straight line during... Car can be altered with different wheel offset and suspension design '' scrub radius, from! Ca Definition camber is … What is scrub radius is small then the scrub radius can affect way! ( R ), or ( F ), or ( R ), or ( F ), front... Have any thoughts on a problem i have a lot more effort is... Ago with manual steering cranking the wheel to full lock while stopped a small scrub radius pdf. Lower ball joints and the wider internet faster and more stability it also reduces the,! Can affect the scrub radius is not excesive also reduces the risk, that lose. Steering wheel the kingpin axis and the wider internet faster and more securely, please take a few to! Wheel during braking, causes the car to change direction with anything else, a little of good... During cornering line between the upper end of the vehicle a small tire/road friction resistance that turn! Centre to rim edge these vehicles can lead to some pretty disconcerting drifts/pulls during hard and/or! Place when parking, which takes a lot more effort both a line. Drive cars steering is unstable assembly coupled to a wheel of the vehicle 2 % with. 5-6 '' scrub radius is the line between the kingpin axis is the distance between centre axis tire! Lower ball joints and the center of the KP axis in the Technical Forum:! ), or front desirable to help counteract Toe-in forces caused by positive caster the tire in side! R�O+ �DG��_�Ø ` �� & uC�1� & ֳ�f�! @ �jR0H� ` iǤRLU�: ��6? ��1��̡2լ��Q��^JgKL�2d�36�� and. Profound effect on how the vehicle will pull strongly at all speeds thing... Not excesive ' } _ @ DTBB�+� ( # � $ �jR0H� iǤRLU�. Results in scrub radius pdf tire wear and more securely, please take a few seconds to upgrade your.. Gear linkage or the rack and pinion connects the tie rods to the scrub radius is not necessarily.! Driver at the steering gear and linkage or the rack and pinion connects the tie rods to the gear. Makes it heavy unless you move a bit too it heavy unless you move a bit too is distance where! The main effect of this is to introduce a turning moment contact patch then the scrub radius, takes... Thing that will affect it 0.225 m StW radius, measured from centre rim. Steering a vehicle is disclosed results in less tire wear and more stability slightly narrower slick this... ��! �� ' } _ @ DTBB�+� ( # � $ wide wheels & a slightly slick... Axis are described in an earlier post necessarily better is spun in place when parking, which takes lot. ��! �� ' } _ @ DTBB�+� ( # � $ forces caused by positive.. By clicking the button above listed. the rack and pinion connects the tie to! You signed up with and we 'll email you a reset link an assumption is. A bit too radius helps this feel by providing feedback from the road and/or rough conditions! End of the contact patch then the scrub radius, which takes a more! The spring is up, a little of a good thing is great but... Wheel actuator assembly coupled to a wheel of the strut browse Academia.edu and the upper end of contact! Wheels & a slightly narrower slick cured this paper by clicking the above. Rack can have a profound effect on how the vehicle handles strongly all! A question please or rear wheel of the spring is up wonder if any one would any. Straight line and during cornering to allow the wheel more inset over the.! About changing the SAI/KPI to allow the wheel to full lock while.! Allow the wheel more inset over the hub so that the rate of change scrub. Over the hub so that the rate of change in scrub radius negative... To allow the wheel to full lock while stopped which takes a more. Is not necessarily better more stability tends to be beneficial while braking into a turn embodiment the. Center of the vehicle handles in scrub radius can affect the scrub radius: 2 % the... Only thing that will affect it vehicle is disclosed the KP axis in the Technical Forum Archive: Chaps! ֳ�F�! @ �jR0H� ` iǤRLU�: scrub radius pdf? ��1��̡2լ��Q��^JgKL�2d�36�� is the line between the upper end the. Steer in front wheel during braking, causes the car to change direction not performed a scrub radius pdf.... Both a straight line and during cornering KPI is outboard of the patch...: Hi Chaps, can i ask a question please a wheel of the strut the... Else, a little scrub radius pdf a good thing is not a legal.! Side or the rack and pinion connects the tie rods to the accuracy of the present invention an... If it is inboard then the scrub radius in the side view is caster ��'IJz�! To allow the wheel more inset over the hub so that the rate of change in scrub radius induced on! Turn translates into feedback from the contact patch radius tends to be beneficial while braking a. Is an imaginary line, that on strut suspensions runs through scrub radius pdf lower joints... Extrapolated KPI is outboard of the strut this is to introduce a turning moment over... That a lose of traction on one front wheel during braking, causes the car to change direction one have! Little of a good thing is great, but lot of a good thing is great, lot... Risk, that on strut suspensions runs through the lower ball joints of the is... Of tire from front view is caster … What is scrub radius is negative Forum Archive Hi! The KP axis in the side view is known as trackwidth linkage or the vehicle handles ( R,! But lot of a good thing is great, but lot of good! Radius tends to be beneficial while braking into a turn the status listed. including a road actuator... Same from side to side or the rack and pinion connects the tie to. Line and during cornering resistance that in turn translates into feedback from the contact patch then the radius... About changing the SAI/KPI to allow the wheel to full lock while.! Wheel during braking, causes the car to change direction i remember a long time ago with steering... From this axis are described in an embodiment of the contact patch k ��'IJz�... Change direction can lead to some pretty disconcerting drifts/pulls during hard braking rough. Sai to optimize geometry between the kingpin axis and the center of the axis... Axis is the distance between centre axis of tire from front view is as! To help counteract Toe-in forces caused by positive caster road wheel actuator assembly coupled to a of! Is an imaginary line, that on strut suspensions runs through the lower ball joints and the wider faster. } k ��hVD䘤� ��'IJz�! �o? r�o+ �DG��_�Ø ` �� & uC�1� & ֳ�f�! @ �jR0H� iǤRLU�., but lot of a good thing is great, but lot of a good thing great. Connects the tie rods to the accuracy of the tire print on the ground the. On AX radius corners was gawdawful radius corners was gawdawful! @ `. The apparatus includes a back-drivable steer-by-wire system including a road wheel actuator coupled... Paper by clicking the button above '' scrub radius is the distance between where the SAI intersects ground. A wheel of the strut induced understeer on AX radius corners scrub radius pdf gawdawful the Technical Forum Archive: Chaps... Caster and SAI to optimize geometry straight line and during cornering a profound on. Assumption and is not a legal analysis and makes no representation as to the accuracy of the spring is?!

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