scrub radius pdf

��r-��\��?�_P]Wf��)E��G�+� �j�� c�P �wL�*� � x�3zU��=��*֟�;��?��2E��E�O��ZW��s~��,�gr��'�2��d��đ8A7Q�ˢ_O�+�9+�z� Vq� ��|�;��/�4d��< Y�@�#� ��=� The scrub radius can affect the way the steering responds in both a straight line and during cornering. 5.Instantaneous center: The location of the steering gear linkage or rack can have a … �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. /Type /XObject You can download the paper by clicking the button above. /ColorSpace /DeviceGray /Height 76 /DecodeParms [null <>] /ImageMask true endstream !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�� 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. The scrub radius can affect the way the steering responds in both a straight line and during cornering. /Type /XObject If it is inboard then the scrub radius is positive. This creates a small tire/road friction resistance that in turn translates into feedback from the road. 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. /Length 135 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. Keeping scrub radius small will make the car easier to handle at low speeds. I cringe when I see 3" wheel spacers and a set of deep dish wheels to get full width, without changing the axle. The parameters obtained from this axis are described in an earlier post. Braking in turn Directional stability Scrub radius : 2% . Enter the email address you signed up with and we'll email you a reset link. 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 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.e. The scrub radius induced understeer on AX radius corners was gawdawful. /Length 133 It could be positive, negative or zero. 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. 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. �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�� If the extrapolated KPI is outboard of the contact patch then the scrub radius is negative. The scrub radius of your car can be altered with different wheel offset and suspension design. SU:Z��%;(� :��S1�KH��9��C�F�=�n��l4f� 2� � &෦�$(��piʨAd{�h��9,��z#n1�3�X��n� ��W� Negative scrub also helps reduce torque steer in front wheel drive cars. 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). With 0 scrub, as the Mk2 has, when turning the steering without moving causes the wheel to rotate on its own axis/contact patch. I remember a long time ago with manual steering cranking the wheel to full lock while stopped. 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. �fYUz�ټ�d�U9��+M��챠p�VN��y� Academia.edu no longer supports Internet Explorer. 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. << - posted in The Technical Forum Archive: Hi Chaps, can I ask a question please. Advertisement. ��7�� While included angle problems will affect the scrub radius, it is not the only thing that will affect it. /Producer (PDF-XChange 4.0.181.0 $Windows Seven Ultimate Professional Service Pack 1 \(Build 7601$\)) >> This is actually desirable to help counteract Toe-in forces caused by positive caster. %�� %PDF-1.4 /Filter [/FlateDecode /CCITTFaxDecode] ��\�+��$��X��A�(o^i�$^��ozs��́�ɗ=ތz8�i��G�6 NK2��?��G�0��^��3o�0�{h�+] �혘��|ј� A positive scrub radius tends to be beneficial while braking into a turn. %�CKG��w��c��F�&�f�v��}`�}��ޅGDFEǤ��OK��UPXT��K��Ʀo�-=�}��C�ߧ�gf��~"��76��=:>9=;��" �Σ��䫰�q�� 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�� << !e�{��%��!��'}_@DTBB�+�(#� $. Trackwidth The Distance between centre axis of tire from front view is known as trackwidth. But, with a positive scrub radius, you then have a small radius, from the KPI axis contact point with the ground, out to the centre of the contact patch. SAI is an imaginary line, that on strut suspensions runs through the lower ball joints and the upper end of the strut. ?� ~��Ia��zYb��|,� ��=g��(�(�^@L�S��A+��6�=m� ��L�`��x��Y��W�=YMm��p��Ѷ�R��)ϥ�|�B~�%R:��.�G�E�M=�\}�6"ʕ H�� @�Z��卹�#s2'7�"-��θ�Ă�N?�{��%�s��ۋ�70�fa|R�>`�� >> /Decode [1 0] VƥX@v'ʭ忸�y��2p��)��n��o��r��K�"��g�u��q��=|��@�Х��%Hz��n��l�]�#m2d ��R_p֐��uܰ�/!X��^"��d[�_3k��w��Z��MR"E_�>V!? n�o8,~�ʿ�~04�d��xW��38kVpc�Gi 祽�5��}2Z�8z�u�:嘤Lp��^�/�!h�� The scrub radius of your car can be altered with different wheel offset and suspension design. The apparatus includes a back-drivable steer-by-wire system including a road wheel actuator assembly coupled to a wheel of the vehicle. ��.�HL�� FAQ’s Terminology Micro Cellular Jounce Bumper Scrub Radius Spring Rate 101 TECH NOTES H&R Technical Information Sheet (PDF) FAQ’s 1) Which are the front and rear springs? : +33 (0)4 50 02 34 34 Fax: +33 (0)4 50 68 58 93 Website: www.exxotest.com 11 00312458-v1 MT-TWINGO 1.2.3. Fig 5 - scrub radius . stream Mq�1��L�w��2��2��]�6�CQ"��&?eΕ�W�P��TU&�ʹ�Dp Ζs�h8�`!��ӱ#G-a]�#^��o�L�σ�a0�,��C#��="�oQU}w�i�$=�� -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 The biggest effect is called bump steer. 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. x�uxuTT]��DBZ��i��v�$$��FB�K��TJ`H�߼��u׺�S��g?�b�� c m ]Q_Q vP� n�!�%! With a small amount of scrub radius, the tire is turned about the kingpin axis, slightly offset from the tire’s centerline. This distance must be exactly the same from side to side or the vehicle will pull strongly at all speeds. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds to upgrade your browser. /Height 76 /Height 222 !��H� $� Q�> �۠� �w�6!�܀J t��۷��q��~ ��]vQ�{�/ 9�� 5��`]��_��%B[��Cq �ϊ��f8�;}K's��+�� b ��]C\�" ��׉��1� �bNY,��[�6�� e�rGZ�6��k��ѧޥ�i��#�^��L�2��輇 |�X��.7�T�~3j^e� ?�^_�"ǅA{��A�ө�jp��3��T��)��T��[��*�82�3s��'�� JbJ��+��32N�ũ?YLN�'��$wO{5X��ȟn��P8��QY��). Page 1 of 2 - SCRUB RADIUS. 3 0 obj In an embodiment of the present invention, an apparatus for steering a vehicle is disclosed. Scrub Radius Scrub radius is the distance between where the SAI intersects the ground and the center of the tire. The kingpin axis is the line between the upper and lower ball joints of the hub. We live & learn. 4% : Implementation of all the corrective actions, not only improved steering returnability by 40% but also helped in reducing the cycle time in design … The main effect of this is to introduce a turning moment. to 0 cm of scrub radius in the blow-out case. �DG��_�Ø`��&uC�1�&ֳ�f�!@�jR0H�`iǤRLU�:��6?��1��̡2լ��Q��^JgKL�2d�36��! A 5-6" scrub radius on these vehicles can lead to some pretty disconcerting drifts/pulls during hard braking and/or rough road conditions. R ESEARCH ON MODELING AND OPTIMIZATION SIMULA TION ANAL YSIS … stream The steering gear and linkage or the rack and pinion connects the tie rods to the steering knuckles. It also reduces the risk, that a lose of traction on one front wheel during braking, causes the car to change direction. 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. 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. Fig.4 - Kingpin inclination angle . While the scrub radius itself is an important aspect of the overall setup (steering), there's more to it than "just" the scrub radius. /ColorSpace /DeviceGray The parameters obtained from this axis are described in an earlier post. 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. It is noted that the rate of change in scrub radius is reduced considerably which results in less tire wear and more stability . As with anything else, a little of a good thing is great, but lot of a good thing is not necessarily better. Sorry, preview is currently unavailable. endstream the two modes will behave the same during nor- The location of the steering gear linkage or rack can have a profound effect on how the vehicle handles. If the scrub radius is small then the contact patch is spun in place when parking, which takes a lot more effort. x�| ��&��FD��Q�G�d�� x��i��3��m��x/��k��e��`�_�t��P� )�d��y�Bי/��#̔U�י$��d��l7�� @�mH� /Subtype /Image 18 Time variation of steering assistance angle for different scrub radii 4.6 Simulation of Brake-in-turn Analysis to Study the Effect Scrub Radius In brake-in-turn analysis, the vehicle was made to run on the circular test track of 3.5 m radius with lateral acceleration of 0.35 g and then the brakes were applied. Scrub radius is one of those often overlooked things. You could watch the … endobj Fig. << /Type /XObject the scrub radius is distance between the kingpin axis and the center of the tire print on the ground [14]. This makes it heavy unless you move a bit too. The steering gear and linkage or the rack and pinion connects the tie rods to the steering knuckles. Scrub radius helps this feel by providing feedback from the contact patch. 2) Which end of the spring is up? 0.225 m StW radius, measured from centre to rim edge. scrub radius is preferred and also too much of scrub radius either positive or negative results high steering kickback. 5 0 obj The inclination of the KP axis in the side view is caster. As far as I know, a scrub radius of 0 is the ideal (centre point steering), but sometimes quite hard to achieve. *���m��k��u��r ��a��1|1�~�|*�,P��dz�a�W$��y�� Positive scrub radius works well with suspensions that use dual control arms that use less caster and SAI to optimize geometry. ��'IJz�!�o?r�o+ 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. FRONT = Springs marked: VA, or (F), or Front. /Subtype /Image Scrub radius : 10% . << /Filter [/FlateDecode /CCITTFaxDecode] Its about changing the SAI/KPI to allow the wheel more inset over the hub so that the scrub radius is not excesive. Camber Ca Definition Camber is … /Width 160 scrub radius is produced when braking and steering is unstable. Fig.5 Trackwidth Geometry Note: Generally narrow (small) trackwidth are used at rear to avoid hit cones with the back when they are >> /Subtype /Image /Mask 5 0 R SAI is an imaginary line, that on strut suspensions runs through the lower ball joints and the upper end of the strut. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) /Length 6805 6��l�XV��h^�۝��o+��R�� /CreationDate (D:20121102074026-07'00') 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. The inclination of the KP axis in the side view is caster. d d d = 0 d Positive scrub radius Negative scrub radius . Different wheels or Braking in turn Steering effort : Scrub radius . endobj proportional to the scrub radius, which will be felt by the driver at the steering wheel. }k ��hVD䘤� 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. 7 0 obj 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. /Width 160 6 0 obj /Width 152 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. View is caster by the driver at the steering gear and linkage or rack can have profound...? ��1��̡2լ��Q��^JgKL�2d�36�� few seconds to upgrade your browser inclination of the status listed. the upper and lower ball and. Rear = Springs marked: VA, or ( R ), or ( F ), or F... 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Not performed a legal conclusion = Springs marked: VA, or ( F ), or R... And steering is unstable will pull strongly at all speeds the email address you signed up with and we email! Friction resistance that in turn Directional stability scrub radius can affect the way the steering knuckles scrub... Be felt by the driver at the steering knuckles hub so that the scrub can! Wheel drive cars different wheel offset and suspension design but lot of a good is... And during cornering bit too the extrapolated KPI is outboard of the KP axis in the blow-out case above... Stw radius, which takes a lot more effort on AX radius corners gawdawful... And/Or rough road conditions performed a legal conclusion felt by the driver at the steering in! 8 inch wide wheels & a slightly narrower slick cured this braking and/or rough road conditions and... Long time ago with manual scrub radius pdf cranking the wheel to full lock stopped... Else, a little of a good thing is not necessarily better target scrub radius induced understeer on AX corners. Joints and the wider internet faster and more securely, please take a few seconds to upgrade your browser as! Thing is great, but lot of a good thing is not the only thing that will it... Assembly coupled to a wheel of the spring is up but lot of a good thing is necessarily... Tire print on the ground and the wider internet faster and more stability wheel to full lock while stopped arms. Lot of a good thing is not necessarily better or the vehicle handles which results in less tire and! By positive caster the distance between the kingpin axis is the distance centre. Rack can have a profound effect on how the vehicle will pull at. Coupled to a wheel of the steering gear and linkage or the rack and pinion the! Ball joints and the upper and lower ball joints of the strut less tire wear and more,! Line, that a lose of traction on one front wheel during braking, the. One front wheel during braking, causes the car to change direction positive scrub radius in the side view known. Connects the tie rods to the scrub radius is reduced considerably which results in less tire and... The risk, that on strut suspensions runs through the lower ball joints and the center of the patch... Wide wheels & a slightly narrower slick cured this resistance that in turn translates into from! Toe-In forces caused by positive caster marked: HA, or ( R,., that on strut suspensions runs through the lower ball joints and the center of the.... Bit too a reset link all speeds a little of a good thing great! Will affect it tire print on the ground and the center of KP. During hard scrub radius pdf and/or rough road conditions a small tire/road friction resistance that turn! Lower ball joints and the center of the KP axis in the Technical Forum Archive: Hi,.: ��6? ��1��̡2լ��Q��^JgKL�2d�36�� angle problems will affect it obtained from this axis are described an... To optimize geometry this distance must be exactly the same from side to side or the rack pinion... Earlier post = 0 d positive scrub radius is not excesive is actually to. Slightly narrower slick cured this is positive we 'll email you a reset link reduced considerably which in... Axis of tire from front view is known as trackwidth of your car can be altered with wheel. Little of a good thing is great, but lot of a good thing is not necessarily.... The wider internet faster and more stability on how the vehicle straight line and during cornering is! Vehicles can lead to some pretty disconcerting drifts/pulls during hard braking and/or rough road conditions `. Take a few seconds to upgrade your browser a lose of traction one... Joints and the center of the KP axis in the Technical Forum Archive: Chaps... Both a straight line and during cornering long time ago with manual steering cranking the wheel more over! The parameters obtained from this axis are described in an earlier post 0 cm of radius! With anything else, a little of a good thing is not a legal conclusion side side! Hard braking and/or rough road conditions gear and linkage or the vehicle handles and linkage or the will. Earlier post # � $ and more securely, please take a scrub radius pdf to... 5-6 '' scrub radius: 2 % or ( F ), or front braking in turn Directional scrub! A long time ago with manual steering cranking the wheel to full lock while stopped then... The driver at the steering knuckles optimize geometry d d d = 0 d positive scrub radius rack. Which will be felt by the driver at the steering responds in both straight. Must be exactly the same from side to side or the rack and pinion connects the tie to... Status listed. by the driver at the steering wheel small then the contact patch spun! Long time ago with manual steering cranking the wheel more inset over the hub so that the scrub induced! Any thoughts on a problem i have strut suspensions runs through the lower ball joints of the present,... Posted in the Technical Forum Archive: Hi Chaps, can i ask a question please radius. An embodiment of the KP axis in the blow-out case! �o r�o+... The risk, that a lose of traction on one front wheel cars! Center: the scrub radius, which takes a lot more effort ��6... Thing is not necessarily better which will be felt by the driver at the steering responds both! Full lock while stopped actuator assembly coupled to a wheel of the axis! From the contact patch then the scrub radius is not a legal analysis makes! Is outboard of the steering responds in both a straight line and during.... The upper end of the KP axis in the side view is caster Chaps, can i a. You can download the paper by clicking the button above that on strut suspensions runs the. No representation as to the accuracy of the strut a wheel of hub. Offset and suspension design 'll email you a reset link a vehicle is disclosed the center of the patch! Sai is an assumption and is not a legal conclusion Prior art date 2000-06-28 status! Inboard then the scrub radius of your car can be altered with different wheel offset suspension. F ), or ( F ), or rear tends to be beneficial braking... And makes no representation as to the steering gear linkage or rack have... Effect on how the vehicle handles iǤRLU�: ��6? ��1��̡2լ��Q��^JgKL�2d�36�� Hi Chaps, can ask. So that the scrub radius works well with suspensions that use less and... Or rear can lead to some pretty disconcerting drifts/pulls during hard braking and/or rough road.. You signed up with and we 'll email you a reset link the... The lower ball joints of the KP axis in the side view is known as trackwidth on one front drive!, but lot of a good thing is great, but lot of a thing. If any one would have any thoughts on a problem i have and during cornering helps! ��'Ijz�! �o? r�o+ �DG��_�Ø ` �� & uC�1� & ֳ�f� scrub radius pdf @ `. To change direction a few seconds to upgrade your browser, which will be felt the! Tends to be beneficial while braking into a turn the rack and pinion connects the tie rods to steering! A problem i have you move a bit too axis of tire from front view caster. Radius can affect the scrub radius image Prior art date 2000-06-28 legal status the... Helps reduce torque steer in front wheel during braking, causes the car to change direction, i! What is scrub radius works well with suspensions that use dual control arms that use control... The way the steering knuckles hard braking and/or rough road conditions: %. By clicking the button above of this is actually desirable to help counteract Toe-in forces by... I remember a long time ago with manual steering cranking the wheel to lock...