MOTORCYCLE FRONT WHEEL PATTER IN HEAVY BRAKING

The phenomenon of wheel patter as it occurs in the heavy braking of motorcycles in essentially straight line motion is described briefly as probably consisting mainly of vertical and longitudinal motions of the front wheel, which has cyclic variations in its spin velocity. In extreme circumstances, it is likely that the oscillation is selfsustaining until the motorcycle speed has reduced sufficiently for stabilisation or removal of the energy source, that is the motorcycle's forward motion, to occur. Reference has been made to previous work on automobile axle tramping vibrations in order to find an explanation of the phenomenon, and has led to the setting up of a mathematical model of the motorcycle and to the examination of its behavioural properties by digital computer simulation. The model includes only the front frame assembly taken to be pivotted about a horizontal axis and spring restrained to an infinitely massive rear frame. Plunging of the telescopic forks, spinning of the road wheel, and spinning of the tyre tread band restrained by the tyre carcass elasticity are allowed motions, so that the model has four degrees of freedom. The tyre braking force is represented as an empirical non-linear function of longitudinal slip and wheel load, and provision is included for the tyre leaving contact with the ground. With suitable but realistic choices of parameter values, the simulation exhibits self-excited oscillations at a frequency near to the natural frequency of the wheel hop model, but a substantial part of the motion concerns the forks pivotting on the rear frame compliance, giving the wheel spindle an elliptical orbit. The frame compliance parameter controls the tuning of the wheel vertical and horizontal free vibrations and influences the system stability strongly. The effects of several other system design and operational parameters have been studied and recorded. If confirmed by experiment or experience, the theory provides a basis for understanding the mechanics of the oscillations, for designing well damped systems, and for deciding on effective modifications in problem cases. For the covering abstract of the conference see TRIS 395019. (Author/TRRL)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/9026504616
• Supplemental Notes:
  • Papers from the Proceedings of the 8th IAVSD Symposium, the Dynamics of Vehicles of Roads and Railway Tracks, Held at Massachusetts Institute of Technology, Cambridge, Massachusetts, August 15-19, 1983.
• Corporate Authors:

  Swets & Zeitlinger

  Heereweg 347B
  2161 CA Lisse,   Netherlands 
• Authors:
  • SHARP, R S
  • Giles, C G
• Conference:
  • Papers from the Proceedings of the 8th IAVSD Symposium, the Dynamics of Vehicles of Roads and Railway Tracks, Held at Massachusetts Institute of Technology, Cambridge, Massachusetts, August 15-19, 1983.
• Publication Date: 1984

Media Info

• Features: Figures; References;
• Pagination: p. 578-590

Subject/Index Terms

• TRT Terms: Behavior; Braking; Braking performance; Conferences; Digital computers; Dynamics; Mathematical models; Motorcycles; Oscillation; Simulation; Speed; Tires; Vehicle front end; Vibration; Wheel loads; Wheels
• Uncontrolled Terms: Front
• Old TRIS Terms: Braking force coefficient; Front wheels
• ITRD Terms: 9001: Behaviour; 1874: Braking; 8525: Conference; 8673: Digital computer; 5473: Dynamics; 9025: Front; 6473: Mathematical model; 1221: Motorcycle; 9103: Simulation; 5408: Speed; 5558: Vibration; 1372: Wheel
• Subject Areas: Highways; Vehicles and Equipment; I91: Vehicle Design and Safety;

Filing Info

• Accession Number: 00395037
• Record Type: Publication
• Source Agency: Institute for Road Safety Research, SWOV
• ISBN: 90-265-0461-6
• Report/Paper Numbers: REPORT
• Files: ITRD, TRIS
• Created Date: Oct 31 1985 12:00AM