01 Basic%20Suspension%20Geometry, BMW educational info, Dokumentacja

01 ...

01 Basic%20Suspension%20Geometry, BMW educational info, Dokumentacja

[ Pobierz całość w formacie PDF ]
//-->Table of ContentsBasic Suspension GeometrySubjectPageIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Alignment Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Caster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Caster Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Camber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Positive Camber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Negative Camber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Toe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8Toe Out on Turns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Steering Roll Radius (Steering Offset) . . . . . . . . . . . . . . . . . . . . . . . . . . .10Steering Axis Inclination (SAI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Included Angle (IA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Geometric Axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Thrust Line/Thrust Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Positive Thrust Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Negative Thrust Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Alignment Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Wheelbase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Track Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Initial Print Date: 3/06Revision Date:Basic Suspension GeometryModel: AllAfter completion of this module you will be able to:• Understand basic suspension geometry.• Understand the relationship between alignment angles and ride quality.• Understand the effect of alignment angles on tire wear.2Basic Suspension GeometryIntroductionThe safety, stability, handling and performance of a vehicle depends on many factors.One of the most important aspects of these characteristics is the design of suspensionand steering systems. BMW vehicles are known for their superior handling and roadholding performance.The design of the BMW suspension systems is a key factor in achieving these goals.Suspension geometry is defined as: "The angular relationship between the suspension,the steering linkage and the wheels - relative to the road surface."There are several alignment geometry angles which relate to the suspensioncomponents and steering linkages including:• Caster• Camber• Toe-In/Toe-Out• Steering Roll Radius (steering offset)• Steering Axis Inclination (SAI) and Included Angle (IA)• Toe Out on Turns• Thrust Line and Thrust AngleAll of these angles influence:• The ease with which the vehicle can be steered• The overall vehicle stability (handling, tracking and safety)• Tire wearThe suspension geometry for any given vehicle is a result of the design engineersdevelopment of the vehicle and the design criteria for that particular vehicle.3Basic Suspension GeometryAlignment AnglesCasterCaster is the forward or rearward tilt of the steering axis centerline, as viewed from theside of the vehicle, and is measured in degrees. When the steering axis centerline isexactly perpendicular to the road surface, the Caster is considered to be at zero degrees.- 0 +When the top of the steering axis centerline is tilted rearward (toward the bulkhead), thecaster is considered to be “positive”. When the top of the steering axis centerline is tilt-ed forwards, the caster is considered to be negative.Most vehicles have a caster angle from zero degrees to a positive angle. Negative casteris not very desirable because is reduces the vehicle stability especially at high speeds.BMW vehicle always have a positive caster angle. Positive caster promotes high speedstability and provides feedback to the driver.Positive caster also promotes “steering return” which increases driver comfort and safe-ty. Caster angles which are more negative (or not very positive) can increase the effectof wheel “shimmy”, create sensitivity to high winds and creates poor steering return.When the caster angle differs greatly from side to side, the vehicle may “pull” to the sidewhich has the “least positive” caster.4Basic Suspension GeometryOne of the main characteristics of positive caster is the positive effect on high speedsteering stability. However, low speed steering effort is increased. This characteristic iscounteracted by the power steering system and in particular the Servotronic system.Servotronic will be discussed in later training modules.Caster is not a directly measured angle. It can only be measured by sweeping thesteering through an angle of 20 degrees in both directions. This is important to knowduring the alignment procedure.On BMW vehicles, caster can only be measured, there is no adjustment. However, castermeasurement can be used to detect and diagnose alignment concerns. Caster which isout of specification could indicate damaged or worn components.Caster OffsetCaster offset is the distance between the centerline of the wheel contact point and theintersection point of the extended pivot axis. This greater the offset, the more effortrequired to turn a moving wheel. The negative effects of more increased offset arecounter-acted by the BMW double pivot suspension system and the Servotronic steeringsystem (if equipped).1. Caster Angle2. Caster Offset5Basic Suspension Geometry [ Pobierz całość w formacie PDF ]

Podobne

: Strona Główna

: 01 2006 auto technika motoryzacyjna atm, Auto Technika Motoryzacyjna

: 01 2008 auto technika motoryzacyjna atm, Auto Technika Motoryzacyjna

: 01 2007 auto technika motoryzacyjna atm, Auto Technika Motoryzacyjna

: 01.06 South Park - Death [Napisy PL] s01e06, ## %% ## %% ## DO NAUKI ANG South Park Sezon 1 [Napisy PL]

: 00. Doing Business In English, 01. Doing Business In English

: 01.07 South Park - Pink Eye [Napisy PL] s01e07, ## %% ## %% ## DO NAUKI ANG South Park Sezon 1 [Napisy PL]