Steering axis inclination sai reading laser 4 plus sai. Device and method for measuring steering axis inclination. Specifications 126 engine section 6a continued engln. Design methodology of steering system for allterrain vehicles. Based upon these measurements, caster and sai are calculated either directly or through an iterative technique. The kingpin axis is the line between the upper and lower ball joints of the hub. Steering axis inclination sai is the tilt of the steering axis from vertical as viewed from the front.
Device and method for measuring steering axis inclination or. Kingpin inclination angle theory technical theory car. Return steering axis inclination sai sai is the measurement in degrees of the steering pivot line when viewed from the front of the vehicle. It runs from the lower ball joint through the upper ball joint, or on most frontwheel vehicles, through the center of the strut mount. Design and analysis of suspension system for an all terrain vehicle shijil p, albin vargheese, aswin devasia, christin joseph, josin jacob abstract in this paper our work was to study the static and dynamic parameter of the suspension system of an atv by determining and analyzing the dynamics of the vehicle when driving on an off road racetrack. The illustration uses ball joints to represent the angle.
Dec 07, 2016 king pin inclination kpi, steering axis inclination sai the angle formed by a line drawn through the upper and lower pivot points of the steering axis and a vertical line as viewed from the front. Lifters type rocker arm ratio intake hotl volve lad. On a macpherson strut, the top pivot point is the strut bearing, and the bottom point is the lower ball. Reduction of steering effort since the wheel turns to the right or left with the steering axis as its center and the offset as the radius, a large offset will generate a great moment around the steering axis due to the rolling resistance of the tire, thus increasing steering effort. Lubrication and maintenance lubrication magnets and magnetic drain plugs seals. This angle, when added to the camber to form the included angle see below causes the vehicle. The sai steering axis inclination angle is created and measured in degrees. The steering axis is defined by the two ball joints. Steering axis inclination explained besttireandwheelshop. On most modern designs, the kingpin angle is set relative to the vertical, as viewed from the front or back of the vehicle, and it is not adjustable. Troubleshooting troubleshooting front drive steer axle troubleshooting 57 section 10. Steering axis inclination toeout on turns tracking.
A steering axis inclination adaptor 14 of the present invention is shown mounted to the wheel spindle in place for receiving a castercamber gauge 16. The steer angle is achieved by rotation of the wheel about a steer rotation axis. You can adjust the scrub radius by changing the kingpin inclination at the. Steering axis inclination sai diagnostic chart macpherson strut suspension system sai camber included angle probable cause within spec.
The gauge is shown mounted to the steering axis inclination adaptor in fig. Recognize characteristics of steering types such as. It is the angle that the spindle is in relation with an imaginary line drawn between the upper and lower balljoints. The term is also used to refer to part of a fifth wheel coupling apparatus. Initially, all rack and pinion systems are available that have fixed ratio. On a macpherson strut, the top pivot point is the strut bearing, and the bottom point is the lower ball joint. Virtual or physical, the kingpin angle may also be referred to by its acronym kpa, kingpin inclination kpi, or steering axis inclination sai, and remains a fundamental vehicle design parameter. Positive camber works in conjunction with king pin or steering axis inclination sai to reduce steering effort. 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. Steering axis inclination sai steering axis inclination, or sai, is the angle formed between pivot points and vertical line through center of wheel. The kingpin, also kingpin and king pin, is the main pivot in the steering mechanism of a car or other vehicle. King pin inclination kpi, steering axis inclination sai the angle formed by a line drawn through the upper and lower pivot points of the steering axis and a vertical line as viewed from the front.
How to calculate steering system parameters like steering. Angle in front elevation between the steering axis and the vertical. Steering axis inclination sai sai is the measurement in degrees of the steering pivot line when viewed from the front of the vehicle. In alignment terminology, these adjustment angles are called caster, camber, toein, steering axis inclination sai, vehicle ride height and toeout on turns. The 20152016 sae baja team would like to thank the following people for their contributions to this mqp. More specifically, the center of the ball in each ball joint. Caster is the backward or forward tilt of the steering axis that tends to stabilize steering in a straight direction by placing the weight of. The inward tilt of the ball joint or strut at the top. May 08, 2015 steering axis inclination explained duration. Oct 15, 1985 a steering axis inclination adaptor 14 of the present invention is shown mounted to the wheel spindle in place for receiving a castercamber gauge 16.
On older vehicles with individually replaceable wheel bearings, positive camber places the vehicle weight squarely on the larger inner wheel bearing. Steering axis inclination angle is also known as the kingpin inclination angle. The main effect of this is to introduce a turning moment. Originally, with the turntable steering of horsedrawn wagons, this was a single pin on which the. Wheel alignment is the proper adjustment of all the interrelated suspension angles.
Diagnosing a bent steering knuckle using alignment data continued from page 1 is to measure from a straightedge placed on the hub face to symmetrical locations on the strut. Greatercaster,greatercasterlead % when%cornering,% z a p z v v v p p u v z v v p x d z v v p. Checking the steering axis inclination angle route 66 hot. Identify steering and suspension geometric angles significant to proper handling and alignment such as. Diagnosing a bent steering knuckle using alignment data continued from page 2. Caster, camber and king pin inclination measurement with. A steering inclination angle of 0 deg indicates that the spindle is at 90 degrees to the imaginary line. Caster, camber and king pin inclination measurement with the. Applications proper alignment when a set of new tires are installed or suspension parts changed. When measuring the strut in this manner, make sure that struts that have camber adjustments, where the strut and steering knuckle are connected, are. With the help of this tilt caster and king pin inclination are calculated. Us5014227a caster and steering axis inclination measurement. Its formed by drawing a line through the upper and lower ball joint pivots.
The steering axis is the line between the top pivot point of your hub and the lower ball joint of your hub. The sai angle 300 is typically in degrees, and represents the steering pivot line when viewed from the front of a vehicle. I would suggest you find a junk upper and lower ball joint, and slice them in half dremel. Professor planchard for his effort in pushing us to our limits and advising us to produce the best vehicle possible. Bent spindle andor strut or camber adjustment below spec. The steering axis inclination sai is the angle between the centerline of the steering axis and vertical line from center contact area of the tire as viewed from the front. Steering axis inclination sai or king pin inclination is the angle in the front elevation between the steering axis and vertical. Bent spindle andor strut or camber adjstment within spec. Steering axis inclination how is steering axis inclination. The sai angle is an imaginary line drawn through the upper strut and the lower ball joint and another true vertical line that runs through the center of the tire.
Century, grand prix, impala, intrigue, lumina, monte carlo, regal 20012005. Steering axis inclination camber angle 52 caster angle 53 measure and adjust the toe 55 section 9. Steering axis inclination sai is also known as king pin inclination kpi. Steering axis inclination is the inward tilt of the suspension toward the center of the vehicle.
Steer axis inclination saibasics steeraxisinclination. Steering axis inclination is always an inward tilt regardless of whether the wheel tilts inward or outward. To understand scrub, you must first know about steering axis inclination sai. Checking the steering axis inclination angle route 66. He was vital in our engineering design and in bringing both the. Us7181852b2 sensing steering axis inclination and camber. Caster and steering axis inclination measurement technique. The static toe angle of a wheel, at a specified wheel load or relative position of the wheel center with respect to the sprung mass, is the angle between a longitudinal axis of the vehicle and the line of.
Steering axis inclination steering axis inclination sai is the tilt of the steering axis from vertical as viewed from the front. Inclination angle an overview sciencedirect topics. Apr 06, 2012 find out what steering axis inclination is on a vehcile and how to make sure its correct. This axis is not necessary centred on the tyre contact patch. The steering wheel to road wheel angle ratios normally vary with the angle, but have a general value of the order of 15. Trailing arm suspension explained with jake burkey rock rods tech duration. The alteration to the caster and kingpin inclination or camber angle, which is influenced by the body roll inclination figs 3. Steering axle inclination, caster, and camber angles the angle between the vertical line and center of the king pin or steering axle, when viewed from the front of the wheel is known as steering axle inclination or king pin inclination 05 degrees for trucks and 1015 degrees on passenger cars. Effects of sai edit sai urges the wheels to a straight ahead position after a turn. The steering axis is the axis around which the wheel assembly swivels as it turns to the right or left. For more information on this see steering center and thrust angle. Wheel alignment on any bmw vehicle requires an understanding of the bmw kinematic diagnosis system kds, which is an advanced system that maintains the bmw standards of handling, speed, precision and performance.
The angle is measured in degrees and taken as positive if the top of the steering axis leans inwards as shown in figure 4. The included angle can vary only if there is a deformation between the kingpin axis and the wheel hub axis, if, during the checking operation, it is noted that the kingpin inclination angle and the wheel camber angle differs considerably from specified values, then before deciding what action to take it is advised to check to see whether the included angle has remained unchanged. A wheel alignment system measures caster and steering axis inclination sai by positioning the wheels at a right turn position and a left turn position. Toe, camber and inclination angle measurements are made for both wheels at both the left turn position and the right turn position.
In twin lateral arm suspension the steering axis pivot is the centre line drawn between the upper and lower ball joints. Skip essma has 1 discussed the methods used in evaluating and modifying steering effort for a cart series champ car racing on oval track. Find out what steering axis inclination is on a vehcile and how to make sure its correct. On a macpherson or chapman strut suspensions, the steering axis pivot is the centre point of the top pivot bearing and the centre of the lower ball joint. This angle, when added to the camber to form the included angle see below causes the vehicle to lift slightly when you turn the wheel away from a straight ahead. A short course on wheel alignment valley buick gmc. If camber and steering axis inclination are both incorrect by approximately the same amount, upper and lower control arms are bent.
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