Achsvermessung (3D)
About this app
Spur, Sturz, Nachlauf, Spreizung und Fahrachse an einer McPherson-Vorderachse in 3D, mit Messprotokoll, Reifenbild und Ablauf der Achsvermessung.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
What wheel alignment measures
The position of a car’s wheels is described by a few angles, each defined in a different view. Toe is the angle between the wheel centre plane and the direction of travel in the top view, positive as toe-in. Camber is the tilt of the wheel from the vertical in the front view; negative means the top leans inwards. Caster and kingpin inclination describe the steering axis in the side and front view. Where the steering axis meets the road, caster trail and scrub radius follow. The rear toe defines the geometric thrust line, to which the front axle is aligned.
What the app shows
A 3D model of a generic MacPherson front axle with wheel carrier, strut, lower control arm, tie rods and rack-and-pinion steering, plus an indicated rear axle on an alignment bay with turntables and targets. For each value the view turns into the matching projection and shows the angle with its reference line. A magnifier enlarges the tyre contact with the steering axis ground point and the contact patch centre. An alignment report with example specifications flags values out of tolerance. Toe, camber and thrust angle can be drawn exaggerated ×10; the numbers stay real.
Things to try
Set caster to zero and let go of the steered wheels: self-centring becomes much weaker. Load fault patterns such as too much toe-in, unequal camber or a misaligned rear axle and compare tyre wear and handling. In the procedure you work through a workshop case with an off-centre steering wheel: prepare, measure, adjust the rear axle first, then set front toe on the tie rods until the steering wheel is straight.
Frequently asked questions
- What is the difference between toe and camber?
- Toe is a rotation of the wheel about the vertical axis, measured in the top view; toe-in means the wheels point towards each other at the front. Camber is a tilt of the wheel from the vertical in the front view. Toe errors scrub the tyre sideways over the road, camber errors load one tyre shoulder.
- Why does a car have caster?
- With caster, the steering axis leans rearwards at the top and meets the road ahead of the contact patch centre. The lateral force on the tyre acts behind that point and turns the wheel back to straight ahead, similar to a shopping trolley castor. This gives self-centring and straight-line stability.
- Why is the rear axle adjusted first in wheel alignment?
- The individual rear toe values define the geometric thrust line, the direction in which the vehicle pushes. The front axle is aligned to this thrust line. If the front is set first and the rear corrected afterwards, the thrust line moves and the steering wheel is off-centre when driving straight.
- How accurate are the values in the app?
- The app uses a generic passenger car: tyre 205/55 R16, track 1.55 m, wheelbase 2.65 m, steering ratio 15 : 1. The specifications are example values; in the workshop the manufacturer data apply. The caster trail is computed without caster offset, and self-centring is a simplified model.
Subject: Automotive engineering
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