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latest update 15/09/14


To understand what we are speaking about when "talking this tech-stuff".


indicates a particular way of measuring Wheel Alignment angles, based on the observation of 2 wheels only (i.e. each axle, front or rear, is measured separately) by means of 2 sensors.
This way of measuring wheel alignment, is to be considered obsolete due to the fact that Thrust Angle is usually not taken in account by ordinary 2-wheels-aligners thus resulting in a generally poor adjustments of Toe.
Optical Aligners or Laser Aligners are 2-wheel-aligners.

FASEP Digital 2-Wheel Aligners, however, are able to measure and memorize Thrust angle value from the rear axle, and therefore can obtain same measurements of superior 4-wheels-alignment systems.

See as opposed to 4-wheels-alignment.


indicates the modern way of measuring and adjusting wheel alignment angles, where measurements of front and rear axles are reciprocally dependent due to the Thrust Angle.
4-wheels aligners measure wheel alignment by means of sensors on all 4 wheels (both axles, front and rear). In such a way, the reciprocal influence between axles is taken into account and corrected by the aligner.
On 4-wheels-aligners, alignment is generally performed along the Thrust Line as opposed to the Geometric Centerline of the vehicle, thus improving the accuracy of adjustments.
"4-wheel-alignment" can also be referred as Total Wheel Alignment.

Cordless aligners/sensors

referred to Wheel Alignment sensors, particularly the way they are in communication with the main unit.
First generation of cordless aligners "spoke" to main unit by means of infrared beams (like those used in remote controls).
Do not mistake infrared communications with infrared measurement of Toe.
The infrared communications systems are usually very slow and results in poor performances.
The State-of-the-art of Cordless sensors is the second-generation where sensors "speak" to the main unit by means of radio waves.
See FASEP WinTRAX sensors.

Infrared aligners/sensors

referred to Wheel Alignment sensors where Toe-line connection is replaced by an infrared emitter and an infrared sensor on the opposite side. Sensors are "connected" through this infrared beam, angles are detected by the infrared sensor and calculated values are displayed at the main unit.
See FASEP WinIRIS sensors.

Optical aligners/sensors

not to be confused with infrared aligners, optical aligners are one of the oldest and simplest way of measuring alignment angles. The optical ailgners use a light/laser beam usually focused on a scale where read-out is visible.
Optical aligners cannot perform calculations as read-outs are simply visible on a scale and comparison between values is left to the ability of the operator.
For this reason optical aligners should always be considered 2-wheels-aligners.


referred to Wheel Alignment sensors using an elastic string (toe-line) to be reciprocally connected

Total Wheel Alignment

See 4-Wheels-Alignment.

Thrust angle

one of the most important angles for performing a 4-Wheels-Alignment, Thrust Angle is originated by unequal toe values on the rear axle.


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