Measuring the vehicles

For now, let’s concentrate on the items used today beginning with the universal measuring system, which utilizes a track that is centered beneath the vehicle. Three points are located in the torque box areas of the vehicle, which is needeed to center track. A measuring tape is located along the edge to measure the length of the vehicle. Cross bars are attached and placed at specified lengths. The cross bars are calibrated with markings to determine the width of the various points. A height tube is attached to the fixture along with some sort of locating cone or cup. With the measuring system in place, any point on the bottom of the vehicle can be checked against a data sheet to determine the extent of damage. The system also has a bridge to check the upper strut towers and other upper points in the engine compartment.

    Next up is the universal laser system, which is used primarily on the bottom of vehicles. They are universal and can be used on a frame machine as well as with an overhead vehicle hoist. Some systems will furnish a computerized print out both before and after repairs. These systems are not recommended for use during the pulling and repair process.

    The sonar or ultra sonic system utilizes probes that are placed at selected reference points under the vehicle. An ultrasonic signal is generated by the probes at which point the information is transmitted to the central beam where data is converted to measurements. This data is then transferred to a computer where that data is compared with known measurements of the vehicle being measured and a comparison of the two sets of data are made.

    An electromechanical system employs a mechanical arm that rides on a bridge under the vehicle. The bridge is centered underneath the vehicle to create a datum plane. A pointer is attached to the arm and after the system is locked into position, every reference point can be measured for length, width and height. Various attachments to the arm are employed for measuring door opening and strut tower locations. After the data is a accumulated, it is sent to the computer by way of wires or wireless. The data is analyzed and compared with standard values to determine the extent of damage. Data can be received during the pulling process in order to monitor the current status of vehicle dimensions. The computer also stores images of the various reference points so that the technician does not measure the wrong reference points.

    Computerized Laser Measuring systems employ a laser generator under the vehicle and a  series of flags or targets placed at selected reference points to measure length, width and height. Measurements are taken and these dimensions are transmitted to a computer where they are compared with computer-stored data bases. A misalign is diagnosed and a document is created showing any changes to norm.

    [For more information on past measuring devices – self-centering gauges, tram bars, tape measures, see I-CAR’s Measuring Class for details.]

Anchoring methods

Now with a better understanding of the equipment currently being utilized , we’ll return to the anchoring method question. Here is some information on the fundamental differences of the two repair methods – of the four designs of pulling machines or design types that are most common in the market today.

Frame rack

The drive-on frame machine design, commonly called a frame rack, has evolved through the years to not only offer versatile multiple pulling capabilities (with as many as five pulling towers), but also offering universal measuring systems that work in conjunction with the frame machine. This traditional machine was originally designed for the body over frame vehicle, commonly called a “perimeter frame.”

    A number of years later as the unibody vehicle became more prevalent (with the onset of different anchoring requirements), the ability of this pulling machine was broadened; adding pinch weld clamping capabilities – where a specially designed clamp attaches to the rocker panel flange anchoring the vehicle to the frame machine. These adaptations to the unibody vehicle led to the term the “Universal Anchoring & Pulling Method.”

    The traditional frame rack is larger with some machines having a total length of 25 feet or more and a total width of 14 feet. They were designed in this manner to be wider and longer than the vehicle, offering some access to the underside of the vehicle. At last count, there are more than a dozen manufacturers of drive-on rack systems in the market today, with pricing to meet the needs of any size collision facility. Moreover, these machines usually have a minimum of two towers and often come with three or four. This widely-used method of repair has proven to offer time savings in set up and pulling, allowing the user to repair a wide mix of vehicles and damage severity.