There are heavy transports and there are gigantic heavy transports. The latter category includes the transportation of a huge heat exchanger, which was carried out by Viktor Baumann in October 2020. The company is an expert in oversized special transports, which only a few companies in Germany offer. Every transport requires comprehensive planning processes that take a long time: First, all the parameters of the load have to be checked, size, weight, height and length, then the design of the required vehicle is worked out, followed by research into the appropriate route. The latter is complex in that certain roads and bridges may be unsuitable for the weight and height of the load, or bends may be too narrow for the extra-long vehicle to negotiate. "Once we have determined a route using a modern 3D scanning vehicle, the authorities may still not give the green light, for example because there are roadworks on the route, bridges are not load-bearing or similar. Then we have to reschedule and sometimes even change the load," says Reinhard Treutler, CAD technician at Baumann.

The challenge of a high center of gravity

The particular challenge with very large and heavy goods is the high center of gravity of the load, which increases the risk of the entire vehicle tipping over. In the case of the heat exchanger transport, the center of gravity of the load was 3.80 m above the semi-trailer of the modular vehicle with a weight of 324 tons. With such special transports, it is important to continuously monitor the tilt angle of the load over the entire transportation period and, if necessary, to counteract this hydraulically if the tilt angle exceeds a previously defined range.

A heavy transport of superlatives: length of the entire train: 78 m, width: 6.55 m, height: 8.15 m; weight of the plant section: 509 t, total duration: 4 days. A challenge for the route planning, among other things.

© Viktor Baumann

For less critical transports, the company uses a pendulum to monitor the angle of inclination, which is attached to the load together with a scale. If the deflection is too high, the operator of the hydraulic system can correct the inclination of the load during the journey. However, the pendulum variant was too imprecise for a heavy transport with the dimensions mentioned, as it was a very narrow limit range in which the inclination was allowed to deviate from the zero point.

Electronic monitoring solution

In order to ensure safe transportation, Reinhard Treutler thought of an electronic measuring solution for the angle of inclination and approached Althen with this requirement. To date, no suitable measuring device existed, so a new measuring solution was developed for the project. This meant that the requirements for the system in terms of measuring range, measuring accuracy and type of visualization had to be clarified first. The whole thing was then technically implemented, i.e. a suitable inclination sensor element and the appropriate electronics were selected and the software including measurement signal filtering was developed. Everything was implemented individually for the application at hand; it was not possible to fall back on ready-made solutions.

The measuring unit with sensor is located on the blue support structure of the load.

© Viktor Baumann

The result is a mobile measuring system for monitoring the tilt angle called 'MTMS'. It consists of a measuring unit with sensor in a robust die-cast aluminum housing and an associated large, bright LED display that is easy to read from up to 20 m away. Thanks to automatic brightness adjustment, it is also easy to see in daylight. The measuring system is designed to detect a quasi-static change in the angle of inclination of an object to be monitored. The measuring range covers ±10° in relation to the horizontal - a very narrow range, as even a few degrees of tilt can mean that the tipping point is exceeded in the case of critical transports with a high weight and center of gravity.

Easy-to-read LED bar display

In order to be able to assess the danger easily and accurately at all times, Althen, in consultation with Baumann, has chosen a color-graded LED bar display in addition to the numerical display, which immediately signals to the operator if the limit range is exceeded. Unlike a numerical display, bars can be interpreted at a glance, especially when the inclination is monitored over a longer period of time and the operator must constantly assess the operating status. If the limit values are optimally adhered to, green bars light up; if the display changes to yellow, a pre-alarm applies, allowing the operator to react and take hydraulic countermeasures. Finally, red bars indicate the critical range.

The MTMS tilt angle measuring system from Althen ensures safety when transporting heavy loads. Its LED bar display is clearly visible to the operator of the hydraulic system for levelling the load.

© Althen

The solution was supplemented by an acoustic horn signal that also sounds if the limit values are exceeded. There are two red indicator lamps on the sensor measuring unit itself, which also indicate the operating status.

The measuring system is both easy to install on the respective load and to program. The zero position of the object to be transported can be saved in a protected user menu, so that the sensor knows the position to be maintained during the journey. In addition, two limit switching points can be programmed to mark the critical inclination range in which the load may move before the tipping point is reached.

These respective limit values depend on many factors, as Reinhard Treutler explains: "The limit value must be determined individually for each object. This depends on the size, the weight, the height of the center of gravity, the vehicle used, the connection between the vehicle and the load and several other factors. To do this, we use software that calculates the tipping or overload angle, i.e. the maximum inclination." Thanks to the display, it was actually possible to make hydraulic readjustments within the green measuring range during the four-day transport. The inclination measuring system is supplied with a calibration certificate, for which Althen also offers regular recalibration.

Novelty in the industry

The electronic tilt angle measuring system is a novelty in the field of special heavy-duty transport, which means more safety for transfers of this size.

The author: Holger Piscator is Head of Application Development at Althen Mess- & Sensortechnik in Kelkheim.

© Althen

Both the company that commissioned the heat exchanger transport and the Baumann employees and operators have drawn a positive conclusion and will continue to use the tilt angle measuring system for transports with a high center of gravity and heavy loads that are at risk of tipping.