When the fire ladder is no longer sufficient to reach the source of the fire, firefighters and extinguishing agents are lifted to great heights using mobile aerial work platforms. A boom brings the platform precisely into position. A series of sensors monitor the movements of the platform, platform base and boom. For example, special sensors constantly check the inclination and weight of the platform as well as the angle and length of the boom. In one specific case, the inclination of the crane operator's cage was not allowed to exceed plus/minus seven degrees, while the vehicle base was not allowed to tilt by more than plus/minus three degrees. The user therefore installed a special version of Gefran's GIB inclination sensor both on the boom directly below the personnel platform and on the vehicle base. The contactless sensor uses Mems technology (microelectromechanical systems) and has analog and digital (Canopen) outputs.

In addition, an angle sensor controls the position of the turning station, which can be used to rotate the boom through 360 degrees. The operator therefore knows the position of the turning station at all times. This enables him to detect over-rotation and prevent damage such as hoses or cables being torn off in good time. One such angle sensor is the GR from Gefran, which can be programmed in increments of plus/minus 15 degrees. As the sensor is based on the non-contact Hall effect, it is not subject to wear and has an unlimited mechanical service life.

Sensors on the boom
Draw-wire sensors, such as the GSF potentiometric draw-wire sensor, are used to measure how far the boom has been extended. Depending on the length to be measured, it is available for measuring ranges between 1,800 and 8,300 millimetres. Draw-wire transducers are also used on the stabilizers of the platform base. Here, they measure the distance from the vehicle at which each support is already extended. This is particularly important for passenger platforms, which are often used close to houses. Additional information on the supports is provided by pressure sensors for monitoring the hydraulic pressure. On the one hand, this serves to record the extended length of the support and, on the other, to record the load or load compensation.

It is also necessary to monitor the hydraulic pressure of the hydraulic cylinders that move the boom upwards, as the load on the boom influences the pressure in the hydraulic circuit. The heavier the load, the higher the pressure required to lift it. Permanent pressure monitoring is required to prevent overpressure. For this purpose, pressure transmitters such as the KH are used on the hydraulic pump, which regulates the pressure of the hydraulic system depending on the load. The KH is robust against heavy shocks and vibrations. Equipped with a pressure damper, even high pressure peaks, such as those that occur when opening and closing a valve, cannot affect it. as