Driving safety test drive firefighting vehicleCurrent incidents underline that the overturning, i.e. tipping, of tank firefighting vehicles is currently a hot topic in the firefighting sector. Rosenbauer, as an innovation and world market leader, has always diligently dealt with the topic of safety and accident prevention. Rosenbauer Engineering invests a great deal of time and energy into integrating the best possible accident prevention solutions into its products and of always being at the cutting edge of technology and setting new standards.

Rosenbauer see, first and foremost, their role as including informing relevant persons as to which physical forces act on a tank firefighting vehicle when cornering, and which measures for accident prevention can counteract these.

Weight and centrifugal force when cornering

The faster a vehicle turns into a curve, the greater the centrifugal force FF  acting on its center of mass m. In this view, it is assumed that the vehicle does not push outward, i.e. slide, but instead holds the same line.

If the vehicle drives into a curve with a velocity v greater than vtipping limit, a torque MK is built up between the center of mass and the tipping point, which causes the vehicle to tip outward over the tipping point.

In the following, the force vectors of cornering at the tipping limit are shown on the left, and the force vectors of cornering above the tipping limit are shown on the right:

Figure 1: Forces when cornering at the tipping limit

Figure 1: Forces when cornering at the tipping limit

Figure 2: Forces when cornering above the tipping limit

Figure 2: Forces when cornering above the tipping limit

Mathematically, the following conclusions can be drawn from the pictures and formulas:

  1. The larger the track width b and the lower the center of mass h of the vehicle, the higher the centrifugal forces FF that can be tolerated by the vehicle, that is, the faster the vehicle can drive through a given curve, with a given curve radius r,, without tipping.
  2. The larger the curve radius r,, the faster the vehicle can drive through the curve without tipping.
  3.  Since the mass m affects both the weight force FG and the centrifugal force FF of the vehicle, it has no direct effect on the maximum cornering speed vtipping limit with respect to tipping.

Verification of the tipping angle by means of a tipping test

Rosenbauer subjects each newly designed vehicle to a tipping test. In this test, the vehicle is brought in an inclined position by means of swivel stage. This simulates cornering.

Figure 3: Tipping test on the Rosenbauer swivel stage

Figure 3: Tipping test on the Rosenbauer swivel stage

Figure 4: Force vectors on the swivel stage

Figure 4: Force vectors on the swivel stage

For firefighting vehicles to meet the general safety and performance requirements and to comply with European Standard EN 1846-2, they must be able to be tipped to the following static tipping angles, depending on their weight class and category: