Development of a dynamic stability test for counterbalanced trucks up to 10 t load capacity

Status:

completed 09/2008

Aims:

- Increasing work safety of counterbalanced industrial trucks with maintenance of a high productivity
- Development of a standardised test to assess the dynamic lateral stability
- Development of a Reference Simulation Model for calculating the lateral stability

Activities/Methods:

- Analysis of practical usage and accidental events by on-site investigation
- Determination of the actual state-of-the-art
- Experimental investigation of the lateral driving dynamics of fork lift truck
- Development of a draft standard
- Development of a fork lift truck simulation model as reference for manufacturers for pre-estimating the stability of current and future trucks

Results:

In the described research project a test method to prove the dynamic lateral stability of counterbalanced forklift trucks in addition to the existing static test method following ISO 22915-2 was developed. The new experimental, dynamic test method is related to the use in praxis and focused on little test effort. It allows to rate the dynamic lateral stability by a key figure. Further, the effect of driver assistance systems to reduce the danger of tipping over can be tested.
For the development of the test method an analysis of practical application cases and accident reports concerning possible causes of a lateral turnover has been done. Considering the state-of-the-art the driving dynamics of forklift trucks have been investigated with an extensive test programme in respect to the lateral stability. A veering test manoeuvre at high speed and unladen could be identified as relevant and expressive. This scenario is represented through the new stability test called "L-Test".
In addition to the intended use of forklift trucks, cases of foreseeable misuse should have been taken into account for the test development. Hence, test scenarios with elevated load were carried out. These manoeuvres did not lead to an additional expressive test procedure. Furthermore, for safety reasons it is not advisable to carry out a standardised test with elevated load. In consequence the recent conversion of the research results into standardization is that the stability with elevated load shall be ensured by constructive requirements by manufacturers of the vehicles. One reasonable solution to meet such requirements is a driver assistant system, which influences the truck speed depending on lift height and steering angle.
The development of the test manoeuvre was done in cooperation with the Institut National de Recherche et de Sécurité (INRS) in Nancy. The test specification is worked out by the European Standardisation Group CEN/TC150/WG11, which has been informed about research progress regularly. At the end of the described research project the layout, procedure and criteria of the new dynamic test were fixed in a standard draft. Requirements to fulfil the test criteria could be preliminarily defined from all experimental investigations carried out at INRS, with manufacturers and HSU. To fix these requirements reasonably, more experimental test experience with different truck types, especially disadvantageous and special constructions, has to be gathered.

Last Update: