Cosmin Roszkos^1,, Jozef Bocko¹, Tomáš Kula¹

This paper presents static and fatigue analyses of a fire truck drop tow hitch for an O1 category water pump trailer. In total 4 geometry variants with different features have been analyzed using the FEM. The loading forces have been calculated based on two different weights: the weight of the water pump trailer (the only trailer meant to be towed by the fire truck) and the category O1 gross trailer weight. Two different calculation methods were used: a calculation method recommended by the standard and a calculation method based on the physical breaking tests performed on the fire truck. The results of the performed analyses show the structural differences of the 4 geometry variants. The additional stiffening elements added to the base design have decreased the maximum deformation values, but the maximum stress and strain values have been raised especially in areas where stress concentrators are present.

drop tow hitch, fatigue life, finite element method, loading force, equivalent stress