CHASSIS MODIFICATIONS 2-29 E URO C ARGO E URO 4 - 5 Installing a Towing Device 2.10 Installing a Towing Device 2.10.1 General Specifications Without prior authorisation, the installation of a tow-hook is permissible only on those cross members which are intended for that use and on those vehicles which IVECO has intended for towing a trailer. The subsequent installation of a tow hook in vehicles for which the installation of a tow hook was not originally contemplated, must be authorised by IVECO.
In trailers with one or more axles close together (centre axle trailers), considering the stress resulting in particular from the vertical dynamic load to which the rear cross member is subjected, the instructions given in point 2.10.5 must be taken into account. The tow hook must be suitable for the permissible load and be of a type approved by National Requirements. 2.10.2 Choosing a Hook The hook must be chosen based on the following characteristic values: - for towing gear which is not suitable for transmitting vertical loads, the D value is defined by the following formula:
D = g ⋅ T ⋅ R (T + R) = (kN) - for towing gear for trailers with a centre axle, the Dc, S and V values are defined by the following formula: Dc = g ⋅ (T + S) ⋅ C (T + S) + C = (kN) V = a ⋅ X 2 l 2 ⋅ C (kN) D = representative value of the class of jaw (kN).
This is defined as the technical referenceforce for the horizontal force between the towing vehicle and the trailer; g = acceleration due to gravity (m/s 2 ); T = maximum weight (in tonnes) of the towing vehicle; T+S = maximum weight (in tonnes) of the towing vehicle + the vertical load of a trailer with a centre axle; R = maximum weight (in tonnes) of the trailer; S = value of the static vertical load (in tonnes) which, in static conditions, is transmitted to the point of attachment. S must be ≤ 0,1 ⋅ R ≤ 1000kg; C = sum of the maximum axle loads (in tonnes) of the trailer with a centre axle at maximum load.
It is equal to the maximum weight of the trailer with a centre axle less the static vertical load (C = R - S); V = value V of the intensity of the theoretical dynamic vertical force; a = for the equivalent acceleration at the point of attachment, as a function of the rear suspension of the towing unit, use the following values: - a = 1.8 m/s 2 for air suspension; - a = 2.4 m/s 2 for other suspension types; X = length of the load surfaces (m); l = theoretical length of the drawbar (distance between the centre of the drawbar towing eye and the centre line of the trailer axle (m)); X 2 / l 2 ≥ 1 if the result is less than 1, use the value 1.
Installing a Towing Device Print 603.93.431 Base - July 2006 Revi - June 2007