Iveco DAILY M.Y. 2012, Body Builder Instructions

Page: 51 / 252

CHASSIS MODIFICATIONS
2-25
D
AILY
Printed 603.95.241 Base — 02/2012
Application of the towing hook
Application of the towing hook
2.6.4 Towing hook for central axle trailers
A trailer is defined as a central axle type when it has one or more axles close to each other.
Particularly due to the effect of the vertical dynamic loads, with this type of trailer, the rear vehicle cross member is subjected to
significant stress.
For the same reason, a suitable towing hook is needed.
The values of the towable weights and the permissible vertical loads are specified in the technical documentation of the hook
manufacturer and are indicated on the production plate (see DIN 74051 and 74052).
Towing hooks with special approvals and load and weight values above those specified in the above standard can also be used.
However, these hooks can have constraints connected to the type of trailer used (e.g. drawbar length). Furthermore, these may
require additional reinforcements for the tow cross member, as well as a larger sub-frame section.
The DC and V values of the mechanical attachment device suitable for central axle trailers are defined by the following formulas:
Dc
=
g
⋅
(T
+
S)
⋅
C
(T
+
S)
+
C
V
=
a
⋅
X 2
L 2
⋅
C
Dc = representative value of the hook class (kN). It is defined as the theoretical force of reference for the horizontal force between the towing vehicle
and the trailer;
g = gravity acceleration (9.81 m/s
2
);
T = maximum weight (t) of the towing vehicle;
T+S = maximum weight (t) of the towing vehicle including, if necessary, the vertical load of the central axle trailer;
R
= maximum weight (t) of the trailer;
S = value of the static vertical load (t) that, under static conditions, is transmitted to the attachment point.
S must be
≤
0.1
⋅
R
≤
1000 kg;
C = sum of the maximum axial loads (t) of the central axle trailer with maximum load; is equal to the maximum weight of the central axle trailer
decreased by the vertical static load (C = R - S);
V = value of the dynamic vertical theoretical load (kN);
a = equivalent acceleration in the attachment point; in function of the rear suspension of the tractor, use the following values:
- a = 1.8 m/s
2
for pneumatic suspensions;
- a = 2.4 m/s
2
for other types of suspensions;
X = length of the load surface (m);
L = theoretical length of the drawbar (distance between the entre of the drawbar eye and the middle line of the trailer axle) (m);
X
2
/ L
2
≥
1 if the result is lower than the unit, use value 1.
132088
Figure 2.11
Length of the loading surface of the trailer and the theoretical length of the drawbar