3-10 BUILDING & MOUNTING THE STRUCTURES E UROCARGO Euro 4/5 Connections between frame and counterframe 3.3 Connections between frame and subframe 3.3.1 Choosing the type of body mounting The selection of the type of connection to be used - if not provided initially by IVECO - is very important in terms of the subframe providing strength and stiffness for the appropriate body type.
The subframe connection may be flexible (brackets or clamps) or it may be rigid, resistant to shear stress (longitudinal or transverse plates); the choice must be made based on the type of body that is to be mounted (see points 3.4 to 3.7) analysing the stress forces which the additional equipment transmits to the chassis both under static and dynamic conditions. The number, size and type of fixing device properly subdivided over the length of the subframe, must be such as to ensure a good connection between the vehicle chassis and the subframe. The screws and clamps must be of a strength class no lower than 8.8, the nuts must be equipped with devices that prevents them from working loose.
The first fixing must be located, if possible, at a distance of approx. 250 to 350 mm from the front end of the subframe. Any body fixing brackets already fitted on the vehicle frame must be used first. Compliance with the position for the first mounting mentioned above must be ensured in cases where the body appliesconcentrated loads behind the cab and requires additional stability (e.g. cranes, front end tipping gears etc.) in order to prevent overstressing the chassis frame. If necessary, additional fixings must be fitted.
If the body to be fitted has different characteristics to those permitted on the original chassis (e.g tipper on a haulage chassis), the bodybuilder must provide the appropriate mountings (e.g. the replacement of brackets by cleat plates in the rear area of the chassis). When fixing the body to the frame, no welding is allowed on the frame of the vehicle, nor can holes be drilled in the flanges of the sidemembers.
NOTE In order to improve the longitudinal or transverse securing of the connection, it is permissible to have holes in the top flanges of the side members, but only at the rear end of the members, over a length of not more than 150 mm, providing the fixing of any cross members that may be present is not weakened (see Figure 3.13). The mountings shown in Figure 3.14 may be used, using the screws which connect the rear cross member or underrun brackets to the chassis. In all other cases, holes must not be drilled in the flanges of the sidemembers.
NOTE 3.3.2 Body mounting characteristics Flexible mountings (see Figure 3.9, 3.10 and 3.12) permit limited movement between the frame and the subframe, and permit the use of two parallel working strong sections. Each bears a part of the bending moment in proportion to its moment of inertia. For the rigid type of joint (see Figure 3.14) between subframe and chassis, a single strong section is obtained, provided the number and position of the mountings are adequate to support the resulting shear stresses.
When using sheer resisting plates to secure the subframe to the sidemembers, a single strong section is formed which has a higher strength capacity when compared with the MTG made using brakets or clamps. This has the following advantages: - Lower height of the subframe profile under the same bending moment acting on the section. - Higher bending moment under the same subframe profile dimensions. - Further increase in the strength capacity, when the subframe is made up of high mechanical characteristic materials. Connections between frame and counterframe Base - January 2008 Print 603.93.431