Ethical issues in engineering design - 3TU.Centre for Ethics and ...
Ethical issues in engineering design - 3TU.Centre for Ethics and ...
Ethical issues in engineering design - 3TU.Centre for Ethics and ...
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Design of a lightweight trailer<br />
produced. The term “produced” had different mean<strong>in</strong>gs <strong>for</strong> the customer <strong>and</strong><br />
the eng<strong>in</strong>eers. The eng<strong>in</strong>eers specified a way <strong>in</strong> which the trailer could be<br />
produced <strong>and</strong> calculated the material costs to estimate the costs. The customer<br />
expected that CLC would contact companies about produc<strong>in</strong>g, <strong>for</strong> example, the<br />
side panels <strong>and</strong> the floor. For him a trailer is producible once he knows that<br />
companies will produce the parts he needs <strong>for</strong> a reasonable price. These<br />
differences regard<strong>in</strong>g the mean<strong>in</strong>g of “producible” may have contributed to the<br />
customer’s decision to stop the <strong>design</strong> process after the prelim<strong>in</strong>ary <strong>design</strong><br />
phase.<br />
Transport <strong>in</strong> Europe is a highly competitive bus<strong>in</strong>ess; profit marg<strong>in</strong>s are<br />
small. Every tonne of freight that can be transported extra <strong>in</strong>creases a company’s<br />
profit marg<strong>in</strong>s. The motivation to have a lightweight trailer is mostly economic.<br />
Lighter trailers use less fuel if driven empty <strong>and</strong> can transport more load be<strong>for</strong>e<br />
exceed<strong>in</strong>g load<strong>in</strong>g regulations. The total mass bear<strong>in</strong>g on the axles of a truck <strong>and</strong><br />
trailer is limited to 9 tonnes <strong>and</strong> the total mass of a truck, trailer <strong>and</strong> load<br />
comb<strong>in</strong>ation is also regulated by national laws. The mass of the total comb<strong>in</strong>ation<br />
is not allowed to exceed 44 tonnes <strong>in</strong> the Netherl<strong>and</strong>s, <strong>in</strong> Germany it is 40<br />
tonnes. 1 In a few years these national laws will be substituted by a European law.<br />
The maximum mass permitted <strong>for</strong> truck, trailer <strong>and</strong> load will be around 40<br />
tonnes. A mass reduction of 1000 kg <strong>for</strong> the physical trailer means that an<br />
additional 1000 kg of freight can be transported. The motivation <strong>for</strong> lightweight<br />
<strong>design</strong> is there<strong>for</strong>e not to obta<strong>in</strong> a more susta<strong>in</strong>able trailer but to transport more<br />
load.<br />
The lightweight trailer had to be <strong>design</strong>ed <strong>for</strong> use beh<strong>in</strong>d conventional<br />
European trucks. The truck-trailer configuration would stay more or less the<br />
same. The trailer had to comply with exist<strong>in</strong>g regulations <strong>for</strong> traffic, <strong>and</strong> it was<br />
expected to <strong>in</strong>clude a new unload<strong>in</strong>g system lead<strong>in</strong>g to some changes <strong>in</strong> the<br />
normal configuration of the trailer. The materials that the eng<strong>in</strong>eers proposed<br />
have not yet been widely used <strong>in</strong> trailer production. The CLC has <strong>design</strong>ed a<br />
cool<strong>in</strong>g trailer us<strong>in</strong>g composites. However, a cool<strong>in</strong>g trailer has a roof, whereas<br />
trailers <strong>for</strong> bulk load such as s<strong>and</strong> <strong>and</strong> agricultural products do not have a roof.<br />
Hav<strong>in</strong>g a roof closes the perimeter <strong>and</strong> provides <strong>for</strong> a torsionally stiff box, so<br />
hav<strong>in</strong>g no roof is very important <strong>for</strong> stiffness calculations. The normal<br />
configuration of a bulk transport trailer was changed to <strong>in</strong>clude a new unload<strong>in</strong>g<br />
——————————————————————————————————<br />
1 The maximum total loads of truck <strong>and</strong> trailer comb<strong>in</strong>ations <strong>and</strong> axles load<strong>in</strong>g are based on<br />
<strong>in</strong><strong>for</strong>mation obta<strong>in</strong>ed from the eng<strong>in</strong>eers <strong>and</strong> the customer. In a version of the Dutch “voertuigreglement”,<br />
I found a maximum of 10 tonnes on axles [voertuigreglement, 2005]. This<br />
difference is probably due to harmonization <strong>in</strong> the European Union. The maximum load on axles<br />
<strong>and</strong> the maximum total load of truck trailer comb<strong>in</strong>ations will eventually become the same<br />
throughout Europe. The eng<strong>in</strong>eers <strong>and</strong> customer possibly anticipate the lower, harmonized,<br />
masses that will eventually be en<strong>for</strong>ced.<br />
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