{"id":191945,"date":"2021-10-12T10:36:54","date_gmt":"2021-10-12T08:36:54","guid":{"rendered":"https:\/\/rothschenk.de\/episode-10-force-closure\/"},"modified":"2025-06-30T17:03:08","modified_gmt":"2025-06-30T15:03:08","slug":"episode-10-force-closure","status":"publish","type":"post","link":"https:\/\/rothschenk.de\/en\/episode-10-force-closure\/","title":{"rendered":"Episode 10: Force closure"},"content":{"rendered":"\n

The form-fit securing of the load has already been described in \n episode 8<\/a>\n<\/strong> has already been dealt with. Now let’s take a closer look at the frictional connection <\/strong>. What is meant by adhesion, how does it work and what is important when securing loads?<\/p>\n\n

Definition of<\/h2>\n\n

A frictional connection is a connection of two parts via the surface, whereby both surfaces have a high coefficient of friction. How does it work? <\/p>\n\n

A load presses on a surface with an assumed 10 kg. The normal force is calculated by multiplying the mass (example 10 kg) by the gravitational force g (9.81 m\/s2<\/sup>). <\/p>\n\n

The normal force is therefore<\/strong> 10 kg * 9.81 m\/s2= <\/sup> 100 N.<\/strong><\/p>\n\n

The normal force always acts vertically on the surface.<\/p>\n\n

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Each surface has a certain roughness, which creates a micro-serration when the two surfaces come into contact. The dimension is indicated by the letter \u00b5 and is called the coefficient of friction<\/strong>. <\/p>\n\n

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If an attempt is now made to move the surfaces against each other, this roughness creates a counterforce<\/strong>. It is precisely this effect that is used in force closure <\/strong>. <\/p>\n\n

The counterforce depends on the specific coefficient of friction \u00b5 and is referred to as the frictional force.<\/p>\n\n

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If, for example, a manufacturer of truck bodies specifies a coefficient of friction of \u00b5=0.3<\/strong> for its loading surfaces, this means that the force required to move pallets is 30% of the normal force<\/strong>.<\/p>\n\n

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Force-locking load securing<\/h2>\n\n

How does the force-locking securing of a free-standing load of 1,000 kg against displacement during full braking at 0.8 g work? (see VDI-2700 and EN-12195-1).<\/p>\n\n

The required securing force<\/strong> according to the regulations is FS<\/sub> = m * g * a = 1,000 kg * 9.81 m\/s2<\/sup> * 0.8 g = 8,000 N = 800 daN<\/strong><\/p>\n\n

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A load is usually lashed down with tension belts<\/a>. The force that now counteracts the displacement now consists of two components: the normal force + the preload force.<\/p>\n\n\n\n

However, the influence of three boundary conditions must be taken into account:<\/p>\n\n\n\n