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A tiedown is made up of a combination of securing devices (that is, an assembly) that restrains cargo on a trailer (or vehicle), and that is attached to anchor points.
There are two types of tiedowns that are used to restrain cargo:
Direct tiedowns provide direct resistance to oppose the forces that are acting on the cargo. This direct resistance keeps the cargo in place, and prevents movement.
Indirect tiedowns create a downward force that increases the friction between the cargo and the deck. This increased friction restrains the cargo.
Tiedowns (except for steel strapping) must be designed, constructed and maintained so they can be tightened by the driver. Each tiedown must be attached and secured so it does not become loose or unfastened while the vehicle is in transit.
All tiedown parts must be within the rub rails for platform type vehicles (this does not apply when the load extends beyond the rub rails).
Edge protection must be used if a tiedown may be cut or worn. The edge protection itself must also resist crushing, cutting and abrasion. An edge protection device should fit properly on the edge of the article, with no space under the device for it to crush into.
Timber used between tiedowns and cargo must be strong enough not to split or be crushed.
Any timber used should be properly seasoned, and free of rot or decay.
The grain should run lengthwise along the timber when it is used for structural purposes like blocking and bracing.
Timber should be free of knots, knotholes and splits that may affect its strength or interfere with nailing.
All types of cargo must satisfy one of the following three conditions when being secured:
Note: If additional securement is required for a specific commodity (such as metal coils), the specific requirements for securing that commodity take precedence.
The Working Load Limit is the maximum load that may be applied to a component of a cargo securement system during normal service.
This value is assigned by the component manufacturer or the default rating in the Working Load Limit Table.
Note: Welded steel chain that is not marked or labeled with a grade or working load limit, is considered to have a working load limit equal to that for grade 30 proof coil chain.
The load carrying area of a truck, trailer, or intermodal container.
Material used to fill a void between articles of cargo and the structure of the vehicle that has sufficient strength to prevent movement of the articles of cargo.
A short piece of material, usually wood, nailed to the deck to reinforce blocking.
A tapered or wedge-shaped piece used to secure round articles against rolling.
Cargo must satisfy one of the following securement conditions except:
All types of cargo must satisfy one of the following three conditions when being secured:
A cleat is a short piece of wood used:
A short piece of material, usually wood, nailed to the deck to reinforce blocking.
A chock is generally used to secure:
A tapered or wedge-shaped piece used to secure round articles against rolling.
In cargo securement, the deck is:
The load carrying area of a truck, trailer, or intermodal container.
Void filler is:
Material used to fill a void between articles of cargo and the structure of the vehicle that has sufficient strength to prevent movement of the articles of cargo.
Timber used for dunnage must be all of the following except:
Timber used between tiedowns and cargo must be strong enough not to split or be crushed.
Any timber used should be properly seasoned, and free of rot or decay.
The grain should run lengthwise along the timber when it is used for structural purposes like blocking and bracing.
Timber should be free of knots, knotholes and splits that may affect its strength or interfere with nailing.
Indirect tiedowns create what direction of force?
Indirect tiedowns create a downward force that increases the friction between the cargo and the deck. This increased friction restrains the cargo.
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