The Load Restraint Guide defines lashings as:
Fastening devices (e.g. hooks, winches, etc.), chains, cables, ropes or webbing straps used to restrain loads. Webbing, chains and wire rope are the main types of lashings and there are several different types of tensioning devices used to tension these lashings to ensure they perform correctly.
When using any type of lashing it is important to understand that the number of lashings or rating of the lashings is NOT THE SAME AS THE MASS OF THE LOAD. This means that a 2,500 kg rated strap is not sufficient to tie down a 2,500 kg load. The ANGLES between the lashing and the direction of the force being restrained NEEDs TO BE TAKEN INTO ACCOUNT. This will be discussed in more detail in Lessons 4.1.1 and 4.1.2.
Webbing is a lightweight restraint system that is widely used in the transport industry. It is typically used to tie down load such palletised goods, or goods that can settle such as bags and sacks (webbing has greater flexibility that chains or steel bands and is therefore more suitable for these loads)
Webbing is supplied as an assembly that included end fittings, tensioning devices and a rating tag showing the capacity of the lashing assembly measured using AS/NZS standard 4380 (Motor Vehicles Cargo Restraining Systems).
There are a few key factors that need to be considered when using webbing:
Tensioning the Webbing
Ensuring the webbing is adequately tensioned is absolutely critical. Tensioning is typically achieved by the use of In-Line Hand rachets which come in two different types which either add tension when pulled down or pushed up.
To achieve their rated capacity webbing needs to be tensioned according to Manufacturers specifications. The load restraint tables which will be discussed further in Lessons 4.1 and 4.4 make assumptions that the webbing has been tensioned to the required level of pre tension. (mouseover show this image.
If you do not achieve the required level of pre tension the webbing will not achieve its required capacity and you may need more lashings.
Calculating the required number of lashings
See Lesson 4.4 for more details
Transport chain is typically used to restrain rigid load that are not easily damaged or where the product can be protected from damage due to contact with the chain.
Transport chain is highly durable and has low stretch characteristics. As a result it should not be used with loads that can crush or settle.
Transport chain should also not be used for lifting or loading as it is not designed for that purpose
The most common size is 8mm chain made from high tensile steel which has a capacity of 3,800-4,000 kg, however chain is also available in other sizes.
Chain used for load restraint should be compliant with AS/NZS 4344 which is marked with the rated capacity at least every 500mm.
Mention 2 types of inline tensioners push up and pull down illustrate their use – same for winches – mention triangle fittings illustrate points re one and a half and three turns and impact of tension as discussed on page 169.
Webbing is tensioned by in line Hand Ratchets attached to tie rails or by Trucks Winches that are clipped onto tie rails or slide into special tracks under the coming rails.
Make video showing various types of chain tensioners and explain how to use them – see pages 174 And 175 ad 187- 189, 197 of LRG
Another option for lashing some loads is to use wire ropes which have a higher stretch capacity than chains while still having high capacity see page 179-180 of t he LRG for tips on using wire ropes.
This video shows inspection of chains and a turnbuckle tensioner.
As is the case with webbing straps chains need to be pre tensioned to achieve the required level of restraining force.