Decanewtons (daN) – previous product standards used kg or tonnes as a unit of measure. With BS EN 12195-2:2001, the unit of measure has been changed from a static weight (i.e. kg or Tonnes) to a dynamic force because they are designed to secure a load that is moving on road transport. For the purposes of the product standard 1.0kg = 1.0daN, i.e. 5000kg/5.0 Tonnes = 5000daN.
Lashing Capacity (LC) - This is the maximum force the ratchet strap is designed to sustain in a straight pull. Ratchet straps should be selected so when used the force they may encounter NEVER exceeds their defined LC
Breaking Force min (BFmin) – The minimum force the strap can withstand before breaking (in this case when new). NB At or above the BFmin the ratchet strap lashing will fail and will no longer be able to secure the load. Never confuse the Lashing Capacity (LC) with the Breaking Force min (BFmin), always base the number and type of lashings used based on the Lashing Capacity (LC). In service a lashing should never be used to its full breaking force as it may cause premature failure if sustained use is repeated.
For example, a specific 50mm · 5000daN · LWH · Ratchet Lashing System · Claw Hooks (5LS50-7) - Tensys Direct may have a Breaking Force min (BFmin) of 5000daN, but a corresponding Lashing capacity of 2500daN, providing a safety factor of 2:1
NOT FOR LIFTING - never use a ratchet strap for lifting, they are not designed for lifting applications, they don’t have a suitable safety factor, certification or a mechanism that can raise & lower a suspended load
Standard Hand Force (SHF) – In the product standard BS EN12195-2:2001, Standard Hand Force is defined as 50 daN (kg), this is the average force a user can apply to the ratchet handle to tension the webbing
Standard Tension Force (STF) – This is the tension stored in the webbing lashing after the Standard Hand Force (SHF) has been applied. STF can vary between ratchet types, longer handles and geared ratchets apply more tension. A typical 5000daN x 50mm push up to tension ratchet strap will provide an STF of 350daN, for some loads a higher STF required, a 500daN STF is available using ergo type ratchets that pull down to tension 50mm · 5000daN · EK · Ratchet Lashing System · Claw Hooks (5LS50EK-7) - Tensys Direct.
Understanding Load Restraint Principles
The principle of load restraint using ratchet straps is to prevent the load from moving under normal transport forces. To prevent the load from moving it’s a combination of the friction between the load and the load platform and the force the ratchet strap applies to the load stopping it from moving. Friction can be increased between the load and platform using friction mats Friction Mats from TensysDirect.
The force applied from the ratchet strap is known as the Standard tension Force (STF) as detailed earlier in this blog. Ratchet straps can be directly connected to the load or placed over the top of the load. The angle of the strap to the load will also affect the force applied by the lashing.
This article is informational only: always do your own research and read labels carefully before proceeding with any work.
DVSA Guidance on use and inspection of of ratchet straps is available here
Securing loads on HGVs and goods vehicles - 4. Ways to secure a load in an HGV or goods vehicle - Guidance - GOV.UK (www.gov.uk)
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Ratchet Straps
For professional, industrial ratchet straps, rely on Tensys Direct. We provide great load securing equipment, as well as a range of other products. Supported with great customer service, so if you are still unsure about the type of ratchet strap required you can speak to a member of our team.
Read More: Ratchet Strap Labels Simplified