STF – Standard Tension Force

The abbreviation STF “Standard Tension Force” stands for the pretensioning force also called “Normal Tensioning Force”, this describes the force of the lashing strap. Put simply, with an STF value of 350 daN: you pull or push on a ratchet lever with exactly 50 daN (SHF) and can lift/move a weight of 350 kg with this force. The main reason for high pretensioning forces are the high-quality products, in this case the ratchet and the lashing strap, which have been optimized for your application. The STF value to be achieved is defined by the European standardization: STF = min. 0.1 x LC and max. 0.5 x LC
No aids such as rods or levers etc. may be used unless they are part of the clamping element.

Illustration: Pressure ratchet

LC (Lashing Capacity)	STF min.	STF max.
400 daN	40 daN	200 daN
750 daN	75 daN	375 daN
1.000 daN	100 daN	500 daN
1.500 daN	150 daN	750 daN
2.000 daN	200 daN	1.000 daN
2.500 daN	250 daN	1.250 daN
3.500 daN	350 daN	1.750 daN
5.000 daN	500 daN	2.500 daN

Cam buckles and heavy-duty pressure ratchets
The specification of the normal hand force (SHF) and the normal tension force (STF) can be omitted on labels of lashing straps with cam buckles if these lashings are not designed by the manufacturer for the intended use – tie-down lashing.

Cam buckle
As a rule, no or only slight tensioning forces are achieved with cam buckles, so that the intended use is limited to direct lashing procedures or bundling.

Heavy-duty pressure ratchets
The same applies mutatis mutandis to many heavy-duty lashing straps with nominal widths of 75mm to 100mm. The tensioning elements used in these lashing straps also generally do not achieve any useful tensioning forces for the intended use – tie-down lashing, but are used for direct lashing due to their high LC values.

* All products in our assortment of cargo safety are tested according to DIN EN 12195-2. STF – Standard Tension Force according to DIN EN 12195-2, always applies to a lashing belt system (ratchet, webbing and end fittings). The webbing, its length, composition, elongation, sewing and material thickness have a very large influence on the STF value of a lashing belt system. The STF value for pull- and pressure ratchets is given by us only for guidelinde.

Example:
71CQ050 Pressure Ratchet 50mm – 50kN
Breaking Strength (BS) 50 kN corresponds to a LC of 25 kN (1/2 BS)
The STF value here must be between (0,1 x LC) 250 daN and max. (0,5 x LC) 1.250 daN.

Structure:

A two-part tensioning belt consists of one tensioning element: a pressure or pull ratchet, webbing and end fittings. A tensioning belt is divided into a loose end and a fixed end. Both parts are marked with a label in accordance with the DIN EN 12195-2 standard, so that the product can always be traced precisely.

Both the fixed end and the loose end have an end fitting, e.g. a pointed hook, flat hook or snap hook, these are thoroughly selected depending on the application.

The tensioning element is called a pressure ratchet or pull ratchet

The most commonly used ratchet is the pressure ratchet whose STF value (Standard Tension Force) reaches values up to 350 daN. If more force is required, an ERGO long lever ratchet, also known as a pull ratchet, is used, which achieves STF values of up to 800 daN, depending on the design.

LC – Lashing Capacity

The value LC “Lashing Capacity” stands for the permissible lashing force. It indicates when the load limit for the lashing system in straight pull (direct pull) is reached. This value is determined from the breaking strength.

Example:
71CQ050 Pressure Ratchet 50mm – 50kN
Breaking Strength (BS) 50 kN = LC 25 kN (1/2 BS)

Direct pull / Strapping

Label explanation

• PES (polyester) = blue label (standard LABEL)
  Working range: -40 °C to + 120 °C
  Resistant to mineral acids, but not to alkalis.
• PA (polamide) = green label
  Operating range: -40 °C to + 100 °C
  Resistant to alkalis (substances that form alkalis with water), but not to mineral acids.
• PP (polypropylene) = brown label
  Working range: -40 °C to + 80 °C
  More resistant to acids and alkalis (except some organic solvents).