What DIN 6899 covers
DIN 6899 specifies wire rope thimbles, supplied in Form A and Form B patterns. A thimble sits inside the eye of the rope to protect it from wear and to keep the rope's natural bend radius.
- Form A and Form B differ in groove profile and overall dimensions — see the dimension drawings on each model page for the pattern you need.
- Thimbles are sized by the rope diameter they suit; match the thimble to the actual rope diameter, not to the sling's rated capacity.
Sources: DIN 6899 pattern listings; our catalogue dimension drawings for Form A and Form B.
DIN 6899 is the German standard for wire rope thimbles. A thimble is fitted inside a rope loop so that the loop keeps its natural shape, and so the load never bears directly on the wires at the point where the loop is tightest.
Using a thimble in a loaded loop is standard practice rather than an option: without one the rope can bend far tighter than its design radius, especially where the loop sits on a shackle pin, a hook or an eye bolt.
Key facts
- Fitted inside a wire rope loop to preserve the natural shape of the loop.
- Prevents the load bearing directly on the wires at the tightest point.
- The A and B profiles are defined by the standard — confirm which suits the rope and fitting.
- Carbon steel, electro galvanized or hot-dip galvanized.
- Sized by rope diameter; the full range is supplied on request.
How it compares
The U.S. equivalents are the G-411 standard thimble and the G-414, which has a heavier section for use where the rope bears on a small pin or where abrasion is expected. If you are terminating to a North American specification, ask for the G patterns; for a European specification, ask for DIN 6899.
Applications
Form A and Form B: what actually differs
Supplier catalogues for this standard give a dimension table and stop there. The two forms differ in section, and the difference decides which one a termination needs.
| Form A | Form B | |
|---|---|---|
| Standard designation | Form A (also written Type A) | Form B (also written Type B) |
| Inner side profile | Straight. The rope sits against a flat inner face. | Curved. The groove follows the rope's natural path more closely. |
| Section / wall thickness | Thinner wall, lighter weight, rounder section. | Thicker wall, heavier section, deeper groove. |
| Duty level | Standard grade. General purpose, lashing, static lines, light work. | Heavy duty. Lifting, towing, crane and sling terminations. |
| Typical rope size range | 2.5 – 28 mm | 2.5 – 34 mm |
| Relative weight at the same rope size | Baseline | Substantially heavier — several times the Form A weight at larger sizes |
| Where it runs out of room | Where weight matters or the profile must stay compact. | Nothing structural, but it costs more and is heavier than the same job needs. |
Choosing between the two forms
The questions below are ordered by how quickly they settle the choice — in most cases the first one is enough.
| Question | What to do | Why |
|---|---|---|
| Is the loop going to be loaded or just hold something in place? | Loaded → Form B. Merely retaining a rope → Form A is usually enough. | This single question decides most cases. |
| How heavy is the rope, and how many legs share the load? | The heavier the rope and the more legs into one termination, the more the extra section of Form B earns its cost. | Form B's extra section is about surviving the load path, not about a higher rating. |
| Does the rope bear on a small pin or a hard edge? | Use the heavier Form B. This is the same reason G-414 exists in the US pattern range. | Abrasion and bending at the termination are where the section pays for itself. |
| Is weight critical, or is the installation space tight? | Form A. This is the one case where the lighter section is the right answer. | Marine and offshore rigging often weight-penalises every component. |
| Does the specification name a pattern rather than a form? | If it names a manufacturer's part number, supply what is asked and note the equivalent form on the packing list. | DIN 6899 fixes the A/B forms. Individual manufacturers number their own products and those numbers do not map back to the forms. |
Reading a thimble dimension table
These tables carry one trap, and it accounts for a large share of wrong orders: the letter in each row is the form, not a size.
| Point | Detail |
|---|---|
| The first column is rope diameter, not thimble size | Thimbles are ordered by the rope they fit. A thimble listed under 10 mm fits 10 mm rope. |
| The letter in the row is the form, not a variant | A single rope diameter usually appears twice — once for Form A, once for Form B. The two differ in weight and section, and only one of them is the one you meant. |
| Weight is the quickest sanity check | Form B at a given rope diameter weighs substantially more than Form A. If a quoted weight looks like the other form's, the form has been misread. |
| Galvanizing changes the numbers | Hot-dip galvanized fittings are heavier than electro galvanized ones for the same nominal size. Compare like with like when checking a supplier's figures. |
| The seat length must suit the rope construction | The internal length has to take the loop without the rope being pinched or free to flatten. Where the rope is larger in diameter than the nominal entry, confirm the fit with the supplier. |
FAQ
Why use a thimble?
Which size do I need?
Galvanized or hot-dip galvanized?
Related pages
These pages cover the same job from a different angle.
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