Step 1: which dimensions come from the fill?
The thickest cable sets the inner height; the sum of the thickest layer sets the inner width. Add 10% clearance for calm applications and 20% at high speed, heat or outdoors. Include separator widths and reserve 15 to 20% for future additions.
Step 2: how do you determine the bend radius?
Take the strictest requirement of all cables: 7.5 × diameter for fixed installation, 10 × for moving applications and 15 × for fibre optics and some bus cables. Then pick the next radius in the series range. When in doubt go one step larger: it costs length but measurably extends cable life.
Step 3: how do you calculate the chain length?
Use Lk = S/2 + π × R + allowance. The π × R term is the half circle of the bend; the allowance covers the end connectors plus a small reserve so the bend does not hit the fixed point. For gliding arrangements add length for the driver height.
Step 4: where do you place the fixed point?
With a symmetrical travel the fixed point sits in the middle; the chain then only spans half the travel. If the fixed point can only be at the end, calculate with the full travel: Lk = S + π × R + allowance. That nearly doubles the chain length, so moving the fixed point pays off.
Step 5: how do you round to links?
Divide the calculated length by the pitch and round up. There is no half link; too short means the bend does not fully roll out. We supply chains in the link count matching your length, with end connectors already fitted.
| Bend radius R | π × R | Bend build height | Extra with central fixed point |
|---|---|---|---|
| 75 mm | 236 mm | ≈ 2 × 75 + Hi | 1–2 schakels |
| 100 mm | 314 mm | ≈ 2 × 100 + Hi | 1–2 schakels |
| 150 mm | 471 mm | ≈ 2 × 150 + Hi | 2 schakels |
| 200 mm | 628 mm | ≈ 2 × 200 + Hi | 2 schakels |
Frequently asked questions
- Should cable length be calculated differently from chain length?
- Yes. Take the chain length plus the connection lengths at both ends, plus 3 to 5% reserve for strain relief and terminating in the cabinet. Cables in the chain must never be installed under tension.
- Does the formula change for a vertical arrangement?
- The length formula stays the same, but the permissible free-hanging length is smaller and cables must be relieved axially with a clamp in each link group. Always ask for a check of such an arrangement.
- Can I have the calculation checked?
- Yes. Send travel, fill, speed and environment through the quote form; you receive a sizing proposal with chain length, link count, accessories and lead time.
Read next
- What minimum bend radius does my cable need?The 7.5×, 10× and 15× rules of thumb explained, plus what happens when you go below them.
- How do you calculate unsupported length and sag?Fill weight sets the unsupported length. When to switch to gliding, and how much sag is acceptable.
- How do you determine the inner height and inner width of a cable carrier?Measure the fill, add clearance and divide compartments — including the 60% rule of thumb and a full worked example.