A C-hook is designed around the coils it will carry. Its lower arm passes through the coil eye and carries the coil from below, so the length and section of the arm, the mouth opening and the position of the lifting point all follow from the coil dimensions. This guide explains which coil data sets which dimension of the hook. To see the same calculation with your own coils, you can use the C-hook configurator.
Which coil data is needed
A C-hook is sized for the range of coils it will carry, not for a single coil. If the same hook carries coils of different widths, the narrowest and the widest coil both enter the calculation.
| Coil data | Hook dimension it sets |
|---|---|
| Largest outside diameter | Mouth opening and overall height of the hook |
| Smallest inside diameter | Section of the lower arm that fits into the coil eye |
| Widest coil | Lower arm length and position of the lifting point |
| Narrowest coil | Position and balance of the load on the arm |
| Material and weight | Capacity, plate thickness and crane connection |
If the coil weight is not known, it can be calculated from the material and the dimensions. Steel and aluminium coils of the same size differ greatly in weight, so the material is asked for as well.
Lower arm: fits into the coil eye, carries the widest coil
The lower arm must be long enough to carry the whole width of the widest coil. If the arm is too short, part of the coil overhangs the tip and the load moves towards the end of the arm.
The section of the arm is limited by the smallest inside diameter. The arm, with its support parts, must enter the coil eye with clearance. The arm sees its largest bending at the root, so it is thicker at the root and tapers towards the tip. The lower-arm geometry is designed to the coil inside diameter.
Mouth opening and hook height
The mouth is the opening between the lower and the upper arm. The coil wall, from the eye to the outside surface, must enter without touching the mouth. The coil with the largest outside diameter sets the mouth opening; a larger mouth also lengthens the spine and the upper arm and makes the hook heavier.
The overall height of the hook matters on the crane side. The distance from the point where the crane hook sits to the lowest point of the C-hook is taken off the lifting height. In plants with limited headroom, this dimension should be known from the start.
Lifting point and balance
On a C-hook the load hangs on the lower arm, not directly under the lifting point. So that the loaded hook hangs level, the lifting point is placed according to the centre of gravity of the coil. Coils of different widths are centred on a mark at the middle of the arm, so the centres of gravity of the narrow and the wide coil stay close to the same vertical axis.
An empty hook tends to tilt under its own weight, because the lower arm reaches out to one side. A counterweight can be added on the spine side to balance it. Unloaded and loaded balance are considered together in the engineering design.
Crane connection
The hook can be connected to the crane directly with an eye, or with two lugs and a chain. With an eye, the crane hook sits in the eye of the C-hook, which is opened to suit the size of the crane hook. Lugs and a chain change the headroom and how the hook swings. For the C-Hook, the crane connection can be a pin, a lifting hole or a sling connection.
Capacity and limits
The upper limits of the HENDL C-hook family are below; the exact dimensions are set with the coil data at the quotation stage.
| Product | Capacity (family upper limit) | Coil width |
|---|---|---|
| C-Hook | 50 tonnes | 300–2,200 mm |
| Motorized Rotating C-Hook | 50 tonnes | 300–2,200 mm |
Sizes and capacities outside these ranges are handled by engineering evaluation. If the coil has to be rotated during handling, the Motorized Rotating C-Hook is designed for that task. If you are choosing between a C-hook and a coil tong, see the guide Coil Tong or C-Hook?
Preliminary calculation with the configurator
The C-hook configurator follows the steps of this guide in order. You enter the outside and inside diameter of the coils, the narrowest and widest width and the material; the configurator calculates the mouth opening, the lower arm length, the capacity and the overall height of the hook, and draws the hook with the coil in 3D. If a dimension does not fit, it shows why and suggests a correction that you approve.
The result is a preliminary design. When you send your request, our engineering team reviews the calculation and prepares the final design with the quotation.
Information needed for a quotation
- Outside and inside diameter of the coils, narrowest and widest width
- Coil material and the weight of the heaviest coil
- Crane capacity, crane hook and available headroom
- Need for rotation and frequency of use
You can send the details through the quotation form.