How to choose a telescopic prop: class, height and capacity

A telescopic prop is chosen on two pieces of data: the height to be covered and the capacity at that height. In the collection you will find class D (20 kN) and class E (30 kN) props for heights from 180/300 cm to 230/400 cm, plus one aluminium model. The more extended the prop, the less it bears: always check the capacity for the extension you will use, not the maximum value in the catalogue.

The types

• Steel telescopic props: the choice for slabs, beams and formwork. They are adjusted with the inner tube, pin and collar. In the collection codes the data sheet states class, capacity and adjustment range, for example “Class E30 kN 180/300 cm”. Example: the Panalex PANAPUNT props.
• Aluminium props: lighter to move; always read the capacity on the data sheet, because it is different from that of the steel models. For example the Mafi aluminium telescopic prop.
• Fork heads and hooks: heads for supporting beams and boards: the Mafi fork head for props or the Mafi hook for props.
• Tilting accessories: for resting the prop on sloping surfaces, like the CSC Edilizia tilting accessories.
• Tripod stands: accessories that hold the prop upright, like the Mafi tripod stand for props.
• Support towers: stackable structures for greater loads and heights, like the Panalex support towers.
• Containers and washers: for transporting and storing the props and completing the supports, like the Mafi container for props.

How to choose by job

The prop must not be chosen by eye: the height of the slab, the load of the pour and the formwork design tell you which class is needed. If you do not have the data, ask the site manager or the engineer who designed the formwork, before ordering.

The features to look at

• Class and capacity: D20 and E30 kN indicate the nominal capacity. 1 kN corresponds to about 100 kg, so 20 kN is about 2 t and 30 kN about 3 t. On some data sheets the capacity is given in kg (100 and 450 in the collection): these are different units and orders of magnitude, so compare them only after converting them to the same unit.
• Adjustment range: for example 180/300 cm indicates minimum and maximum height. The working height must fall within this range.
• Material: galvanised or painted steel for durability on site; aluminium for lightness.
• Telescopic: the height adjustment is what allows the same prop to be adapted to several levels.
• Accessories: fork head, hook or plate must be those of the model, because the profiles are compatible only between parts of the same family.

Common mistakes

• Looking only at the maximum capacity. The capacity drops with extension: check the value at the height you will use.
• Placing it on soft ground. The prop goes on a solid, level surface, with the base plate well seated.
• Prop not plumb. If it is tilted it bears much less and can slip.
• Mixing accessories of different brands. Fork heads and hooks must be chosen for the model.
• Striking too early. Props are removed only when the design allows striking.

Frequently asked questions

What does “class E30 kN” mean?

That the prop has a nominal capacity of 30 kN (about 3 tonnes) within the stated adjustment range. Class D20 has 20 kN.

Can I use a shorter prop by extending it to the maximum?

It is best to avoid it: at maximum extension the capacity is lower. Choose a model whose range contains your height.

Do I need the fork head and the hook?

It depends on what you are supporting: the fork head for beams and boards, the hook for other supports. They are chosen according to the type of work.

Is the prop always made of steel?

No: there is also an aluminium model, lighter to handle. The capacity must always be read on the data sheet.

To choose the right height and class look at the high-capacity telescopic props collection, or request a quote or ask the AMES technicians for advice.