Calculate a portal crane: capacity, height and floor loading

You calculate the capacity of a portal crane in three steps. First, the capacity: the crane's working load must be at least equal to the weight of the load plus everything hanging from the hook, and the lowest working load in the chain (crane, trolley, hoist, lifting attachment) is the limit. Next, the height: add the height over which you need to lift the load, the load itself, the lifting attachment, and the hoist's minimum hook distance; that is the minimum hook height the crane must reach. Finally, the floor: calculate with the weight of the crane and hoist plus the full load on one side frame, because the trolley can drive up to a leg. Below is an example calculation for each step using the dimensions from Schilling's technical data.

What capacity does your portal crane need?

Start with the weight of the load. Add the weight of the lifting attachments: lifting slings, round slings, shackles, or a lifting beam also hang from the hook. Then choose a crane, trolley, and hoist with a working load of at least that total. The weakest link determines what you can lift: a 1,000 kg crane with a 500 kg hoist is a 500 kg setup.

The aluminum portal cranes in our range have a working load of 500 kg to 1,500 kg. At Schilling, the maximum beam length depends on the working load: 1,000 kg is available with a beam length of up to 8 m, 1,500 kg up to 6 m. Schilling expressly states that exceeding the maximum working load, pulling at an angle, and dragging loads across the ground are not permitted uses.

How do you calculate the required hook height?

At Schilling, the hook height is the height of the trolley bolt, i.e., the point from which the upper hook of your hoist hangs. Below that point, you lose height to the hoist itself, the lifting attachment, and the load. Add up from the bottom to the top:

1. the height over which the load must be lifted, for example a workbench, trailer, or machine bed;
2. the free space below the load;
3. the height of the load;
4. the height of the lifting attachment between the load and the hook;
5. the hoist's minimum hook distance (upper to lower hook, fully extended).

Example calculation. You want to place a load 900 mm high on a 1,000 mm workbench, with 100 mm of free space. The round slings hang 800 mm above the load. The hoist is a Kito CB010 of 1 t, with a minimum hook distance of 295 mm according to the user manual. Required hook height: 1,000 + 100 + 900 + 800 + 295 = 3,095 mm. The medium-height Schilling version reaches a maximum of 2,980 mm and therefore does not fit. The high version (2,310 to 4,010 mm) does fit.

What heights and widths do the versions have?

The table below comes from the technical data of the stationary Schilling portal crane with a single beam (1,000 kg). The leg width is the width of one side frame on the floor; you need this if the crane must fit through a door or between machines.

Version	Hook height (trolley bolt)	Total height	Leg width	Weight with 4 m beam
Small	1,249 to 2,349 mm	1,695 to 2,795 mm	1,297 mm	118 kg
Medium	1,730 to 2,980 mm	2,175 to 3,425 mm	1,736 mm	125 kg
High	2,310 to 4,010 mm	2,755 to 4,455 mm	2,238 mm	178 kg

If you place the stationary crane on the Schilling undercarriage with wheels for indoor use (24001), the minimum hook height increases by 400 mm and the maximum by 200 mm. For the undercarriage for indoor and outdoor use (24002), that is 440 mm and 240 mm. With such an undercarriage, you only move the crane without a load. The Estil portal crane of 1,500 kg can also be on wheels, but according to the product data, it is also not drivable under load. If you want to move the load by driving, choose a version that is drivable under load.

How much beam length can you actually use?

The trolley does not cover the entire beam. With a 4 m beam, the free width between the side frames is 4,000 mm, but the usable length for the trolley is 3,679 mm (small and medium) or 3,479 mm (high). So measure the position of the load and the set-down point, and compare that with the usable length, not the beam length.

Beam length	Free width	Usable for trolley	Crane outer dimensions	Weight (medium, 1,000 kg)
4 m	4,000 mm	3,679 mm	4,250 mm	125 kg
5 m	5,000 mm	4,579 mm	5,277 mm	136 kg
6 m	6,000 mm	5,679 mm	6,250 mm	143 kg
7 m	7,000 mm	6,579 mm	7,277 mm	183 kg
8 m	8,000 mm	7,679 mm	8,250 mm	194 kg

If you do not place the side frames at the ends of the beam, follow Schilling's rule: the beam length between the side frames is always at least 1.6 times the beam length outside the side frames. For safety, calculate with the total that protrudes on both sides. With a 6 m beam, a maximum of 2.3 m can therefore fall outside the side frames together (6 / 2.6 = 2.31 m), so that at least 3.7 m remains between them.

How do you calculate the floor load?

Schilling prescribes that the portal crane must only stand on a flat and solid surface. Whether your floor is that depends on the force per foot. You estimate that as follows:

1. Add the weight of the crane, the hoist, and the load with lifting attachments.
2. Assume that the trolley stands above one side frame. That side frame then carries the load, the hoist, and half of the crane.
3. Divide by the number of feet of that side frame (two).
4. Multiply kilograms by 9.81 for newtons.

Example calculation. High version, 4 m beam, 1,000 kg: the crane weighs 178 kg, the Kito CB010 with a 2.5 m lifting height weighs 11.5 kg, the load with slings weighs 1,000 kg. One side frame then carries 1,000 + 11.5 + 89 = 1,100.5 kg, approximately 10.8 kN. Per foot, that is approximately 5.4 kN. This is the static load without impacts or swinging. If the crane stands on a floor slab, a manhole cover, a basement hatch, or paving stones, have the load-bearing capacity assessed by a structural engineer. The pressure on the floor also depends on the surface area of the footplate; measure that on your crane.

Under what conditions may you work with it?

• Temperature between -20 °C and +50 °C.
• Wind speed below 40 km/h.
• Beam horizontal, side frame uprights vertical, all bolts and locking pins installed.
• Engage the brake on the trolley if you are not driving: if the beam is slightly crooked, a free-rolling trolley can start moving.
• Never stand or walk under the suspended load, and do not transport persons.

How often must a portal crane be inspected?

According to Schilling's maintenance plan, you perform a visual inspection and functional test before the first use, and a visual inspection before each subsequent use. At least once a year, and immediately after an adjustment or repair, have the crane inspected by an expert, with a load test. Also check the hoist and the lifting attachments during that inspection.

Frequently asked questions

Does the weight of the hoist count towards the working load of the crane?

The hoist hangs from the trolley and is therefore carried by the crane. The Schilling manual does not mention a deduction for the hoist weight; ask the supplier about it at full load. For the floor load, you always include the hoist weight.

Can I drive a stationary portal crane with a load?

No. The Schilling undercarriage is intended to move the crane without a load. For driving with a load, there are versions that are drivable under load, such as the Estil of 1,000 kg and the drivable Schilling cranes.

Can a portal crane stand outside?

Yes, within the limits of the manual: wind speed below 40 km/h, -20 °C to +50 °C, and a flat, solid surface. For moving outdoors, Schilling has an undercarriage with solid rubber tires (24002).

What is the difference between beam length and usable length?

The beam length is the free width between the side frames. The usable length is the part over which the trolley can drive. With a 4 m beam, that is 3,679 mm or 3,479 mm, depending on the version.

Why an aluminum portal crane?

The cranes are modular and demountable. The small Schilling with a 4 m beam weighs 118 kg and the Estil of 1,500 kg weighs 96 to 138 kg, so you can assemble and store them at the workplace.

Read further and products

• Portal crane tool: find the portal crane that fits your dimensions
• Stationary portal cranes and mobile portal cranes
• Schilling aluminum portal crane single beam large
• Schilling undercarriage for stationary portal crane
• Kito hand chain hoist and other hoists and accessories
• Inspections and inspections
• Knowledge base: Calculate the working load of a lifting sling and Machinery Regulation 2027 for lifting equipment and hoists

Sources: Schilling, user manual aluminum portal crane (stationary and drivable under load, single beam), chapters 4.2, 4.3, 9, 10, 11 and 12; Schilling, technical data stationary portal crane single beam 500 and 1,000 kg (February 2025); Kito, user manual hand chain hoist CB (specification and dimension tables); product data Estil aluminum portal cranes 1,000 and 1,500 kg in our shop. Photos: Schilling and Estil (product images), diagram Hef en Hijs Online. Last checked on November 14, 2026. This article does not replace the user manual of your portal crane and hoist; example calculations are static and do not replace an assessment of the floor by a structural engineer.