Overhead slewing cranes

Frequently asked questions

For many years now, STEPA has used a drive wheel made from Vulkollan, which is considerably better though more expensive.

By using Vulkollan, STEPA sets standards with regard to durability and resistance to wear, as well as reducing maintenance costs.

For further information, please see the manufacturer and commercial companies’ websites.

You can find clear information on Vulkollan here:

http://www.rader-lenkrollen.de/Vulkollan.aspx

Ropes have the following

Benefits:

- No need for degreasing and lubrication

- Runs more quietly

- Ideal for tensile loads (see rope winch)

- Low maintenance

- Lower wear through low maintenance requirements

(The chain runs into the runner, increased wear if the chain is soiled, etc.)

Disadvantages:

- Larger space requirement due to larger deflection pulleys (approx. 16-18 times the rope diameter)

The larger space requirements are also the reason why ropes are not used in some areas, e.g. Palfinger Epsilon forestry and recycling cranes, forklifts, etc.

In these areas, the pull-in forces are significantly higher and using larger ropes is not an option as it results in significantly larger space requirements.

To that effect, the issue of greater space requirements has been solved by STEPA by using 2 ropes instead of a single rope for drawing in. For this reason, the deflection pulley does not need to be enlarged and it is possible to achieve a very high pull-in force.

Ropes have been used successfully in our agricultural and forestry cranes for 25 years in over 15,000 cranes.

The compressive lifting cylinder was introduced by STEPA in 2000. The lifting cylinder, which lifts and lowers the main boom, is found behind the crane column. For lifting, the cylinder must be “pushed” out. Previously, the cylinder had to retract to lift the load arm = a “pulling” cylinder.

Why did STEPA do this?

The compressive lifting cylinder has 7 significant benefits, which the pulling cylinder does not have.

Benefit 1: Lower oil consumption (136% less when lowering, 19% less when lifting). This means the pump has a greater residual capacity for other functions.

Benefit 2: Better handling performance, above all when carrying out multiple functions at the same time as less oil is used for the main function of lifting and lowering.

Benefit 3: The lifting boom no longer swings up. On the other hand, with a pulling cylinder, the pump cannot get sufficient oil into the cylinder compared to the amount that can flow out. This deficiency leads to the lifting boom encountering “holes” and swinging up. The only solution was to integrate throttles, which reduce the outflow of oil = heat and speed reduction.

NOTE: At high temperatures, the viscosity of the oil increases and the throttle must be set accordingly so that see-sawing of the lifting boom is reduced.

Benefit 4: No throttle required = no integrated oil heating.

Benefit 5: An oil cooler is not needed as quickly because throttles are not needed.

Benefit 6: Better crane geometry - STEPA uses the full piston area for lifting.

Benefit 7: The lifting cylinder is shorter and stronger - lower tare weight.

This very important and difficult question depends on many factors.

Here is a short list of important factors to consider:

- Roof truss design
- Size of the building (required crane boom length)
- Particular circumstances (pit silo, ventilation boxes, etc.)
- Size of farm (average daily quantity in ha)
- Other specific requirements (radio remote control, curved rails, crosswise drive)

Based on these points and several more, we can establish - preferably in an on-site meeting - the possible variants for you.

Each crane is adapted for best results in specific conditions and to make work processes simple for our customers.

With the STEPA modular system, you can select from over 45 different crane types with a wide range of equipment variants.

If we haven’t answered your question here,

please contact us. We will be happy to help.

more info