Design engineers usually associate industrial gas springs with machine elements that support the opening and closing of flaps, covers, lids or portholes and reduce the strength users need to apply. Triggering the metal pin does not require much strength in this application, but it helps to slow down tonne weight masses in an emergency. The use of gas springs on mobile folding cranes is impressive proof.
Who says that trolleys are always manoeuvrable and gas springs usually work slowly? The cooperation between ACE Stoßdämpfer, with its distributor in the Netherlands, Doedijns, together with the Dutch company Spierings Kranen, points in a completely different direction - way up high. There is a quick explanation for the trolleys. The Dutch solution is not referring to the use of shopping trolleys, but crane trolleys weighing approx. 200 kg. This is the name for the components of a crane that can move along a cross-member and ensure that the lifting cable moves along the boom. These booms are used horizontally or inclined at an angle of up to 30 degrees depending on the operation and weight.
The company Spierings Kranen, established in 1987, counts as an innovator and the market leader in the area of mobile folding cranes throughout Europe. The company manufactures cranes in various sizes for other European countries in the Northern Brabant town of Oss. Depending on whether a customer needs a mobile folding crane with four, five, six or seven axles, the right solution is produced under the management of boss, Leo Spierings. This creates cranes with varying ranges and the authorised weights for the trolleys correlate with their sizes. The further the distance between the load and the vertical cross-member, the higher the tilting torque. This means that up to 1.7 tonnes can be hung on the trolleys with a 60 metre range and up to 18 tonnes if the distance is shorter.
Industrial gas springs are important for emergency stops and putting cranes in the parking position
Great care is taken in production due to the shear extent of the individual crane assignments and because there are always high demands on the statics and safety. However well a mobile folding crane is constructed, there is always a residual risk involved with operation of moving crane parts. A particularly focus is put on the cables that serve as tools. After all, there is the risk of cables breaking in time due to the heavy loads applied. An associated loss of power would lead to the trolley running uncontrollably if inclined. The heavy masses would in turn lead to immense damages once they start moving. Preventing this was, and still is, the job of industrial gas springs.
Pre-loaded with guide pulleys, these extend in an emergency pushing out a locking pin, which then clicks into the crane boom strut construction and therefore stops the trolley with its full weight after a short distance. Alongside this emergency stop function, gas springs also play an important role in keeping the crane in the parking position: they ensure a secure hold for parts locked in place thanks to the gas springs.
Due to the fact that the Spierings Kranen research and development team under the management of Leo Spierings is orientated towards the future and is always improving the current concepts, the gas springs that were previously installed were put through their paces a short time ago. Doedijns, as a consulting company, drew Spierings' attention to the new industrial gas spring models from ACE, which display much faster extension speeds than those from another provider used before.
Industrial gas springs not only slow down quicker
Conversion of the gas springs in the mobile folding cranes and the change of provider were agreed to after several tests, as the new machine elements were not only able to convince with their extension forces and speeds. Another advantage was displayed by the fact that they can be mounted in a variety of positions. A compelling argument; especially when they are being attached subsequently on several mobile folding cranes, like in this case. Thanks to the advice given to Doedijns, the best gas springs including the assembly points could be quickly established. This is something that also facilitates integration. The model called GS-28-500-EE-1300 was therefore identified from the large product range offered by ACE, the damping specialist, located in Rhineland. With a stroke of 500 mm, this gas spring with a body diameter of 28 mm displays an extension force of 1,300 N. This is enough to press the locking pin out quickly and safely. Two smaller gas springs from ACE were also attached. The two GS-19-50-AA-350N type models achieve an extension force of 350 N, each with a 50 mm stroke length. They do not serve as an emergency stopper or parking device, but provide the counterpressure in the construction. Although you can't always be guaranteed to choose the trolley without a wobbly wheel at the supermarket, you can be sure that the trolley on a mobile folding crane from Spierings Kranen always locks into place when necessary.