SPRINGS & SHOCK ABSORBERS FEATURE


realised. One example is the state-of-the-art student dormitory ‘Te Puni Village’ in Wellington, New Zealand. The objective was to compensate the ground acceleration during an earthquake. In cooperation with Aurecon Group, Ringfeder opted for a combination of slip joints and its own friction springs. Thanks to this construction, damage caused by a tremor can be reduced to a minimum. The friction springs absorb the shocks while the slip joints make sure that the building returns to its original position.


THE MARS ROVER Back to the Mars rover, and its robotic arm includes a percussion drill to crush rock and take samples. For this, a friction spring, designed specifically by Ringfeder, is being used as a vital shock-absorbing component to cushion blows with an energy value of up to six joules. This project began back in 2008 when


SPRINGING INTO ACTION to cushion against vibration


Friction springs fromRingfeder Power Transmission are being used throughout a range of industries. Here we take a look at two diverse applications –their use on the Mars rover Curiosity, and protecting buildings against seismic vibrations


A


s a developer of shock-absorbing technology, Ringfeder Power


Transmission’s springs have been used in a range of equipment and industries that demonstrate their reliability. In one example, a friction spring from the company was used on the Mars rover Curiosity. In another, these springs are helping to protect architectural structures in earthquake-prone areas. Ringfeder’s friction springs consist


of meticulously manufactured cups and cones which can be combined randomly according to the desired cushioning distance and arising forces, enabling the customer to select the solution that meets their specific requirements. As well as producing standard sizes, the company also offers special solutions for individual cases. When the acting forces are expected to


be exceptionally large, the spring rings can be arranged parallel or in rows. This means the spring material is exploited perfectly, the company explains, and the dimensions and weight of the cushioning


element could be reduced to a minimum. In addition, the friction springs offer freedom from maintenance and unfold their maximum suspension qualities even when subject to low stress speeds. In terms of earthquake protection,


the elements are mainly used in industrial facilities. In fact the company is currently developing a solution to absorb seismic vibrations which could affect the switchgears in electrical substations across North America. Switchgears are usually firmly connected to the floor slab with bolts and nuts – a fact which can have fatal consequences in the event of a tremor. To counteract this scenario, a two-way cushioning element equipped with a long and a short spring has been mounted to the foot of the switchgear to absorb upwards, downwards and sideways movements. Many successful projects in the housing sector have also been


/ DESIGNSOLUTIONS


A Ringfeder friction spring is being used as a vital shock-absorbing component on the robotic arm of the Mars rover Curiosity


Ringfeder was approached by NASA’s Jet Propulsion Laboratory (JPL) in California to design a friction spring that would be employed in the percussion drill, which would have to operate in vacuum. The component, however, would


Springs are helping to protect buildings during earthquakes


have to withstand harsh conditions. Not only did it have to offer high reliability, but it would have to withstand temperatures averaging -55˚C, as well as violent sand storms. Robert E. Maul of Ringfeder Power


Transmission USA passed the enquiry on to his German colleague Udo Krämer, product manager for shock absorbing technology in Groß-Umstad. For this application, Krämer developed the desired element, opting for special high-strength stainless steel. Ringfeder also investigated special


coatings that could substitute grease as lubricant for the spring. After an in-house trial phase, the team sent samples to the JPL for evaluation. In California, the application was tested on different types of rock, drilling 1200 holes to make sure the tool worked properly. Despite having a diameter of just 18mm,


the resulting friction spring played a key role in guaranteeing smooth operation of the robotic arm.


Ringfeder Power Transmission www.ringfeder.com Enter 219


DESIGN SOLUTIONS | APRIL 2014 25


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44