Rosta Product Applications
Everybody has come into contact with rubber suspension units at some time, mostly unknowingly. In every amusement park there are hundreds of ROSTA units in ships, rafts, sledges and roller coasters. They ensure that the passengers can race on there vehicles through rapids and curves without shock and above all, injury. Safety rails, buffers and river bends are literally covered in elastic elements so that the ‘horse and rider’ survive the ride with amusement and not injury or shocks. (figs 1 & 2)
ROSTA rubber suspension units carry cable cars, ski lift seats (fig 3) and suspend railways in collieries. They also make sure that the electrical power from rails or overhead lines reach the motor at all times via pantographs maybe you have been on a tram or train that has had such a system. The applications that Rosta units can be put into are as extensible as the units themselves.
fig 3fig 4.
The rubber suspension unit is a torsion spring with four pre tensioned special inserts placed between the outer casing and inner square section rotated at 45°C. The high pretensioning force on the rubber inserts makes additional axial anchorage for the inner part unnecessary. The operating angle of the torsion spring is plus or minus 30°C. (fig 4) The rubber suspension system offers a broad selection of muti-functional machine components; it combines within a compact design spring, a torsion bearing and an oscillating damper. The natural inertia of the rubber results with rotational motion in intrinsic damping in the element that can absorb upto 30% of the excitation energy.
This torsion spring principle was developed by ROSTA over 50 years ago, originally as a low cost suspension for vehicles, today, however the emphasis is on the application of components for machinery construction, such as rubber suspension units in a standardised module, chain and belt tensioners, oscillating elements for screen suspensions and motor bases with automatic tensioning.
Oscillating suspension for screening and conveying equipment are one of the specialties within the product range. In mines and ore processing plants (fig 5) the units have made a name for themselves over the last decade as long lasting components in rugged use above and below ground. In the recycling of building rubble and waste (fig 6) too, one cannot do without the anti-overload supports for screens and oscillating conveyor troughs; they have replaced the fault-prone steel springs in several areas of screening technology.
Rubber components are important components of our “daily bread” for many machines and installations in flourmills and the subsequent processing of cereal products. As maintenance free and long lasting supports for all kinds of gyratory sifters (fig 7) and screens, ROSTA elements are to be found in the production of food stuffs wherever refinement and selection has to be done using vibration, e.g. when white flour has to be separated from the course grist in sifting screens. Corn flakes, nuts, fruit, vegetables and salads are sorted and de-watered using cost-saving oscillating processing. There is hardly a canning or packing factory where ROSTA suspensions are not used on oscillating equipment to simplify processing in a reliable manner.
Chain and Belt Tensioners
A list of possible applications for these rubber suspensions would be incomplete without mentioning chain and belt tensioners. Over 40 years ago this component was the first standardised product from ROSTA.
All chains wear, all belts wear and stretch, some considerably during there working life. Without some form of automatic tensioning (figs 8 & 9) device to compensate for this wear / stretch, belts would screech and only transmit a fraction of the torque and chains would tend to wear prematurely and be noisy, with the whipping action and eventual jumping of the sprockets perhaps causing damage to the rest of the drive or even the machine. With over 500,000 tensioning units installed every year, quiet, efficient and low maintenance operation can be obtained in virtually all open drive units.