ROSTA – yesterday, today, tomorrow It started in the mid forties with the production of a few elastic wheel suspensions and, over the years, developed into a company that manufactured standardised rubber suspension axes for trailers. But it was the design and marketing of machine components such as the unique chain and belt tension elements that opened up the world market for the ingenious ROSTA rubber suspension system. Best-selling machine components such as the vibratory suspensions for screening technology helped ROSTA rubber suspensions to achieve their international breakthrough. This was followed by motorbases and anti-vibration mounts, which have now become indispensable in general machine construction. ROSTA rubber suspension units will also make their mark in the future in machine construction technology – whether in the recycling industry or in the production of renewable energy – the blue spring-loaded assemblies from Hunzenschwil in Switzerland are already fully involved in these forward-looking technologies! ROSTA www.rosta.com

ROSTA – a unique spring system from experienced specialists Quality validation obtains highest importance at ROSTA. The well-equipped Research and Development department leaves nothing to chance; the material tests that take place before and periodically during the series production are the guarantee for a comprehensive quality standard – a spare part element produced in ten years time will still have the same characteristics as the series product supplied today! Production machines, handling equipments, tooling machines and processing systems equipped with state-of-the-art technology can only...

ROSTA Element Determination The adjacent exploded view shows a rubber suspension type DW-A 45 x 100. Wherefrom comes this (relatively old) designation based on the German language? “D” stays for Drehelement (e: torsion-element) “W” stays for Winkelsupport am Aussengehäuse (e: included fastening bracket) “A” stays for Aluminiuminnenvierkantprofil (e: core-profile made of aluminium) “45” stays for the core dimension 45/45 mm (dimension a) “100” stays for the effective element-length 100 mm (dimension b) An AB 50 is an Abstützung = support element for oscillating screens with inner core dimensions...

ROSTA Technology 1 Function The ROSTA rubber suspension elements are mainly designed for applications as torsional spring devices offering operation angles of ± 30°. Depending on the particular function, not only torsional moments are generated by pivoting the spring device. According to the specific application additional radial Fr, axial Fa and/or cardanic Mk forces have usually to be taken in consideration. The occurring torques of the different element sizes and the additional load characteristics are indicated in the table on page 1.5. 2 – Torsion Range 2 Spring Characteristic By pivoting...

4 Natural Frequency of a ROSTA suspension The determination of the natural frequency of a ROSTA suspension has to be carried out by spreading the tangent at the loading point “A” on the parabolic arc of the load deflection curve. The resulting distance s1 on the axis of abscissa comes up to the arithmetical spring deflection in mm, required for the determination of the natural frequency. Initial deflection Cold flow 5 old flow and settling of the rubber C suspensions If, over a certain period of time, load is permanently applied on an elastic component (e.g. rubber suspension) consistent deformation...

7 Service Life Provided the rubber suspension elements are selected according to our technical specifications, i.e. are operating within the given frequencies and oscillation angles and under the mentioned surrounding conditions, no loss of performance and functionality can be expected for many years. Extremely low or high permanent surrounding temperatures considerably shorten the lifetime expectancy of the rubber suspension elements. The opposite service life curve indicates the relevant life deduction at extreme ± temperatures from factor 1 at room temperature of +22 °C. 8 Quality Control...

9 Permissible Element Frequencies Alignment chart for the determination of the permissible frequencies at different angles of oscillation in relation to the appropriate element size (DR 11, 15, 18, etc.). The higher the frequency in rpm, the lower the angle of oscillation has to be and vice versa. Example: (see blue indication on chart) A rubber suspension of type DR 50 may be rotated from the neutral position (0°) to an oscillation angle of ± 6° by a max. frequency of 340 min-1. For applications of “pre-tensioned” elements working, e.g. under 15° of pre-tension and describing oscillation angles...

  1 Chemical Consistency 1 The standardized ROSTA rubber suspension elements are equipped with elastic inserts of quality type “Rubmix 10”. This rubber quality is based on a high content of natural rubber. It offers against large media a high chemical consistency. In some specific applications, however, some additional protective barrier or the application of elements with synthetical elastomeric inserts (qualities “Rubmix 20”, Caustic soda solution up to 25 % (20°) Citric acid Formic acid Hydraulic fluid Javelle water Lactic acid Liquid ammonia Nitro thinner Petrol (fuel) Tannic acid “Rubmix...

ROSTA Stainless Steel Range In the food processing and pharmaceutical industries the very high hygienic standards are raising permanently. We accommodate these facts in our component development through expanding and improving continuously our range of stainless steel machine components. As a result, many of the ROSTA oscillating and tensioning elements are as standard elements in stainless steel material available from stock. For production-related reasons some dimensions of our stainless steel elements do slightly differ from the measurements of the standard range (steel versions). Please ask...