Friction Springs

Your Benefits

RINGFEDER^® Friction Springs have multitude features in opposite to other damping systems:

• High spring work combined with low weight and volume – As RINGFEDER^® Friction Springs completely utilise the material of which they are made only a minimum of dimensions and weight are required. The decisive parameter here is therefore the spring work.
• High Damping Potential – The damping of RINGFEDER^® Friction Springs is standard with 66 % wherewith the energy will be soon absorbed and resonances complete disabled. Variations are possible with different greases.
• Overload-safe in blocked position – RINGFEDER^® Friction Springs are generally designed to “block”, so it is therefore ensured that the admissible stresses cannot be exceeded and the RINGFEDER^® Friction Spring do will not be damaged.
• Independent of loading rate – The force-travel-diagram of the RINGFEDER^® Friction Springs applies for all operating conditions. In contrast to other damping systems, RINGFEDER^® Friction Springs provide full spring work and damping effects even, when the load is applied extremely slowly or quickly.
• Diagram independent of temperature – With hydraulic dampers and springs made of synthetic material, the force-travel diagram will be influenced by temperature fluctuations and inherent temperature rises. The characteristic curve of the RINGFEDER^® Friction Springs, however remain independent of these factors and can be used in the temperature range of -20 °C to +60 °C without the curve changing appreciably, as the inherent temperature rises of the spring due to the dampening effect have been taken into account. For extreme applications going beyond the indicated temperature range please consult our technical department.
• Maintenance-free – Normally, during operation no regreasing of the spring is necessary; however when regreasing is required then only RINGFEDER^® specified lubricants can be used to ensure correct spring function.
• Versatility in design – As well as the standard RINGFEDER^® Friction Spring range we can offer special solutions based on you specific application. The graph shows the ratio of outer diameter to spring end force, this can be used to quickly see if an application is possible even though a standard spring is not available.
• Parallel and series arrangement – The geometry of the RINGFEDER^® Friction Springs allows an optimum utilisation of the available mounting space due to a nested construction, using parallel or series spring arrangements.

RINGFEDER^® Friction Spring Design

If a RINGFEDER^® Friction Spring consisting of “e“ elements terminates with half rings its untensioned length will be:

• L_o = e · h_e

The total spring travel can be calculated according to the equal:

• s = e · s_e

When eliminating the pretensioning force the spring work is given by:

• W = e · W_e

The end force does not change with the number of elements.

Selection and Fitting of RINGFEDER^® Friction Springs

• Pretensioning – RINGFEDER^® Friction Springs have to be pretensioned with min. of 5 %, preferably 10 % of the total spring travel. In order not to impair the lubricant film, the pretensioning force should not exceed 50 %. Exceptions are possible after consultation.
• Pretensioning – For RINGFEDER^® Friction Springs some form of guiding is necessary. Exceptions apply for short springs with a length ≤ 1.5 D₁, in this case they need to be loaded between parallel thrust plates.
• Lubrication – Only the special greases recommended by RINGFEDER^® must be used for lubrication purposes, this is because the cone surfaces are under a high contact pressure. Generally, the grease provided with the spring is sufficient. Re-greasing is not required.
• Observe the diagram – With buffer springs the available spring work in J, i.e. the area under the loading-curve (above curve), is of interest. If the spring is to be used as a tension device, the recoil curve has to be taken into account (lower curve). Of course, the lower curve can be increased by using a friction reduction lubricant. For this, please let us have your specifications.
• Sealing – RINGFEDER^® Friction Springs have to be assembled with protection against dust and moisture, in order not to impair the lubricating film. Simple sliding guides are sufficient. Under strong dust and moisture, we recommend to use gaiters.

Buffers with RINGFEDER^® Friction Springs

The buffer types are standard delivered in one of four designs. These buffers are suitable for operation temperatures from -20 °C to +60 °C. Above that, modifications allow an extended temperature range from -73 °C to +200 °C. For geometrical and technical special solutions according to specific requirements please contact our engineering team.