Product category:
Pneumatic Actuators, Motors, Accessories
News Release from: Freudenberg Simrit LP | Subject: Hydropneumatic suspension systems
Edited by the Engineeringtalk Editorial
Team on 27 November 2003
Hydropneumatic suspension evolves to new
levels
Simrit offers two different types of hydropneumatic suspension system, both of which allow for very different types of fine-tuning.
The trend toward hydropneumatic suspension systems in tractors is set to continue and intensify It is becoming clear that the combination of hydropneumatic front axle suspension and cab suspension improves ride quality and increases comfort and top speeds
Recent developments - which have seen a shift toward active, individually adaptable hydropneumatic suspension systems - have extended the range of available solutions.
Diaphragm accumulators are used in hydropneumatic suspension systems.
In order to be able to use the diaphragm accumulator at both maximum and minimum axle loads, a hydraulic opposite load is built up in the cylinder ring chamber and generally controlled at a constant level.
The Simrit system uses a pressure control valve to keep the ring chamber pressure at a constantly low level and regulate it with every new control procedure.
This allows for two different strategies.
The first generation hydropneumatic suspension system works as follows: the pressure level in the ring chamber is adapted by the structure in such a way that the components and accumulator design are harmonised for completely different tractor types.
This reduces the number of part designs and increases quantities in an economical way.
The size of the suspension cylinder is adapted in such a way that the reduced difference in pressure at the cylinder seals is beneficial for the suspension function as it creates low frictional behaviour.
Moreover, this variant is not dependent on maximum pump pressure.
The second-generation hydropneumatic system was developed for suspension systems whose axles are subjected to high load ratios.
Here, the pressure level in the cylinder ring chamber is automatically controlled by the axle load.
Once the minimum axle load falls below a structurally fixed level, the pressure is automatically raised to a higher level.
Similarly, once the minimum axle load is exceeded, the pressure is reduced to a lower level.
The fact that the pressure in the ring chamber can be adjusted means that load ratios of up to 1:20 can easily be managed.
Changing the ring chamber pressure influences the axle's elastic spring rate so that the functions can accurately be adapted to suit the operating conditions.
For example, increasing the pressure in the ring chamber notably reduces pitching when driving with a raised, heavy plough.
This innovative suspension system's variety of adaptation possibilities allows more effective use to be made of the functional advantages of a hydropneumatic suspension system no matter what the operating conditions.
The load-dependent change in pressure in the ring chamber of the hydropneumatic suspension system with position control provides an economical way of meeting customers' requests for higher speeds even with high load ratios.
In short, Simrit offers two different types of hydropneumatic suspension system, both of which allow for very different types of fine-tuning.
It is worth noting that the machine's interfaces are always included in the design of these systems.
This means that the fine-tuning of the electronic and hydraulic systems is always taken into consideration.
The fact that the entire system is taken into account in this way means that a complete system for a new tractor model can be developed within a very short space of time.
The standardisation of components also allows samples to be produced very quickly.
The self-adapting settings of these intelligent, active systems open up completely new opportunities.
Consequently, planned developments such as combined front axle, cab and rear axle suspension will exploit the full safety potential that is of such vital importance for tractors that are travelling at ever-increasing speeds.
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