Membrane Air Springs

Membrane air spring insulators

The Air Spring Insulator BiAir® consists of a cast steel or aluminum housing, within which the air space is contained by thin-walled flexible and pressure-resistant rolling membrane. A piston sits on top of the membrane and is pressed into the air space. This design allows a highly-effective isolation of vibration. In order to simultaneously achieve a high degree of damping, the air space is divided into two chambers connected with an air tube. (load/damping volume) A choke valve can be used to adjust from outside the cross-section of air flowing into the connecting tube from outside according to the degree of damping required. The friction on the flow of air caused by the choke valve can create a damping effect of up to 20%. Damage to the rolling membrane caused by overpressure is prevented by additional safety valves.


Range of Applications

Highly-effective isolation of vibration for sensitive measurement and testing equipment, precise finishing machines, laser equipment and optical and electronic instruments. Another important application is the vibration-insulated mounting of test benches for the motor vehicle, transmission and other industries. BiAir® Air Spring Insulators provide excellent isolation of foundation and equivalent machine loads.

Advantages over Conventional Steel Springs

BiAir® Air Spring Insulators with level control provide active isolation. The correct level of machines and foundations is maintained constantly! Level control and adjustment is conducted automatically! Furthermore, changes in load result in appropriate adjustments to the air pressure in the air springs such that the required isolation remains constantly effectively despite changes in load.

Bilz Leveling Systems

Air springs are available for greater maximal loads and lower natural frequency. Level control provides an important contribution toward the optimal function of an air spring system. If a change in load likely occurs on equipment mounted with an air spring system, such that compression of one of the springs or an inclination of the equipment will result, a leveling system might be the only solution available. The change in air pressure in the air spring insulators adjusts the height of the individual elements (BiAir® or FAEBI®). By quickly pressurizing or de-pressurizing the springs, the proper level can be maintained despite variations in the position of the load.

Control System

The leveling system consists of at least three air springs. Even if several insulators are required for design or load reasons, three control groups are necessary in order to avoid a statically over-determined system. In such a case, multiple air springs are grouped together and controlled in parallel.

BiAir® Mechanical Pneumatic Control Valves

One simple, but effective solution is the mechanical pneumatic proportional valve. A small plunger is used to continually check the level. The plunger position is transmitted to the push valve. In accordance with the position, the air spring will be pumped up with or relieved of pressure. The level can be maintained constantly to within ± 1/10 mm. There are three control valves working together with an air compressor which limit system pressure to a maximum of 6 bar, remove any accumulated condensation and cleanse the system air of solid particulates such as rust and dust.


BiAir® Electro-pneumatic Level Control

Important Advantages of Bilz Level Control are:

  • The high degree of re-set accuracy and of level maintenance of ± 1/100 mm
  • The extraordinarily fast response time
  • The possibility of adjusting the speed of the system (amplification and re-set time) optimally with regard to the specific conditions (control loop)
  • The robust proportional valve with large air volume flow
  • The exceptional ease of use

System Components

Each system is comprised of 3 position sensors, 3 electro-pneumatic proportional valves, a control unit (digital processor) and a compressor. The electro-pneumatic control meets the most strenuous demands. It is primarily used when high re-set precision and extremely short response times are necessary. Very accurate position sensors are used to measure the deviation between real position and nominal position of the air spring insulators to within 1/100 mm. The control unit processes the electronic signals and determines the extent to which the springs are either pressurized or de-pressurized via the electro-pneumatic proportional valve.

Control Unit

The control unit consists of a printed circuit board containing the entire logic circuitry of the three control loops, the three air pressure displays, setting screws for the adjustment of the machine and nominal speed, and a switch allowing the operator to completely de-pressurize the air springs. The control unit is also available as a 19-inch rack component or with its own case. Software

A special software package is also available which allows the operator to set and optimize nominal values, to log setting parameters and to conduct error diagnostics. The integrated interface also enables the operator to connect to the computers of the machines to be isolated allowing him to manage a wide range of diverse operating modes..

More information >

Please feel free to contact us at any time if you need more information or want to discuss your needs and requests with us.


Tel +358 (0)20 730 6070


Tel +46 (0)76 525 5000