Air Actuators Design & Fitting Considerations

Lateral guidance

The stability of actuators varies greatly and depends on the type, size as well as on internal pressure and height. Therefore, lateral guidance is advisable. In many applications lateral guidance is already provided by the overall design (lever arm, scissors construction,etc).

Down and up stops

Air actuators must be equipped with external stops at the ends of the stroke. The air actuator is not designed to withstand forces that arise when it is extended or compressed excessively without external stops. If the actuator is inflated without any load, the product can be damaged and there is a risk of injury.

Down stops
An actuator fitted with, and without, down stops
Up stops
An actuator fitted with, and without, up stops

Tilt angle

Air actuators can execute their stroke at an angle. The maximum tilt angle varies according to type and kinematics. The following are approximate angles:

  • Single convolution air springs: 10 to 20°
  • Double convolution air springs: 15 to 25°
  • Triple convolution air springs: 15 to 30°
  • Sleeve type air springs: ca. 15°
  • Rolling lobe air springs: ca. 15°

At the design stage, ensure that the height is not below the minimum height or exceeds the maximum height at any point. To determine the available force, the height of the centre point of the plate from the base applies (see below). In case of doubt, consult us first or carry out kinematic tests.

Avoid chaffing
Tilt angle on convolution air springs
Bellows must not rub against itself
Tilt angle on rolling lobe air springs

Air consumption

The outer diameter of an air actuator is somewhat larger than the effective diameter. The air consumption is calculated using the volume curve on the corresponding datasheet and not the effective area and stroke.

Installation space

The space available for installation must be sufficient for the changes in the actuator’s diameter during the entire stroke. The bellows must not rub against any machine part or against itself (chaffing). Extra care must be taken that there is no chaffing when the actuator is in the tilted position.

Support area of actuator

The entire support area of the actuator should be used to ensure uniform distribution of forces. If this is not possible, a minimum of at least two thirds of the support area must be utilised.

Protect from mechanical damage

Air actuators must be installed such that they cannot be damaged mechanically.

Lateral offset possible

Because of their flexibility, actuators permit the top and bottom plates/pistons to be slightly out of alignment; however, misalignment should not exceed 30 mm for triple convolution types, 20 mm for double convolution types and 10 mm for all other types.

Maximum pressure

For the standard construction, do not exceed a maximum pressure of 8 bar when in operation. When air actuators with extra reinforcement are used, a maximum pressure of 16 bar is possible. Information about actuator types and design data available on request.