Low maintenance Airstroke actuators from Firestone provide a compact and easily installed way to continuously orient solar trackers’ payload towards the sun to optimise the amount of energy produced from installed power generating capacity.

The rubber and fabric actuators can be used to solve the problem of stationary solar collection panels becoming inefficient as the sun shifts from a 90-degree angle to the panels.

Usually inflated or deflated by standard fixed or mobile compressed air (typically 7 bar (100 psi), they move photovoltaic systems to minimise and angle of incidence between the incoming sunlight and a photovoltaic array.

Alternatively, an ingenious actuation alternative uses the expansion and contraction of Freon gas as it is heated and cooled within the actuators to extend and retract them and change the angle of the collection panels (as per illustration above).

Airstrokes are particularly beneficial for commercial installations, where continuous focusing of the arrays through single or dual-axis arrangements enhances energy returns. Such installations – sometimes in remote locations and subject to climatic extremes over 24 hours – need extremely reliable actuators to continuously reposition payloads such as solar panels, reflectors, mirrors or lenses.

Airstroke bellows offered by for use by solar engineers and installers have been proven in widespread heavy duty industrial actuation throughout Australia, including providing millions of cycles of service on conveyors and mineral processing screens and vibrators, where they have to withstand dust, heat, moisture and extremes of Outback climate.

They are identical in construction to the airbags proven in truck and train suspension so they are extraordinarily tough. In addition to having no internal rods of seals to wear – unlike conventional metal cylinders – they have the ability to rotate through an angle without a clevis.

In addition to making air springs easy to install in compact spaces, this ability to bend with load (and to tolerate high side loadings) means the air springs will perform where more rigid alternatives would break or wear.

Advantages of Air Springs

* Cost. Air springs can be used instead of more expensive hydraulic systems when applying large forces. Sizes are available from fewer than 80mm to more than nearly 1000mm (3in to 38in) in diameter, in single, double and triple convolutions.

* Suitability for aggressive environments. Since there are no seals sliding against exposed surfaces, an air spring can often survive abrasive and corrosive environments that require special consideration when a conventional cylinder is used.

* Compact installation. The way a flexible-wall air spring operates is as follows: it is compressed to its minimum height then extends when pressure is applied. In most cases, the minimum height is considerably less than the available stroke. As a result, air springs can be put in a very compact space and extended to more than twice their starting height.

* Ease of attachment and low maintenance. Since the bellows bends, its bead plates don’t have to remain parallel. No lubrication is required once it is in place. Ease of attachment. The lack of seals also means lack of friction and jerkiness in operation.