The controls are arranged in columns above each unit. Because there are twelve units, most controls are in twelve fold, and this makes the control panel look rather crowded.
The controls are all straight forward and logical, therefore the fatigue tester is easy to use and does not require extensive instructions.

The high force (F-high), the low force (F-low), and the on-time can be set individually for each sample.
The forces can be set between 1.8 and 200 Newtons. The on time can be adjusted from 0.1 to 10 seconds.
The cycle time, which is a common setting for all twelve units can be set in 0.01-seconds steps from 0.1 to 99.99 seconds.
For our experiments on dental materials, the cycle time is usually set at 1 second and the on time at 0.5 seconds.

Samples need to be mounted in suitable sample holders. For several types of testing sample holders are available.
In fatigue testing, shapes of samples and types of loading come in a wide variety. Therefore for each type of experiment a suitable sample holder has to be designed, which transfers the forces from the end of the rod to the sample.

The fatigue tester uses compressed air, and pneumatic cylinders (1) to generate the forces. Friction of pistons would cause irregular errors of the forces. To avoid this, the cylinders have rubber diaphragms rather than ordinary pistons.
The forces are transferred over the extendable rods (2) to the sample mounted in its holder (3), which is simply represented by a triangle.

The fatigue tester produces relatively little audible noise. This is mainly because the units are triggered sequentially rather than simultaneously during cycling. Without this feature and with a 1 second cycle time one banging sound a second would be produced. Because of the sequential cycling feature the fatigue tester will click twelve times a second.
The fatigue tester uses pneumatic valves which have a very high fatigue life (MTBF>300x10⁶ times switching). These valves have a very small moving mass and therefore produce very little sound.
Although the area of the pneumatic cylinder (1) is about 8cm², the volume is only 2.4cm³. This also leaves only little air for the exhausting hissing pulses.

During an electric power failure all units will temporarily be decompressed and the cycling will stop. When the power is restored again within 5 days all experiments will be continued.

The pneumatic system is designed to be stable. All pressures are set with diaphragm type regulators. In a previous design piston type regulators were used, but the friction of the piston produced random variations in the forces.

The pressurized air comes in at the left, into the central pressure regulator (P-c) that stabilizes the pressure fed into the regulators of the twelve units at a very constant value of about 350 kPa. At the same time this limits the maximum output force to about 250 Newtons per unit, to prevent damage to the load cells.
P-Hi and P-Lo are the user settable regulators on the control panel. V-a and V-b are electrical valves. 
In the drawn situation the valves are off. When the unit is started V-b is activated and feeds the cylinder (C-1) the pressure selected by V-a. During cycling V-b is switched on and V-a switches continuously between the high and the low pressure.
V-c establishes a leakage path. This basically increases the sensitivity of the regulators.