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Warning
An LA34 actuator is not designed for repeated dynamic push-to-pull movements. This cause extra strain to the actuator and can give safety
considerations, the consequence being possible damage to the actuator. Therefore, if repeated dynamic push-to-pull movements are essential
for the application, perform tests to validate the performance and use a steel piston rod eye (contact LINAK A/S).
LA34 actuators for patient hoists are marked with a label to ensure the user is aware that it is not permitted to handle the patient hoist by
pulling the actuator or otherwise expose it to side forces.
Tests show that uneven running can occur when retracting the LA34 composite actuator with a low load below 500N.
This has no impact on the safety of the actuator and is caused by internal frictions.
If the LA34 actuator is used in connection with a non-LINAK power supply the system must be equipped with current trip cut-off.
Adjustment of the installation dimension N
As standard the installation dimension on the LA34 actuator can be manually adjusted by +4 / -0 mm (not possible for mechanical splines).
The adjustment of the installation dimension must only be made without use of tools only, or hand). It is not allowed to use tools to adjust the
installation dimension of the LA34 actuator as there is a risk that the inner tube may be unscrewed.
Hall
The Hall principle is very similar to the Reed principle. It is a control box, which based on Hall signals, can decide whether the actuator runs out or in.
Hall, however, can detect whether the actuator runs in or out. The number of pulses is like Reed. Hall and Reed are placed opposite the potentiometer
on the actuator’s worm wheel. Therefore, it is not suitable for use in quick release /free wheelingactuators. see figure 10.
Potentiometer
The potentiometer function is mechanically attached to the spindle and registers the number of spindle revolutions. The signal from the potentiometer
is measured in Ohm, where the lowest value is measured when the actuator has been run into inward switch stop. The potentiometer is a 10 - turn
and therefore it is dependent on the stroke length/spindle pitch. see figure 6.5
Mechanical spline:
The splines function so that the actuator can only push, not pull. During pull in the actuator, the inner tube is lifted off the thread bush, and the
actuator can therefore never pull a load, only push. See Figure 8.
Functional test of mechanical splines:
When the piston rod is at the innermost position, it must be possible to pull it out manually to its full travel length and to press it in again. When
used in a vertical position the force needed to activate the mechanical spline is maximum 60 N + the weight of the application. To reengage the
spline function, a force of maximum 60 N is needed. If this is not possible, contact your nearest LINAK dealer.
Electrical splines:
In the rear fixture on the actuator, a microswitch is fitted, which turns off the motor, if the actuator is exposed to pull forces.
Functional test of electrical splines
It is important that the actuator is correctly fixed with regard to the section on page 11. For mounting, see Figure 7.
When the actuator is correctly fixed/mounted, the inward movement of the piston must stop, when the actuator is pulled or the movement is blocked,
so that the back fixture is not put under undue stress/tension.
Quick Release
LA34 (34xxxF/H) is equipped with a function which permits operation of the actuator should the power source fail. Condition for functioning: the
actuator must be loaded in push direction (LA34xxxF) or pull direction (LA34xxxsH).
Warning
• If the actuator does not work as described above, the risk of injury due to squeezing can arise. Therefore, the actuator must be sent immediately
for service at the nearest, authorised LINAK workshop.
• The actuator must not be used in pull applications when the Quick Release is activated, as the risk of personal injury can arise.
• Do only use the actuator within specified working limits.
Activation of Quick Release
Pull the release handle in the direction of the piston rod eye (outwards), the harder you pull the button the quicker the actuator runs down.
When releasing the button the emergency lowering stops immediately. The emergency lowering is activated as long as the load on the actuator is
above 100 - 150 kg. The actuator is ready for normal use when the emergency lowering is finished.
Safety device regarding functional failure of the nut (Safety nut):
The LA34 has a built-in safety nut in push as standard and is available with a safety nut in pull as an option. Actuators with safety nut in push can
only function when used in push applications. The safety nut comes into operation should the main nut fail.
Afterwards it is only possible to drive the actuator into the innermost position. Safety nut in pull is for pull applications and works the opposite way
as described above. Thereafter, the actuator will not function any more and must be sent for service.
Built-in end-stop circuit
In the actuators mentioned the end-stop switch is part of the actuator construction. Each time the actuator reaches end-stop position, the switch is
activated and the current is cut off.
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