Maintenance-free and lightweight plastic plain bearings in resuscitation device

Profile

• What was needed: iglidur plain bearing technology
• Requirements: Maintenance-free, fast installation time, small dimensions and low weight for mobile use, as well as affordable for aid organisations.
• Industry: medical equipment
• Success for the customer: By using the iglidur bushings, weight and costs could be reduced. 22 cylindrical, a thrust washer and 9 flanged bushings are installed per unit. During the endurance test by the testing and certification body BerlinCert, the device withstood the loads without any problems from the beginning.

Problem

The animax resuscitation device enables all rescuers, from laymen to professionals, to perform optimal cardiopulmonary resuscitation (CPR Cardio Pulmonary Resuscitation). Without tiring effort, it is possible to perform a perfect resuscitation even over a longer period of time. The device is simply placed over the patient's chest and pulled together to the point of contact. By pressing the lever, cardiac massage is performed. The respiratory pressure is throttled and can be seen via a pressure manometer on the patient valve. To protect the patient, a pressure relief valve and a spontaneous breathing valve have been integrated. It is also possible to connect oxygen to ventilate the patient. As the animax is also intended for non-clinical and semi-professional use, the device must fulfil many other requirements in addition to the actual functions: maintenance-free, very fast set-up time, small dimensions and low weight for mobile use as well as an affordable price for aid organisations.
Bearing solutions which are used at various points, such as on the changeover mechanism, pressure cylinder and in the frame, and have to perform axial and rotational movements have been particularly decisive factors here.

Solution

With only one push-button on each handle, the animax can be engaged simultaneously in the width as well as in the height virtually continuously, according to the respective body dimensions, when setting up the device. The change-over mechanism has two cylindrical iglidur plain bearings one behind the other in two hollow shafts. Within each of these, the inner hollow-shaft is mounted without danger of edges. To make it easier to turn the slotted link, the tolerance of the inner guide sleeve was placed further into the negative. It is therefore necessary to intercept the torque generated by the lever at another point. This is done in the plain bearings of the component "bridge". On the test rig, bearings with steel jacket and PTFE coating did not withstand the loads. By testing various bearing bushings, the igus Z-bearing turned out to be the best solution. The frame has a gantry shape in which a total of four tubes are telescoped. For this purpose, an extruded aluminium profile was manufactured, into each of which a plain bearing is pressed in. Due to the thin-walled igus film plain bearings, it was possible to design the profiles themselves thinner. This saved weight and costs. The same film bearings are used in the lever extension mechanism. The entire lever mechanism was designed with igus plastic plain bearings at all pivot points. This allows for precise, solid, yet effective operation. 22 cylindrical and 9 flanged bushings are installed per unit, as well as a thrust washer. During the endurance test by the testing and certification body BerlinCert, the device withstood the loads without any problems at the first attempt.