User reportLow-noise and durable polymer bearings replace cloth bearings in organ building

An organ builder usually has three wishes: a sufficient installation height, an appropriate floor space and beautiful acoustics. Today, it is not just a question of traditional construction methods, but also of harmonising musical and functional objectives. The end result is a sound experience that captivates organists and audiences alike.
Every turning and swivelling movement in the organ and every friction point places high demands on the product and requires a suitable bearing. Baumgartner Orgelbau, a workshop for historical musical instruments, is well aware of this. The specialist refurbishes and reconstructs organs on the one hand, while on the other it manufactures vendor parts for traditional organ building and supplies customised components and assemblies to the actual organ builder. The expert team's references range from the organ at St Ludwig's in Darmstadt to the collegiate church in Stuttgart and the Walt Disney Concert Hall in Los Angeles.
In a new project, a console, up to 3,000 bushings and bearings were to be installed in the instrument after completion. The demands on the bearings are greater than one might think: Apart from rain and direct UV radiation, all the environmental influences that also occur outdoors have an effect here. Added to this is the material wood. Unlike metal or plastic, wood is a hydroscopic material. It absorbs moisture and releases it again. The storage environment therefore moves and presents major challenges. At the same time, a hard and precise bearing should be achieved that does not allow zero clearance. And the noise development should also be minimised by a narrow bearing clearance. All of this under constantly fluctuating environmental conditions in the church. Because if an instrument has to be completely dismantled due to corrosion damage, costs can quickly run into tens of thousands of euros.

The organ builder saw polymer plain bearings as a way of replacing the inaccurate and costly cloth bearings that are otherwise traditionally used. The latter suffer extremely from the special installation conditions. While oak, hornbeam and walnut are predominantly used in organ building, the material and bearing are constantly exposed to cold, moisture and soot.
Instead, plain bearings made of iglidur® J were used. The material is generally characterised by its low wear against many shaft materials, is resistant to chemicals, vibration-damping and only absorbs low levels of moisture. The bearing offers a low coefficient of friction in dry operation and very good behaviour with soft shafts. The absolute silence in combination with the high precision has proven itself in organ building from the very beginning. In this project, for example, a hard and precise bearing was achieved for the action angle corner bearings, which allows a clearance of just five to ten microns. The thick-walled bushes hold their ground in the wood despite the constantly fluctuating ambient conditions, making rattling noises a thing of the past.
The installation of polymer plain bearings can also considerably reduce the need for regular maintenance.
The cost benefits also speak for themselves: a cloth bearing would have to be replaced three to four times. Although the material price of polymer plain bearings is slightly higher than that of cloth bearings, the cost of dismantling cloth bearings is thirty to forty times higher than the material price.
But it was the development of the igubal ® series in particular that enabled the organ builder to take the next decisive step. The articulated and clevis joints are particularly easy to use in the stop action, for example. Among other things, absolute freedom from lubrication is important here. The polymer bearings are installed dry and - unlike the cloth bearings - do not need to be impregnated with Vaseline or oily materials.

For Baumgartner Orgelbau, the initial focus was not only on technical issues such as the performance of the bushings under constant movement due to climatic fluctuations or noise development and service life? It was also very important that the tradition-conscious market would accept plastic components in the organ.
In the meantime, the new technology has been well received by organ builders and musicians alike. If the organist doesn't like the instrument, the organ builder has a problem. The end user has to accept the instrument. Word of the advantages of plastic slider bearings is getting around in the industry, and demand for dome bearings in particular is constantly increasing. Organists want to minimise the clearance in the action. The more direct the clearance is, the more expressive it is. Direct contact with the playing valve means that it can be opened more slowly or more quickly. With a spongy keyboard, the individual clearance suffers and the expressive possibilities diminish. The plastic plain bearings open the door to new customers and instruments for the organ builder Baumgartner.