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Precise axial play compensation in XXL format

MARTIN producing oversized shims for use in heavy-duty gearboxes


Precision shims from MARTIN’s Laminum® series are being recognized more and more in many sectors of modern transmission construction as a flexible and efficient solution for adjusting the preload of roller bearings. Proof of the extremely high degree of customer orientation the company can produce in the realization of these multilayer compensation elements is given among many other things in the manufacture and handling of over-dimensional shims for use in the heavy-duty systems used in construction machinery, mining, metallurgical and wind power technology applications.


The optimization of preloading is regarded as the key factor in extending the service life of roller bearings. This applies to their use in the construction of gearboxes, as well as other applications. Traditional methods for adjusting the preload of bearings and compensating their axial play in drive system modules include alignment with the help of numerous individual shims, or the elaborate machine finishing of the mating surfaces. 

📷 The XXL shims from MARTIN are a single unit made up of a Laminum® element, comprising several dozen laminated films, and a steel ring with a thickness of up to 15 mm which serves as a carrier.

The use of Laminum® shims from MARTIN, however, has proven to be much more flexible and considerably more cost effective in this regard. These multilayer elements are reduced to the required thickness by manually peeling off their laminated, wafer-thin metal or polymer films precisely to the micrometer, which means that no machining is required.


MARTIN precisely matches their mixture of materials (steel, stainless steel, aluminium, brass, plastic), range of thicknesses (0.025 – 5.0 mm) and shapes (circular, ring etc.) to the constructional details of the installation point and assembly process. Just how far the company can go with this individualization can be seen among other things when customers from the construction machine, mining, metallurgy and wind power technology sectors demand customized Laminum® shims for use in heavy-duty machinery, because the dimensions required here extend way beyond all conventional limits, even where the manufacture of the compensation elements is concerned. It’s not so much the diameters (1,000 mm and more) that pose a special challenge here as much more the question of how a mega shim of this kind can be moved safely to the point of installation and how to handle it once it gets there. “When we started to produce the first big Laminum® rings many years ago, it was clear that the prerequisite for their handling and assembly was the development of an overall concept for identifying ways to transport large shims of this kind. Accordingly, if you order an XXL shim with us today, you get a complete solution comprising a customer-specific, configured shim and a carrier ring designed to facilitate easy handling,” explains company CEO Christoph Martin.


Handling-friendly overall system
What complete solutions of this kind look like in detail can be demonstrated using the example of the massive shims MARTIN produced recently to adjust the backlash of roller bearing transmissions and set the angular contact roller bearings in wind power gearboxes. These typically form a unit comprising a Laminum® element consisting of several dozen laminated films and a solid steel ring that serves as a carrier. The Laminum® element is made up of two or more segments, whereas the carrier is a solid, closed 360° ring with a thickness of up to 15 mm. It protects the Laminum® segments during transport and stabilizes their handling during installation. Christoph Martin emphasizes: “The high stability of the entire ring solves the problem of handling the huge, thin film shims and even enables their vertical positioning”.

📷 Laminum® shim from MARTIN with customer-specific segmentations and drill holes and an external diameter of 1,146 mm.

Precision solution with fewer parts
Because the numerous individual rings that are otherwise required are substituted by a solitary carrier ring in this XXL solution from MARTIN, there is a considerable reduction in the number of parts required. Another fundamental advantage is the option of combining films of different thicknesses to suit the requirements of each specific customer, thus guaranteeing high-precision tolerance compensation. Unlike when working with solid, undivided shims, the Laminum® variety can be used to produce ultra thin foil layers, which provide an elegant solution to the often difficult problem of procuring and processing very thin, extra wide metal films.
MARTIN can also construct the shim in such a way that a desired number of peelable film segments are attached to the carrier ring. In this case, thickness can be reduced during assembly by simply peeling off the individual segments to suit requirements. “Through the partial peeling of the ring, the user can achieve several different thicknesses to compensate problematic, non-parallel installation surfaces in the shim,” explains Christoph Martin. In this way, the fitter has the necessary flexibility to adjust the topography of the shim to fit the joint on-site.

Preload optimization prolongs service life
Setting the optimum preload and precisely adjusting axial play are decisive in determining the efficiency of roller bearings in drive technology components. Both have a direct influence on the service life, vibrational behaviour, noise and heat values of a roller bearing application. This applies in particular when using single and double-row angular contact ball bearings, as well as four-point contact bearings and single-row tapered roller bearings. As a supplier and project partner for many years, MARTIN satisfies the needs of many renowned transmission and engine manufacturers in this area. The German company is one of the premium producers of shims with which users can adjust the preload precisely to the micrometer, thus optimizing the axial play of roller bearings. As can be seen from the example of the over-dimensional XXL shims for the heavy duty sector, it is often only the use of Laminum® (or Lamivario®) shims from MARTIN that enables constructors and fitters to realize the proper degree of preloading , thus making full use of the service life of the roller bearings calculated by the manufacturers.