Schaeffler: New generation of TAROL axlebox bearings: optimized design offers shorter mounting times and lower frictional torques

Safe and cost-effective operation in railway applications begins with the mounting process

Safe and cost-effective operation in railway applications begins with the mounting process. This is where Schaeffler’s optimized FAG TAROL tapered roller bearing units for automated mounting together with a new fitting device come into play. An optimized seal design for railway bearings reduces frictional power and thus operating costs.

The assembly of railway bogies is among the areas in which automation is making advances. To facilitate the process of mounting axlebox bearings here, Schaeffler’s engineers have combined three individual components – axlebox bearing, labyrinth ring, and axle cover – to create a ready-to-fit unit. Two plastic retaining rings hold the components together on the inner diameter, and handling of individual components is no longer required. The new FAG TAROL tapered roller bearing units can thus be pressed on more quickly during the mounting process.

The retaining rings have been specially designed for every size and ensure that the labyrinth ring and the axle cover are seated firmly on the axlebox bearing without compromising the flow of force between the components. These retaining rings are also equipped with a rubber seal that seals the joining surfaces between the rings and prevents the ingress of moisture into the gap, thus preventing corrosion damage to the axlebox shaft.

New ergonomic mounting device

The mounting device for railway bearings has been completely redesigned. The entire hydraulic system is now mounted on a height-adjustable scissor lift truck platform, and the mounting technician can set the platform to the required height using a foot pedal. The hydraulic cylinder has an articulated support and can be easily positioned to match the shaft end. The new mounting device is not only more ergonomic in its operation but also more cost-effective than the previous version. Schaeffler will be holding live demonstrations of how its FAG TAROL bearings are mounted and dismounted using this mounting device at the InnoTrans 2018. A version of the mounting device that is equipped with a digital force-travel measurement system and touchscreen to allow the user to document the mounting and pressing-on of the bearing up to the shaft shoulder as part of his or her quality assurance process will soon also be available. The standard version of the new mounting device can be retrofitted to include this force-travel measurement system subject to customer request.

Cassette seal with optimized design envelope and friction characteristics for railway applications

The axlebox bearing’s seals are responsible for a large proportion of the total friction and thus the required drive power. Because the friction on the seal continuously transfers heat to the axlebox bearing, the development of the new cassette seal also focused on reducing friction in addition to ensuring a high level of protection against the ingress of contamination into the bearing. The design is structured in several stages: An outer dust shield prevents the ingress of coarse contaminant particles. A converging gap between the dust shield and the bearing ring additionally reduces the ingress of water and dust. The secondary shield gathers and ejects any residual contamination. The optimized design of the interference between the main seal lip and bearing ring allows friction to be significantly reduced. The new cassette seal thus offers operators a way to save energy and operating costs, and also features optimized grease recirculation to the axlebox bearing and thus improves its lubrication and operating life. Despite its high level of functional integration, the new seal design has allowed a reduction of up to 25% in the overall seal width to be achieved.

SOURCE:  Schaeffler
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