Construction and Utility

UEA Reduces Weight of Crane Rotary Union


Link-Belt was looking for design a rotary union to implement in a new rough terrain crane in the 81-110.9mt class that would directly compete with the biggest players in that market segment. These machines will be used on job-sites in manufacturing plants, transportation, and general construction to use as an assist crane, utility work or in mining operations.

Link-Belt came to United Equipment Accessories (UEA) looking for a design of rotary union that could be incorporated into their new rough terrain cranes that reduced the weight of previous designs while maintaining the same functionality. The main challenge with weight reduction in the swivel was keeping the required passages needed for the application. UEA engineers also needed to take into consideration the large variance in flow and pressure settings required for crane function into in the design of the new rotary union. Mounting and torque of the swivel were also evaluated to ensure that the configuration needed for this application would operate without failure.    


UEA worked closely with Link-Belt to identify the requirements of the new rotary union and find solutions to meet the goal of the application. In order to reduce the weight and meet the mounting requirements of the swivel, UEA engineers explored different port configurations, machining techniques and seal options.

One of the defining features of the hydraulic swivel was a large 2.5-inch thru hole that was drilled and bored out to remove a large amount of material.  UEA engineers also utilized differently-shaped flow grooves which allowed for a skinnier housing.The thru hole and flow grooves both helped reduce the weight of the swivel while maintaining the same functionality needed of the rotary union. The weight savings was ultimately passed to the customer when the machine is shipped from the factory and to and from job sites and served as a benefit in purchasing this new crane model.

For this specific crane design, Link-Belt needed the rotary union to mount on one end and the torque arm on the other end. Typically, this configuration is not successful because it could create chatter in the rotary union as the mounting structure flexes. UEA utilized Finite Element Analysis (FEA) to determine the material requirements for the mounting plate, leading UEA engineers to use a higher strength steel for the mounting plate. Additionally, UEA developed a lower friction seal to minimize the effects of chatter.Ultimately, these solutions allowed for the preferred mounting and torque arm set-up.

Through UEA’s custom-designed solutions, Link-Belt’s requirements were met in a specifically-designed solution for their project. Weight reduction, mounting and torque were the primary challenges of the project and were achieved through the problem solving of the UEA and Link-Belt teams to find a customized solution.

The ingenuity that UEA displayed throughout this entire project was remarkable. UEA was very responsive in the design process and was willing to go the extra mile to work with Link-Belt from inception to product delivery

Matt White

Senior Design Engineer

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