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Grotnes Circumpress: A Step Forward in Truck Axle Forming Technology

Engineered as a self-contained unit, the Grotnes Circumpress is a key machine in the field of cold-forming truck axle tubes. It’s an integrative system, boasting an all-steel welded frame construction that promises durability and stability.


The axle housing in question is constructed from welded halves, which can sometimes be slightly misaligned. The Circumpress addresses this issue by reshaping the ends into a more precise circular form, facilitating a smoother transition to the machining phase. Without this re-rounding process, machining could potentially be problematic. The Circumpress also enhances the axle housing by thickening its ends, preparing them for subsequent processing stages.

Core Components of the Circumpress

Grotness Circumpress for Forming Truck Axles
Grotnes Circumpress

Central to the Circumpress is the shrinkerhead, an assembly featuring a high-pressure ring housing 12 steel wedges on the inside. These wedges are positioned against a dozen steel jaws, each fitted with wear plates for longevity and consistent performance. The jaws are designed to slide radially, driven by hydraulic cylinders, allowing them to adapt to the varying diameter of truck axles with ease.

Mechanical Ingenuity

The jaws’ sliding mechanism is maintained by T-keys, ensuring constant contact with the wedges. These wedges back the jaw surfaces, which are angled precisely for shrinkage control. As the jaws converge, they uniformly decrease the gap, enveloping the axle tubes in a perfect fit.


Accommodating a range of diameters, the internal contours of the jaws are crafted to grip various component sizes. The system also features automatic lubrication, reducing wear and tear on the contact surfaces, while replaceable plates on the wedges allow for easy maintenance.

Part Transfer Automation: Efficiency in Motion

The Circumpress is paired with a part transfer system, consisting of four components:


  • Infeed and Outfeed Conveyors: Built with heavy-duty tubular steel, these 6-foot conveyors utilize electric motor-driven roller chains to smoothly transport axle housings.

  • Walking Beam: This two-station system handles the loading and unloading of parts with precision, seamlessly integrating with the Circumpress.

  • Part Handling: The handling system orients the axle housing for processing and rotates it for dual-side sizing. Additionally, a key feature is the part compliance system which allows for proper part presentation to the Circumpress, eliminating off-center sizing and improving concentricity.

  • Centering Pushers: These hydraulic devices ensure each part is aligned as it transitions from the conveyor to the Circumpress.

Sophisticated Automation

The Circumpress performs a range of automated actions, including optional pneumatic clamping for part rollover, hydraulically actuated centering pushers and electro-mechanical linear transfers. This automation enables a consistent and efficient workflow, minimizing manual handling and optimizing the production cycle.

State-of-the-Art Hydraulic Unit

The hydraulic unit is an independent entity, characterized by its on-demand, high-efficiency design. Variable displacement pumps paired with a variable speed drive controller ensure hydraulic power is supplied only when necessary; this not only saves energy but also reduces the need for cooling, making the unit more sustainable and cost-effective.

Control System and Panel

The Circumpress is equipped with an Allen-Bradley PLC and a user-friendly touchscreen HMI, allowing for manual or automatic operation. The control system is capable of storing various part recipes, adjusting parameters to accommodate different axle configurations. It also provides immediate feedback on system diagnostics and alerts, keeping operators informed and in control.

Tooling Changeover with Ease

Adapting the Circumpress to handle different diameters is straightforward, with an estimated changeover involving 12 segments taking less than an hour. This flexibility allows users to quickly shift between product specifications without significant downtime.

Partner with Grotnes to Meet Your Challenge


At Grotnes, our focus falls on our industry-leading machinery and ability to guide customers to the right metal-forming solutions for their needs — from custom prototyping to the final form and ongoing support.


With more than 125 years of expertise in evolving our Circumpress and other technology, Grotnes stands ready for your manufacturing challenge. Connect with us today to learn more about comprehensive line of machines!

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