The STS (Side-to-Side) Boom System: Born from the Field, Challenging Conventional Thinking

The evolution of construction equipment always begins in the field.

Since its founding, Takeuchi has always stayed close to its customers, listening to their needs and developing machines to solve the challenges they face on the jobsite. This field-first approach is at the heart of Takeuchi’s product development.

The STS (Side-to-Side) Boom System was born from this approach - a technology that significantly improves work efficiency in confined spaces and under challenging conditions.

What Is the STS (Side-to-Side) Boom System?

The STS Boom System is Takeuchi’s unique boom offset mechanism, which moves the base of the boom horizontally from side to side in front of the excavator. It combines intuitive operation with excellent stability comparable to that of a conventional excavator.

When digging trenches along walls or sidewalks, for example, operators can face the direction of work and maintain a natural posture, helping reduce fatigue during long hours of operation.

The boom can also move across the full width of the machine, reducing the need to reposition the machine as work progresses. This makes the STS Boom System especially effective in densely built urban areas and confined spaces, such as utility installation projects involving water and sewer lines, gas lines, and communication cables.

Limitations of Conventional Boom Offset Systems: Focusing on Inconveniences in the Field

Boom offset mechanisms were not new. However, conventional designs came with several limitations.

1) Reduced Stability

Conventional offset mechanisms typically use a structure similar to a two-piece boom, with a joint in the middle of the boom. Hydraulic cylinders move this joint to shift the arm horizontally from side to side. With this type of design, however, the boom bends in the middle, which can move the load of excavated material significantly away from the machine’s center of gravity. This could reduce stability during high-load operations. The machine could also become less stable when equipped with heavy attachments.

2) Limited Digging Depth

Another challenge was digging depth. When the boom was offset, part of the offset mechanism could interfere with the edge of the trench, limiting how deep the machine could dig. To continue digging, operators often had to reposition the machine. Having to move the machine repeatedly was a major obstacle to efficient work.

3) Limited Versatility

There were also limits to how much additional functionality could be incorporated. Concerns about stability made it difficult to combine the offset mechanism with functions such as boom swing. As a result, conventional boom offset systems could not fully meet a need in the field:

“We want one machine that can handle more tasks efficiently.”

These were not simply technical limitations. They were everyday inconveniences faced by operators on the jobsite.

Takeuchi engineers listened to these concerns and saw them not as unavoidable limitations, but as challenges that needed to be solved.

Challenging Conventional Thinking: One Machine for a Wide Range of Tasks

Takeuchi engineers set out to overcome the technical limitations that had long been accepted as the norm. Their goal was simple: develop a machine that delivers greater productivity while making the operator’s job easier. The desire to “deliver products that exceed customer expectations” became the driving force behind breaking through conventional thinking.

The result was the STS Boom System, developed by Takeuchi in 1999. Based on the concept of “bringing the ultimate maneuverability of small excavators to mid-sized machines,” the system was introduced on the first FR Series model, the TB75FR.

The STS Boom System places the heavy offset mechanism near the machine’s center of gravity. This helps keep the machine stable while delivering excellent digging power. Because the base of the boom itself moves sideways, the machine can maintain digging depth comparable to that of a conventional excavator, regardless of the boom’s offset position. And by moving the boom from side to side, the STS Boom System allows a single machine to handle a wide range of tasks.

1) Stability Without Compromising Offset Functionality

The STS Boom System places the heavy offset mechanism near the machine’s center of gravity, providing a high level of stability. In addition, by offsetting the boom as far as possible to the right side of the cab, the machine's center of gravity is shifted rearward, enabling stable digging performance comparable to that of a fixed-boom excavator.

2) Sufficient Digging Depth at Any Offset Position

The STS Boom System features a design that offsets the base of the boom itself. As a result, the boom mechanism is less likely to interfere with digging, regardless of the boom's offset position, allowing sufficient digging depth to be maintained. This enables efficient digging operations without the need to frequently reposition the machine.

3) One Machine for a Wide Range of Tasks

The STS Boom System can position the boom directly in front of the cab, providing a wide working range comparable to that of a boom-swing excavator. With its wide working range and flexible boom offset mechanism, the STS Boom System enables a single machine to handle a wide range of tasks, even in space-constrained job sites.

From the Voice of the Field: A Takeuchi Model Loved Across Generations

Takeuchi has never accepted the inconveniences of conventional offset mechanisms as simply “the way things are.”

That mindset comes from the founding spirit of Takeuchi: “never imitate others” and “make products based on the needs of the field.” This spirit has been passed down from generation to generation of Takeuchi engineers.

The STS Boom System was born by listening to the voices of operators and challenging the conventional thinking behind machine design.

Since the launch of the TB75FR in 1999, the FR Series equipped with the STS Boom System has continued to be loved by users around the world as one of Takeuchi’s truly distinctive models.

The STS Boom System is more than just another feature. It is an innovation born from Takeuchi’s field-first approach—one that improves work efficiency, safety, and operator comfort.

Takeuchi will continue listening to the voices from the field, developing products that exceed customer expectations and shaping the future of construction equipment.