A long-reach boom is an extended boom-and-stick assembly fitted to a hydraulic excavator base machine to increase horizontal reach and working depth beyond the range of a standard monobloc or two-piece boom. The configuration is used where the excavator must remain on stable ground while the attachment accesses material at a distance or in soft, sloped, or submerged terrain.
Design and Construction
Long-reach booms are typically supplied as two-piece or three-piece articulated assemblies that replace the standard boom and stick. Total reach figures commonly range from about 18 m to 24 m on medium excavator classes, with specialized dredging and canal-maintenance configurations extending to 30 m or more. To limit added weight at the tip, boom and stick sections are fabricated from high-strength steel with reduced wall thickness compared to standard components. Hydraulic cylinder mounting points are relocated along the structure to maintain adequate breakout force over the extended geometry.
Because the extended lever arm shifts the center of gravity forward, base machines are fitted with additional counterweight, and bucket capacity is reduced relative to standard configurations to keep tipping loads within the stability envelope. A 20–30 t class excavator with a long-reach boom typically carries a bucket of 0.3–0.5 m³, compared with 1.0–1.5 m³ on the same carrier with a standard boom.
Applications
Typical uses include maintenance and desilting of canals, rivers, and drainage ditches, slope and dyke rehabilitation, material placement on embankments, and excavation work where the machine must stay back from unstable banks or water edges. The configuration is also used for reaching over obstacles such as existing structures or stockpiles.
Distinction from High-Reach Demolition Booms
Long-reach booms should not be confused with the booms used on high-reach demolition excavators (often referred to by the designation UHD for ultra-high demolition). High-reach demolition booms are purpose-built for vertical working height, reaching 30–45 m upward to carry shears, crushers, or pulverizers against building facades. Long-reach booms, by contrast, are optimized for horizontal reach and working depth at or below grade. The two boom types use different kinematics, counterweighting, and attachment mounting, and are not interchangeable between applications.
Selection Criteria
Selection depends on required reach and depth, ground bearing pressure of the base machine, permissible attachment weight at full extension, and transport constraints, since boom sections exceeding standard lengths often require separate low-loader transport. Planners should also verify the base machine's load-moment limiting system is matched to the long-reach configuration, as factory stability data for standard booms does not apply once the boom is extended.