Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Why Do Excavator Booms and Sticks Get Bent So Often
#1
Bent booms and twisted sticks are more common than most operators admit, especially in demolition, pile extraction, and improper side loading. A battered Case 9020B excavator with a visibly bent stick and damaged counterweight sparked a broader discussion on how such damage occurs—and why some machines seem more prone to it than others.
Case 9020B Overview
The Case 9020B is a mid-size hydraulic excavator introduced in the late 1990s, designed for general excavation, trenching, and light demolition. It features a 133-horsepower Cummins engine, a maximum dig depth of around 20 feet, and an operating weight of approximately 45,000 pounds. Case Construction Equipment, founded in 1842, has produced thousands of units across its B-series lineup, with the 9020B being a popular choice for contractors seeking reliability and affordability.
Despite its solid reputation, the 9020B has been criticized for boom and stick durability under extreme stress. Several operators report structural failures when used with oversized buckets or hydraulic hammers.
Terminology Notes
  • Stick (Dipper Arm): The hydraulic arm between the boom and bucket, responsible for reach and digging force.
  • Boom: The primary lifting arm attached to the excavator’s upper frame.
  • Side Loading: Applying force perpendicular to the stick’s axis, often during demolition or grading with wide buckets.
  • Relief Valve: A hydraulic safety device that limits pressure to prevent system damage.
Common Causes of Structural Damage
  • Demolition Misuse: Operators swinging buckets sideways into concrete walls or using the boom as a battering ram often exceed design limits. Relief valves protect hydraulics, but not steel.
  • Oversized Attachments: Using grading buckets or shears beyond the machine’s rated capacity introduces torsional stress. One operator noted a twisted stick after grabbing a beam off-center with a shear.
  • Tandem Machine Forces: In pile extraction, one excavator may assist another. Uneven pulling can cause the stick to fold or twist, especially if the assisting machine pulls at an angle.
  • Transport Accidents: A grader on a float trailer hit by a train bent its stick beyond repair. No hydraulic system can prevent that kind of impact.
  • Operator Error: A common “add-on” to many machines is the untrained operator. One story involved a man swinging a bucket into a masonry wall until the stick snapped and hydraulic lines tore loose.
Field Anecdotes and Lessons Learned
In Ontario, a contractor bought a used Case 210 in the rain and missed a twisted boom. On its first job, the filler and paint cracked off. In Australia, an operator noticed uneven grading and discovered the dipper arm had been rebuilt after a pile extraction mishap. The repair was so subtle it took a top-pin alignment check to confirm.
In California, a developer used a rental EX-750 as a demolition hammer. When the machine returned, the damage bill was enormous. The rental company had watched but didn’t intervene due to the client’s size.
Recommendations for Preventing Boom and Stick Damage
  • Use Attachments Within Rated Limits: Check bucket width, weight, and hydraulic flow requirements.
  • Avoid Side Impact Demolition: Use hammers or shears designed for lateral force.
  • Train Operators on Structural Limits: Emphasize that steel bends before hydraulics fail.
  • Inspect Machines Before Purchase: Look down the stick from the top pin to detect misalignment.
  • Monitor Relief Valve Settings: Ensure they’re calibrated to protect the system without masking abuse.
Final Thoughts
Bent sticks and booms are not just signs of wear—they’re often scars from misuse, poor judgment, or overlooked physics. Excavators are powerful, but they’re not indestructible. Whether caused by demolition shortcuts, oversized attachments, or untrained hands, structural damage is preventable with discipline and awareness. Machines tell stories through their scars; the wise operator learns to read them before they break.
Reply


Possibly Related Threads…
Thread Author Replies Views Last Post
  CAT 350L Excavator Troubleshooting and Solutions MikePhua 0 10 2 hours ago
Last Post: MikePhua
  Yanmar B15 Mini Excavator: Common Issues and Troubleshooting MikePhua 0 9 2 hours ago
Last Post: MikePhua
  Restoring a Fire-Damaged Takeuchi TB135 Excavator MikePhua 0 4 7 hours ago
Last Post: MikePhua
  How Can You Reduce Swing Play on a MZ145 Excavator MikePhua 0 7 7 hours ago
Last Post: MikePhua
  Diagnosing Swing Circle Rattling on a Bobcat 320 Mini Excavator MikePhua 0 5 9 hours ago
Last Post: MikePhua
  Troubleshooting Metal-on-Metal Noise in a John Deere 490D Excavator in Low Range MikePhua 0 7 9 hours ago
Last Post: MikePhua
  Troubleshooting Slow Left Track Movement on the KX91-2 Mini Excavator MikePhua 0 7 9 hours ago
Last Post: MikePhua
  Kobelco SK03 Excavator Service: Maintenance and Troubleshooting MikePhua 0 6 9 hours ago
Last Post: MikePhua
  Why Is P Mode Sluggish on the John Deere 690ELC Excavator MikePhua 0 5 10 hours ago
Last Post: MikePhua
  Why Did the Kobelco 120 Excavator Suddenly Lose Hydraulic Power MikePhua 0 6 10 hours ago
Last Post: MikePhua
  Hydraulic Power Loss in Hitachi 270EX Excavator MikePhua 0 12 11 hours ago
Last Post: MikePhua
  Troubleshooting Slew Brake Problems on Hitachi EX-120-3 Excavator MikePhua 0 6 11 hours ago
Last Post: MikePhua
  Red Warning Light and Overheating on Daewoo 450 Excavator MikePhua 0 12 11 hours ago
Last Post: MikePhua
  Turntable Clunk Diagnosis on a 1989 CAT E120B Excavator MikePhua 0 4 Yesterday, 12:03 AM
Last Post: MikePhua
  Case 688 Excavator Hydraulic Slowness and LS Valve Adjustment MikePhua 0 7 Yesterday, 12:01 AM
Last Post: MikePhua

Forum Jump:


Users browsing this thread: 1 Guest(s)