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Bobcat 337 Swing Mechanism and Common Issues
#1
The Bobcat 337 is a compact excavator model known for its maneuverability and efficient performance in confined workspaces. A critical system for its operation is the swing mechanism, responsible for rotating the upper structure smoothly to position the boom and bucket precisely.
Swing Mechanism Specifications
  • Swing Speed: Approximately 11.3 revolutions per minute (RPM)
  • Hydraulic Swing Motor: Powers rotation, driven by the machine’s hydraulic system
  • Swing Brake: Engages to hold the upper structure in place when the swing control is released
  • Control System: Hydraulic joystick controls regulate swing direction and speed proportionally
Common Swing Issues
Operators sometimes report the swing motor overheating, especially after continuous use. Symptoms include:
  • Excessive heat buildup on the top cover of the swing motor
  • Sluggish or jerky rotation when slewing in a full circle
  • Temporary restoration of normal function after cooling periods
Possible causes include:
  • Swing brake sticking or dragging within the motor, causing additional friction and heat
  • Internal wear or damage to the motor’s bearings, seals, or stators
  • Hydraulic pressure or flow irregularities limiting motor efficiency
  • Contamination or debris causing binding within motor components
Maintenance and Troubleshooting Suggestions
  • Inspect and adjust the swing brake clearance to prevent drag and overheating
  • Check the hydraulic oil level, quality, and filters to avoid pressure loss or contamination
  • Monitor hydraulic temperature and pressure during operation for abnormalities
  • Perform routine cleaning and lubrication of swing motor components
  • Replace worn or damaged motor parts proactively to avoid costly failures
Practical Experience
A user with 3,300 hours on their Bobcat 337 shared that after some time of heavy rotary work, the swing motor got very hot and sluggish. Letting the machine rest for about 10 minutes allowed normal function to resume temporarily. They suspected that a hanging brake or early motor wear caused the behavior, based on similar experiences shared in professional operator communities.
Glossary
  • Swing Motor: Hydraulic motor converting fluid power into rotational motion.
  • Swing Brake: A friction device that stops or holds the rotation of the excavator’s upper structure.
  • RPM (Revolutions Per Minute): Measure of rotational speed.
  • Hydraulic Pressure: The force exerted by the hydraulic fluid in the system, influencing component operation.
  • Slewing: The act of rotating the upper section of the excavator.

The Bobcat 337’s swing system is vital for precise and efficient excavator operation. Routine inspection and maintenance of the swing motor and brake systems help prevent overheating and mechanical wear, thereby sustaining machine performance and operator safety. Understanding typical issues and timely troubleshooting ensures prolonged service life of this critical component.
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