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The boom and arm cylinder assemblies are critical components of an excavator’s lifting and digging system. Proper maintenance and timely replacement of hydraulic cylinders and related parts ensures optimal excavator performance and productivity.

Function Of Boom and Arm Cylinder Assemblies

The boom cylinder assembly consists of:

  • The hydraulic cylinder – Which pivots the boom up and down
  • Pin connections – Attaching the cylinder to the boom and the base

The arm cylinder assembly includes:

  • The hydraulic cylinder – Which actuates the articulating arm linkage
  • Pin connections – Attaching the cylinder to the arm and boom

The hydraulic cylinders work by:

  • Extending and retracting their rods in response to hydraulic pressure
  • Raising and lowering the boom and stick arms
  • Opening and closing the articulating arm at the joint
Bucket Cylinder Assy

Components Of Excavator Hydraulic Cylinders

Hydraulic cylinders used in boom and arm assemblies include:

  • Piston – Acts on the hydraulic fluid to extend or retract the rod
  • Rod – Connects to the boom or arm and transmits force
  • Cylinder tube – Houses the piston and rod assembly
  • Seals – Prevent fluid leakage around the piston and rod
  • Bushings – Reduce friction within the pin connections

Maintaining Excavator Hydraulic Cylinders

Routine maintenance should include:

  • Checking for leaks around seals, cylinders and hoses
  • Inspecting rods/tubes for dents, scratches or excessive wear
  • Lubricating bushings and pins with grease every 50 hours
  • Checking hoses/fittings for cracks, damage or loose fittings
  • Testing for full range of motion – Cylinders should move freely

Proper maintenance and timely replacement of the boom and arm cylinder assemblies is critical to maximizing the performance, productivity and life of an excavator. Neglected or worn hydraulic cylinders can drastically reduce excavator efficiency, costing operators time and money.