Flow Rate Equation: Q = A x v

The flow rate required to achieve a target cylinder speed is the piston area multiplied by the desired velocity:

Q = A x v

• Q = Required flow rate (L/min or GPM)
• A = Effective piston area (cm2 or in2)
• v = Target velocity (m/s or in/s)

Extension Flow

Flow required for extension (fills the larger bore area):

Q_extend = A_bore x v = (pi x D^2 / 4) x v

Extension requires more flow because it fills a larger volume.

Retraction Flow

Flow required for retraction (fills the smaller annular area):

Q_retract = A_annular x v = pi x (D^2 - d^2) / 4 x v

Retraction requires less flow to achieve the same speed.

Cycle Flow Calculation

For cycle time-based calculations:

Q = Volume / Time = (A x Stroke) / Cycle_time

• Total extend volume: A_bore x Stroke
• Total retract volume: A_annular x Stroke
• Average cycle flow: (Extend + Retract volume) / Cycle time

Practical Considerations

• Pump sizing: Select pump for maximum required flow (usually extension)
• Regeneration: In regen circuits, rod-side oil adds to cap-side flow for faster extension
• Simultaneous operation: Multiple cylinders need combined flow
• Efficiency factor: Add 5-10% for leakage and valve losses