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How It Works

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What is a Regenerative Circuit?

A regenerative (or "regen") circuit routes the oil from the rod side of a cylinder back to the cap side during extension. This combines the pump flow with the discharged rod-side oil, dramatically increasing extension speed at the cost of reduced force.

Speed Increase Ratio

The speed increase in regen mode depends on the ratio of bore area to annular area:

Speed Ratio = A_bore / (A_bore - A_rod) = D^2 / (D^2 - d^2)

Where D = bore diameter and d = rod diameter

Force in Regen Mode

In regenerative mode, pressure acts only on the rod area (the differential area), not the full bore area:

F_regen = P x A_rod = P x (pi x d^2 / 4)

This is significantly less than normal extension force:

F_normal = P x A_bore = P x (pi x D^2 / 4)

Flow Analysis

In regen mode, the effective flow to the cylinder is the sum of pump flow and regenerated flow:

Q_effective = Q_pump + Q_regen = Q_pump x (A_bore / A_annular)

Regenerative Circuit Flow Diagram CAP ROD Port A Port B REGEN VALVE (DCV + Check) PUMP TANK Q_pump Q_regen REGENERATED FLOW Q_pump + Q_regen BORE (D) ROD (d) Speed Ratio D^2 / (D^2 - d^2) Regen Force F = P x (pi x d^2 / 4) Normal Force F = P x (pi x D^2 / 4)

When to Use Regenerative Circuits

  • Fast Advance: When quick approach is needed before working stroke
  • Light Loads: When extending against low resistance (gravity assist, rapid traverse)
  • Press Operations: Fast close, then switch to full force for pressing
  • Machine Tools: Rapid approach before machining engagement

When NOT to Use Regenerative Circuits

  • Heavy loads requiring full cylinder force
  • Applications needing precise speed control
  • When working against high back-pressure
  • Systems with significant line losses (long hose runs)

Regenerative Circuit Calculator

Analyze regenerative hydraulic circuit performance. Compare regen mode speed increase with normal extension, and calculate force reduction trade-offs.

Cylinder Dimensions

System Parameters

1.46x
Speed Increase in Regen Mode

Regenerative Mode

Extension Speed --
Extension Force --
Extension Time --
Effective Flow --

Normal Extension

Extension Speed --
Extension Force --
Extension Time --
Pump Flow Used --

Performance Ratios

Speed Increase Ratio --
Force Reduction --
Area Ratio (Bore/Annular) --
Rod/Bore Ratio --

Area Calculations

Bore Area (Full Piston) --
Rod Area --
Annular Area (Bore - Rod) --

Flow Analysis

Pump Supply Flow --
Regenerated Flow --
Total Effective Flow (Regen) --

Volume Requirements

Cap Side Volume (Normal) --
Rod Side Volume --
Net Volume (Regen Mode) --

Force Trade-off Warning

In regenerative mode, available force is limited to pressure acting on the rod area only. Ensure this is sufficient for your application before engaging regen mode.

Reference Formulas

Speed Ratio:

R = A_bore / A_annular = D^2 / (D^2 - d^2)

Regen Speed:

v_regen = Q_pump / A_annular

Regen Force:

F_regen = P x A_rod = P x (pi x d^2 / 4)

Normal Force:

F_normal = P x A_bore = P x (pi x D^2 / 4)