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## What the Counterbalance Does
The pneumatic counterbalance supports the weight of the slide and upper die on the return stroke. Without it, the servo motor must lift the full slide weight, increasing motor size and energy consumption.
## Setting Counterbalance Pressure
Correct counterbalance pressure = slide weight + upper die weight, expressed as air pressure.
Formula: P = (W_slide + W_die) / A_cylinder
Where A_cylinder is the total piston area of all counterbalance cylinders.
Example: 200T press, slide weight 800kg, die weight 400kg, two cylinders each 200cm2:
P = (800+400) x 9.81 / (2 x 200 x 100) = 0.29 MPa = 2.9 bar
Most press manuals provide a table of counterbalance pressure vs. die weight.
## Signs of Wrong Counterbalance Pressure
**Too low:** Motor overload alarm on return stroke, A.74 or F07801 on return.
**Too high:** Press bounces at TDC, slide does not stop smoothly at top.
## Maintenance
- Check pressure daily (should be within 10% of set point)
- Check for air leaks at cylinder seals and fittings monthly
- Replace cylinder seals every 3-5 years or when leakage is detected
- Check accumulator pre-charge pressure annually (should be 60-70% of working pressure)