10 tips for working safely with hydraulic cylinders

1. Bleed the hydraulic system before use

Air trapped in a hydraulic system can be dangerous because, unlike hydraulic oil, air is compressible. This makes the movement of the cylinder piston unpredictable.

Always bleed the hydraulic system before use by extending the cylinder upside down. Then allow the oil to flow back to the hydraulic pump, ensuring the pump is positioned higher than the cylinder. The air will escape through the pump's bleed valve, removing it from the system.

2. Always connect both hydraulic lines when using a double-acting cylinder

A double-acting hydraulic cylinder requires both an oil supply and an oil return line.

Hydraulic pressure extends and retracts the piston. When the piston extends, oil enters the lower chamber through the lower port, forcing the piston upwards. At the same time, the oil in the upper chamber must be able to return to the pump through the upper port.

When the piston retracts, the oil flow is reversed.

If your hydraulic pump has only one connection, it is not suitable for operating a double-acting hydraulic cylinder.

3. Protect the hydraulic system from damage

• Shield all hydraulic components from welding and grinding sparks to prevent damage and leaks.

• Protect the piston with a suitable saddle to prevent deformation. A damaged piston can seize during retraction and cause uneven loading.

• Never lift a hydraulic cylinder by its coupling or hose. Always use the handle, cylinder body, or lifting eyes.

• Prevent hydraulic hoses from kinking, twisting, or becoming trapped, as this can lead to damage and leakage.

4. Use cylinder accessories correctly

• When fitting or removing accessories from the piston, fully retract and extend the piston under approximately 50 bar of pressure to prevent it from rotating.

• Never place packing or shims on top of the piston. Position them beneath the cylinder instead.

• Always use original accessories designed specifically for the hydraulic system to prevent components from slipping or failing under pressure.

• Extension tubes must only be fitted to the base of the hydraulic cylinder—never to the piston. A maximum of two extension tubes may be connected using a coupling piece.

• Ensure the load-bearing surfaces are parallel, for example between the centre of the base plate and the saddle.

5. Position the hydraulic cylinder on a stable surface

Always place the cylinder on a firm, stable surface to prevent it from rolling or tipping over during operation.

6. Apply only axial loads to hydraulic cylinders

Avoid side loads and angled loads on the piston, as these can damage the inside of the cylinder.

For off-centre loads of up to 5°, use a tilting saddle. Do not use hydraulic cylinders where off-centre loading exceeds 5°.

7. Use sufficient cylinder capacity

Always select hydraulic cylinders with a capacity greater than the expected load:

• Symmetrical loads: total cylinder capacity = 1.5 × the load

• Asymmetrical loads: total cylinder capacity = 2 × the load

8. Release system pressure before disconnecting hoses or cylinders

Always relieve the hydraulic pressure before disconnecting hoses or cylinders.

This allows couplings to be disconnected by hand and prevents residual pressure from remaining in the system, which could cause problems during the next use.

9. Keep the hydraulic system clean

• Prevent dirt from entering hydraulic couplings.

• Connect the dust caps together while the system is in use and clean them afterwards.

• Painted, plastic, and rubber components are not resistant to corrosive acids or aggressive chemicals. If exposed, rinse them thoroughly with clean water (excluding electrical components).

• Dry the hydraulic cylinder after use in wet conditions and apply a thin protective layer of corrosion-inhibiting oil to unpainted or blackened metal surfaces.

• Store hydraulic cylinders with the piston facing downwards to prevent dirt from entering the cylinder.

10. Have hydraulic cylinders maintained and tested annually

Like all hydraulic tools, hydraulic cylinders can develop faults over time. Regular maintenance and annual inspection and testing by a competent person are essential to ensure safe and reliable operation throughout the equipment's service life.

A competent person should be able to demonstrate appropriate qualifications, certificates, or training. As a minimum, they should have completed recognised basic hydraulics training. If they cannot demonstrate this level of competence, they should not carry out maintenance, inspection, or testing of hydraulic equipment.

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What should you look out for? What are the key risks? How can you prevent accidents and avoid costly downtime?

This white paper provides practical tips and expert guidance for working safely with hydraulic systems. Covering everything from storage and transport to inspection, testing, and maintenance, it offers valuable insights into the key considerations for safe, reliable hydraulic operations.