Comprehensive Guide to Double Acting Hydraulic Cylinders
Hydraulic cylinders are essential components in various industrial and mobile applications. Among these, double-acting hydraulic cylinders are particularly versatile, offering bidirectional force and motion. This article explores the key features, materials, seals, and recommendations for double-acting hydraulic cylinders, with a focus on a specific model featuring a 50mm bore, 30mm rod, and 100mm stroke.
Key Features
A typical double-acting hydraulic cylinder designed for rigorous applications includes the following specifications:
Bore Size: 50mm
Rod Size: 30mm
Stroke Length: 100mm
Maximum Working Pressure: 200 bar
Maximum Testing Pressure: 300 bar
Maximum Working Speed: 0.5 m/s
Working Temperature Range: -30ºC to +90ºC
Port Size: 3/8″ BSP
These features ensure that the cylinder can handle substantial loads and operate effectively in various environmental conditions.
Material Composition
The construction materials of hydraulic cylinders are crucial for their durability and performance:
Rod
Made from chrome-plated steel F-1140, with a minimum chrome layer thickness of 20 microns. The rod has a surface roughness of Ra < 0.2 and a minimum surface hardness of 900 HV, providing excellent corrosion resistance (minimum 200 hours in neutral saline fog as per ISO 9227 rating 9).
Tube
Constructed from steel ST-52-3, DIN 2393, with an inside diameter tolerance of ISO H9 and a surface roughness of Ra < 0.8 microns.
Guide-Bushing
Crafted from nitrited steel F-1140 for enhanced wear resistance.
Piston
Also made from steel F-1140, ensuring robustness and longevity.
Sealing Mechanisms
Effective sealing is vital for the performance and longevity of hydraulic cylinders. The seals used in these cylinders include:
Guide-Bushing Seals
Dynamic: Compact polyurethane rod-seal with a double lip, and an NBR metal wiper seal.
Static: NBR 90 shore O-ring.
Piston Seals
Dynamic: Compact double-acting polyurethane seal, plus a nitrile O-ring as an activator, and special polyacetal guides reinforced with glass fiber.
Static: Polyamide locking sealing guide.
These seals ensure minimal leakage and wear, maintaining the cylinder’s efficiency over time.
Finishing and Maintenance
The cylinder is finished with black prime painting, providing an additional layer of protection against environmental factors. Proper maintenance and handling are crucial for extending the life of hydraulic cylinders.
Key recommendations include
Protecting the Circuit
Use a relief valve set at 200 bar to safeguard the hydraulic circuit.
Ensuring Oil Cleanliness
Regularly check and maintain the cleanliness of the hydraulic oil, using filters to prevent contamination.
Bleeding the Circuit
Slightly loosen the cylinder fittings to bleed the circuit before starting up.
Welding Precautions
Avoid welding on the cylinder tube. If welding on the rod or bottom is necessary, dismount the cylinder first.
Proper Storage
Store cylinders indoors if possible. If outdoor storage is unavoidable, ensure the rod is fully retracted or greased.
High-Pressure Cleaning
Protect the rod and oil ports during high-pressure cleaning or blasting.
Single Acting Operation
When using a double-acting cylinder as single-acting, connect the unused oil port to the tank.
Dismounting
When dismounting, remember that the piston is screwed onto the rod end and fixed with industrial glue. Use industrial glue for reassembly.
Double-acting hydraulic cylinders are essential for various industrial and mobile applications, offering robust performance and versatility. By understanding their features, materials, sealing mechanisms, and proper maintenance practices, users can ensure their hydraulic systems operate efficiently and reliably. This specific model, with its 50mm bore, 30mm rod, and 100mm stroke, exemplifies the quality and durability expected from modern hydraulic cylinders.
