Long Stroke Hydraulic Cylinders

Tonghesheng Machinery is one of the competitive manufacturers and suppliers of high-quality long stroke hydraulic cylinders, and we are also equipped with a professional factory, welcome to buy long stroke hydraulic cylinders products from our company.

 

Long stroke hydraulic cylinders generate linear motion over extended operational distances, typically exceeding 2,000 mm and reaching up to 12,000 mm. These cylinders convert fluid power into force across applications that require high load capacity over long travel paths, such as heavy material handling, telescopic booms, mining equipment, marine cranes, and industrial presses.

Operating high-stroke cylinders introduces specific mechanical challenges, including piston rod deflection, column buckling under compressive loads, fluid volume expansion, and seal friction along the extended stroke path. To maintain alignment and structural stability, these cylinders use heavy-wall honed seamless tubing, induction-hardened piston rods, and specialized internal guide rings.

Depending on application requirements, configurations include heavy-duty welded single-stage cylinders, multi-stage telescopic cylinders (for installations with limited axial space), and tie-rod constructions for industrial setups.

 

 

Parameter	Specification Range	Notes / Standard Options
Bore Diameter	40 mm – 500 mm (1.5 in – 20 in)	Custom bore sizes available upon request
Rod Diameter	25 mm – 360 mm (1.0 in – 14.1 in)	Proportioned based on stroke length & buckling load
Maximum Stroke Length	Up to 12,000 mm (472 in / 39.3 ft)	Single-stage or multi-stage telescopic
Operating Pressure	16 MPa – 35 MPa (2,300 psi – 5,000 psi)	Rated peak pressure up to 42 MPa (6,000 psi)
Operating Temperature	-40°C to +120°C (-40°F to +248°F)	Seal materials tailored to working fluid & climate
Working Medium	Mineral hydraulic oil, synthetic fluid, water-glycol	ISO VG 32 / 46 / 68 compatibility
Mounting Types	Clevis, Flange (front/rear), Trunnion, Spherical Bearing, Foot Mount	ISO 6020/2, ISO 6022, or custom dimensions
Stroke Velocity	0.1 m/s – 1.0 m/s	Adjustable internal cushioning available for end position impact mitigation

 

 

Buckling-Resistant Piston Rods: Manufactured from high-tensile carbon or alloy steel (such as CK45, 42CrMo4), precision ground to Ra 0.2 µm and hard chrome plated (minimum 25–30 µm layer thickness) to withstand side loading and prevent bending.
Honed Cylinder Tubes: Heavy-wall cold-drawn seamless steel tubes (ST52.3 / E355) precision-honed to an internal surface roughness of Ra <= 0.4 µm, ensuring minimal friction and extended seal lifespan over thousands of duty cycles.
Multi-Guide Bearing System: Extended guide sleeves fitted with wear-resistant bronze or PTFE-filled phenolic resin guide rings support the rod over its full extension, reducing unit contact pressure and preventing internal metal-to-metal contact.
Low-Friction Sealing Package: Incorporates primary step seals, secondary U-cup seals, and double-lip wipers made from Polyurethane (PU), Viton (FKM), or PTFE (Teflon) to prevent fluid leakage and exclude environmental contamination.
End-Position Hydraulic Cushioning: Optional integrated throttling valves gradually decelerate the piston at stroke limits, reducing mechanical shock, noise, and vibration in long-reach equipment.

 

 

Designing and selecting a long stroke cylinder requires addressing physical factors that do not affect short-stroke models:
Rod Buckling (Euler's Column Load)
Long extension paths under push loads increase the risk of column failure. Permissible compressive loads must be calculated using Euler's buckling formula, accounting for mounting method end-fixity factors (K-factor), rod diameter, and stroke length.
Safety Factor S >= 2.5 to 3.5 under maximum dynamic loads.
Deflection and Side Loads
Gravitational sag and transverse forces create eccentric loads on the rod gland and piston. Incorporating wider bearing spacing, external guide tracks, or stop tubes reduces internal strain on seals and bushings.
Fluid Volume and Thermal Expansion
Long cylinders hold large volumes of hydraulic oil. System reservoirs must accommodate the fluid volume differential between full retraction and full extension. Thermal expansion during continuous operation requires stable fluid cooling to maintain viscosity and oil film integrity.
Stick-Slip Effect
At low operating speeds (< 0.05 m/s) over long travel distances, high static friction can cause stick-slip behavior. Specifying low-friction PTFE seals with elastomeric energizers ensures smooth linear motion.

 

 

Mining and Drilling Rig Extensions: Feed cylinders, mast elevation legs, and long-reach boom positioners operating under high shock and dust conditions.
Heavy Material Handling & Cranes: Telescoping booms, outriggers, port cranes, and shipboard loading rams requiring long reach with compact retracted profiles.
Industrial Hydraulic Presses: Main ram cylinders for deep drawing, extrusion, rubber molding, and scrap metal balers demanding high force across continuous strokes.
Civil Engineering & Infrastructure: Bridge launching jacks, tunnel boring machine (TBM) thrust cylinders, and dam gate control systems requiring corrosion-resistant, high-tonnage operation.
Specialized Marine & Offshore Platforms: Deck cranes, davits, and heave compensation systems equipped with nickel-chrome or stainless steel rods to withstand marine environments.

 

 

Structural Construction

• Welded End-Cap Design: Compact outer dimensions suited for mobile machinery and tight space envelopes.
• Tie-Rod Construction: Standardized NFPA/ISO dimensional profiles allowing straightforward teardown and service in factory automation.
• Telescopic Multi-Stage: 2 to 5 stage arrangements maximizing stroke length relative to a short collapsed body length.

Rod Surface Treatments

• Hard Chrome Plating: Standard corrosion resistance (96-hour neutral salt spray test rating per ISO 9227).
• Double Chrome / Heavy Chrome: Enhanced wear resistance for abrasive mining and construction sites.
• Nickel-Chrome Plating: High-corrosion resistance (500+ hours salt spray test) for marine and offshore installations.

Integrated Accessories

• Position Transducers: Internal magnetostrictive linear position sensors (LVDT / SSI / CANopen) providing real-time stroke measurement.
• Proximity Sensors: Inductive end-of-stroke switches mounted on the cylinder body.
• Integrated Safety Valves: Counterbalance valves, pilot-operated check valves, or burst-disc assemblies mounted directly on cylinder ports to prevent load drops during hose failure.

 

 

Material Selection & Traceability: Raw steel tubes and bar stock undergo chemical composition analysis and ultrasonic non-destructive testing (NDT) to verify internal structural integrity before machining.
Deep-Hole Drilling & Honing: Seamless steel tubes are bored and honed using multi-pass CNC honing machines to achieve precise internal diameter tolerances (ISO H8/H9) and surface finishes (Ra <= 0.4 µm).
Rod Machining & Surface Finish: Piston rods are turned, induction hardened (HRC 55–60, depth 1.5–3.0 mm), centerless ground, and hard chrome plated in computer-controlled plating tanks.
Precision Weld Assemblies: Cylinder bases, flanges, and ports are welded using automated Submerged Arc Welding (SAW) or Gas Metal Arc Welding (GMAW). Critical load-bearing welds undergo Ultrasonic or Dye Penetrant Inspection.
Cleanroom Assembly: Cylinder components undergo ultrasonic degreasing prior to assembly in controlled environments to avoid contamination of sealing elements and internal surfaces.

 

 

Every long stroke hydraulic cylinder undergoes rigorous quality control protocol prior to dispatch:
Dimensional & Geometry Verification: Full CMM and laser tracker verification of concentricity, straightness along the entire stroke, port alignments, and mounting pin tolerances.
Hydrostatic Proof Pressure Testing: Tested at 1.5 times maximum working pressure held for a minimum of 10 minutes to verify structural stability and seam integrity.
Internal and External Leak Testing: Low-pressure (2 MPa) and high-pressure (35+ MPa) testing to confirm zero internal bypass across the piston seals and zero external leakage past the rod gland.
Friction and Breakout Force Test: Measures minimum pressure required to initiate rod movement, verifying smooth motion without stick-slip or binding along the entire stroke length.
Fluid Contamination Analysis: Oil cleanliness tested according to ISO 4406 (Target: 16/14/11) prior to sealing ports for shipment.
Documentation Provided: Material Test Reports (EN 10204 3.1), Hydrostatic Test Certificates, Plating Thickness & Salt Spray Test Reports, and Dimensional Inspection Sheets.

 

 

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