Custom Double Acting Hydraulic Cylinders

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

 

Double acting hydraulic cylinders utilize hydraulic pressure to drive linear motion in both extend and retract directions. Unlike single-acting units that rely on gravity or external spring return, double-acting configurations offer precise two-way force control, position repeatability, and predictable cycling times.

We manufacture custom double acting hydraulic cylinders tailored to exact OEM specifications. Built using honed cold-drawn seamless tubes and high-tensile induction-hardened chrome rods, these cylinders handle operating pressures up to 35 MPa (5,076 PSI) under severe duty cycles, high mechanical shock, and abrasive ambient conditions.

Operation Principle
Extend Port: Hydraulic fluid enters the extend port to push the piston forward, generating extension force.
Retract Port: Hydraulic fluid enters the retract port to push the piston backward, generating retraction force.
Two-Way Control: Hydraulic pressure controls both directions, providing consistent stroke acceleration and holding power.

 

 

Parameter	Standard Capability / Specification Range
Bore Diameter	40 mm – 400 mm (1.5" – 16")
Rod Diameter	20 mm – 280 mm (0.75" – 11")
Stroke Length	Up to 6,000 mm (236")
Working Pressure	16 MPa, 21 MPa, 25 MPa, 35 MPa (2,300 PSI – 5,076 PSI)
Operating Temperature	-40°C to +120°C (-40°F to +248°F) (Depending on seal system)
Velocity / Speed	Standard: 0.1 m/s – 0.5 m/s; High-speed config: Up to 1.5 m/s
Fluid Compatibility	Mineral hydraulic oil, water-glycol, phosphate ester, biodegradable fluids
Barrel Material	ST52, E355, 4140, 20# cold-drawn seamless steel tube (Honed ID Ra ≤ 0.4 µm)
Piston Rod Material	C45E, 42CrMo4, 316 Stainless Steel (Hard chrome plated 25–50 µm, Ra ≤ 0.2 µm)
Sealing System	Hallite, Merkel, Parker, or NOK multi-stage composite seals
Mounting Types	Clevis, Flange (Front/Rear), Trunnion, Cross-tube, Spherical eye, Foot mount

 

 

Core Engineering Specifications
Hard Chrome Plated Rod: Induction hardened (HRC 50–55), 25–50 µm plating thickness, Salt Spray test >96h.
Honed Seamless Tube: Inner surface roughness Ra ≤ 0.4 µm, yield strength ≥ 520 MPa.
Multi-Stage Seal System: Step seal, U-cup polyurethane seal, PTFE wear rings, and metal scraper wiper.
Integrated Cushioning Valves: Adjustable stroke-end deceleration prevents end-cap impact shocks.

Performance Characteristics
Skived and Honed Steel Tubing: Barrels are processed using internal burnishing and precision honing to achieve an inner wall roughness of Ra ≤ 0.4 µm. This minimizes seal friction, reduces internal bypassing, and extends seal operating life.
Induction Hardened, Chrome-Plated Rods: Carbon or alloy steel rods undergo medium-frequency induction hardening (depth 1.5–3.0 mm, HRC 50–55) prior to hard chrome plating. The surface layer resists stone impacts, scoring, and corrosion.
Low-Friction Multi-Stage Sealing: Configurations utilize polyurethane primary seals, PTFE ring combinations, and double-lip wipers. This setup maintains zero static leakage and prevents contamination ingress in dirty environments.
Precision Stroke-End Cushioning: Optional internal cushions decelerate the piston at extreme stroke positions. Adjustable needle valves regulate backpressure to eliminate structural shock loads on pin connections.
Direct-Welded End Connections: Automated MIG/MAG friction and robotic welding processes yield full-penetration joints between cylinder barrels, end caps, and mounting lugs, verified via ultrasonic testing.

 

 

Selecting or replacing a double-acting cylinder requires evaluating mechanical load and hydraulic circuit dynamics:
Cylinder Selection Workflow
Calculate Force Output: Determine required push and pull tonnage.
Determine Bore and Rod Size: Prevent rod buckling under dynamic compression loads.
Define Stroke and Envelope: Verify pin-to-pin retracted length and mounting clearance.
Match Environmental Seals: Select seal materials based on operating temperature and hydraulic media.

Force Calculation Rules
Output force differs between push and pull strokes due to rod cross-sectional area:
Push Force (Fpush):
Fpush = P × Abore = P × π × D² / 4
Pull Force (Fpull):
Fpull = P × (Abore − Arod) = P × π × (D² − d²) / 4
Where: P = System Pressure; D = Bore Diameter; d = Rod Diameter; Abore = Bore Area; Arod = Rod Cross-Sectional Area.

Rod Buckling Resistance
Long-stroke applications under push loading require buckling evaluation using Euler's formula. When stroke length exceeds 10 times the rod diameter, increasing the rod size or adding stop tubes prevents deflection under high compressive loads.

Operating Environment Considerations
High Ambient Heat (>100°C): Requires Fluorocarbon (FKM/Viton) seals and high-temperature guide rings.
Sub-Zero Operations (-40°C): Demands Low-Temperature Nitrile (LT-NBR) seals and low-viscosity fluid compatibility.
Contaminated Environments: Requires metal-cased scraper wipers or protective rod boots.

 

 

Sector	Equipment Applications
Construction	Excavator booms, wheel loaders, dozers, backhoes
Agriculture	Tractors, combines, balers, tillers, sprayers
Material Handling	Forklifts, aerial work platforms, mobile cranes, boom lifts
Industrial Presses	Metal stamping presses, hydraulic balers, injection molding machines
Mining & Drilling	Hydraulic roof supports, rock crushers, underground drilling rigs
Municipal Vehicles	Refuse collection trucks, hook loaders, street sweepers

 

 

Mounting Interfaces
Male / Female Clevis with spherical bearings
Front or Rear Flange (SAE / ISO patterns)
Intermediate or End Trunnions
Cross-tube with grease fittings
Threaded rod ends or custom clevis blocks

Surface Coatings & Corrosion Protection
Standard Chrome Plating: 25–30 µm layer, rated 96–120 hours Neutral Salt Spray (NSS) test per ISO 9227.
Double Chrome / Nickel-Chrome: 30 µm Nickel + 20 µm Chrome for marine or off-shore splash zone service (NSS >500 hours).
Corrosion Resistant Paints: Epoxy primer with polyurethane topcoat tested to 1,000+ hours salt spray exposure.

Integrated Hydraulics & Sensing
Internal Linear Transducers: Magnetostrictive sensors integrated inside a hollow-bored piston rod for real-time position feedback.
Manifold Blocks & Valves: Direct-mounted counterbalance valves, pilot-operated check valves, and burst valves to eliminate external hose connections.

 

 

Every double acting cylinder follows a controlled manufacturing workflow to maintain structural consistency:
Raw Material Verification: Spectrographic analysis and ultrasonic flaw detection on incoming seamless steel tubes and alloy steel bars.
Machining & Deep Hole Drilling: CNC turning of cylinder heads, pistons, glands, and end mounts; gun-drilling for internal rod ports.
Tube Honing & Rod Grinding: CNC cross-honing to achieve strict roundness and straightness tolerances; centerless grinding and polishing of piston rods.
Automated Welding: Robotic MIG/MAG welding of end caps, ports, and mounting lugs with constant linear speed and heat control.
Cleanroom Assembly: Ultrasonic cleaning of components followed by assembly in a temperature and particulate-controlled cleanroom environment.

 

 

Quality control checks are performed throughout production to maintain manufacturing standards:
Proof Pressure Testing: Every assembled cylinder undergoes static testing at 150% of rated operating pressure to confirm structural weld integrity and shell strength.
Internal Bypass / Leakage Testing: Pressure is maintained on isolated chambers for a minimum specified dwell time to verify zero piston seal bypass.
Low-Pressure Breakout Test: Motion initiation is checked under low pressure (≤0.5 MPa) to confirm proper seal alignment and smooth operation without stick-slip.
Dimension & Concentricity Verification: Coordinate Measuring Machines (CMM) verify critical pin-to-pin centers, mounting hole alignments, and thread pitch tolerances.
Surface Roughness & Plating Checks: Surface profilometers measure internal tube and rod roughness; magnetic/eddy-current gauges verify chrome thickness.

 

 

To receive an accurate engineering quotation and technical drawing, provide the following specifications:
Bore Diameter & Rod Diameter
Stroke Length & Retracted / Extended Pin-to-Pin Distance
Maximum Working Pressure & Peak Shock Load Target
Mounting Configuration (Clevis, Flange, Cross-Tube, Trunnion)
Operating Environment (Temperature range, dust exposure, marine or corrosive media)
Oil Port Sizes & Orientation (SAE, NPT, BSPP, Metric)
Annual Target Quantity & Batch Order Sizes

 

 

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