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Troubleshooting Guide: Hydraulic Cylinder Drift and Creep - Diagnosing Internal Leaks, Checking Seals, Testing Relief Valves, and Checking Pilot Pressure

Technical analysis: Troubleshooting hydraulic cylinder drift and creep: internal leak diagnosis, seal inspection, counte

1. Description of the problem and scope of application

This manual is intended to diagnose and troubleshoot drift (unwanted slow movement of a hydraulic cylinder under load) and creep (unwanted short, jerky movements of a hydraulic cylinder) in industrial hydraulic systems. These phenomena can lead to inaccurate positioning, reduced equipment performance, risk of product damage and, in critical cases, dangerous situations for personnel. The problem is relevant for presses, machine tools, lifting mechanisms, industrial robots and other machines that use hydraulic drives.

Severity classification:

  • Critical: Drift or creep that poses an immediate threat to operator safety, significantly affects product quality, or results in a complete stoppage of production. Requires immediate intervention.
  • Significant: Performance degradation, increased component wear, increased cycle time resulting in noticeable efficiency losses. It needs to be eliminated as soon as possible.
  • Minor: Minor deviations from the desired position that do not critically affect the production process or safety, but indicate the initial stage of the development of a fault. Needs diagnostic and repair planning.

2. Precautions

WARNING! Before starting any diagnostic or repair work on hydraulic systems, be sure to observe the following safety precautions:

  • LOCKOUT AND TAGOUT (LOCKOUT/TAGOUT): Ensure complete shutdown of equipment power supply and apply LOTO procedures according to internal enterprise standards and DSTU requirements EN 1037.
  • DISCHARGE OF STORED ENERGY:Hydraulic systems can retain significant pressure even after the pump is turned off. Ensure all pressure is completely relieved before disconnecting any components or piping. Use pressure gauges to confirm zero pressure. Do not attempt to disassemble components under pressure.
  • PERSONAL PROTECTIVE EQUIPMENT (PPE): Always use safety glasses or a shield, protective gloves, suitable work clothes and safety shoes. Hot hydraulic fluid and high-pressure jets can cause serious burns and injuries.
  • FLUID TEMPERATURE CONTROL: Hydraulic fluid can be very hot (up to 80°C and above). Allow the system to cool to a safe temperature before contact.
  • FLUID INJECTION HAZARD: Leaks of high-pressure hydraulic fluid can penetrate the skin, causing serious injury requiring immediate medical attention. Never check for leaks with your hands. Use a piece of cardboard or other suitable material.
  • CYLINDER SUPPORT: If the cylinder is in a raised position or supporting weight, use mechanical supports or interlocks to prevent it from dropping unexpectedly during operation.

3. Necessary diagnostic tools

The following set of tools is required for effective diagnostics and troubleshooting of drift and creep of hydraulic cylinders:

Tool Specification / Model Measurement range Purpose
A set of hydraulic manometers Accuracy class not lower than 1.0, liquid filling, ranges: 0-100 bar, 0-250 bar, 0-400 bar, 0-600 bar. With pulsation dampers. 0-600 bar Measurement of static and dynamic pressure at various points of the hydraulic system (pump, cylinder lines, pilot pressure lines, drain lines).
The flow meter is hydraulic Portable, with the function of measuring pressure and temperature. Examples: Flo-tech PFM, Parker EO-Flow. 0-200 l/min, 0-400 bar, 0-100°C Measurement of volumetric leakage through cylinder seals or valves; assessment of pump and valve efficiency.
Infrared pyrometer (non-contact thermometer) Range -30°C to +500°C, accuracy ±1°C. -30°C to +500°C Rapid temperature measurement of components (cylinder, valves, hoses) to detect areas of overheating or uneven heat distribution, indicating internal leaks or friction.
Digital multimeter With voltage (DC/AC), current (DC/AC) and resistance measurement functions. CAT III 600V. Voltage: up to 1000V; Current: up to 10A; Resistance: up to 40 MΩ Checking the electrical signals for controlling valve solenoids, checking the integrity of the windings.
A set of special keys and sockets Metric, high strength, for hydraulic fittings. According to the dimensions of the fittings Disassembly and assembly of hydraulic components.
Kit for measuring clearance (feelers) A set of probes 0.02 - 1.0 mm with a step of 0.01/0.05 mm. 0.02 - 1.0 mm Clearance measurements that may indicate rod, sleeve, or piston wear.
Technical illuminator (endoscope) Flexible probe, diameter 6-8 mm, length 1-2 m, with illumination. Not applicable Visual inspection of the internal surfaces of the cylinder (if there are corresponding holes) and valves for damage, burrs, corrosion.

4. Initial evaluation checklist

Before starting detailed diagnostic procedures, it is necessary to collect baseline information and perform an initial visual assessment. This will help narrow down the potential causes.

Parameter What to watch / Record The goal
Cylinder Behavior Record exactly how the drift or creep manifests itself (for example, raising or lowering, extending or retracting), whether it occurs under load or without, with a fixed or variable position. Determination of the type and nature of the malfunction.
Drift/Creep Speed Measure the rate of unwanted cylinder movement per unit time (eg mm/min). Assessing the severity of the problem and documenting it for comparison after repair.
Working cycle Does the problem occur all the time, or only during certain phases of the operating cycle, at certain temperatures or pressures? Establishing the dependence of the malfunction on the operating conditions.
Alarm History Check the equipment management system crash and warning log. Identify related faults or previous events that may have caused the problem.
Hydraulic fluid level Check the fluid level in the tank. Low levels can lead to aeration and cavitation. Exclusion of basic problems with the system.
Quality of hydraulic fluid Evaluate the color, smell, presence of extraneous impurities (sediment, metal shavings, emulsion). If necessary, take a sample for laboratory analysis. Contaminated fluid is a common cause of seal and valve wear.
External sources Inspect the cylinder, hoses, tubes, fittings, and valves for external hydraulic fluid leaks. External leaks reduce fluid volume and may indicate overpressure or damaged seals.
Cylinder rod damage Visually inspect the cylinder rod for scratches, dents, corrosion, or damage to the chrome plating. Stem damage leads to rapid wear of seals and external leaks.
Mechanical load/obstacles Check for mechanical obstructions preventing the cylinder from moving freely or creating an uneven load. Exclusion of mechanical causes simulating hydraulic malfunctions.

5. Systematic diagnostic algorithm

This step-by-step algorithm will help systematically identify the root cause of hydraulic cylinder drift or creep.

  1. Drift/creep confirmation and system isolation:
    1. Shut down hydraulics, apply LOTO. CAUTION: Release the pressure!
    2. Mechanically lock the cylinder in position (if possible and safe).
    3. Disconnect both hydraulic lines from the cylinder. Plug disconnected lines and cylinder ports.
    4. Leave the cylinder under load for a while (if possible and safe) or in a position where drift was previously observed.
    5. IF cylinder continues to drift (slowly change position) after disconnecting lines and plugging ports THEN:
      • ROOT CAUSE: Internal cylinder piston seal leaks. Go to 7.1.
    6. ELSE IF cylinder does not drift after disconnecting lines and plugging ports THEN:
      • ROOT CAUSE: Leaks in external hydraulic system components (valves, hoses, pump). Go to point 5.2.
  2. External Component Diagnostics:
    1. Check Relief/Check Valves:
      • IF system has relief or check valves on the cylinder lines (often integrated into the cylinder or control unit), THEN:
        • Visually inspect the valves for external leaks.
        • Measure the pressure at the inlets and outlets of the valves while holding the load statically.
        • IF valve outlet pressure (to cylinder) drops faster than inlet pressure (from distributor), THEN:
          • PROBLEM COMPONENT: Relief/check valve failure (dirt, wear, spring damage). Go to 7.2.
        • ELSE IF pressure holds but cylinder drifts THEN:
          • The problem is probably upstream or in the cylinder itself (if the plug was unreliable).
    2. Distributor (directional control valve) diagnostics:
      • Disconnect the pressure (P) and drain (T) lines from the distributor (if safe and technically possible) or block the respective ports.
      • Apply pressure to the cylinder lines remaining connected to the distributor and hold the cylinder in the operating position.
      • IF cylinder drifts THEN:
        • PROBLEM COMPONENT: Internal distributor spool leaks. Go to 7.3.
      • ELSE IF cylinder does not drift THEN:
        • The problem is probably pilot pressure or electrical control. Go to point 5.2.3.
    3. Pilot pressure and electrical control check (for pilot operated valves):
      • Measure the actual pilot pressure applied to the valve. It must meet the manufacturer's specifications (usually 10-30 bar).
      • Measure the voltage and current at the valve control solenoids. They must comply with the norm (for example, 24V DC or 230V AC).
      • IF the pilot pressure is low or unstable, or the electrical signal is incorrect THEN:
        • PROBLEM AREA: Problems with the pilot pressure source (reducing valve, line leak) or electrical part failure (solenoid, wiring, controller). Go to 7.4.
    4. Diagnostics of hydraulic accumulators (if present in the system):
      • Check the hydraulic accumulator charge pressure. Insufficient charge can cause system instability and drift. The charge pressure must correspond to the manufacturer's instructions (usually 70-80% of the minimum operating pressure).
      • IF charge pressure below normal THEN:
        • PROBLEM COMPONENT: Accumulator failure (gas leak, diaphragm/bladder damage). Go to 7.5.

6. Malfunction-cause matrix

Symptom Probable causes (by probability) Diagnostic test Expected result when confirming the cause
Cylinder drift under load after stopping movement 1. Internal leakage of cylinder piston seals
2. Internal leak of distributor spool
3. Malfunction of relief/check valve on cylinder
4. Loss of pilot pressure (for valves with pilot control)		 1. Disconnect the lines from the cylinder and plug the ports, observe the movement
2. Measure the pressure on both sides of the piston under load
3. Check for leakage through the distributor drain port with a blocked cylinder
4. Measure the pilot pressure		 1. The cylinder continues to drift
2. Pressure on the rod side drops, pressure on the piston side increases (or vice versa)
3. Significant fluid flow from the drain even if the cylinder is not moving
4. Pressure below specification (eg <10 bar) or unstable
Creep / jerky movements of the cylinder during operation 1. Insufficient stiffness of the system (liquid aeration)
2. Contamination or wear of the rod/piston seals
3. Control problems (unstable signal to the solenoid, contamination of the distributor spool)
4. Mechanical interference or misalignment of the cylinder		 1. Visual inspection of the liquid in the tank (foam), listening to the pump (noise)
2. Inspection of seals during disassembly, checking the quality of the liquid
3. Oscillogram of the electrical signal on the solenoid, an overview of the spool
4. Manual free movement test without pressure		 1. Foam in the tank, typical pump noise, uneven pressure drop
2. Visible damage to seals (cracks, hardening), contamination with metal shavings
3. Uneven signal, solenoid does not actuate clearly, spool jams
4. Perceptible resistance or friction when moving the cylinder by hand
Cylinder drift without load 1. Worn piston seals
2. Leakage through distributor spool
3. Non-return valve failure (if present)		 1. See test for "Cylinder drift under load"
2. See test for "Cylinder drift under load"
3. Checking the check valve (clogged valve ports)		 1. See result for "Cylinder drift under load"
2. See result for "Cylinder drift under load"
3. Pressure drop after the valve in the closed state

7. Analysis of the root causes of malfunctions

7.1. Internal leaks of hydraulic cylinder piston seals

Explanation: This is one of the most common causes of cylinder drift. Piston seals (cuffs, O-rings, combined seals) are designed to separate the cylinder chambers and prevent fluid from flowing from one side of the piston to the other. Over time, due to mechanical wear, exposure to abrasive particles in the fluid, high temperature, chemical degradation of the fluid, or improper installation, seals lose their elasticity and tightness. This causes pressurized fluid to flow through the piston from the high-pressure chamber to the low-pressure chamber, causing unwanted cylinder movement.

Confirmation: The best way to confirm this is to isolate the cylinder as described in 5.1. If the cylinder drifts after disconnecting and plugging the hydraulic lines, the piston seals are almost certainly the cause. Additionally, internal leakage can be measured using a hydraulic flow meter. Connect the flow meter to one of the cylinder lines (shut off the other), apply pressure to the opposite side of the piston. Liquid leakage of more than 0.5-1% of the maximum volume of the cylinder per minute at nominal pressure may indicate worn seals. Also, when disassembling the cylinder, the seals will look worn, hardened, have cracks or traces of damage.

Consequences: If not corrected, internal leaks lead to: loss of positioning accuracy, excessive energy consumption by the pump (which is constantly trying to compensate for the leak), overheating of the hydraulic fluid, accelerated wear of other system components due to contamination and overheating, and potential failures in the production process.

7.2. Malfunction of relief/check valve on cylinder

Explanation: Counterbalance valves or lock valves, often integrated directly into the cylinder or installed in its immediate vicinity, are designed to prevent free fall or uncontrolled movement of the cylinder under the action of an external load (for example, gravity) in the absence of pressure in the control lines. Wear on the valve internals, dirt, foreign particles trapped under the spool, damage to the valve seat, or a loose/broken spring can all cause internal leakage through the valve, allowing the cylinder to drift.

Confirmation: With the power off (LOTO) and the system drained, disconnect the drain line from the valve and apply pressure to the valve inlet holding the cylinder. If there is a significant flow of liquid from the drain line (over 0.2 l/min at nominal pressure), this confirms an internal leak. Also, when disassembling the valve, look for signs of wear on the spool, seat, spring damage or contamination.

Consequences: Uncontrolled fall or movement of the cylinder, which can cause damage to equipment, risk of injury to personnel and inability to precisely position the load. Also leads to overheating and loss of energy.

7.3. Internal leaks of distributor spool (directional control valve)

Explanation: The distributor (hydraulic directional control valve) is responsible for directing the flow of hydraulic fluid to the respective cylinder chambers. It consists of a housing and a precision spool. Over time, due to abrasive wear from contaminated fluid, cavitation, or improper installation, spool-to-body clearances increase. This allows fluid to flow from the pressure line (P) to the drain line (T) or between the ports leading to the cylinder (A, B) when the spool is in the neutral or closed position. This results in cylinder drift as the pressure is not held sufficiently.

Confirmation: Isolate the distributor from the cylinder as described in point 5.2.2. Apply pressure to inlet P of the manifold and shut off lines A and B on the manifold. If there is a noticeable flow of fluid from the drain port T (above 0.5 L/min for a new valve, 5-10 L/min for a worn valve), this indicates an internal leak. It is also possible to increase the temperature of the distributor housing in the leakage zone, which can be detected with a pyrometer (difference > 5°C).

Effects: Loss of cylinder control, drift, slow system response, hydraulic fluid overheating, reduced system efficiency, and increased pump power consumption.

7.4. Pilot pressure or electrical control problems

Explanation: Many hydraulic valves (especially large or remote control valves) use pilot pressure to actuate the spool. If the pilot pressure is insufficient (eg, due to a leak in the pilot control line, a malfunctioning pilot pressure relief valve, contamination or plugging of the small holes) or the electrical signal to the pilot control solenoid is unstable/absent (faulty solenoid, open wiring, PLC problem), the valve may not close completely or hold position, causing drift.

Confirmation: Measure the pilot pressure directly at the control valve inlet. Compare it with the manufacturer's specification. Check the electrical signal on the solenoids with a multimeter (voltage, winding resistance). The typical resistance of the solenoid winding is 10-30 ohms. Low pilot pressure (eg <10 bar when 15 bar is required) or no/unstable electrical signal (voltage below 90% of nominal) confirms the problem.

Consequences: Impossibility of full valve control, cylinder drift, incorrect system operation, equipment failure.

7.5. Hydraulic accumulator failure

Explanation: Hydraulic accumulators are used to maintain pressure, compensate for fluid volume differences, dampen pulsations, and provide a reserve volume of fluid. If the hydroaccumulator loses its gas charge (due to leakage from the gas chamber or damage to the separating element - bubble/diaphragm), it cannot perform its functions effectively. This can lead to system pressure instability, insufficient load retention and, as a result, cylinder drift.

Confirmation: Measure the pressure of the gas charge using a special device for refueling and testing batteries. It should meet the manufacturer's specifications, usually 70-80% of the system's minimum operating pressure. A drop in pressure below 50% of normal is critical. Fluid draining from the gas side of the battery indicates damage to the separating element.

Consequences: Unstable pressure in the system, jerks of the cylinder, increased wear of the pump and other components due to hydraulic shocks, cylinder drift.

8. Sequence of actions for troubleshooting

After determining the root cause using the diagnostic algorithm, perform the following troubleshooting steps:

8.1. Replacement of hydraulic cylinder piston seals

  1. SECURITY: Apply LOTO, relieve pressure. Lock the cylinder mechanically.
  2. Remove the hydraulic cylinder from the equipment.
  3. Clean the outer surface of the cylinder from dirt.
  4. Disassemble the cylinder following the manufacturer's (OEM) instructions and using special tools.
  5. Remove the piston and rod.
  6. Carefully inspect the inner surface of the cylinder liner and the surface of the rod for scratches, burrs, corrosion or mechanical damage. Permissible defects: see UNITEC Maintenance Guide "Diagnostics of rod wear". If significant damage is found that exceeds ISO 8132 / ISO 8133 tolerances, consider repairing or replacing the cylinder.
  7. Remove the old seals from the piston.
  8. Clean the sealing grooves.
  9. Install new seals using special installation tools to avoid damaging them. Make sure the orientation of the seals is correct according to the manufacturer's instructions. Use only original spare parts or certified analogues that meet the ISO 6020-2 / ISO 6022. standard
  10. Assemble the cylinder in reverse order, tightening the threaded connections to the recommended tightening torque (eg 80 Nm for M16).
  11. Install the cylinder on the equipment.
  12. VERIFICATION: Start the system. Carry out several cycles of operation of the cylinder without load, then under load. Check the absence of drift, external leaks and smoothness of movement. Record drift parameters (if still observed) for comparison.

8.2. Repair/replacement of relief/check valve

  1. SECURITY: Apply LOTO, relieve pressure.
  2. Disassemble the defective valve.
  3. Disassemble the valve. Inspect spool, seat, springs and seals.
  4. Clean all components. Replace worn or damaged parts (seals, springs, spool - if available as spare parts) with original ones. If the valve cannot be disassembled or the components are not available, replace the entire valve.
  5. Assemble the valve, tighten the connection according to the manufacturer's tightening torque (for example, for Cartridge valves up to 40 Nm).
  6. Replace the valve.
  7. VERIFICATION: Start the system. Check cylinder load retention. Record the absence of drift. You can perform a leak test through the drain port of the valve (no more than 0.1 l/min).

8.3. Distributor repair/replacement (directional control valve)

  1. SECURITY: Apply LOTO, relieve pressure.
  2. Dismantle the distributor.
  3. Disassemble the distributor following the manufacturer's instructions.
  4. Inspect the spool and housing for wear, burrs, corrosion, or foreign particles.
  5. If the leak is minor and caused by dirt, try cleaning the spool and housing. If there is significant wear (visually noticeable spool play or surface discoloration), the valve will need to be replaced, as spool repair is not usually expected.
  6. Assemble or replace the distributor.
  7. VERIFICATION: Start the system. Check the smoothness and accuracy of cylinder control. There should be no drift. Check the temperature of the distributor housing. It should not exceed the ambient temperature by more than 15°C during nominal operation.

8.4. Troubleshooting pilot pressure or electrical control problems

  1. SECURITY: Apply LOTO.
  2. For pilot pressure problems:
    1. Check pilot pressure relief valve: clean, replace gasket, replace valve if necessary. Set the pressure according to the OEM specification (eg 15 bar ±1 bar).
    2. Inspect the pilot pressure lines for leaks and blockages. Replace damaged lines or clean clogged lines.
  3. For electrical control problems:
    1. Check the solenoid: measure the winding resistance (eg 20 ohms ±10%). If the resistance does not meet the norm or the winding is broken, replace the solenoid.
    2. Check electrical wiring and connectors for breaks, short circuits, corrosion. Repair or replace damaged items.
    3. Check the output signal from the controller (PLC). If necessary, diagnose the controller.
  4. VERIFICATION: After troubleshooting, measure the pilot pressure again (with a pressure gauge) and the electrical signal (with a multimeter). They must meet the norm. Check the operation of the cylinder.

8.5. Repair/replacement of hydraulic accumulator

  1. SAFETY: Apply LOTO, depressurize the hydraulic system completely, and release gas from the accumulator through the special valve.
  2. Dismantle the hydraulic accumulator.
  3. Check the integrity of the bladder/diaphragm using a special battery charging and testing kit.
  4. If the bladder/diaphragm is damaged, replace it following the manufacturer's instructions.
  5. Charge the accumulator with nitrogen to the required pressure (for example, 100 bar) according to the OEM specification and DSTU EN 14359.
  6. Install the hydraulic accumulator.
  7. VERIFICATION: Start the system. Check pressure stability. Check for cylinder drift. Record gas charge pressure and operating parameters.

9. Preventive measures

The root cause Prevention strategy Monitoring method Recommended interval
Wear of piston/rod seals Maintenance of hydraulic fluid purity (filtration), temperature control, regular replacement of seals according to the regulations, use of quality seals (ISO 6020-2). Analysis of the condition of the hydraulic fluid (according to ISO 4406), visual inspection of the rod, measurement of the drift rate. Replacement: 2000-4000 hours of operation or once every 2 years. Fluid analysis: every 500-1000 hours.
Contamination/wear of valves Regular replacement of filters, use of high-quality fluid, control of valve seals, installation of valves in accordance with ISO 4401. Analysis of the state of the hydraulic fluid (ISO 4406), pressure measurement, thermal imaging control (to detect overheating). Replacement of filters: every 500-2000 hours. Valve inspection/repair: every 4000-8000 hours.
Hydraulic accumulator failure Regular check of the pressure of the gas charge, replacement of the bladder/diaphragm according to the regulations. Measuring the pressure of the gas charge of the battery. Every 6-12 months.
Incorrect pilot pressure/electric control Regular checking of electrical connections, calibration of reducing valves, protection of electrical components from moisture and vibration. Measurement of pilot pressure, checking of electrical signals (voltage, current), visual inspection of wiring. Every 1000-2000 hours of operation or annually.

10. Spare parts and components

Timely replacement of worn or damaged components is critical to maintaining hydraulic system reliability. Use only certified spare parts.

Part description Specification / Standard When to replace Category UNITEC
A set of hydraulic cylinder piston seals Material: NBR, FKM, PTFE (depending on liquid and temperature); Profile: U-shaped, compact, O-rings. Corresponding to ISO 6020-2 / ISO 6022. When drift is detected, after disassembling the cylinder, according to the maintenance regulations. Seals and rings
A set of hydraulic cylinder rod seals Material: NBR, FKM, PTFE; Profile: Chevron, compact, mudslides. Corresponding to ISO 6020-2 / ISO 6022. In case of external leaks, after disassembling the cylinder, according to the maintenance regulations. Seals and rings
Relief/check valve Type: Cartridge, modular; Pressure range: according to OEM specification. CE certification. In the event of a confirmed internal leak or malfunction. Hydraulic valves
Hydraulic distributor (directional control valve) Type: spool, electromagnetic; Size: CETOP 3, CETOP 5; Voltage: 24V DC, 230V AC. According to ISO 4401. With significant internal leakage or mechanical jamming of the spool. Hydraulic valves
Electromagnetic solenoid for the valve Voltage: 24V DC, 230V AC; Power: As per OEM. In case of winding breakage, short circuit, mechanical damage. Electrical components
Hydraulic accumulator Type: bubble, diaphragm; Volume: according to OEM; Max. pressure: as per OEM. According to DSTU EN 14359. If the bladder/diaphragm is damaged or the gas charge cannot be contained. Hydraulic accumulators
Hydraulic fluid Type: HVLP, HLP (ISO VG 32, 46, 68); Purity Class: According to ISO 4406 (eg 18/16/13). Certification ISO 11158. According to the regulation of replacement, in case of contamination or degradation. Hydraulic fluids
Hydraulic filters Fineness of filtration: 10 μm, 25 μm; Type: reverse, pressure. According to ISO 16889. According to the replacement regulations or when the pollution indicator is triggered. Filters and elements

To order quality spare parts and components, visit our UNITEC-D E-Catalog.

11. Links

  • DSTU EN 1037: Machine safety. Prevention of unexpected start.
  • ISO 4406: Hydraulic power transmission. Liquid. The method of coding the level of pollution by solid particles.
  • ISO 11158: Lubricants, industrial oils and related products (Class L). Classification. Group H (hydraulic systems).
  • ISO 6020-2: Hydraulic drives. Hydraulic cylinders with a maximum permissible working pressure of 21 MPa (210 bar). Type 2. Metric series with fasteners.
  • ISO 6022: Hydraulic drives. Hydraulic cylinders with a maximum permissible working pressure of 25 MPa (250 bar) and 32 MPa (320 bar). Metric series.
  • ISO 8132 / ISO 8133: Hydraulic drives. Hydraulic cylinders. Bore sizes and connection sizes for rod seals and mud flaps.
  • DSTU EN 14359: Gas accumulators with bubble/diaphragm/piston.
  • UNITEC Maintenance Guides
  • OEM equipment maintenance manuals.

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