In industrial maintenance operations, hydraulic equipment should be selected according to the task to be performed, rather than solely on the rated force specified in the technical data sheet.
Lifting machinery, removing a bearing, spreading a flange, pressing a component or cutting a metal section involves different requirements in terms of force, stroke, operating speed, available space and motion control.
The correct selection should take the entire hydraulic system into account: the hydraulic cylinder or tool, pump, control valve, hoses, couplers, pressure gauge and safety accessories. The maximum operating pressure of the system must not exceed the pressure rating of the component with the lowest allowable working pressure.
Hidromold supplies equipment for lifting, pressing, pulling, spreading, cutting, punching, bending, crimping and other industrial maintenance applications, as well as custom hydraulic systems developed for specialised applications.
Before selecting any equipment, it is essential to determine the required movement and the conditions under which the operation will be performed.
Typical applications may include:
For lifting applications, load stability and control are essential. In pulling applications, the geometry of the tool and the alignment of the applied force must be considered. For cutting or punching operations, the compatibility between the tool, the material and the maximum permissible dimensions must be verified.
Therefore, two applications that appear to require the same force may require completely different equipment.
The force generated by a hydraulic cylinder depends on the system pressure and the effective piston area. For this reason, equipment capacity must always be assessed in relation to the operating pressure.
The equipment must not be operated above the rated capacity specified by the manufacturer. It is also advisable to select a capacity higher than the estimated load so that the system does not operate continuously near its maximum limit.
Some lifting equipment manuals recommend using approximately 80% of the rated capacity and stroke. However, this is not a universal rule and must be confirmed against the technical documentation of each product.
For lifting operations, the following factors must be considered:
In a multi-cylinder system, the load is not automatically distributed equally between all cylinders. When controlled movement is required at several lifting points, a synchronised lifting system or a system with individual flow control may be necessary.
A hydraulic cylinder may provide the required force but still be unsuitable if it cannot be positioned within the available working area.
Before selecting the product, the following dimensions and conditions should be checked:
For applications with limited vertical clearance, low-profile or ultra-low-profile cylinders may be used, provided that their capacity, stroke and support conditions are suitable for the operation.
Telescopic cylinders provide a long stroke relative to their retracted length. However, they must be selected according to the application configuration, load stability and the manufacturer’s recommendations.
Operating the cylinder at the end of its stroke under conditions other than those specified in the technical documentation should be avoided. Some equipment is not designed for repeated operation at maximum stroke.
Single-acting cylinders use hydraulic pressure to move the piston in one direction only. Retraction may be achieved by a return spring, the weight of the load or another mechanism incorporated into the cylinder design.
They are commonly used for lifting, pressing and positioning applications.
Double-acting cylinders use hydraulic pressure for both extension and retraction. They have two hydraulic ports and require a pump, a directional control valve and two hoses compatible with this configuration.
A double-acting cylinder may be suitable when:
The retraction force of a double-acting cylinder is generally lower than its extension force because hydraulic pressure acts on a smaller effective area due to the piston rod cross-section. The exact values must be checked in the product data sheet.
The pump converts mechanical energy into hydraulic energy and supplies the oil flow required to operate the cylinder or hydraulic tool.
Pressure is not generated independently of the load. It increases when the oil flow encounters resistance within the circuit and is limited by the pressure relief valve.
When selecting a pump, the following factors should be checked:
The pump flow rate directly affects the operating speed. For the same cylinder, a pump with a higher flow rate will, under comparable conditions, provide faster piston movement.
The pump’s usable oil capacity must be sufficient to fill the cylinder, hoses and all other circuit components without allowing the reservoir level to fall below the minimum permissible limit.
Manually Operated Hydraulic Pumps
These pumps are suitable for occasional maintenance work, field operations and applications where operating speed is not the primary consideration. They do not require an external power source and are easy to transport.
Electric Hydraulic Pumps
Electric pumps are recommended for repetitive operations, larger-volume cylinders and applications where productivity or cycle speed is important.
Engine-Driven Hydraulic Pumps
These pumps can be used in the field or in areas where an electrical power supply is unavailable. Requirements concerning ventilation, noise, exhaust emissions and the conditions of the working environment must be observed.
Hidromold supplies manually operated, electric and engine-driven hydraulic pumps, as well as custom hydraulic power units.
A hydraulic system must be assessed as a complete assembly. It is not sufficient for the pump and cylinder to have the same pressure rating.
The following must be checked:
The maximum operating pressure of the system is determined by the component with the lowest pressure rating. An improperly connected coupler may restrict or block oil flow and cause the system to operate incorrectly.
A pressure gauge allows the operator to monitor system pressure and identify when the system is approaching its operating limit.
The theoretical force generated by the cylinder can be estimated using the following formula:
Force = pressure × effective piston area
In practice, it is advisable to use the pressure-to-force conversion tables provided by the manufacturer. Calculations must account for the different effective areas during extension and retraction, pressure losses within the circuit and the system’s actual efficiency.
A pressure gauge does not replace the pressure relief valve or any other safety device.
Hydraulic hoses must be selected according to the operating pressure, flow rate, hydraulic fluid and temperature of the application.
Before use, the hoses and connections should be inspected for:
Hoses must not be crushed, twisted, pulled across sharp edges or used to carry or move equipment. A pressurised hose must never be handled, and no component should be disconnected until the system pressure has been fully and safely released.
Pressurised hydraulic oil can penetrate the skin and cause a serious injection injury. This is a medical emergency, even if the visible wound appears minor.
When lifting machinery or heavy structures, the cylinder must be placed on a flat, stable surface capable of supporting the load.
The contact point between the piston and the load should be centred as accurately as possible. Eccentric or side loading may cause instability and damage the cylinder.
Once the load has been raised, it must be secured using a suitable mechanical support system. A hydraulic cylinder must not automatically be regarded as a permanent load-holding device.
Depending on the application, the following may be used:
All such equipment must be used strictly in accordance with the manufacturer’s instructions and the applicable operating procedure.
Hydraulic presses and pullers are used to install or remove bearings, bushings, shafts, gears and other components.
Before selecting the equipment, the following must be checked:
Applying force off-axis may damage both the component and the equipment. Adapters, plates and accessories must be designed and rated for the applied force and must not be improvised from components of unknown capacity.
Mechanical and hydraulic flange spreaders allow flanges to be separated in a controlled manner without using wedges or improvised tools.
When selecting a flange spreader, the following factors should be assessed:
Before flange spreading begins, the installation must be isolated, fully depressurised and prepared in accordance with the applicable procedures.
For these operations, rated force is not the only selection criterion.
The following must also be checked:
A tool designed for copper or aluminium cables must not automatically be used for steel cables. Similarly, cutting capacity may vary according to material hardness, even when the diameter is identical.
Only the material and dimensional combinations specified by the manufacturer must be used.
Standard equipment is suitable for a wide range of maintenance operations. However, a custom hydraulic solution may be justified when:
In such cases, the entire operating cycle must be assessed, including workpiece positioning, force generation, motion control, load holding, retraction and operator safety.
To prepare an appropriate technical recommendation, the following information is useful:
Photographs, sketches and the dimensions of the working area can help identify a suitable configuration.
The selection of hydraulic equipment for industrial maintenance must start from the application itself and the actual working conditions.
Force, stroke, dimensions, operating speed, oil volume and compatibility between components must be assessed together. A correctly sized solution helps reduce intervention time, protect equipment and improve operational safety.
For applications where the required configuration is not yet clear, the Hidromold team can assess the job requirements and recommend either standard equipment or a tailored hydraulic solution.
Important: The information presented is of a general nature and does not replace the manufacturer’s manual, risk assessment, internal working procedures or operator training. The installation and use of high-pressure hydraulic equipment must be carried out only by trained personnel.
