The OMCN double-acting hollow plunger hydraulic cylinders are high-pressure actuators designed for professional pushing, pulling, extraction, tensioning, positioning and controlled movement of mechanical components. Their through-bore piston design allows a threaded rod, tie rod or pulling element to pass through the cylinder axis, creating a compact and precise system for applications where force cannot be applied directly to the component surface.

This configuration is selected when bearings, bushes, pins, couplings, pulleys, shafts, taper pins, flanges or interference-fitted parts must be extracted, or when controlled tension must be applied to tie rods, bolts, structures, flanges and large mechanical components. The central bore keeps the pulling rod aligned with the cylinder axis, reducing the risk of side loads, bending and misalignment that could affect safety or damage the workpiece.

The cylinders are double acting, meaning that hydraulic pressure controls both piston extension and piston retraction. Unlike spring-return cylinders, the return stroke does not rely on an internal spring but is directly powered by pressurized hydraulic oil. This provides accurate control in both directions and makes the system particularly suitable for heavy-duty work, repetitive cycles, deep extraction, controlled tensioning and applications where the piston must retract against external resistance.

The maximum operating pressure is 700 bar. For correct operation, these cylinders must be connected to a hydraulic pump, hoses, quick couplers, pressure gauges and directional valves rated for the same nominal pressure. Because the cylinder is double acting, the pump must include a valve suitable for controlling both hydraulic chambers, typically a four-way directional control valve or an equivalent arrangement. A standard single-acting pump cannot fully operate the hydraulic return function of the cylinder.

The double-acting design provides a practical advantage when full control of the stroke is required. During bush removal, for example, the cylinder can produce pulling force through a threaded rod connected to an extractor or bearing separator. Once the operation is complete, the piston can retract hydraulically in a controlled manner, without waiting for spring return and without manually releasing residual load from the system. During tensioning operations, the cylinder can apply progressive force to a tie rod and then return it precisely to the initial position, facilitating work on structures, plants and mechanical joints.

Available versions provide push capacities from 24 ton to 48 ton and pull capacities from 14 ton to 32 ton. The difference between pushing and pulling force depends on the effective hydraulic area: during extension, oil acts on the larger piston area, while during retraction or pulling, it acts on the annular area reduced by the rod section. The correct model must therefore be selected according to the actual force required in the working direction. An extraction operation using a puller rod must be sized according to the stated pulling capacity, not the pushing capacity.

Oil volume is a key factor when selecting the most suitable pump. Compact versions require volumes such as 301.4 cm³ or 471.2 cm³, while long-stroke models may require 753.6 cm³, 1472.3 cm³ and up to 1790.4 cm³. A cylinder with moderate oil capacity can be operated effectively with a two-speed hand pump, especially for occasional work. For cylinders with large oil requirements, long strokes or frequent use, an air-hydraulic pump or electric hydraulic power pack is recommended in order to reduce cycle time and operator effort.

The pump reservoir capacity must exceed the maximum oil volume required by the cylinder in the working direction, always allowing an adequate operating margin. For demanding applications, the use of a pressure gauge is recommended because it allows the operator to monitor applied pressure and estimate the force transmitted to the system. Pressure control is essential not only for process accuracy, but also to avoid overloading puller rods, reaction plates, nuts, extractors and all mechanical accessories connected to the cylinder.

Hollow plunger cylinders can be used with a wide range of accessories, including threaded puller rods, hydraulic or mechanical nuts, reaction plates, extraction bridges, bearing separators, pushing sleeves, adapters, flanges, reaction discs and dedicated fixing systems. Every accessory must be selected according to the expected pulling or pushing force. An undersized accessory can become the weakest element of the assembly even when the cylinder itself has a high rated capacity.

For safe and efficient use, the cylinder must remain perfectly aligned with the puller rod and the component being moved. Reaction surfaces must be rigid, flat and properly dimensioned. The threaded rod must have sufficient thread engagement and must not operate at an angle or under bending load. Before pressure is applied, it is advisable to check for set screws, retaining rings, locking pins, threaded stops or other mechanical elements that may prevent movement.

Pressure should always be increased progressively. If the component does not move, the circuit should not immediately be brought to 700 bar; mechanical constraints, corrosion, tight interference fits or assembly errors should first be checked. In many cases, penetrating lubricant, controlled heating of the outer component or a correctly sized extraction tool can reduce the force required and prevent damage to the part or its seating.

These cylinders are particularly suitable for mechanical workshops, steel fabrication, industrial maintenance, railway applications, energy plants, infrastructure projects, construction sites, industrial assembly, technical lifting, automotive, marine, steelworks, cement plants, recycling systems, machine tool maintenance and service work on production equipment. They are ideal where high force must be applied in limited spaces, where controlled axial extraction is needed or where components must be tensioned without dismantling complete structures.

With a maximum operating pressure of 700 bar, double-acting operation, a through hollow piston and multiple combinations of force, stroke and oil volume, OMCN hollow plunger hydraulic cylinders provide a reliable technical solution for pulling, extracting, tensioning, moving and positioning industrial components with high precision, consistent performance and controlled force.