What Are Hollow Plunger Cylinders?

Hollow plunger hydraulic cylinders (also known as center-hole cylinders) feature a piston with a central opening, enabling rods, cables, or bolts to pass through for pulling or tensioning. This hollow design makes them ideal for both pushing and pulling forces.

Enerpac offers these in single-acting and double-acting versions, with return mechanisms that suit applications requiring rapid cycling or sustained pulling force.

Where Are They Used?

These cylinders are used in a wide range of applications across U.S. industries:

• Anchor bolt tensioning

• Post-tensioning in concrete

• Cable tensioning and de-tensioning

• Bushing removal or insertion

• Bearing maintenance

• Heavy-duty pulling operations

The through-hole capability allows direct engagement with threaded rods, allowing force to be applied in either direction for precise control.

Required Accessories

To operate efficiently and safely, Enerpac hollow plunger cylinders typically require:

• Threaded rods or tensioning bars

• Pulling plates or bearing adapters

• Hydraulic hand or electric pumps

• High-pressure hoses and fittings

• Hollow saddles or rod guides

• Pulling nuts and reaction washers

Enerpac systems are modular, so components can be mixed and matched to suit your application.

Industries in the USA That Use Hollow Plunger Cylinders

These highly flexible cylinders are widely used in:

• Construction & Infrastructure – For cable tensioning and post-tensioning concrete beams

• Power Generation – Tensioning anchor bolts in turbines or generators

• Mining & Heavy Equipment – Removing pins or installing press-fit parts

• Transportation & Rail – Pulley and bushing extraction during maintenance

• Manufacturing – For mechanical testing, press fits, and bearing pulls

Why Choose Enerpac Hollow Plunger Cylinders?

Enerpac is known for quality and safety. Their hollow plunger models:

• Are machined for concentric alignment to ensure accurate tensioning

• Offer high-tonnage capacity even in compact models

• Are made with corrosion-resistant finishes

• Come with built-in handles for portability

• Support horizontal or vertical use

They’re also easy to maintain, with seal kits and replacement parts readily available.

Interesting Facts

• Enerpac hollow cylinders are commonly used in geotechnical testing, including pull-out testing for anchors.

• Many models have integrated handles for easy maneuvering onsite.

• They’re often used with hydraulic nuts in bolting operations for turbine and flange systems.

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