Is a Hydraulic Ram the Same as a Hydraulic Cylinder?

by | Jul 15, 2026 | single acting cylinder


A hydraulic ram and a hydraulic cylinder are related but technically distinct designs. In the most precise engineering usage, a hydraulic ram is a plunger-type actuator where a solid steel plunger rod slides through a single seal at one end of the cylinder body — with no internal piston. A hydraulic cylinder has an internal piston sealed inside the barrel, with a smaller-diameter rod attached to the piston. In everyday commercial and agricultural use across the UK, the term hydraulic ram is used broadly to mean any single acting hydraulic cylinder, and the two terms are treated as interchangeable in most practical contexts.

Compact hydraulic cylinder plunger ram type for pressing and jacking comparison

How a True Hydraulic Ram Works

In a true plunger-type hydraulic ram, the moving element is a solid steel plunger rod that fits closely inside the cylinder body bore. The hydraulic port is at the closed cap end. When pressurised oil enters the cap end, it acts on the full cross-sectional area of the plunger end face, pushing the plunger out of the bore. The only seal is at the gland where the plunger exits the cylinder body — a single seal zone. There is no internal piston, no rod-end port, and no rod-end seal. Retraction is by gravity or by the load weight — the plunger does not have hydraulic retraction capability in the basic design.

The force produced by a hydraulic ram is: Force (N) = Pressure (Pa) × Plunger Area (m²), where Plunger Area = π × (plunger diameter ÷ 2)². Unlike a piston-cylinder where the rod is smaller than the bore, in a hydraulic ram the plunger diameter determines both the force output and the structural stiffness — a large plunger provides both high force and high column buckling resistance.

Technical Differences: Ram vs Cylinder Side by Side

Feature Hydraulic Ram (Plunger) Hydraulic Cylinder (Piston-Rod)
Internal piston None — solid plunger only Yes — piston sealed inside bore
Force-producing area Full plunger cross-section Bore area (extension) or annular area (retraction)
Seal zones One — gland seal only Two — rod seal + piston seal
Double acting operation Not possible in basic design Yes — standard for piston-rod design
Rod/plunger buckling resistance High — solid plunger, large diameter Lower — rod smaller than bore
Typical stroke Short — 50–300 mm Short to long — 50 mm to several metres
Typical applications Jacks, presses, bolt tensioners Full range from light to heavy duty
Collapse height More compact for same force Less compact — piston and gland add length
ZG series hydraulic cylinders harvesting machinery ram cylinder type selection

When the Terms Are Used Interchangeably

In UK agricultural machinery, construction plant, and general industrial use, hydraulic ram is the common term for any single acting hydraulic cylinder — regardless of whether it uses a true plunger design or a piston-and-rod design. A tractor three-point hitch cylinder is routinely called a hydraulic ram even though it uses a conventional piston-and-rod construction. This loose usage is deeply embedded in the industry and causes no practical confusion among experienced users who understand the context.

When specifying a replacement or custom unit, however, use the technically precise description: specify bore diameter, rod diameter, stroke, mounting configuration, and whether a true plunger design (one seal, solid plunger) or a conventional piston-rod design is required. Contact Ever-Power with your application details — the team will confirm which design is appropriate and provide specifications for both options where a choice exists.

Request a Free Specification Review

Send your application details to [email protected] or call +86-571-88220653. Our engineers respond within 24 hours.

Frequently Asked Questions

1. Is a hydraulic ram the same as a hydraulic cylinder?+
The terms hydraulic ram and hydraulic cylinder are often used interchangeably, but technically they describe different designs. A hydraulic ram (also called a plunger cylinder) has a solid plunger rod that extends from a single sealed end — there is no internal piston, and the hydraulic pressure acts on the full cross-sectional area of the plunger rod. A hydraulic cylinder has a piston inside a barrel, with the piston rod being smaller in diameter than the bore. In common usage, however, ‘hydraulic ram’ is widely used to mean any hydraulic cylinder, particularly in the UK agricultural and construction industries.
2. What is the difference between a hydraulic ram and a hydraulic cylinder?+
A hydraulic ram (true definition) uses a solid plunger rod moving through a sealed bore — the oil pressure acts on the full rod cross-section, and there is no separate internal piston. A hydraulic cylinder has an internal piston sealed inside the barrel, with a smaller-diameter rod attached. The ram design is simpler (one seal at the rod end only), more compact at a given force output, and typically single acting. The cylinder design supports double acting operation and longer strokes without rod buckling issues at the same force.
3. Why is a hydraulic cylinder called a hydraulic ram?+
The term hydraulic ram is a historical usage that predates the modern hydraulic cylinder design. Early hydraulic actuators were solid plunger rams, and the term transferred informally to the piston-and-rod design that replaced it for most applications. In the UK, agricultural and construction industries commonly call any single acting hydraulic cylinder a ‘hydraulic ram’ regardless of whether it uses a true ram or a piston-and-rod design. In formal engineering and ISO standard contexts, hydraulic cylinder and hydraulic ram are distinct designs.
4. Which is better, a hydraulic ram or a hydraulic cylinder?+
For short-stroke, high-force, single acting applications — hydraulic jacks, log splitters, press tooling — a hydraulic ram (true plunger design) is often preferable: simpler construction, single seal zone, and more compact for the same force output. For longer stroke applications or those requiring double acting operation, the hydraulic cylinder with a piston-and-rod design is more practical because the rod diameter can be optimised for buckling resistance independently of the bore diameter.
5. What are typical uses of a hydraulic ram?+
Hydraulic rams (true plunger design) are used for: hydraulic floor jacks and workshop presses (high force, short stroke, gravity return); log splitters (high splitting force, short stroke, gravity or spring return); hollow plunger bolt tensioners (through-bore allows the bolt to pass through the ram); bridge jacking and structural testing (very high tonnage in compact format); and baling press plungers where the simplicity of a single seal zone is preferred over the dual-seal zone of a piston-cylinder design.