Question 1

How do I size a hydraulic cylinder correctly?

Accepted Answer

The force required on the rod results from the load to be moved and the working pressure available in the system (force equals pressure multiplied by the piston area), from which the required bore is derived. The stroke must cover the real travel plus a safety margin, and for long strokes with high compressive forces the risk of rod buckling must be checked, which limits the minimum permitted diameter. The desired travel speed also matters, as it determines the oil flow required from the pump. A cylinder undersized for buckling bends permanently at the first overload.

Question 2

What is the difference between a single-acting and a double-acting cylinder?

Accepted Answer

A single-acting cylinder receives pressure on one side of the piston only and returns by the force of a spring or by the dead weight of the load - simple and cheap, but with useful force in one direction of movement only. A double-acting cylinder receives pressure on both faces of the piston, actively controlling movement in both directions, with speed and force that can be adjusted independently on extension and retraction. For applications that require precise control in both directions (presses, manipulators), double-acting is practically the only viable option.

Question 3

How do I choose the type of hydraulic pump - piston, vane or gear?

Accepted Answer

A gear pump is simple and cheap, suited to moderate pressures (up to about 250 bar) and applications without low-noise requirements. A vane pump offers quieter operation and better volumetric efficiency at medium pressures, and is often used on machine tools. A piston pump (axial or radial) covers high pressures (over 300-400 bar) and controlled variable flow, and is the choice for mobile machinery and high-power hydraulic systems. The required flow rate (l/min) and the maximum system pressure remain the starting criteria, regardless of type.

Question 4

What does the notation 4/3 or 4/2 mean for a hydraulic directional valve?

Accepted Answer

The first number indicates the number of ports (ways) of the valve, and the second the number of positions the spool can occupy. A 4/3 valve has four ports and three positions - usually extend, retract and a centre position (blocked, floating or bypass, depending on the model) - and is frequently used for bidirectional cylinder control with intermediate stopping. A 4/2 has no centre position, the spool switching directly between the two active states, suited to simple on/off controls with no need to stop mid-stroke.

Question 5

What do I need to send for a quotation for hydraulic or pneumatic components?

Accepted Answer

For cylinders: the bore, rod diameter, stroke, working pressure and mounting type. For pumps: the required flow rate (l/min), the maximum pressure and the drive speed. For directional valves and valves: the number of ways/positions, the type of actuation (manual, electric, pneumatic) and the coil voltage, if electric. Also state the type of hydraulic fluid used (mineral, biodegradable, fire-resistant), for seal compatibility. With the original code of the part to be replaced, identifying the correct equivalent is immediate.

Question 6

How long does delivery of hydraulic and pneumatic components take?

Accepted Answer

For cylinders, valves and fittings in standard sizes, the lead time is 24–72 h when the item is available locally or at the supplier. Hydraulic cylinders with special strokes and bores, pumps configured to order or complete systems designed for a specific application are made to order, usually 1–4 weeks; it can take longer depending on the brand and the specifications. For machinery stopped for lack of a critical component, send the part code and in the quotation we will tell you the availability of compatible variants.

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