Radial piston pumps

Stucchi HydroPower: a leading manufacturer of reliable and durable radial piston pumps

Radial piston pumps are a key component of the machinery and hydraulic engineering industries. These pumps are renowned for their efficiency, durability and versatility across a wide range of applications.

Stucchi HydroPower specialises in the manufacture and production of these exceptional hydraulic machines. We constantly invest in innovations that improve the efficiency and performance of our pumps, ensuring our customers receive the best products available on the market.

Radial piston pumps: what they are and how they work

Radial piston pumps are mechanical devices used to transfer fluids from one point to another through the reciprocating movement of the pistons. This movement is essential for generating pressure and forcing the fluid through the system.

Radial piston pumps are characterised by their innovative design, which makes them suitable for a wide range of industrial applications, from heavy construction to precision industrial machinery.

Single pumps

In radial piston pumps, the pumping cylinders – fitted with suction and delivery valves – are arranged in a star pattern around an eccentric which, with the aid of the piston return springs, causes the reciprocating suction and delivery motion.

The pistons are available in five sizes, with the smaller ones allowing for higher pressures whilst the larger ones deliver higher flow rates. Thanks to their modular design, the pump elements (like the associated valves) are easily replaceable or can be swapped for others with a different bore if the pump’s characteristics need to be altered.

As they are designed for submersion or outdoor installation and are available with different types of shafts, radial piston pumps offer a range of installation options, including combination with pumps and gearboxes.

Installation of radial piston pumps

Radial piston pumps must be installed flush with the cover and in a position that ensures they are properly supplied with fluid.

• In installations where the pump is located outside the tank, the pump must be positioned in such a way as to prevent stagnation and the formation of air bubbles inside the tank, so that the unit remains fully filled with oil at all times, whether it is stationary or in operation. This also applies to any external suction filter and to the inlet pipe, the internal diameter of which must not be less than 15 mm.
• For rods longer than 3 metres, please specify a pump with a support on the shaft seal.
• In submerged installations, only pumps without caps should be used; these must be positioned so that the suction ports are below the minimum level that the oil can reach during operation.

Filtering

As a general rule, install a filter on the return pipe that is suitable for the maximum discharge flow rate.

A filtration rating of 40 microns is generally recommended, or:

for intermittent service and/or light-duty operation: 90 to 60 microns;

for continuous service and/or heavy-duty operation: 60 to 25 microns;

In exceptional cases, a suction filter is permitted; however, this does not apply to pumps without suction caps. The use of these filters should be restricted to systems operating intermittently and/or under light loads, and they should be inspected frequently if submerged or if not fitted with a clogging indicator. An air filter appropriate to the level of environmental pollution should also be fitted to the tank.

Instructions for starting and operating radial piston pumps

Once the oil has been filled and the air has been thoroughly bled, prime the pump by operating it in short bursts, without subjecting it to pressure. Excessive noise and/or irregular pulsations indicate incomplete priming: continue with the short bursts and, if necessary, very brief periods of pressurisation. It will rarely be necessary to fill the cylinders via the orifices of the suction valves.

During the first few hours of operation, check the filter several times, especially if it is on the suction side.

When starting from cold, only begin operation after several minutes of running at low pressure.

Particularly in heavy-duty or continuous service applications, we recommend:

checking the oil and air filters monthly for cleanliness, the degree of ageing and contamination of the fluid, and its level;

replacing the oil after approximately 2,000 hours of service or 1 to 2 times a year, after flushing the reservoir;

check occasionally that, during operation, the oil temperature does not exceed 60–70°C.

General and hydraulic characteristics of radial piston pumps

• Pump type: fixed-displacement pump.
• Construction: radial pistons with eccentrically actuated valves.
• Mounting type: flanged shaft connection.
• Speed range: 300–1,800 g/min; ideal 900–1,500 g/min.
• Mounting position: any position that ensures correct fluid supply.
• Flow direction: from inlet (Asp.) to outlet (P), including reverse rotation.
• Ambient temperature range: from –20°C to +60°C.
• Hydraulic fluid: mineral oil in accordance with DIN 51524 and 51525.
• Inlet pressure range: 0.01–0.3 bar; non-self-priming pumps must be installed below the liquid level.
• Delivery pressure range: 200–600 bar; depending on the model.
• Fluid temperature range: from –10 °C to +70 °C, optimum 30–50 °C.
• Fluid viscosity range: generally 4–300 cST (1.3–4°E), in operation 10–300 cST (1.8–4°E).
• Filter rating: 40–90 microns.
• Flow rate (nominal at 1450 g/min): 0.57–6 l/min.

Available bore sizes

Thanks to the modular design of Stucchi HydroPower’s radial piston pumps, it is possible to select the bore size of the pistons to create a pump that fully meets the customer’s pressure and flow rate requirements.

In fact, we offer custom-designed radial piston pumps to meet the specific needs of each customer. Whether for large-scale industrial applications or small-scale projects, we at Stucchi HydroPower have the ideal solution.

Diameter	CC/lap	Maximum pressure (bar)	Peak pressure (bar)
Pump ø 8	1.23	250	280
Pump ø 10	0.63	500	550
Pump ø 12	0.91	350	390
Pump ø 13	1.06	300	340
Pump ø 14	1.23	250	280