A concrete pump cylinder’s bore and stroke set the theoretical volume moved per working stroke, so comparing bore alone does not establish real output rate.
The practical selection links cylinder geometry to the hydraulic pump, stroke frequency, pipeline resistance, and mix characteristics, using published examples from 30 to 50 m³/h.
Cylinder Bore, Stroke, and Theoretical Output
The bore is the internal diameter of the concrete cylinder, while the stroke is the piston travel between reversal points. A basic geometric relationship gives the swept volume of one complete cylinder as πD²L/4, with D as bore and L as stroke, before accounting for the division of the cycle into suction, discharge, and any dead volume. [S4]
Published pump data demonstrate why bore must not be treated as an output rating. The HBT30-6-52R combines a 200 mm diameter with a 500 mm stroke and a maximum theoretical output of 30 m³/h. The HBT40-10-82R uses a 180/130 mm diameter with a 1,300 mm stroke and a maximum theoretical output of 40 m³/h [S4].
The first example has a larger bore but a shorter stroke, while the second has a longer stroke and a higher published output. The relevant comparison is therefore swept volume and cycles per hour, not diameter in isolation. For duplex pumping, the effective output also depends on how the two cylinders are phased and whether their strokes overlap.
Output Rate Comes from a System Equation
The geometric displacement must be converted into an hourly rate through stroke frequency and operating efficiency. As a first approximation, theoretical output equals total effective cylinder displacement per cycle multiplied by pumping cycles per hour. A 200 mm bore and 500 mm stroke create about 0.0157 m³ of geometric volume per stroke, before accounting for the share of the cycle devoted to discharge. [S2]
That volume can only be delivered if the hydraulic cylinder completes the intended stroke at the scheduled rate. Concrete pump hydraulics use displacement-controlled motion to move the pumping cylinders smoothly, and the production-critical quantity is the rate at which the hydraulic cylinder moves concrete through the material cylinder [S1].
Published comparison data gives a concrete-pump hardware reference point. REED B-Series hydraulic pumps cover 71 to 180 cm³/rev, while K3V and K5V axial-piston families span 63 to 280 cm³/rev. Truck-mounted concrete line-pump hydraulics can operate at about 32 MPa, or 320 bar, with maximum concrete-pump-module pressure also listed at 320 bar [S2].
Bore-Size Comparison Against Four Criteria
For a fixed stroke and cycle rate, a larger bore offers more swept volume but also presents a larger concrete cross-section to fill and pressurize. The comparison changes once stroke, hydraulic capacity, and duty requirements are included. [S2]
The 200 mm × 500 mm cylinder gives roughly 0.0157 m³ of geometric volume per stroke, while the 180 mm × 1,300 mm cylinder gives roughly 0.0331 m³. The longer-stroke example therefore has about 2.1 times the geometric volume per stroke, despite its smaller bore. Their listed outputs are 30 m³/h and 40 m³/h, respectively, with pressure ratings of 6 MPa and 10 MPa [S4].
Against delivery capability, the 180/130 mm × 1,300 mm configuration is stronger on theoretical output and pressure, although its long stroke imposes greater length, packaging, and motion-control demands. Against installation space, the 200 mm × 500 mm cylinder is shorter and easier to package between chassis rails. Against duty cycle, the larger swept volume per stroke can reduce reliance on very high stroke frequency, but only if the hydraulic pump, valve, reinforcement, and concrete cylinder can complete each cycle reliably. Cost cannot be derived from the available data because no cylinder pricing or service-life figures were supplied.
Selection by Concrete Delivery Duty
Use bore and stroke to establish the displacement target, then select the hydraulic system and concrete cylinder as a matched package. A 30 m³/h machine with a 200 mm bore and 500 mm stroke is a reasonable published configuration for moderate output, while the 40 m³/h, 180/130 mm by 1,300 mm example suits a higher-output package with a longer pumping cylinder [S4].
These selections apply to piston pumping with a properly sized distribution valve and pipeline. A concrete pump truck must also provide a matched placing boom, outriggers, engine power, hopper, and control system. A truck-mounted concrete pump with a larger hydraulic pump cannot compensate for a pumping cylinder that cannot fill and discharge at the required rate.
For placement planning, compare the pump’s published output with the delivery target in cubic metres per hour. A 40 m³/h pump does not guarantee 40 m³ delivered in every hour because line resistance, aggregate size, mix design, pipeline diameter, switching delays, and material interruptions can reduce effective output [S7].
Pipeline and Mix Constraints Set the Ceiling
Maximum attainable volume and pressure depend on aggregate size, mix design, and pipeline diameter, so the cylinder’s geometric output is only the upper starting point [S7]. A high-displacement cylinder can raise the potential delivery rate, but it also requires adequate suction and sufficient hydraulic pressure to accelerate the mix through the delivery line.
Research on twin-cylinder pumping identifies a measurable operating penalty from alternating flow. Pipe pressure and exciting force vary periodically with pumping speed under nonconstant pumping, while discontinuous pumping makes the peak-to-peak pressure and excitation dependent on gas volume fraction and distribution in the pipe [S3]. A large bore does not remove those effects.
The practical limits are therefore clear. Wider cylinders are justified where high volume per stroke and lower required cycle frequency are priorities. Longer strokes suit higher theoretical output but need additional longitudinal packaging space. Small-diameter cylinders reduce swept volume per stroke and demand faster reciprocation for the same output, increasing sensitivity to displacement control and acceleration limits.
Booms, Distribution, and System Integration
The pumping cylinder sets the production boundary, but the placement system must accept that flow without creating an unstable discharge at the end hose. Duplex plunger arrangements divide delivery across two long concrete cylinders, and their alternating motion produces the nonconstant flow described in the twin-cylinder research [S1][S3].
Long pump cylinders can measure as much as 8 ft and are commonly mounted at an angle between chassis rails. This geometry explains why duplex arrangements dominate many concrete pump trucks and why adding a third long pumping cylinder is packaging-constrained [S1]. Distribution-valve timing must synchronize intake from the hopper and discharge toward the placing line.
Published examples also show the effect of the broader machine package. The HBT30-6-52R lists 52 kW engine power, a 180 mm outlet, and theoretical vertical and horizontal conveying distances of 100 m and 300 m. Its larger 200 mm concrete cylinder does not make it a higher-pressure machine than the HBT40 example [S4].
Verification Checklist for Procurement
Require the supplier to identify the concrete cylinder diameter, stroke, theoretical output, maximum concrete pressure, outlet diameter, and conveying limits as separate data points. Published HBT30 and HBT40 specifications demonstrate that one 200 mm × 500 mm cylinder, 180/130 mm × 1,300 mm cylinder, and 180 mm outlet should not be treated as interchangeable [S4].
Ask for operating frequency and acceleration data for the hydraulic cylinder, the displacement control method, and the measured output test configuration. Axial piston pumps are the common high-volume hydraulic option, but overspeeding or cavitation can damage them, and their output depends on plate position and engine rpm [S5].
Track three commissioning signals: actual cubic metres delivered per operating hour, pressure stability during the stroke reversals, and variation in discharge at the placement hose. If the machine meets its published cylinder and pump figures but misses the project output target, inspect pipeline diameter, mix aggregate size, and valve timing before replacing the pumping cylinder [S3][S7].