Concrete Iran

concrete mixer pump PV21

The PV21 and PV23 hydraulic pumps, manufactured by Sundstrand, are axial piston pumps designed for high-reliability operation in concrete mixer hydraulic systems. They can be used in both open and closed circuit systems, providing sufficient flow and pressure for heavy-duty concrete mixing. The PV21 has a displacement of 21 cm³ per revolution, while the PV23 displaces 23 cm³ per revolution. Maximum operating pressures reach 350 bar for PV21 and 360 bar for PV23, with maximum flows of 120 and 130 liters per minute, respectively. Each pump weighs approximately 55–60 kg, and the required input power at operational speed is around 100 kW.

The repair process begins with removing the pump from the hydraulic system and inspecting the housing and external connections for leaks or cracks. The cylinder block, pistons, swash plate, and drive shaft are measured using precision tools such as micrometers and gauges. Worn or damaged components are replaced to restore hydraulic performance and flow to factory specifications. All auxiliary components, including seals and O-rings, are also replaced to minimize leakage and prevent future failures.

After reassembly, the pump undergoes comprehensive performance testing. Operating pressure, output flow, input torque, and noise levels are mea

Concrete machine hydraulic pump repair

The REXROTH A4VG concrete mixer boom hydraulic pump is an axial piston variable displacement type, capable of adjusting flow according to load requirements. Its nominal power reaches up to 75 kW, and flow rate ranges between 50 and 180 liters per minute. Maximum operating pressure is 350 bar, and oil temperature is controlled between 40 and 70 degrees Celsius under standard conditions. This pump supplies hydraulic force to lift cylinders and mixer rotation and requires precise monitoring of pressure, flow, and operating temperature.

The repair process includes complete disassembly of the pump body, inspection of the shaft and bearings, and checking pistons and gears. O-rings, seals, and gaskets are commonly replaced. Internal and external leakage tests, volumetric flow measurement, and output pressure verification are performed before and after repair. Adjusting the swashplate angle for accurate flow is essential. Using precision tools and hydraulic test equipment reduces repair errors to less than 2 percent.

Consumable parts include pistons, swashplate, shaft bearings, O-rings, and high-pressure washers. Repair costs depend on part condition and usually range between 25 and 40 percent of the new pump price. After reassembly, the pump is tested at standard pressures of 250�

Concrete pump accumulator

The accumulator used in concrete pumps is typically of the bladder type, designed to withstand working pressures between 250 and 350 bar. Its body is made of high-strength carbon steel with a tensile resistance above 950 MPa and is coated with anti-corrosion protection. The working volume is selected based on the pump’s capacity, usually ranging from 4 to 20 liters. The nitrogen pre-charge pressure is generally set between 90 and 120 bar to maintain hydraulic system efficiency.

The installation location of the accumulator in a concrete pump is on the main hydraulic line, close to the hydraulic pump, where it can absorb pressure surges and flow fluctuations. It is typically mounted near the control valve or directly on the hydraulic manifold, preferably in a vertical position. This installation ensures stable operation during sudden load changes and helps reduce wear on system components.

The capacity of the accumulator is determined by the hydraulic motor power and the pump’s output flow rate. For example, in concrete pumps with a delivery capacity of 60 to 80 cubic meters per hour, a 10-liter accumulator is commonly used. In larger models with outputs above 100 cubic meters per hour, 15- to 20-liter accumulators are applied. Proper capacity selection ensures sufficient

Prestressed Concrete Strand and Prestressing Wire

Prestressed concrete strand is a high tensile steel element used to apply prestressing force in concrete structures. It is typically composed of multiple steel wires with diameters of 5 to 7 mm helically wound around a central wire. The ultimate tensile strength of prestressing strands usually ranges from 1770 to 1960 MPa, with yield strength approximately 85 to 90 percent of the ultimate value. The strand surface may be smooth or low friction to ensure proper bond with concrete. These products are manufactured according to ASTM A416 and EN 10138 standards.

Prestressing wire is produced from high carbon steel and supplied as a single wire with diameters typically between 4 and 10 mm. Its tensile strength ranges from 1570 to 1860 MPa and features minimal plastic deformation to control creep and stress loss. Prestressing wires are widely used in precast elements, concrete pipes, slabs, and beams. Precise heat treatment, uniform metallurgical structure, and tight diameter tolerances enhance structural durability and reduce long term concrete cracking.