Hydraulic Gear Pump

In a hydraulic fluid power system, power is transmitted and controlled through a liquid under pressure within an enclosed circuit (ISO 4406, introduction). The gear pump enters that circuit as a positive displacement pump: theoretical flow is proportional to speed, and pressure results from what the circuit imposes. A hydraulic power unit combines a pump, drive, reservoir and other components specified by its design, and external gears do not make two pumps equivalent. The 2026 FBE catalogue (p.3) lists the series in hydraulic machines and equipment, filter presses, lubrication systems and oil burners, with discharge pressure up to 22 kgf/cm², subject to configuration. This limit does not support presenting the FBE as a high-pressure press pump. In an oil circuit, assess the specific function, whether transfer, circulation, lubrication or another duty, and the model limits.

• Function: circulation, transfer, lubrication or hydraulic power.
• Pressure: differential value and project transients.
• Flow: demand at each operating condition.
• Oil: composition and viscosity at startup and in operation.
• Interfaces: shaft, mounting, connections and rotation direction.
• Limits: confirm the execution before proposing replacement.

The 2026 FBE catalogue (p.3) publishes, for the series, discharge pressure up to 22 kgf/cm², a maximum speed of 1,750 rpm and viscosity from 30 to 100,000 SSU. These are series maximums: they do not apply together or to every model. The selection table (p.6), built for viscosity below 1,000 SSU, shows each model's limit. In it, the 22 kgf/cm² column only has values for models from 1/8″ to 1″ DA at 1,150 rpm; at 1,750 rpm the table goes up to 16 kgf/cm², and models from 1.1/2″ upward stop at 14 kgf/cm² or less. For a circuit with pressure peaks, state the value and duration, and the proposal checks the model in the applicable column. In construction, the shafts turn in bushings of self-lubricating bronze, cast iron, PTFE, graphite or babbitt metal, and sealing is by packing, mechanical seal or lip seal (p.3). Models from 1/8″ to 1″ have a BSP threaded body, and those from 1.1/2″ to 10″ have ANSI B16.5 150 lbs flanges (p.6). Accessories include the internal relief valve, in brass or AISI 304 stainless steel, and the external bearing housing (p.3).

Define the flow and differential pressure required by the circuit, including transient conditions provided by the designer. Add the oil, viscosity at startup and in operation, available speed and suction feed conditions. On the FBE, speed follows viscosity at pumping temperature, per the table in the 2026 FBE catalogue (p.5): 1,750 rpm from 30 to 250 SSU, 1,150 rpm from 250 to 2,500 SSU and 850 rpm from 2,500 to 7,500 SSU, with direct drive and the models listed in each row. The ISO VG grade applies only at 40 °C (ASTM D2422): an ISO VG 68 oil has about 68 cSt at 40 °C, or 315 SSU by the catalogue conversion (SSU ≈ cSt × 4.635 above 300 SSU), and falls in the 1,150 rpm row. At cold start, viscosity rises and the row may change. With flow Q in m³/h and pressure Δp in kgf/cm², shaft power is P (cv) = Q × Δp ÷ (27 × η), where cv is metric horsepower. The catalogue efficiency table η (p.5) starts at 1,000 SSU. Below that, use the selection table (p.6), built for viscosity below 1,000 SSU: it gives flow in l/min and pump shaft power, in cv, by model, speed and discharge pressure. To choose the commercial motor, add the catalogue power margin (p.5): 50% up to 2 cv, 30% from 3 to 5 cv, 25% from 6 to 10 cv, 15% from 11 to 25 cv and 10% above 25 cv.

DIN 51524 sets minimum requirements for hydraulic oils in three parts: HL in part 1, HLP in part 2 and HVLP in part 3. According to the abstracts published by DIN Media, part 1 applies to hydrostatic systems in which thermal stress would unduly shorten the life of an oil without additives and in which corrosion is expected, for example from water ingress. Parts 2 and 3 add oils with anti-wear additives for mixed friction, required in pumps or hydraulic motors by design or operating conditions. The ISO VG grade classifies the oil by kinematic viscosity at 40 °C, in cSt, from ISO VG 2 to ISO VG 3200, and says nothing about other temperatures (ASTM D2422). State in the enquiry the type and grade declared on the oil data sheet, with viscosity at startup and in operation. Composition and additives affect material and elastomer compatibility: on the FBE, the standard mechanical seal is type 21, in ceramic × graphite × viton (MTEC-01/01, item 2.5), with packing and lip seal options. Before changing oil or sealing, consult equipment and fluid-supplier specifications; ambient temperature alone does not define the grade or the elastomer.

The ISO 4406 code describes the quantity of solid particles in the fluid of a hydraulic system with three numbers separated by slashes: particles equal to or larger than 4 µm(c), 6 µm(c) and 14 µm(c) per millilitre, counted by an automatic particle counter. Going up one number generally represents a doubling of contamination. In the standard's own example, code 22/18/13 means more than 20,000 and up to 40,000 particles of 4 µm(c) or larger, more than 1,300 and up to 2,500 of 6 µm(c) or larger and more than 40 and up to 80 of 14 µm(c) or larger in 1 mL. The ISO 4406 introduction notes that most hydraulic component manufacturers require a cleanliness level for warranty purposes. The target class therefore comes from the most demanding component in the circuit, not from the pump. This guide does not publish one class for all FBE pumps, and the MTEC-01/01 manual asks for FB to be consulted when the fluid carries suspended solids (item 2.3). Describe the actual oil condition, including known water and particles. Place filters with pressure loss in mind, at suction too, because viscosity increases the pressure required at the pump inlet (Hydraulic Institute), especially at cold start.

FB manufactures the FBE in Cabreúva-SP, and the company has operated since 1944. Supply can be the bare pump or the motor-pump set, with direct drive on an electric motor or on a gear motor, both on a metal base with a flexible coupling (2026 FBE catalogue, p.3 and p.4). Catalogue accessories include a heating chamber, internal relief valve and external bearing housing, and the spare-parts list covers shafts, gears, bushings, covers, packing gland, lip seal, mechanical seal and relief valve. Some FBE models are held in stock, and availability is given in the quotation. Assessment starts with the pump's function in the circuit. To replace an existing unit, send the nameplate, code, hydraulic diagram and duty point, together with dimensions and mechanical interfaces. The proposal must confirm that FBE limits cover the service. Where pressure or another condition exceeds the documented scope, no high-pressure adaptation is promised without its own design and specification. Tests and documents are confirmed for the supply.