A Deep Dive Into Hydraulic Pump Mounting Options

Selecting the correct hydraulic pump requires consideration of pressure ratings, flow rates, and displacement. Yet, an equally important factor that directly impacts the system's longevity and performance is the mounting method. The right mounting configuration stabilizes the pump, aligns it correctly with the power source, and prevents premature wear on its components.

Understanding the different hydraulic pump mounting options helps you choose one that enhances system reliability and efficiency. Here's a deep dive into hydraulic pump mounting options, detailing the most common configurations and their specific applications.

Foot Mounting

Foot mounting secures the hydraulic pump to a mounting surface using feet or brackets attached to the pump housing. This method provides a stable and rigid foundation, making it a common choice for industrial stationary applications. The pump sits on a flat base, and bolts pass through the feet to secure it.

Characteristics of Foot Mounting

• Stability: The broad base of support offers excellent stability, minimizing vibration during operation. This vibration reduction protects the pump's internal components and the connected couplings from excessive stress.
• Alignment: Proper alignment between the pump and motor shaft is manageable with foot mounts. Installers can use shims under the pump's feet to adjust its height and achieve precise shaft alignment. Misalignment is a primary cause of bearing and coupling failure, so this adjustability is a significant advantage.
• Accessibility: Foot-mounted pumps offer good access for maintenance. Technicians can inspect, service, or replace couplings, seals, and bearings without removing the pump from its base.

Foot mounts work well in factory environments, such as on hydraulic power units (HPUs) for presses, machine tools, and production lines. Their sturdy design ensures reliable support during continuous operations typical of these settings.

Flange Mounting

Flange mounting involves attaching the hydraulic pump directly to another component, like an electric motor, a gearbox, or a bell housing, using a flange. The flange is a flat, rimmed collar on the pump that aligns with a corresponding flange on the mating component. Bolts then secure the two flanges together. This creates a compact and integrated unit.

There are several standard flange types, often designated by SAE (Society of Automotive Engineers) codes, such as SAE A, B, C, D, or E. These standards define bolt patterns, pilot dimensions, and shaft specifications, enabling interchangeability among components from different manufacturers.

Sub-Types and Applications

• SAE 2-Bolt and 4-Bolt Flanges: These are the most prevalent standards. The number of bolts affects mounting security and torque capacity. A 4-bolt flange, for instance, typically supports larger, higher-torque pumps than a 2-bolt flange.
• Direct Drive: In many flange-mount setups, the pump shaft connects directly to the motor shaft via a flexible coupling. This arrangement eliminates the need for a separate baseplate and simplifies alignment, as the machined flanges dictate concentricity.

Flange mounting is standard in mobile machinery where space is limited. Construction equipment, agricultural vehicles, and commercial trucks frequently use flange-mounted pumps. The compact assembly saves space and protects the coupling from external contaminants.

C-Face Mounting

C-face mounting is a specific type of flange mounting used to connect a hydraulic pump directly to the face of an electric motor. The term "C-face" refers to a NEMA (National Electrical Manufacturers Association) standard for motor frame dimensions. The motor has a machined face with threaded holes for bolts, and the pump has a corresponding C-face adapter.

Advantages of C-Face Mounting

• Perfect Alignment: Because both the motor and the pump adhere to NEMA standards, the C-face mount ensures near-perfect shaft alignment. This precision reduces wear on bearings and couplings, extending the service life of both components.
• Compact Design: The direct connection creates a single, streamlined unit. This design is beneficial in applications where space is at a premium and a separate mounting bracket would be impractical.
• Ease of Assembly: Assembling a C-face-mounted pump and motor is straightforward. The pilot on the motor face fits into the recess on the pump adapter, aligning the shafts. After that, insert and tighten the bolts.

This mounting style is popular in industrial hydraulic power units and other stationary equipment where an electric motor serves as the prime mover.

Submerged (In-Tank) Mounting

For some applications, particularly with hydraulic power units, the pump is mounted inside the hydraulic reservoir and submerged in the fluid. This configuration offers several unique benefits related to pump performance and system design.

Benefits of Submerged Mounting

• Flooded Inlet: The pump inlet is always below the fluid level, which provides a constant, positive head of pressure. This "flooded inlet" condition prevents cavitation, a damaging phenomenon in which air bubbles form and collapse within the pump.
• Cooling and Lubrication: The surrounding hydraulic fluid helps to dissipate heat generated by the pump, contributing to stable operating temperatures. The fluid also provides continuous lubrication to the pump's external seals and surfaces.
• Noise Reduction: Submerging the pump dampens the noise it produces during operation. This can be a helpful benefit in environments where noise levels are a concern.
• Compact HPU Design: Placing the pump inside the tank saves considerable external space, allowing for a more compact and self-contained hydraulic power unit.

The main drawback is maintenance access. Servicing or replacing a submerged pump requires draining the reservoir and lifting the pump-motor assembly out of the tank, which can be a more involved process than with externally mounted pumps.

Piggyback Mounting

Piggyback mounting involves stacking two or more hydraulic pumps, with one driving the next. The primary pump is attached to the power source (such as a motor or engine PTO), and its shaft extends through its body to connect to the second pump's shaft. This configuration allows a single power source to drive multiple hydraulic circuits.

How Piggyback Mounting Works

• Tandem Pumps: This arrangement often uses specialized tandem pumps designed with a through-shaft. The rear pump mounts to the back of the front pump using a flange and a coupling.
• Multiple Circuits: Each pump can supply a separate hydraulic circuit, allowing for independent functions. For example, on a piece of mobile equipment, one pump could power the steering while a second pump powers the hydraulic lift.

This setup is highly efficient for mobile applications that require several independent hydraulic functions without adding multiple power take-offs. Waste collection vehicles, for example, often use piggyback pumps to operate the compactor, lifter arms, and other tasks from a single engine PTO.

Selecting the Correct Mounting Option

Having a deeper understanding of your hydraulic pump mounting options reveals how each method offers specific advantages for different systems. The operating environment, space limitations, and maintenance needs all influence the choice of mounting style. For a stationary industrial power unit with plenty of space, a foot-mounted pump provides stability and easy service access. In a compact mobile machine, a flange-mounted or C-face pump conserves space and maintains proper alignment. Choosing the right option helps create a more reliable and efficient hydraulic system.

For assistance with your specific application or to explore a comprehensive inventory, browse our selection of hydraulic pumps or contact our technical support team for expert guidance.