FAQs: Let’s Talk About Hydraulic Pumps

Pumps are the heart of hydraulic systems, which literally “pump” fluid to deliver the energy needed to power movement. This is an important action, and one that promotes a variety of questions.

Let’s begin by summarizing how hydraulic pumps operate.

Hydraulic pumps are responsible for converting mechanical energy into hydraulic energy. The resulting mechanical energy powers the motors in a hydraulic system.

Pumps provide this mechanical action by performing two functions:

1. Creating a vacuum at the pump inlet that allows pressure to force liquid from the reservoir into the inlet line
2. Delivering fluid to the pump outlet and into the hydraulic system

The system is dependent on this conversion of power for it to function.

End-users and distributors alike may have questions about how they function, when they don’t, or how to problem solve solutions to common issues.

Let’s walk through some frequently asked questions about hydraulic pumps and end by assuring you that when it comes to our line of hydraulic pumps, we supply top-notch service and quality at HPS.

Frequently Asked Questions About Hydraulic Pumps

Q: Which Type of Pump Should I Use?

A: Many hydraulic pump brands offer pumps that meet various specifications based on common features and types. In general, there are three major types of pumps in a hydraulic system:

1. Gear pumps are economical, reliable, durable, and easy to install. However, they become inefficient over time and tend to be noisy when operating.
   
   
2. Vane pumps are more efficient than gear pumps but less efficient than piston pumps. Advantages include many control options (such as pressure compensation, load sensing, and displacement controls) and less noisy. There are a few areas where a vane pump is not a suitable solution, such as when an application requires a high-viscosity fluid at high pressure.
   
   Image: Power & Motion
   
   
3. Piston pumps can handle high pressure, are efficient (95%), and have nearly infinite methods of control. The downsides are that they are more expensive to purchase and repair and require complex service, which is unfortunate considering the mechanical parts in a piston pump are also more prone to wear.
   

Q: What Happens When Pump Rotation is Reversed?

A: There are several potential outcomes depending on the pump and design. Here are the most common:

• Reduced flow
• Noise
• Seal failure
• Bearing failure
• Loose impeller, which can damage the pump

If internal gear pumps are run in reverse, they can be converted from one direction of rotation and flow to the other or run in two directions of rotation and flow.

Q: Where Is the Pump Located Within a Hydraulic System?

A: Pumps are located between the fuel reservoir and motor, and both are easy to spot on a schematic.

The pump-motor connection is important to note, as motors are the prime movers used to rotate hydraulic pumps.

Motors are easy to spot, represented by the letter “M” inside a circle (3). A curved arrow (like in the illustration) represents the direction of shaft rotation.

Hydraulic pumps (1) do not look much different than motors on the schematic, as they are represented by a circle with a black triangle that points to which direction flow will go in. If the triangle is clear, it indicates a pneumatic pump (or compressor).

Q: Why did my Vane Pump Stop Flowing?

A: Vane pump failures most often happen after an overload, a leak, or a specific event that is visibly evident or that some easy trouble-shooting can uncover. However, more than 80% of all failures in vane-type pumps can be traced back to a single cause: dirty hydraulic fluid.

Keeping fluid clean assures the user of a cost-effective approach to vane pump maintenance that allows the price of the filters to be quickly recovered by savings from improved performance and oil life.

For more on protecting vane pumps from contamination, visit Eaton’s Guide to Systemic Contamination Control.

Q: What is the Pressure on a Vickers Vane Pump?

A: Vickers VMQ pumps provide continuous pressure ratings up to 293 bar (4,250 psi) for the 25-frame size and displacements up to 488 cm3/r (29.78 in 3/r) with the triple pump version.?

HPS Values Quality Pumps

As already mentioned, pumps are pivotal instruments in producing hydraulic power. We strive to supply quality pumps and services to keep hydraulic motors running.

At HPS, every person we choose to involve in the process — from our suppliers to remanufacturers to distributors to the end users — has a passion for delivering quality and a desire to work with the best.

To do so, HPS maintains four unique standards that we absolutely will not waver on:

• Great Customer Service
• Best Quality Products
• Value Added Suppliers
• Immediate Availability

Our product lines—Vickers, Denison, the Rexroth A10VSO series, and Servo and Proportional valves—are top-notch, and these standards, along with the delivery of customer service and our core values, allow us to supply distributors with confidence.

Hydraulic Parts Source is a leading fluid power remanufacturer, and we’re ready to serve you. Contact us today to experience OE quality for a fraction of the time and cost by calling (866) 985-8401 or get a quote by emailing sales@hydparts.com.