FAQ

Welcome to the FAQs page, where we give you the answers to your most frequently asked questions. Read on below for general maintenance, tips and recommendations.


Frequently Asked Questions

What Is the Difference Between a Pump and a Motor?

A pump converts rotational force on its shaft into pressurized oil to supply hydraulic components.
Example: Electric or gas motor turns pump shaft, pump supplies oil to a cylinder. Pumps generally have a large suction port and a smaller pressure port. A hydraulic motor converts pressurized oil to one of its ports into rotational force on its shaft.


Motors generally have equal size ports. Pumps & motors sometimes look alike. A major difference is the shaft seal. The low-pressure suction chamber of a pump provides an ideal place to drain pressure away from the inside of the seal. So most pumps have very low-pressure shaft seals. Hydraulic motors usually require higher pressure shaft seals.

How Do I Measure a Hose?

Measure the overall length of the hose, including fittings. Also, determine the type and size of fittings. The outer diameter is usually 1/4″ – 3/8″ larger than the nominal size.

How Do I Measure a Seal?

The inner diameter (I.D.), outer diameter (O.D.), and height are the most common ways to measure a seal. It’s best to take these measurements from the cavity where the seal is located and the shaft which goes through it.

What Oil Should I Use?

Use the oil recommended by the equipment manufacturer. Most systems use AW32 (light viscosity) or AW46 (medium viscosity) hydraulic oil. Hydraulic oil is not cheap when your system overheats and your pump is ruined.

Do I Have an Open or Closed Center System?

On an open center system, oil can flow through the valve when it is neutral. These systems normally use gear pumps or vane pumps. When the valve is neutral the system pressure is close to zero. On a closed center system, the oil flow will be blocked when the valve is neutral. These systems normally use piston pumps. When the valve is neutral there is pressure in the system.

What Pump Do I Need for My Application?

Pump selection depends on what flow & pressure will be required by the hydraulic system, i.e., how fast the cylinder or motor should run and how much force or torque it must develop. Then a pump can be selected which is capable of that flow & pressure. And then an engine or motor can be selected which is capable of driving that pump with sufficient power.


Selecting components for a hydraulic system can get complicated. We have a lot of experience replacing system components or building new ones. We’ll be happy to help you get the right one.