what is a 2 stage hydraulic pump in stock

A two-stage hydraulic pump is two gear pumps that combine flow at low pressures and only use one pump at high pressures.  This allows for high flow rates at low pressures or high pressures at low flow rates.  As a result, total horsepower required is limited.

Pumps are rated at their maximum displacement.  This is the maximum amount of oil that is produced in a single rotation.  This is usually specified in cubic inches per revolution (cipr) or cubic centimeters per revolution (ccpr).  Flow is simply the pump displacement multiplied by the rotation speed (usually RPM) and then converted to gallons or liters.  For example, a 0.19 cipr pump will produce 1.48 gallons per minute (gpm) at 1800 rpm.

Simply put, gear pumps are positive displacement pumps and are the simplest type you can purchase. Positive displacement means that every time I rotate the shaft there is a fixed amount of oil coming out.  In the diagram shown here, oil comes in the bottom and is pressurized by the gears and then moves out the top.  The blue gear will spin clockwise. These pumps are small, inexpensive and will handle dirty oil well.  As a result, they are the most common pump type on the market.

I found that I was constantly waiting for the cylinder to stroke so that I could insert the next piece.  I was really good at determining how much stroke I would need so that wasn’t wasting time over stroking the cylinder.

A piston pump is a variable displacement pump and will produce full flow to no flow depending on a variety of conditions.  There is no direct link between shaft rotation and flow output.  In the diagram below, there are eight pistons (mini cylinders) arranged in a circle.  The movable end is attached to a swashplate which pushes and pulls the pistons in and out of the cylinder.  The pistons are all attached to the rotating shaft while the swashplate stays fixed.  Oil from the inlet flows into the cylinders as the swashplate is extending the pistons.  When the swashplate starts to push the pistons back in, this oil is expelled to the outlet.

So, we don’t actually turn one of the pumps off.  It is very difficult to mechanically disconnect the pump, but we do the next best thing.  So earlier in the article I mentioned that pumps move oil they don’t create pressure.  Keeping this in mind, we can simply recirculate the oil from the pressure side back to the tank side.  Simple.   So, let’s look at this as a schematic.

Luckily, turning off the pump is quite simple and only involves two components: a check valve and an unloader valve.  The check valve is there to keep the higher-pressure oil from the low flow pump separate from the oil in the high flow pump.  The higher-pressure oil from the low flow pump will shift the unloader valve by compressing the spring.  This allows flow from the high flow pump to return to the suction line of the pump.  Many pumps have this return line internal to the pump, so there is no additional plumbing needed.  At this point, the high flow pump uses little to no power to perform this action.  You will notice that the cylinder speed slows dramatically.  As the log splits apart, the pressure may drop causing the unloader valve to close again.  At this point, the flows will combine again.  This process may repeat several times during a single split.

The graph above shows the overlay of a performance curve of a piston pump and two stage gear pumps.  As you can see, the piston pump between 700 psi and 3000 psi will deliver the maximum HP that our engine can produce and as a result, it will have maximum speed.  Unfortunately, it will also have maximum cost.  If we are willing to sacrifice a little performance, the two-stage pump will work very well.  Most of our work is done under 500 psi where the two pumps have identical performance.  As pressure builds, the gear pump will be at a slight disadvantage, but with good performance.  The amount of time we spend in this region of the curve is very little and it would be hard to calculate the time wasted.

After the pump on my log splitter died, I replaced it with a two-stage pump.   While I was missing out on the full benefits of the piston pump, there was a tremendous increase in my output (logs/hr.).  I noticed that instead of me waiting on the cylinder to be in the right position, I was now the hold up.  I couldn’t get the logs in and positioned fast enough.  What a difference!

As you go from a standard two-stage pump to your own custom design, you will find that you will need to add the check valve and unloader separately.  However, there are many available cartridges manifold out there already that make this simple.  Some even have relief valves built in!

Two stage pumps are wonderful creations!  They allow for better utilization of pressure, flow and power by giving you two performance curve areas.  They also show their versatility in conserving power which leads to energy savings while remaining inexpensive.  A lot of these pumps come pre-made and preset, but you can make your own!  See if your next project can get a boost from one of these wonderful devices.

VEVOR is a leading brand that specializes in equipment and tools. Along with thousands of motivated employees, VEVOR is dedicated to providing our customers with tough equipment & tools at incredibly low prices. Today, VEVOR has occupied markets of more than 200 countries with 10 million plus global members.

VEVOR is a leading brand that specializes in equipment and tools. Along with thousands of motivated employees, VEVOR is dedicated to providing our customers with tough equipment & tools at incredibly low prices. Today, VEVOR has occupied markets of more than 200 countries with 10 million plus global members.

This is an excellent replacement pump for log splitters, hydraulic presses, snow plow power units and a variety of other agricultural power equipment. Mounting Positions: Horizontal & Vertical This two-stage gear pump provides faster cycle times with an over-all higher pressure rating, so you can squeeze every bit of power out of your equipment.

The motor is built to last, and the tank has been specifically designed to not crack & leak under harsh conditions. Its high-quality starter ensures long life and a fast-starting each time.

This log splitter hydraulic fluid constructed with high-quality oil suck pipes, which needed to be cleaned often, our pump work in a low-noise condition.

This hydraulic pump is equipped with other hydraulic tools that can carry out lifting, pressure type, elbow, bending row, straightening, cutting, assembly, demolition and many other works. Reduce labor intensity.

Used in applications where extending a hydraulic cylinder is needed, truck tailgate lift, RV leveling, scissor lift, dump trailer, lift truck, snow plow, aerial platform, road signs, material handling, wheelchair lifts, etc.

Hydraulic pumps come in a wide range of styles and designs, and Flowfit Hydraulic two stage hi-lo gear pumps are amongst the most efficient available. These models can give you much faster cycle times and provide a higher maximum pressure, whilst only utilising a small engine. Typically, two-stage hi-lo gear pumps are excellent for use on log-splitters and hydraulic press applications.

Running at 85% efficiency, our range of hydraulic pumps are amongst the most effective in compactly designed hydraulic components available in the UK. With various designs, all available with a range of GPM specifications, you will be able to find the ideal model for your systems requirements amongst our extensive range.

Hi/Lo 2 stage hydraulic gear pump. 12 GPM @ 3600 RPM, 2 GPM @ 400 PSI and 10 GPM @ 3000 PSI. 3600 RPM rated speed, SAE 4 bolt flange mount. 1" metal tube inlet port with 1/2" NPT outlet port. 1/2" keyed shaft. Right hand rotation (clockwise). Cast iron housing. The pump will automatically switch from low pressure (400 PSI) to high pressure when it reaches 900 PSI and then advance to 3000 PSI.

Ideal for log splitters, presses, and other machinery, this 11 GPM 2-stage pump requires 5 HP for operation. The gear displacement is 0.517 cubic inches for low pressure and 0.194 cubic inches for high pressure. Built with a 1/2 in. shaft, this two stage gear pump has a 1 in. tube inlet port and a 1/2 in. NPT outlet port.

Brand new 19GPM, 2 stage hydraulic replacement pump for log splitters. Fits many different applications, including newest models sold at Tractor Supply Co.

- The 2-stage pump can give you faster cycle times and higher possible pressure with a small engine. Excellent for use on log splitters. 85% efficient.

- This 2 stage pump can give you much faster cycle times and higher possible pressures with a small engine. Excellent for use on log splitters. 85% efficient.