single stage vs two stage hydraulic pump factory

2-stage hydraulic pumps are used in motor-driven operations wherein a low-pressure, high rate inlet must be transferred to high pressure, low flow-rate outlet. Single-stage pumps are rated to a static max pressure level and have a limited recycle rate.

To achieve high pressure without a 2-stage unit, the drive engine would require significantly higher horsepower and torque capacity but still lack an effective cycle rate. Other hydraulic pump variants exist – such as piston pumps – but are expensive, making 2-stage units more feasible.

For example, a single gear hydraulic pump might be designed to generate a high-pressure output. Still, it will be unable to repeat a cycle rapidly due to a necessarily low flow rate at the intake. A 2-stage unit ensures consistent flow to increase cycle turnover.

Compactors utilize a similar 2-stage process. High-pressure flow drives the compacting rod, while the low-pressure flow retracts the mechanism and feeds the high-pressure chamber for repeated impacts.

2. Once the first-stage pressure meets a certain pressure threshold, a combiner check valve will open and feed into the second-stage, small-gear unit – joining flows at relatively low pressure.

A piston pump operates according to variable displacement. Flow is determined by the angle of an internal slant disk attached to the pump shaft. Pump adjustments – like torque or horsepower limiters – allow piston pumps to emit a max flow rate regardless of pressure level.

In most cases, hydraulic piston pumps are an order of magnitude more expensive than gear-based pumps. Potential downtime and part replacement in high volume work conditions exacerbate price disparities further.

Chiefly: fuel and power consumption. A piston pump operating in high-pressure ranges will regularly demand the full horsepower capabilities of its associated drive engine – increasing the power utilization of the system.

Opportunity cost may also be considered when using a piston pump. Depending on the application (e.g., log splitting), work output can be heavily impacted by the cycle speed of the pump. Not only is a piston pump more expensive to peruse, it is also slower than 2-stage pumps.

Panagon Systems has specialized in manufacturing industry-standard and custom hydraulic assemblies for 25 years. Reach out to our team for a consultation on your specific operational and equipment needs.

A single stage hydraulic pump is a pump that uses a single impeller to generate flow, while a double stage hydraulic pump uses two impellers in series to generate flow. This means that the double stage hydraulic pump has more pressure output than a single stage hydraulic pump of the same size, but it also means that it is typically larger and more expensive. Double stage hydraulic pumps are often used in high pressure applications where a high level of pressure is required to operate the hydraulic system.

A single stage hydraulic pump is typically used in applications where a moderate level of pressure is required, such as in a hydraulic system that is used to operate a lift or a small crane. These pumps are relatively simple in design and are often less expensive than double stage pumps.

Double stage hydraulic pumps, on the other hand, are typically used in applications where a high level of pressure is required, such as in a hydraulic system that is used to operate a large piece of heavy machinery or a hydraulic press. These pumps are more complex in design and are often more expensive than single stage pumps. The increased complexity and cost of double stage pumps is due to the fact that they have two impellers instead of one, which allows them to generate higher pressure.

The main advantage of a double stage hydraulic pump over a single stage pump is its ability to generate higher pressure. This makes it suitable for applications where a high level of pressure is needed to operate the hydraulic system. Additionally, double stage pumps are typically more efficient than single stage pumps, which means they can produce more flow with less input power. This can result in energy savings and can make the hydraulic system more efficient overall.

However, there are also some disadvantages to using a double stage hydraulic pump. As mentioned earlier, these pumps are typically more complex and more expensive than single stage pumps. They are also generally larger and heavier, which can make them more difficult to install and maintain. Additionally, the increased pressure output of a double stage pump can put more stress on the other components of the hydraulic system, which can lead to increased wear and tear and a shorter lifespan for the system overall.

It is difficult for me to provide a comparison of the performance data for single stage and double stage hydraulic pumps without more specific information about the pumps in question. The performance of a hydraulic pump can vary depending on a number of factors, such as the size and design of the pump, the type of fluid it is designed to work with, and the pressure and flow requirements of the hydraulic system it is used in. In general, however, a double stage hydraulic pump will have a higher pressure output than a single stage pump of the same size, but it will also typically have a lower flow rate. This means that a double stage pump is better suited for applications where high pressure is required, but a lower flow rate is acceptable.

Customers often ask, “when do I need a two-stage hand pump versus a single-stage hand pump?” Well, that depends on the type of work you are trying to do inside your hydraulic system. There is a measurable difference between the two of them and both have benefits depending on the application. To explain, let’s look at the new PowerX International line of hand pumps.

First up is the PowerX P43 single-stage 10,000 psi (700 bar) hand pump. The reason why it is called a “single-stage” pump is because the flow of oil produced is the same on each stroke of the handle. For the PowerX P43, the flow is a continuous 0.20 in3 of oil per stroke. The pumps flow rate remains constant, whether it is simply raising a single acting cylinder with no weight on it, or pushing 10 tons at 10,000 psi. A single-stage pump is great if your hydraulic ram does not have to travel far before it starts to lift or push the load. But if the ram needs to travel any significant distance to meet the load, there would be a lot of excessive pumping by the operator before they actually started to do any work. This would get tiresome very quickly!

Enter the PowerX P37 “two-stage” 10,000 psi (700 bar) hand pump. Two stage hydraulic hand pumps give the operator higher flow rates up until the cylinder or ram starts to do work. In the case of the PowerX P37 hand pump, the first stage has a flow of 0.79 inches3 of oil per stroke (almost 4 times more than the P43) before making contact with the work load where the pressure builds. Once the ram makes contact with the load, and the pressure inside the system raises above 200 psi, the second stage kicks in at 0.17 in3 of oil volume. This two-stage pump allows the operator to do less work (or hand pumping) before coming into contact with the load. Your operators will thank you!

Both the PowerX P43 and the PowerX P37 are built with rugged steel construction and both have internal pressure relief valves to protect against overload. To learn more about the PowerX line of 10,000 psi (700 bar) hand pumps, click here.

One important aspect of designing your new pumper is deciding what type and capacity pump you want to install. One of the concerns you should have is the water supply availability in your response area. Do you have a response district that has an abundant amount of fire hydrants? Or is your area mostly rural where you might have to rely on tanker operations. A 2,000 gpm pump for a rural operation might not be the best solution.

The difference between the two is really simple. A single-stage pump has one dual suction impeller located on both sides of the vehicle, providing volume to all discharges on the vehicle. A two-stage pump has two suction impellers operating side by side. The operator must decide if he wants volume or more pressure by selecting a switch on the pump panel.

The decision to use single-stage pumps is common in 75 percent of the current apparatus purchases. If you feel that you need more than the 350 psi provided in a single-stage pump, then maybe the two-stage is right for you.

Training is also a factor in using a two-stage pump. The pump operator must be comfortable with a transfer valve and decide when to use volume versus pressure.

If you’re looking for information on what is a two stage hydraulic pump, you’ve come to the right place. A two-stage hydraulic pump is a positive displacement pump that uses two pistons to move fluid through a chamber. The first piston, called the “suction” piston, draws fluid into the chamber from the inlet port. The second piston, called the “discharge” piston, pushes fluid out of the chamber through the outlet port.

The suction piston is the first piston in a two-stage hydraulic pump. It is responsible for drawing fluid into the chamber from the inlet port. The suction piston typically has a larger diameter than the discharge piston and may also have a different number of slots or windows cut into it.

The discharge piston is the second piston in atwo-stage hydraulic pump. It is responsible for pushing fluid out of the chamber through the outlet port. The discharge piston typically has a smaller diameter than the suction piston and may also have a different number of slots or windows cut into it.

Two-stage hydraulic pumps are often used when high pressure is required, such as in construction equipment or heavy machinery. They are also sometimes used in automotive applications, such as power steering or brakes. Depending on the application, two-stage hydraulic pumps can either air or water-cooled.

Two-stage hydraulic pumps offer some benefits over other types of positive displacement pumps. They can generate higher pressures than single-stage pumps, making them ideal for use in applications where high pressure is required. Two-stage hydraulic pumps are also more efficient than single-stage pumps, which can move more fluid per cycle while using less energy.

Additionally, two-stage hydraulic pumps are less likely to cavitate than single-stage pumps, making them less likely to damage the pump or cause disruptions in fluid flow.

A two-stage hydraulic pump is a device that uses two pistons to move fluid through a cylinder. The first piston, the low-pressure stage, draws the fluid from the reservoir and moves it into the second stage. The second piston, called the high-pressure stage, forces the fluid through the outlet port at high pressure.

Two-stage hydraulic pumps are used in various applications requiring high volume and pressure. For example, they are commonly used in construction equipment, agricultural machinery, and manufacturing machinery.

Gear pumps and vane pumps. Gear pumps are the most common type of two-stage hydraulic pump. They use gears to move fluid through the pump and are typically used in applications where high pressures are required. Vane pumps use vanes to move fluid through the pump and are typically used in applications with high volumes.

Gear pumps typically have a pressure rating of 3000 psi or more. They are also very efficient, with some models achieving efficiencies as high as 99%.

Always check the pressure relief valve to make sure it is functioning correctly. The pressure relief valve protects the pump from damage if the pressure gets too high.

If the pump is not working correctly, check the inlet and outlet ports to ensure they are clear. Sometimes debris can build up in these ports and block fluid flow.

One-stage hydraulic pumps are less efficient than 2 stage hydraulic pumps. Additionally, 1-stage hydraulic pumps are more likely to cavitate than 2-stage hydraulic pumps, making them less reliable. 2-stage hydraulic pumps are more expensive than 1-stage ones, but they offer superior performance and reliability.

One-stage hydraulic pumps are less efficient than 2 stage hydraulic pumps. This is because they have to pump the fluid twice to reach the high pressure required for most applications.

2 stage hydraulic pumps are more expensive than 1 stage hydraulic pumps. Still, they offer superior performance and reliability. 2 stage hydraulic pumps are more efficient than 1 stage hydraulic pumps because they only have to pump the fluid once. Additionally, 2-stage hydraulic pumps are less likely to cavitate than 1-stage hydraulic pumps, making them more reliable.

Gear pumps and vane pumps. Gear pumps are the most common type of two-stage hydraulic pump. They use gears to move fluid through the pump and are typically used in applications where high pressures are required. Vane pumps use vanes to move fluid through the pump and are typically used in applications with high volumes.

Always check the oil level in the pump before starting it. The pump will not work correctly if the oil level is too low. Always check the pressure relief valve to make sure it is functioning correctly. The pressure relief valve protects the pump from damage if the pressure gets too high. If the pump is not working correctly, check the inlet and outlet ports to ensure they are clear. Sometimes debris can build up in these ports and block fluid flow. If the pump is still not working correctly, check the piston seals. These seals can wear out over time and need to be replaced. Always consult the owner’s manual for your specific model of the two-stage hydraulic pump before performing any maintenance or repairs. By following these tips, you can help ensure that your two-stage hydraulic pump will work correctly and last many years. We hope this guide has helped teach you what is a two-stage hydraulic pump.

It has a large single stage Hydreco pump est 20 gpm and a 7hp Kohler. I bought a worn out 2000 series Cub Cadet tractor and yanked the single cylinder Kohler Command 16 hp engine out along with the fuel system, harness and choke/throttle cables. It may be only 13 useable hp according to the dealership I got it from but says 16hp all over it. The motor does not mate to the old pump arrangement and coupling and we need to cut it off and reweld it.

I just came across a 16gpm 2 stage Speeco hydraulic pump for cheap (have not purchased yet). I should be able to go to the farm store, buy a pump bracket and bolt this pump on no problem. Keeping the Hydreco pump will be more work for dad to reweld.

I have an idea to two stage the cylinders to make cycle times faster. Prince hydraulics sells an RD-1000 sequence valve. That, a line check valve, a few extra hoses, and I have one cylinder that receives all the flow and the other has both ends open to tank, and then under load both cylinders receive flow to the head end. It will work much like a 2 stage pump. So combine that with a 2 stage pump and you have 3 potential stages.

What I"m afraid of: I"ll be forced to go 3 stage if I move to the Speeco pump to get good cycle times as the old single stage Hydreco pump which likely flows more. If I just use the old pump and do the 2 stage cylinders, it will cost less. But in general, this year we just need to split some wood. Not having to spend a weekend changing and aligning and welding a pump bracket and chain coupling seems to be worth the price.

The Hydreco pump does not use a standard size pump bracket, it"s somewhere between SAE A and SAE B mounting pattern with a deep pilot bore and long shaft that will force me to space it out with an adapter from any standard pump bracket. Also I have no idea what the Hydreco pump actually flows, never got around to emailing the company. I think it could work just fine if we reweld the bracket.

The size of the section of pump that goes to high pressure is defined by the engine hp. One stage or two stage it does NOT matter! The small section is defined by the engine hp.

A two stage pump simply adds another section in the same body. When less than maximum psi is needed, the larger gearset adds into the flow. You get way more flow to use the entire engine hp.

BTW, I published in an earlier thread topic here I think, but a two stage pump runs the small one always to the outlet. The larger section either adds to the flow from the small one (say 3 + 8 = 11 gpm out) or it unloads back to the inlet at almost no pressure. Then the outlet is just the small one (3 gpm for instance). The pump does not vary its displacement in any way, just loads and unloads the larger section.

Sure, a single stage pump is constant speed, but the two stage is not "slowing down" from that speed. The single stage pump STAYS on SLOW speed always, as the max size that the engine can pull. The two stage runs at the same speed in low, or speeds up when pressures are low.

Or I could put on a single stage pump and run 7 gpm all day, and use under 10 hp most of the time. SLOW! Or I could put on a 28 gpm single stage pump and a 45 hp engine to turn it….

The only place I would ever consider using a single stage pump is if there was a free, big engine already there running say a processor or elevator, or farm tractor PTO pump package. Then you have more than enough power, so no reason to use a two stage.

Consideration must be given to the pump rated capacity, number of pump stages required, how the pump is to be driven, pump location, the need for pump-and-roll capability, special pump performance requirements, the need for special materials for pump construction (based on local water conditions), the type of pressure control system, the size and location of intake connections and discharge outlets – and the list goes on. These are all important considerations, and each one must be carefully studied to ensure that the apparatus will function as intended.

One of the most important considerations is the number of pump stages required.  Many people struggle with this decision. There seems to be a lack of understanding of the options available and the advantages of each. We will deal with the differences between single- and two-stage pumps. Three- and four-stage pumps are also readily available, but generally are only specified when very high discharge pressures are required.

It should be noted that the National Fire Protection Association 1901 Standard for Automotive Fire Apparatus makes no distinction between a single-stage and a two-stage pump. Both must pass the same performance tests listed in the standard. So in essence, either pump will do the same thing. The difference is that they are not designed to do the same thing.

One pump will operate more efficiently than the other at certain operating conditions. The reasons for this are beyond the scope of this discussion, but the actual differences are worth exploring.

Single-stage pumps are designed to flow large volumes of water.  If you have an apparatus that frequently flows at or near the rated capacity of the pump, then a single-stage pump will probably be the best choice. It will flow rated capacity more efficiently (with less engine speed) than a two-stage pump (even though both pumps may have the same 1,500-gpm rated capacity).

Single-stage pumps work best when pumping at or near their rated capacity, but most fire departments pumpers don’t operate at or near their rated capacity all the time. In fact, most commonly pumps are used at only a fraction of their rated capacity. Look at the apparatus in your fleet. When was the last time a pump flowed rated capacity at a fire call? For many departments (including the big ones) most fires are extinguished with one handline flowing about 100 gpm.

Two-stage series/parallel pumps are really ‘two pumps in one.” When operated in the volume (parallel) position, they mimic the design of the single-stage pump. In the pressure (series) position, they will flow up to 70 percent of their rated capacity more efficiently (with less engine speed) than a single-stage pump.

The chart on the facing page shows the pump speeds and horsepower required to obtain various common fireground flows using a 1,500-gpm pump.  The actual numbers may vary between pump manufacturers, but the comparisons will be similar.

So the two-stage pump is more efficient at most flow rates, but what does that really mean to me? The short answer is it means a lot. If you are using a single-stage pump to flow less than rated capacity, you will need to spin it faster than a two-stage pump. This results in additional fuel consumption for the engine. A typical diesel engine consumes about 20 gallons of fuel per hour when run at governed speed. This may not sound like much, but over the life of the apparatus – and with today’s fuel prices – the dollars can add up quickly.

Also, running the engine faster than necessary results in additional wear-and-tear on the engine, chassis transmission and driveline components. This is not a huge consideration for most departments since today’s engines, transmissions and drivelines used in fire apparatus are basically the same design that are used in over-the-road trucks, which run hundreds of thousands of miles before needing to be overhauled. But there is still no getting around the fact that using a two-stage pump will decrease the amount of wear-and-tear on these components.

By far the biggest advantage to using two-stage pumps is they will last longer. As stated above, if you are using a single-stage pump to flow less than rated capacity, you will need to spin it faster than a two-stage pump. This will cause the pump to wear out faster. For busy departments this could result in an unexpected premature budget-busting pump overhaul job.

More importantly, the faster you run a diesel engine, the more horsepower it will develop. The pump, however, will only require a fraction of the horsepower being sent to it from the engine. The excess horsepower will be converted into heat energy. This will cause the water in the fire pump to heat up. If the water gets too hot, a catastrophic pump failure is imminent.

Finally, while single-stage pumps are designed to flow large volumes of water, they are not designed to produce high pressures. In fact, to develop 125 gpm at 200 psi (a typical 300-foot 1-1/2-inch attack line), a single-stage pump will need to spin faster than it would to pump 1,500 gpm at 150 psi. At this speed, the impeller wants to flow in excess of 1,500 gpm. But the nozzle at the end of the hose is limiting the flow through the impeller to 125 gpm. This results in an extreme amount of turbulence inside the pump, as the water leaving the impeller has no place to go. This phenomenon results in what is known as “recirculation cavitation,” which can quickly destroy a centrifugal pump.

Using a two-stage pump to develop the same 125 gpm at 200 psi requires about 25 percent less speed, which greatly reduces the amount of recirculation cavitation inside the pump.

There is no question that a single-stage pump is simpler to operate than a two-stage pump because the operator of the latter must decide whether to place the pump in volume or pressure. No such decision is necessary with a single-stage pump.

If more flow or pressure is required when operating a single-stage pump, the operator only needs to increase the engine speed to attain it. However, that is the only thing the operator can do. With a two-stage pump the operator has the ability to transfer the pump from pressure to volume (or vice versa) to obtain the desired output without necessarily changing the engine speed.

In actuality, this decision needs to be made rarely because the two-stage pump can deliver up to 70 percent of its rated capacity in the pressure mode. This means that the operator can leave the pump in the pressure mode for the vast majority of working fires. On the rare occasion when more than 70 percent of rated capacity is required to extinguish the blaze, the operator will quickly observe that not enough water is being pumped at full engine throttle and realize the need to transfer the pump to the volume mode.

Two-stage pumps are slightly more expensive than single-stage pumps, but the cost differential is not a significant amount when compared to the overall cost of the complete apparatus over its useful life. And, as noted above, the additional initial cost will be offset by fuel savings over the life of the apparatus.

• Pumper performance is better with a two-stage pump over almost the entire operational range, and particularly at capacities less than 70 percent of rated capacity and at pressures greater than 150 psi.

Steve Morelan, who has 32 years of fire service experience, is the assistant fire chief of the Little Canada (Minn.) Fire Department and global service manager at Waterous Company. He has instructed hundreds of pump operation, maintenance and overhaul classes worldwide. He is also a Minnesota state certified apparatus operator.

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At D & D Compressors, Inc., we specialize in offering high-quality air compressors and vacuum pumps to our valued industry members throughout San Jose, CA. We have years of experience in the sale, rental, and service of air compressors and vacuum pumps of all makes and models, and can quickly help you find any replacement parts or supplies you need. We also provide reliable, professional routine maintenance services to prolong the life of your equipment. We pride ourselves on offering exceptional customer service and being a one-stop shop for industry members who need high-quality equipment that will last a long time. Our staff has more than 30 years of experience in the industry.

This 2-Stage pump fits a wide variety of log splitters and outdoor power equipment and works in both horizontal and vertical orientations. The inlet (suction) port is 1" NPT and the minimum suction hose inner diameter (ID) is 1-1/4". The inlet barbed fitting is not included but is available separately. Use a 1-1/4 ID Suction Hose and 3/4" ID high-pressure hose.

Be sure to use AW-32 10-Weight (ISO 32) or AW-46 20-Weight (ISO 46) light hydraulic fluid. This pump is not designed for use with “universal” or "tractor" transmission oil, such as "303". The use of incorrect fluid may damage the pump and void the warranty.

Make sure the hydraulic fluid reservoir is not below the pump to ensure a sufficient flow of fluid to the pump. The hydraulic fluid reservoir should have a capacity of at least 12 gallons to allow sufficient cooling. Suction-side filtration should be no finer than 150 microns. The use of a 10-25 micron filter on the suction side of the pump is too restrictive and will cause failure.

We recommend using an L-style jaw coupling to connect the pump to an engine. Couplings and mounting brackets are available. You should use at least a 15hp engine to maintain 3,600 RPM under load.

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.

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.

This product is a Hi-Lo cast iron hydraulic gear pump with max pressures of 900 PSI for the low pressure and 3000 PSI for the high pressure pump. Typical applications are log splitters and presses, where alternating low and high pressures are required to move a cylinder.