The hydraulic pump is the heart of every machine. It is responsible for pumping life-giving oil to hydraulic cylinders and motors. When an old pump in a tractor or excavator breaks down, many mechanics face a dilemma: should they buy the same one, or perhaps invest in a "more powerful" one?
Choosing a pump is not just about the price. Using the wrong technology or oversizing parameters can lead to system jamming, oil overheating, and even immediate engine shutdown.
BRhydraulic experts have taken a closer look at the two most popular types of pumps. Find out what you're dealing with and how to avoid the most expensive mistake when buying!
1. Gear pump – A reliable workhorse (For agriculture and simple machines)
This is the most common type of pump on the market. If you open the hood of most agricultural tractors, log splitters, or forklifts, 90% of the time you'll find a gear pump there (with an aluminum or cast iron casing).
-
How it works? Inside the housing, two meshed gears rotate. Oil enters between the teeth and the housing and is mechanically pushed to the pressure side.
-
Advantages: They are inexpensive to buy, simple in design, and relatively resistant to minor contaminants in the oil (they are more forgiving than other pumps).
-
Disadvantages: They have a fixed displacement (they always pump the same amount of oil per revolution) and typically operate up to pressures of 200-250 bar. Above these values, they wear out quickly and become very noisy.
2. Piston pump – Elite power and precision (For construction and forestry)
When a machine needs to lift huge weights and space is limited, piston pumps (angled or axial) come into play. This is premium equipment.
-
How it works? Instead of gears, small pistons work inside a rotating barrel (similar to an internal combustion engine), sucking in and pushing out oil under enormous pressure.
-
Advantages: They generate monstrous pressures (even 350-400 bar and more!). They are extremely efficient and can have variable displacement (Load Sensing systems) – meaning they only pump oil when you move the lever, which incredibly saves fuel in excavators or harvesters.
-
Disadvantages: They are very expensive to buy and service. Additionally, they are terribly sensitive to dirt – one scratch from a grain of sand and the pump loses pressure. They require perfect filtration (remember our article on pressure filters?).
3. The biggest myth: "I'll buy a pump with a higher flow rate, the machine will be stronger!"
This is the most common mistake when upgrading machines (e.g., homemade log splitters). A mechanic has a 20 l/min pump and buys a 40 l/min pump, expecting greater crushing force. What happens after starting? The engine stalls or chokes when trying to apply pressure. Why?
You must remember one golden engineering rule:
-
Pump flow (liters per minute) = MACHINE SPEED. The more liters, the faster the cylinder will extend.
-
Pressure (bar) = MACHINE FORCE. The greater the pressure the system can generate, the more weight you can lift.
Doubling the pump's capacity (liters) will make the cylinder operate twice as fast, but it will require twice as much power (horsepower) from the engine to maintain the same pressure! Before buying a "bigger" pump, make sure your electric or internal combustion engine can even handle it.
Summary
Pump selection is mathematics, not guesswork. For a front loader, dump truck, or simple press, a solid, cast-iron gear pump will suffice. If you are building an advanced forestry machine, a piston pump is indispensable. At the BRhydraulic store, our advisors will help you calculate your power requirements so you don't have to buy equipment twice.
