Hydraulic Pump Guides: Choosing, Running and Troubleshooting Hydraulic Pumps

Guide 1: Choosing a Pump Type

Gear pumps are simple, tough and affordable. They suit mobile equipment, power packs and moderate pressures where a fixed flow is fine. Vane pumps run quieter and handle medium pressures well, which makes them popular on industrial machines and presses. Piston pumps cost more, but they handle the highest pressures and offer variable displacement, so flow can follow demand and save energy.

As a rough rule, choose gear for simple and rugged, vane for quiet and steady, and piston for high pressure or variable flow.

Guide 2: Matching a Replacement Pump

A replacement must match more than flow. Check these before ordering:

• Displacement, in cc per revolution.
• Maximum working pressure.
• Rotation direction, viewed from the shaft end.
• Flange type and shaft size, such as SAE or ISO.
• Port sizes and thread types.
• Control type on variable pumps, such as pressure compensated or load sensing.

The nameplate and part number usually give most of this. If the nameplate is gone, measurements of the shaft, flange and ports let us identify an equivalent.

Guide 3: Working Out Flow and Power

Flow depends on displacement and speed. A 20 cc pump turning at 1,450 rpm delivers about 29 litres per minute, before allowing for internal leakage. Power depends on flow and pressure. As a quick check, litres per minute multiplied by bar, then divided by 600, gives an approximate kilowatt figure before efficiency losses. At 150 bar, that pump needs about 7.3 kW of hydraulic power, so allow roughly 8.5 kW at the motor once losses are included.

Guide 4: Why Pumps Get Noisy or Hot

A noisy pump is usually telling you about its suction. A blocked strainer, a restricted suction line, cold thick oil or air leaks on the inlet side all starve the pump and cause cavitation or aeration. A hot pump often points to internal wear, a relief valve set too low, or a pump making flow the circuit doesn’t need. Check the simple things first: oil level, suction filter, inlet fittings and oil temperature.

Guide 5: Keeping Oil Clean

Most hydraulic pump failures start with dirty oil. Fine particles act like grinding paste on pistons, vanes and gears. Keep oil at or below the cleanliness code the pump maker states, change filters on condition rather than guesswork, and keep breathers and fill points sealed. Our standards & ISO guides explain how cleanliness codes work.

Guide 6: Repair or Replace?

Repair makes sense when the pump body and shaft are sound, parts are available, and the pump suits the duty. Replace when wear is severe, parts are obsolete, or the pump was the wrong choice in the first place. A replacement is also a chance to fit a more efficient variable pump if the machine spends long periods waiting.

Getting More Help

These guides cover the basics. For ongoing reviews of how your pumps are running, our lifecycle support service sets a baseline and tracks it. If a pump keeps failing, a failure review looks at the cause. For new installations, system commissioning makes sure the pump starts right.

Why Work With TSA Hydraulics Engineering

Our guides answer the questions customers most often ask. When you’re ready to buy, the same engineers can match a genuine or equivalent pump to your numbers, with practical engineering support, clear technical consultation.