Servo Hydraulic Pump Units: Less Energy, Less Heat, More Control

What "Servo Hydraulic" Means

In a traditional power unit, an electric motor runs at one fixed speed all day. Valves then throttle or dump the flow the machine does not need, and that wasted energy turns into heat.

A servo hydraulic setup flips that around. A servo motor, driven by a servo drive, changes the pump's speed in real time. A pressure sensor feeds back what the machine is doing, and the drive adjusts the speed to deliver exactly the flow and pressure required. When the machine waits, the motor slows to a crawl, just fast enough to cover internal leakage.

Why Machine Owners Make the Switch

• Lower power bills: savings of 30 to 60% are common on machines with long hold or idle times, and some duties save more.
• Cooler oil: less wasted energy means less heat, smaller coolers and longer oil life.
• Quieter floors: the motor is almost silent at low speed, so idle noise drops sharply.
• Better repeatability: closed loop control gives consistent pressure and speed every cycle.
• Smaller tanks: with less heat to remove, many systems need less oil.

Which Pumps Work Best With a Servo Motor?

Internal Gear Pumps

The most popular choice. Gap-compensated internal gear pumps handle stop-start running, low speeds and high pressure while staying quiet. They suit most injection moulding and press retrofits.

Axial Piston Pumps

Fixed or variable axial piston pumps suit higher pressures and larger flows. Pairing a variable pump with a servo motor gives two ways to save energy: lower speed and smaller displacement during the hold phase.

Vane Pumps

Some vane pumps also suit servo drives. Check the minimum speed first, as the vanes need enough speed to stay in contact with the ring.

The Parts of a Servo Hydraulic Unit

A complete unit usually includes:

• The pump, rated for variable speed and low speed running.
• A servo motor sized for the peak torque the pump needs at full pressure.
• A servo drive that controls speed, torque and pressure.
• A pressure sensor that feeds back the real system pressure.
• A bell housing and coupling to join motor and pump.
• Cooling and filtration sized for the new, lower heat load.

If you want a fully packaged answer rather than separate parts, our servo hydraulic systems range covers complete units.

Is Servo Hydraulic Right for Your Machine?

A servo upgrade usually pays off fastest when:

1. The machine spends long periods holding pressure or idling.
2. Oil runs hot and the cooler works hard.
3. Power bills for the machine are high.
4. Noise near the machine is a concern.
5. The existing pump or motor is due for replacement anyway.

On machines that run flat out at full flow all day, the savings are smaller. In that case, a well-sized fixed or variable pump may be the better buy.

How a Servo Retrofit Usually Runs

1. Assess: record pressures, cycle times and power use on the existing machine.
2. Select: choose the pump, servo motor and drive to match the duty.
3. Install: mount the new pump and motor, then wire the drive and pressure sensor.
4. Tune: set the pressure and speed control so the machine runs smoothly.
5. Verify: compare energy use and cycle times against the original figures.

Our energy efficiency and servo retrofits team can guide the first two steps. Once the hardware is in, our system commissioning support helps you start it up safely.

Specifications to Check

• Pump: displacement, maximum pressure, and the minimum and maximum speed for servo use.
• Motor: rated torque, peak torque, speed and encoder type.
• Drive: supply voltage, current rating and the control functions you need.
• Sensor: pressure range, and an output signal that suits the drive.
• Mounting: pump flange and shaft, motor frame and the right bell housing.

Getting the motor torque right matters most. An undersized motor cannot hold full pressure, while an oversized one adds cost for no gain.

Common Mistakes on Servo Upgrades

Most disappointing retrofits trace back to a handful of avoidable errors:

• Undersized motor: it cannot hold full pressure, so cycle times suffer.
• Wrong pump: a pump not rated for low speed wears quickly or loses pressure at the hold.
• Leaking valves: worn valves force the servo to keep spinning just to cover the leak, eating into the savings.
• Poor tuning: a rushed setup leaves the machine jerky or slow.

A short check of the existing valves and cylinders before the upgrade often protects most of the savings.

Where Servo Hydraulic Units Work

Servo hydraulic units now power injection moulding machines, presses and forming lines, die casting cells, test benches and press brakes. They also suit any hydraulic power unit that idles for long periods between cycles. In plastics plants, many owners convert one machine first, measure the savings, then roll the upgrade across the floor.

Servo Hydraulic or a Standard Pump?

If your machine needs simple, steady flow and runs at full output most of the time, a standard pump makes more sense. Gear pumps are the low cost option, while vane pumps give quiet running at medium pressure. For special duties outside these ranges, our specialty hydraulic pumps are worth a look.

Why Buy From TSA Hydraulics Engineering

As a servo hydraulic supplier, we provide pumps, motors and drives that are matched to work together, not just sold side by side. Our engineers check torque, speed range and pressure before quoting, and we tell you upfront whether each part is genuine or an equivalent. You get clear servo hydraulic pricing in AUD and help sourcing servo hydraulic replacement parts such as pressure sensors, couplings and seal kits.