How to Use a Hydraulic Oil Press: First Run, Daily Operation and Fixes

Most problems buyers have with a new hydraulic oil press are not machine faults. They come from the first hour of use: the pump started with too little hydraulic oil, the timer settings changed by hand, or the cake left in the barrel overnight. This guide follows the instruction manual we ship with every press and covers what to do after the machine is assembled: the first test run, the control panel, loading, pressing, unloading, routine oil changes and the faults you can fix yourself.

If the press is still in its crate, start with the installation and commissioning video (handle, hoses, three-phase wiring, rotation check). Come back here once the press head moves up and down smoothly.

Before the first run: hydraulic oil

The pump must never run dry. Fill the tank through the filler cap with a funnel before you switch on, and keep the level above the red line in the oil window at all times. Grade equivalents (ISO VG 46 AW, HM 46, HLP 46), amounts and the six-month change are covered in which hydraulic oil to use in an oil press.

Item	What to use
Oil grade	46# anti-wear hydraulic oil (bulk or drummed). Better oil means a longer cylinder life.
First fill	About 4½ drums of 16 L, roughly 75 kg. The exact amount depends on the cylinder model.
Never use	Soybean oil or any edible oil. It damages the pump and cylinder, and that repair is not covered.
Change interval	Every 6 months: change the hydraulic oil and the filter, and clean the tank.

First test run, step by step

• Power on with the valve in the middle. The control box display lights up. The reversing valve handle stays horizontal (the stop position) and the tank is full.
• Manual mode, valve down. Turn the start switch on, set the mode switch to Manual and push the reversing valve handle down until you hear it engage. The motor must turn clockwise; if it does not, have an electrician swap two supply phases.
• Watch the oil window. The pump draws oil from the tank into the cylinder, so the tank level falls while the piston moves. The level must not drop below the red line.
• Reverse just before the bottom. When the piston is close to its lowest point, move the handle up to Raise. The piston returns.
• Stop at the top and top up. At the top, put the handle back to horizontal and refill the tank. While raising, the pressure gauge should stay below 10 MPa. If it climbs higher or anything sounds wrong, switch off or return the handle to horizontal and call our technician.
• Switch to Auto. In Auto the hydraulic station runs for a moment, pauses, then runs again, and the run light on the display follows the motor. That on-off rhythm means the press is ready for production.

The control panel: Manual, Auto and the two timers

In Auto mode the motor does not run continuously. It tops the pressure up in short bursts while the press holds the load. Two pairs of buttons set that rhythm:

Setting	Buttons	Typical range	What it controls
Interval	Interval + / −	5–30 s	How long the motor rests between bursts
Run time	Run + / −	0.1–0.8 s	How long each burst lasts

Leave the timers alone unless our technician asks you to change them. Changing them yourself is a common reason for a drop in oil yield. The same goes for the high- and low-pressure relief valves: they are mechanical valves set at the factory and must not be adjusted.

Prepare the oilseed

A hydraulic press only presses. How the seed is prepared decides most of the yield. Hot-pressed seeds are roasted or steamed first; cold-pressed seeds are only crushed or pre-pressed. This is the preparation we quote for common materials:

Material	Pressing	Preparation before the press
Peanut	Hot	Pre-press machine + flat-bottom thermal-oil roaster
Sesame	Hot	Pre-press machine (after cleaning and roasting)
Sunflower seed	Hot	Pre-press machine + flat-bottom thermal-oil roaster
Rapeseed	Hot or cold	Hot: drum roaster + pre-press + steamer. Cold: pre-press only
Tea seed (camellia)	Hot	Drum roaster + high-speed crusher + electric steamer
Flaxseed	Hot or cold	Hot: flat-bottom roaster + grinding-mixing machine. Cold: high-speed crusher
Walnut, hazelnut	Cold	High-speed crusher
Almond	Cold	Pre-press machine
Desiccated coconut	Cold	Mixer

Load, press and hold

• Load in layers. Fill the barrel in layers with the carbon-steel separator plates between them. On the 390 mm barrel, pre-pressed material allows up to about 100 kg per load. Loose material fills the barrel with air and gives a smaller load.
• Press to the rated pressure only. The red needle on the gauge marks the factory limit. The system is rated at about 60 MPa, and some custom models are limited to 40 or 30 MPa. Never raise it: overpressure can crack the frame or the barrel.
• Hold long enough. About 30–40 minutes for hot pressing and around 2 hours for cold pressing. Cutting the hold short leaves oil in the cake.
• Check both gauges. One gauge sits on the pump and one on the cylinder. Their needles should match; if they drift apart, stop and check.
• Hands off under pressure. Do not service the machine, strike it or turn any bolt during pressing or holding. If a hose leaks, never try to block it by hand: switch off, release the pressure, then replace the hose.

Unload the cake straight away

When the material is pressed dry, take the cake out at once. If it sits in the barrel, it swells against the wall and becomes very hard to push out. On machines with a stroke scale, the top of the scale must not go below the limit switch when lowering the oil tray, or the cylinder can be damaged. Current models no longer have the scale.

Filter the oil while it is warm

Fresh pressed oil carries fine cake particles. Filter it at about 60–70°C; below 60°C the filtering rate roughly halves. See how to choose oil filtration equipment for which filter fits your sales channel.

Faults you can fix yourself

Symptom	Likely cause	What to do
Pump does not draw oil	Inlet strainer under the pump is clogged	Remove the strainer and clean it
Cylinder seeps oil	Seals worn or damaged, or the piston is scratched	Replace the seals; polish a scratched piston smooth, or have it serviced
Press head moves jerkily	Air in the hydraulic system	Run the piston to its full top and bottom positions to purge the air
Pressure builds slowly or not at all	Pump worn or low efficiency	Have the pump serviced or replaced
Valve does not respond	Valve fault	Have it repaired or replaced by a technician
Hose leaks	Damaged hose or fitting	Switch off, release pressure, replace the hose

If oil yield drops without any of these symptoms, work through the oil yield diagnostic checklist. For a parts-by-parts schedule, see the wear parts and maintenance schedule.

What comes in the crate

The complete machine, one set of separator plates, the instruction manual, a warranty card, a certificate of conformity and our product leaflet. Do not modify the machine or repaint it yourself; doing so voids the warranty.

Not sure about a setting? Send us a photo of the nameplate and the control panel, plus the oilseed you are pressing, and our technician will tell you the right timer values and hold time. Contact us.

Related Reads

• Which Hydraulic Oil Does an Oil Press Use? Grade, Amount and Change Interval
• Hydraulic Oil Press Installation Guide: Assembly, Wiring and Commissioning
• How Does a Hydraulic Oil Press Work?
• Hydraulic Oil Press Wear Parts & Maintenance Schedule
• Oil Yield Dropping? A Diagnostic Checklist

FAQ

What hydraulic oil does a hydraulic oil press use?

46# anti-wear hydraulic oil. The first fill is roughly 75 kg (about 4½ drums of 16 L), depending on the cylinder. Never use edible oil in the hydraulic system.

How often should the hydraulic oil be changed?

Every 6 months, together with the filter. Clean the tank at the same time.

What is the difference between Manual and Auto mode?

Manual is for the test run and positioning the press head with the reversing valve. Auto is for production: the motor runs in short bursts to hold pressure, controlled by the interval and run-time timers.

Can I raise the pressure to get more oil?

No. The red needle on the gauge is the factory limit, and the relief valves are set before shipping. Overpressure risks the frame and barrel. Yield comes from preparation, load and hold time, not extra pressure.

How long does one batch take?

About 30–40 minutes of hold for hot pressing and around 2 hours for cold pressing, plus loading and unloading.