PM checklist
Hydraulic press: a preventive maintenance checklist
A hydraulic press usually warns you before it stops. Oil level drops, a hose weeps, the oil temperature climbs, or a guard switch is tied up with wire. This checklist is a starting point for those signs. Confirm every interval in the press manual and in your own burst-hose history. The method is in the preventive maintenance guide.
Key takeaways
- Shift checks are oil level, oil temperature, leaks at hoses and fittings, and guards that still stop the press.
- A weeping hose is a job today. A burst hose is a stop, a slip hazard and a fire risk.
- Filter changes and oil samples follow hours or a calendar cap, whichever comes first.
- Never defeat a light curtain, two-hand control or interlocked guard to "finish the batch".
- Isolate and lock the press, and release stored pressure, before anyone opens a line.
Every shift
This is a walk around the press before production, not a service. It should fit in a few minutes.
| Check | What to record | Act when |
|---|---|---|
| Oil level | Against the sight marks, cold or as the manual says | Below the low mark |
| Oil temperature after the press is working | The number | Climbing week to week, or near the OEM limit |
| Hoses, fittings and the ram | Dry, weeping, or dripping, and where | Any weep. Do not wait for a drip on the floor |
| Unusual knock, fade or slow approach | A note if the motion changed | A new sound, or a speed the operator says is wrong |
| Guards, light curtains and two-hand controls | Tested, or failed | A bypass, a tied switch, or a test that does not stop the stroke |
| Floor around the press | Clean, or oil on the walking surface | Any oil. Clean it and find the leak in the same shift |
Testing a safety device means using the test the manufacturer specifies, not leaning into the press. If the test fails, the press does not run.
Planned service
These need a locked-out press and someone who can bleed pressure safely.
| Job | Usual trigger | What "done" looks like |
|---|---|---|
| Replace the return-line and pressure filters | OEM hours, or six months, whichever comes first | Hours, part numbers, and whether the old element was collapsed or full of metal |
| Take an oil sample | With the filter change, or on your oil plan | Lab result on the job: water, viscosity, particle count |
| Inspect hoses for rubs, age cracks and the date code | Quarterly | Hoses replaced, and the ones still in date |
| Check accumulator pre-charge, if fitted | OEM interval, by a trained person | Pressure found and pressure left, against the spec |
| Inspect ram seals and the gland | When the shift check finds a weep, and on the planned stop | Seal replaced or monitored, with a photo |
| Function-test the emergency stop and guards | Each planned stop, and after any repair | Pass or fail, and who tested |
A worked example from a typical plant
Worked example (illustrative)
A sheet-metal plant has a 250-tonne press on two shifts. A hose bursts beside the operator station on a Tuesday. Nobody is hurt because the operator has stepped away. The hose was rubbing a bracket, and the weekly check said "OK" with no location and no photo.
The planner splits the work. Operators record oil level, temperature and "dry, weep or drip" at each hose zone, with a photo if it is not dry. A technician changes filters and samples the oil at 1,000 hours or six months, whichever comes first, and walks the hoses for rubs with the press locked out. The story is illustrative. A similar near miss is used in the incident investigation guide.
The useful record is the weep, the zone and the photo, a week before the burst. "OK" would have missed it again.
Common mistakes
- Waiting for oil on the floor. A weep at a fitting is the maintenance job.
- Tying a guard switch because the press "nuisance trips". That is how people lose hands. Stop and fix the switch.
- Changing oil on a date while the press runs three shifts. Hours come first.
- Opening a coupling on a press that is stopped but still pressurised. Release stored energy and lock it out.
- One checklist for every press on site. Tonnage, cushions and light curtains differ. Start from this list, then match the manual.
How to put this list to work
Agree the shift inspection with production so it happens before the first stroke, not "when there is time". Put the filter change on hours. Review hose weeps in the morning meeting for a month. If the word OK is still being written, the checklist is too vague and the next burst will look like a surprise. Name one person who owns the press PM. A checklist with no owner is a poster.
Sources
- Machine guarding (opens in a new tab), Occupational Safety and Health Administration (OSHA)
- Control of hazardous energy (lockout/tagout), 1910.147 (opens in a new tab), OSHA
- Maintenance of work equipment (opens in a new tab), Health and Safety Executive (HSE), UK
Frequently asked questions
What is the most useful daily check on a hydraulic press?
Oil level, oil temperature, leaks at hoses and fittings, and a real test of the guards. Those four catch the failures that stop presses and hurt people.
How often should hydraulic filters be changed?
At the OEM hour interval or at a calendar cap, whichever comes first. Change sooner if the oil sample shows dirt or water, or if a filter indicator says so.
Can a weeping hose wait until the weekend?
No. A weep is the planned job. A burst is the unplanned one, and it puts oil on the floor next to the operator.
Does this checklist cover mechanical presses?
No. Mechanical presses and their clutch, brake and control checks are a different machine. Use the press manufacturer's maintenance sheet for those.