When an EWP misbehaves, the operator rarely sees the cause — only the symptom. A boom that drifts, a platform that judders, a function that has gone slow or weak: each of these could stem from a hydraulic problem or a mechanical one, and the two demand very different repairs. Learning to read the symptom for clues about its origin does not make an operator a technician, but it does let you describe a fault accurately, take the machine out of service for the right reason, and give a repairer a useful starting point. This guide walks through how hydraulic and mechanical faults tend to present differently.
Why the distinction matters
Hydraulic and mechanical systems fail in characteristic ways, and the fix for one rarely resolves the other. A hydraulic fault lives in the fluid power system — pumps, cylinders, valves, hoses and seals. A mechanical fault lives in the structure and moving parts — pins, bushes, bearings, slew rings and the structure itself. Misreading one as the other wastes time and can leave a genuine hazard in service.
Whatever the suspected cause, a machine that is not behaving normally should be taken out of service until a competent person has assessed it. Reading the symptom is about describing the problem, not diagnosing and continuing to work.
How hydraulic faults tend to present
Symptoms that more often point toward the hydraulic system include:
- A boom or platform that slowly drifts down or creeps under load — commonly a sign of internal leakage past a cylinder seal or valve.
- Functions that have become slow, weak or unable to reach full capacity, suggesting low pressure, a failing pump or a restriction.
- Jerky or juddering movement of a function, which can indicate air in the system or a sticking valve.
- Visible fluid leaks, damp hoses or fittings, or a falling reservoir level.
- Movement that varies with fluid temperature, warming up or slowing down as the oil changes.
How mechanical faults tend to present
Symptoms that more often point toward the mechanical side include:
- Knocking, clunking or free play felt through the platform when a function starts or stops — often worn pins or bushes.
- Grinding, rumbling or notchy movement in the slew or turntable, pointing toward the slew ring or its bearings.
- Excessive movement or lash in a joint that should be tight, indicating wear in the pivot points.
- Unusual noise from moving parts that does not vary with hydraulic load or temperature.
- Visible damage, distortion or cracking in structural members, which is always a stop-work signal.
Where the two overlap
The reason diagnosis needs a competent person is that hydraulic and mechanical symptoms can mimic one another. A function that feels rough might be a sticking valve (hydraulic) or a worn pivot (mechanical). Drift might be a cylinder seal (hydraulic) or, in some arrangements, a mechanical issue in how a joint is holding. Some faults are also a combination — a mechanical problem loading a component abnormally can accelerate a hydraulic failure, and vice versa.
This overlap is exactly why the operator's job is to observe and describe rather than to conclude. A clear description of when the symptom appears, under what load, at what temperature and with which function is far more useful to a repairer than a guess at the cause.
Describing a fault well
A description at this level lets a repairer arrive prepared and shortens the time the machine spends out of service.
When reporting a fault, note down:
- Which function is affected and exactly what it does wrong — drifts, slows, judders, knocks.
- When it happens — under load, at full extension, when cold, when hot.
- Whether the behaviour is getting worse and how quickly.
- Any noises, leaks, warning indicators or unusual smells that accompany it.
Getting the right repair
Whether a fault turns out to be hydraulic or mechanical, the repair should be carried out by a competent person and, where structure is involved, engineered and certified appropriately so the machine returns to service compliant. A machine showing any of these symptoms should not be worked until it has been assessed. To arrange diagnosis and repair — hydraulic, mechanical or structural — call a qualified provider on 0416 689 689.
This guide is general information prepared by EWP Australia and is grounded in publicly available Australian Standards and Safe Work Australia material. It is not a substitute for the current published edition of the relevant standard or for site-specific engineering advice. Always work from the current standard and consult a competent person for your specific equipment and application.