Hydraulics are the muscles of an EWP — they raise the boom, extend the reach and hold the platform steady while someone works from it. A hydraulic leak is therefore never just a mess on the ground; depending on where it is, it can be a housekeeping nuisance, a slow loss of the ability to hold position, or a sudden failure at height. Understanding the range between those extremes is what lets an operator judge whether a leak means finish carefully or stop immediately. This guide covers the common leaks on access machines, how they are found and what a proper fix looks like.
Symptoms across the severity range
Not every leak is equal. A film of oil on a fitting is a very different matter from a platform that slowly sinks while the controls are neutral, and knowing the difference is a safety skill in its own right.
- Weeping — a damp film or slow drip at a fitting, hose end or seal, often the first warning that something is on its way out.
- Cylinder drift — the boom or platform slowly creeping down under its own weight with the controls centred, which points to internal leakage past a piston seal or a leaking holding valve.
- Spongy, jerky or slow operation, which can indicate air ingress or a loss of system pressure from a leak.
- A sudden loss of oil — a burst hose or blown seal — which can drop a function without warning and is a genuine emergency at height.
Why hydraulic leaks develop
Leaks come from the components wearing, ageing or being damaged:
- Perished, chafed or age-hardened hoses, which crack or split after years of flexing, heat and UV exposure.
- Worn cylinder seals and rod seals, which let oil weep past externally or bypass internally to cause drift.
- Loose, cross-threaded or corroded fittings and unions that no longer seal.
- Scored or pitted cylinder rods, often from corrosion or grit, which then chew out the rod seal.
- Contaminated oil, where grit and moisture accelerate wear on seals, valves and pump internals.
How a leak is traced
Finding the source of a leak is a methodical job, because oil travels and the wet patch is often not where the leak actually is. A competent technician cleans the system down, runs it and works back to the origin rather than guessing from the drip.
External leaks are usually found by inspection under operating pressure. Internal leakage — the cause of cylinder drift — cannot be seen from outside; it is diagnosed by function testing, measuring the rate of drift and, where necessary, isolating cylinders and holding valves to identify which component is bypassing. Because holding valves and load-holding devices are safety-critical, drift is treated as a fault to fix, not a quirk to live with.
How the system is repaired
- Take the machine out of service so no one is working from a platform with a known hydraulic fault.
- Confirm the source — replace the failed hose, reseal or re-machine the cylinder, or renew the fitting or valve as the diagnosis dictates.
- Use the correct hoses, seals and components rated for the machine's pressures, rather than a nearest-match substitute.
- Bleed the air from the system and check the oil is clean and at the right level, replacing contaminated fluid.
- Function test through the full range of motion and re-check for drift and leaks before the machine returns to service.
Preventing leaks
Most hydraulic leaks are foreseeable. Hoses have a service life and should be replaced on condition before they split, not after. Keeping cylinder rods clean and protected stops the scoring that destroys rod seals, and keeping the oil clean and dry extends the life of every seal and valve in the system.
The daily pre-start is where an operator catches a leak early — a damp fitting noted and reported is far cheaper and safer than a hose that lets go at height. Any drift or unexplained oil loss is a reason to park the unit and hand it to a competent person.
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.