Return to Service After a Wet-Season Shutdown
The crew returns after a six-week wet-season shutdown. The hoist has stood at its full 24 m height, uncovered, with the cage parked at the bottom landing. During the pre-start the operator records: light surface rust on mast sections and tie rods; the level 3 landing gate interlock can be defeated by hand and the cage still travels; the upper limit switch stops the cage 1.2 m below the top landing; and with the cage loaded to its 1000 kg rating, releasing the UP button lets the cage drift about 400 mm before the brake grabs. The logbook's last entry is seven weeks old and reads 'brake adjusted - monitor'. The supervisor wants the renderers working within the hour and says cold-morning drift is normal.
1. Sort the findings into 'stop now', 'must be fixed before next use' and 'needs assessment', with your reasoning for each.
Read the worked answer
Stop now - the hoist must not carry anyone or anything:
- Level 3 gate interlock defeated. The interlock is a primary safety control: it prevents the cage moving while a landing gate is open. Defeated, a person can step through an open gate into a moving cage or into the shaft void - a fall-from-height. It also allows the cage to be called away with a gate standing open at a landing. This alone is a Category A defect.
- 400 mm brake drift at rated load. The brake must stop and hold the rated load, with a proven margin at the specified overload figure in the test. Drift means the brake is not developing its design torque. In a wet season the two most likely causes are moisture/rust on the lining or drum and oil or grease contamination, with wear or maladjustment behind them. The machine cannot be used.
Must be fixed before next use:
- Upper limit switch stopping 1.2 m low. Likely maladjustment, but it may mean the final (over-travel) limit is doing the stopping, or that the working limit is set so the cage cannot reach the landing correctly - which also affects gate alignment and the top landing gap. It must be adjusted and function-tested: both limits, every landing interlock, the emergency stop.
Needs assessment:
- Rust. Surface rust on mast faces is largely cosmetic, but pitting, section loss, or rust at welds, tie collars and tie rods is structural. The ties are what keep a 24 m mast standing. A competent person must assess it - you cannot decide by eye from the ground.
- Logbook seven weeks stale. The inspection regime has lapsed, so no item on the machine can be assumed serviceable. It is evidence of a system failure, not just paperwork.
2. Set out the actions, in order, from the moment you find the faults.
Read the worked answer
- Stop. Tell the supervisor the hoist is out of service. No lifts, no 'just one more'.
- Make the machine safe. If it can be done safely, run the cage down to the bottom landing with the brake drifting no further than it must; if not, leave it parked and keep everyone clear.
- Isolate and lock out at the main isolator, tag it, and fit an 'OUT OF SERVICE - DO NOT USE' tag to the control station and the bottom gate.
- Lock off the bottom landing or barricade it so nobody can enter.
- Record in the logbook: date, time, your name, each finding, the 400 mm drift figure and the load it was observed at, and the isolation.
- Notify the person with management or control of the site and the hoist owner in writing; escalate if the supervisor pushes back.
- Engage a competent person (manufacturer's service agent for brake and interlock work) to repair the interlock, service/repair the brake, adjust the limits and assess the rust.
- Proof test and verify: brake test at rated load and at the required hold test, plus a full function test of every landing interlock, both limits, emergency stop and any overspeed device.
- Document the repair and test in the logbook before return to service, then re-brief the crew on what changed.
3. How do you handle the supervisor's 'start in an hour' instruction, and what do you tell the renderers?
Read the worked answer
State the hazard plainly, not the paperwork problem: 'the gate interlock is the thing that stops a person walking through an open gate into the shaft, and the brake is the thing that stops the cage running away. Neither can be waived.' Do not debate the cost of downtime in the moment - put the refusal in writing (logbook entry plus a message to the supervisor and the PCBU) so there is a record of who gave the instruction and who declined it.
Then be useful, so the pressure has somewhere to go: offer alternatives the renderers can actually work with today - an EWP, scaffold access on the lower levels, or materials moved by another machine while the hoist is repaired - and give the supervisor a realistic return-to-service estimate once the service agent has looked at the brake.
To the renderers, keep it short and specific: the hoist is out of service for a brake and interlock fault, the bottom landing is locked, don't use it or operate the gates, and here is how you get your gear up today. A crew that knows the reason is far less likely to try a workaround than a crew that is only told 'no'.