Scissor lifts: stability, pothole protection and deck loading
Scissor lifts are vertical-lift machines, usually category 3a. The exam tests their stability, pothole protection, deck extensions, crush and entrapment risks, and floor loading. A scissor lift is not a boom: it cannot reach over a fixed obstacle, so positioning close to the work is part of safe operation.
Stability and pothole protection
- Pothole protection bars or plates must deploy before the platform lifts. The interlock prevents lifting if they are not deployed; never disable or bypass it.
- If the tilt alarm sounds, lower the platform and move to level ground. Do not continue working or driving elevated on the slope.
- Drive elevated only where the manual permits it and only on firm, level surfaces. Treat ramps, kerbs, steps and trenches as restrictions, not challenges.
- Check floor or slab capacity. The point load through a wheel can be much higher than the machine's gross weight divided by four.
Platform load and extensions
- Rated capacity includes persons, tools and materials. A deck extension usually reduces the permitted load; check the chart for the extended configuration.
- Load evenly. A concentrated load can damage the deck or reduce stability even when the total is under the rating.
- Keep gates closed and use the designed access opening. Do not climb over or stand on guardrails.
- Do not use ladders, boxes or steps on the platform to gain extra height.
Crush and entrapment
- Keep clear of overhead beams, pipes and ceilings. The operator can be crushed between the platform and an overhead structure.
- Keep hands and feet inside the platform; do not lean over the guardrail.
- Know the emergency lowering procedure and confirm it works during the pre-use check.
Worked example
A slab scissor is rated 230 kg. With a 1.5 m extension deck deployed, the chart allows 150 kg on that deck. Two workers weigh 78 kg and 92 kg (170 kg), and they have 15 kg of tools, giving 185 kg. That exceeds the 150 kg deck limit even though it is below the main platform rating. The correct action is to retract the extension, reduce to one person plus tools, or use a larger machine. Reasoning: the extension changes the stability envelope, so the main deck figure does not apply.
Traps that cost marks
- Treating pothole bars as optional.
- Driving elevated across a ramp or kerb.
- Checking only the main deck rating after adding a person to the extension.
- Using the guardrail as a step.