TLILIC0003 Forklift Stability and the Stability Triangle 2 — Questions and Answers
Question 1: How does raising a load to a greater height affect forklift stability?
- It improves stability by raising the centre of gravity above obstacles
- It has no effect on stability provided the load is within the rated capacity
- It reduces stability by raising the combined centre of gravity and increasing tip-over risk (Correct answer)
- It only affects stability if the load exceeds 500 kg
Correct answer: It reduces stability by raising the combined centre of gravity and increasing tip-over risk
Raising a load elevates the combined centre of gravity, making the forklift more susceptible to tipping in all directions, which is why loads must be lowered to the travel position before moving.
Question 2: What effect does cornering at excessive speed have on a forklift's lateral stability?
- No effect — forklifts are designed to corner safely at any speed
- It increases dynamic forces, shifting the combined centre of gravity outward and increasing tip-over risk (Correct answer)
- It reduces wear on the tyres and improves grip
- It causes only the load to shift, not the forklift itself
Correct answer: It increases dynamic forces, shifting the combined centre of gravity outward and increasing tip-over risk
Cornering at excessive speed generates centrifugal forces that shift the combined centre of gravity outward toward the edge of the stability triangle, significantly increasing the risk of lateral tip-over.
Question 3: How does operating on an uneven or sloped surface affect forklift stability?
- It has no effect if the load is carried low
- It shifts the effective stability triangle and can cause tipping even with a correctly loaded forklift (Correct answer)
- It only affects stability when the load exceeds the rated capacity
- Slopes improve stability by lowering the rear of the forklift
Correct answer: It shifts the effective stability triangle and can cause tipping even with a correctly loaded forklift
Uneven or sloped surfaces tilt the entire forklift, shifting the effective position of the combined centre of gravity relative to the stability triangle and increasing the risk of tip-over.
Question 4: What effect does under-inflation of forklift tyres have on stability?
- It improves cushioning and increases stability on rough surfaces
- It has no effect on stability as long as the tyres are not flat
- It can cause uneven load bearing, reducing stability and causing premature tyre failure (Correct answer)
- It only affects steering, not stability
Correct answer: It can cause uneven load bearing, reducing stability and causing premature tyre failure
Under-inflated tyres cause uneven load bearing across the tyre surface, which reduces the effective support base, increases rolling resistance, and can compromise the forklift's stability triangle.
Question 5: When carrying an asymmetric or off-centre load, what stability risk is increased?
- Longitudinal (forward/backward) tip-over risk only
- Lateral (sideways) tip-over risk, as the combined centre of gravity shifts to one side (Correct answer)
- The risk of the mast collapsing under uneven stress
- No additional risk, provided the total weight is within rated capacity
Correct answer: Lateral (sideways) tip-over risk, as the combined centre of gravity shifts to one side
An off-centre load shifts the combined centre of gravity to one side of the forklift, moving it closer to the edge of the stability triangle and increasing the risk of lateral tip-over.
Question 6: Which condition MOST significantly reduces the stability of a forklift travelling with a raised load?
- Travelling slowly in a straight line on a flat, smooth floor
- Travelling over a small raised edge such as a door threshold (Correct answer)
- Having the mast tilted fully back while the load is at travel height
- Operating in a well-lit, dry warehouse environment
Correct answer: Travelling over a small raised edge such as a door threshold
Travelling over a raised edge or bump with a load at height causes a sudden jolt that can dramatically shift the combined centre of gravity, greatly increasing the risk of tip-over when compared to smooth, flat surfaces.
Question 7: Why does adding an attachment (such as a side-shifter or extension) to a forklift reduce its rated capacity?
- Attachments increase the hydraulic pressure required, weakening the mast
- The weight and extended load centre of the attachment moves the combined centre of gravity forward, reducing stability and capacity (Correct answer)
- Attachments are not permitted in Australia and always void the rated capacity entirely
- Attachments only reduce capacity if they weigh more than 50 kg
Correct answer: The weight and extended load centre of the attachment moves the combined centre of gravity forward, reducing stability and capacity
An attachment adds weight and extends the effective load centre distance, moving the combined centre of gravity further forward toward the fulcrum, which reduces the load the forklift can safely carry.
TLILIC0003 Forklift Stability and the Stability Triangle 2
How does raising a load to a greater height affect forklift stability?