Common patterns include straight rows, pinwheel patterns, staggered layouts, and mixed-load zones based on pallet size and delivery sequence. The main physics ideas are center of gravity, friction, load balance, and force during acceleration or braking. A trailer should usually be loaded with heavy items low and near the center, with weight spread side to side and front to back according to axle limits.
Key Facts
- Total load weight = sum of all pallet weights.
- Average load per pallet = total load weight / number of pallets.
- Center of gravity position: xcg = (m1x1 + m2x2 + ...)/(m1 + m2 + ...).
- Friction holding force: Ff = μN, where μ is the friction coefficient and N is the normal force.
- Braking force estimate: F = ma, where m is cargo mass and a is deceleration.
- A stable trailer load keeps heavy cargo low, centered side to side, and distributed to satisfy steer axle, drive axle, and trailer axle limits.
Vocabulary
- Pallet pattern
- A planned arrangement of pallets inside a trailer to improve space use, stability, and unloading order.
- Center of gravity
- The balance point of a load where its mass acts as if it were concentrated.
- Axle load
- The portion of vehicle and cargo weight supported by a specific axle or axle group.
- Load securement
- The use of straps, bars, airbags, friction mats, or blocking to prevent cargo from moving during transport.
- Pinwheel loading
- A pallet arrangement where some pallets are rotated 90 degrees to fit more tightly or improve stability.
Common Mistakes to Avoid
- Loading all heavy pallets at the rear, because this can overload the trailer axles and make the trailer less stable during turns.
- Ignoring side-to-side balance, because uneven left-right weight distribution can increase tire wear and rollover risk.
- Leaving large empty gaps between pallets, because gaps allow cargo to shift and reduce the effectiveness of friction and blocking.
- Loading only by delivery order, because access matters but the pattern must still satisfy weight distribution and securement requirements.
Practice Questions
- 1 A trailer carries 24 pallets, each weighing 750 kg. What is the total load weight in kilograms?
- 2 Three pallets are placed along the trailer floor at positions 2 m, 6 m, and 10 m from the front. Their masses are 500 kg, 1000 kg, and 1500 kg. Find the center of gravity position along the trailer.
- 3 A warehouse team must load fragile light cartons and dense machine parts in the same trailer. Explain which items should be placed lower and closer to the center, and why this improves safety.