Loading Three Crates and an Unplanned Trailer Before a Timed Delivery
At 06:40 a warehouse loader hands Daichi three crates for a 40 km delivery due at 08:30. Crate A weighs 1,800 kg, Crate B 1,500 kg and Crate C 1,000 kg. His 準中型 truck has a 車両総重量 of 7.2 t, a 最大積載量 of 4,000 kg and a body length of 6.9 m. Because the bed is short, the plan is to stack Crate C on top of Crate A, putting C's top face 4.15 m above the ground, and to let the longest crate overhang the tailgate by 1.2 m so the tailboard will close. The loader also asks him to hook up the company's 900 kg box trailer, which has its own brakes and lights, to save a second trip. Daichi has held only a 準中型 licence for three years and has never towed anything. The forklift has already lifted Crate C into position.
1. Assess the proposed load against the weight, height and length limits, and state precisely what must be changed.
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- Weight: 1,800 + 1,500 + 1,000 = 4,300 kg against a 最大積載量 of 4,000 kg. That is 300 kg over - 過積載, regardless of how short the trip is. Something must be left behind or split into a second run. The 車両総重量 stays inside the 準中型 ceiling of 7.5 t, but that does not cure the overload.
- Height: the limit for a loaded motor vehicle is 3.8 m above the ground. Crate C's top at 4.15 m exceeds it by 35 cm - enough to hit gantries, cables and tree limbs, and illegal even if the route looks clear. C must come off the stack.
- Length: cargo may extend to 1.1 times the vehicle length, i.e. 6.9 m × 1.1 = 7.59 m, so the rear overhang may not exceed 0.69 m. The proposed 1.2 m is roughly double the allowance.
None of the three is negotiable for a timed delivery; the freight is rearranged.
2. Can he tow the 900 kg trailer on his 準中型 licence? Explain the rule and what the alternative is.
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No. Towing a trailer whose weight exceeds 750 kg requires a けん引 licence in addition to the licence for the towing vehicle. The 準中型 licence covers the truck but not the combination, and there is no tolerance for a short trip or for the trailer having its own brakes - the 750 kg figure is the threshold, and 900 kg is over it.
The alternatives are: have a driver holding a けん引 licence take the trailer, or move the box as freight on the truck in a second run. Towing without the class is not a paperwork problem - an unlicensed driver has had no training in the different braking behaviour, the wider swept path on turns, or reversing a combination, and insurance consequences follow the licence offence.
3. Once the load is legal, what securing and driving measures should he take, and how does the load change the vehicle's behaviour?
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Securing: distribute the heaviest crate over the rear axle area, not behind it; place the load against the headboard if there is one; lash with rated straps to the body's anchor points in a pattern that resists forward, rearward and sideways movement; check tension again after a few kilometres. The tailboard must latch - if it will not, the load is still wrong.
Behaviour: a high, heavy load raises the centre of gravity, so cornering speed and sudden steering inputs must be reduced; 制動距離 grows with mass, so following distances increase; tyre loads and pressures need checking; and the whole vehicle leans more in crosswind and on camber changes.
Driving: a walk-round check before departure (lights, straps, tailboard, tyre condition), lower speeds into bends and on wet surfaces, and an early, gentle braking style throughout.