Load a two-wheel cart with its centre of gravity slightly ahead of the axle, so the animal feels 5-10% of the load through the shafts, and keep heavy items low: with a track width of 1.4 m, a load 1 m high tips at a side tilt of 0.58 but a load 4 m high tips at 0.26, barely above the 0.25 that a 10% side slope, a wheel in a 15 cm rut and a turn already supply. A shift of 100 kg by 0.5 m on a 2.5 m shaft changes the shaft load by 20 kg. Stack low, spread the weight over both axles on a wagon, and never trust a tall load on a side slope.
Part of Logistics & Load Planning
Placing cargo on a cart or wagon so that it balances over the axles, loads the animal correctly and stays upright on a rough road.
A Load Fails By Tipping Or Shifting, Not By Breaking The Cart
The parent article gives the loading rules. For a two-wheel cart: centre the load directly over the axle or slightly forward; let the animal feel about 5-10% of the total load through the shafts (for a 400 kg load that is 20-40 kg); put heavy items low and light items high; let nothing protrude where it can snag. For a four-wheel wagon: spread weight evenly between the axles or slightly toward the rear; centre it side to side; put the heaviest items against the headboard at the front, lighter ones toward the tail; and keep the tailgate area free for items needed during the day.
Two of the parent’s rules pull against each other: “directly over the axle” puts zero load on the animal, while 5-10% needs the load forward of the axle. The arithmetic below resolves it: the load must sit forward, and by how much depends on the shaft length. Carts and Wagons gives the same advice: balanced slightly forward of the axle so that the harness stays settled on the animal.
What You Need
- A tape measure for the shaft length from axle to the animal’s attachment point.
- A scale or known weights — see Improvised Weighing.
- The cart’s track width — the distance between the wheels’ ground contacts.
- Ropes and chocks — see Securing Methods.
Method: Balance A Cart Load
Step 1: Weigh and sort the cargo List each item with its weight and place it on a sketch of the bed.
Step 2: Find the balance point Shaft load = total load × distance forward of the axle / shaft length. Put the centre of gravity of the whole load that distance ahead of the axle.
Step 3: Heavy items low Place the heaviest cargo on the floor, near the balance point, and light items above.
Step 4: Check the height Measure the height of the top of the load. See the tipping table below.
Step 5: Test With the cart loaded and the animal unhitched, lift the shaft tip; it should feel light but not be free. Check again after the first kilometre, since loads settle.
Worked Example: Shaft Load, Tipping And Loading Order
Shaft load. Shaft load P = W × d / L, with W the load, d the distance of its centre of gravity ahead of the axle, and L the shaft length from axle to the animal. Take shafts of 2.5-3.0 m from Carts and Wagons. For 5-10% of the load: d = 0.05 × 2.5 = 12.5 cm to 0.10 × 3.0 = 30 cm. So the centre of gravity must be about 12-30 cm ahead of the axle. Directly over the axle gives d = 0 and P = 0.
A shifting load. A 100 kg item sliding 0.5 m forward on a cart with a 2.5 m shaft adds 100 × 0.5 / 2.5 = 20 kg to the shaft load. For a 400 kg load whose shaft load was 20-40 kg, the animal now carries 40-60 kg, which is up to three times as much. Sliding 0.5 m backward subtracts 20 kg, so the shaft load falls to 0-20 kg and the shafts start to float.
Tipping sideways. A rigid cart tips when the sideways tilt exceeds (track / 2) / (height of centre of gravity above the ground). Inputs, mine: track 1.4 m, so half is 0.7 m; bed 0.7 m above the ground; a uniform load, so the centre of gravity is at bed height plus half the load height. Disturbances that add up: a 10% side slope is 0.10; one wheel in a 15 cm rut tilts 0.15 / 1.4 = 0.107; a turn at 1.39 m/s (5 km/h) on a 5 m radius gives a sideways acceleration of 1.39² / 5 = 0.386 m/s², which is 0.386 / 9.81 = 0.039 of gravity. Total 0.10 + 0.107 + 0.039 = 0.246, about 0.25, adding the tilts as a small-angle approximation.
| Load height | Centre of gravity height | Tips at side tilt | Margin over 0.246 |
|---|---|---|---|
| 1 m | 1.2 m | 0.58 | 2.4 |
| 2 m | 1.7 m | 0.41 | 1.7 |
| 3 m | 2.2 m | 0.32 | 1.3 |
| 4 m | 2.7 m | 0.26 | 1.05 |
A 4 m load has almost no margin. A real load also flexes, bounces and shifts, which this rigid-body arithmetic ignores, so it overstates the margin.
Heavy low. Take 400 kg of heavy items and 200 kg of light ones. Heavy at the floor (centre of gravity 0.9 m above the ground) and light on top (2.2 m): combined centre = (400 × 0.9 + 200 × 2.2) / 600 = 1.33 m, tipping tilt 0.7 / 1.33 = 0.53. Reversed, with the heavy items high: (200 × 0.9 + 400 × 2.2) / 600 = 1.77 m, tilt 0.40, about 25% less margin for the same cargo.
Wagon axles. For a wagon with a wheelbase of 2.5 m and 1,800 kg of load: with the centre of gravity at mid-wheelbase (1.25 m from the front axle), each axle carries 900 kg. At 1.4 m from the front axle, the rear carries 1.4 / 2.5 × 1,800 = 1,008 kg and the front 792 kg. A 0.15 m shift moves 108 kg from one axle to the other.
Common Mistakes
- Putting the load over the axle for zero shaft load — the cart tips back whenever the load shifts rearward. Keep it forward.
- Stacking tall to save trips — the tipping margin shrinks quickly with height.
- Heavy items on top — raises the centre of gravity.
- Loose cargo — it moves; see the parent’s rule on securing.
- A lopsided wagon — the parent notes it tracks crooked and wears one wheel; centre the load side to side.
Safety
Cart overturns and runaway loads
A tipped cart can crush the driver and kill the animal. Keep tall loads off side slopes, ruts and bends, walk beside the cart on steep descents, and never ride a high load downhill. See Securing Methods for what holds a load in place when the cart brakes.
What’s Next
- Learn next: Securing Methods — keeping the load where you put it
- Combine with: Mixed Cargo Planning — ordering different cargo types