Build a wagon bed as a flat deck with square stake pockets along its edges, drop in vertical stakes and slide side boards between them, and make the tailgate removable. Loose grain, sand or manure then needs only a liner of canvas or hides, and the side load is modest: a 40 cm depth of grain presses outward at about 294 N for each metre of side board, which light stakes carry easily.
Part of Cart & Wagon Construction
A wagon bed with removable sides is a flat deck fitted with stake pockets and slide-in boards, so the same wagon can carry flat loads or loose bulk.
A Flat Bed With Removable Sides Does Most Jobs
The parent article calls a flat bed with removable side boards the most versatile configuration. With the sides off, it carries timber, stone and bales. With them in, it holds loose cargo. A removable back board makes loading and unloading heavy items much easier.
- Stake pockets: drill or chop square holes along the bed edges. Drop in vertical stakes, then slide side boards between them.
- Tailgate: a removable back board.
- Lining: for loose materials (grain, sand, manure), line the bed with canvas or hides.
How Hard Does Grain Push On The Sides?
Loose material pushes sideways on the boards, and the pressure grows with depth. Take assumed figures: grain at 750 kg/m³ (the corpus’s 20-litre bucket holds 15 kg of grain, Weight Calculation & Measurement), a side-pressure coefficient K = 1 - sin φ = 0.5 for an assumed friction angle φ = 30° (a recalled soil-mechanics rule for material at rest), and a grain depth h = 0.40 m (40 cm).
- Pressure at the bottom = K × ρ × g × h = 0.5 × 750 × 9.81 × 0.40 = 1,470 Pa
- Force per metre of side board = ½ × pressure × h = 0.5 × 1,470 × 0.40 = 294 N/m, about 30 kgf per metre
- For a 4 m side, 4 × 294 = 1,177 N
Share this among stakes 1 m apart. Each stake holds 294 N, acting about a third of the way up the grain, 0.40 / 3 = 0.133 m above the bed:
- Moment at the pocket = 294 × 0.133 = 39 N·m
- For a 5 × 5 cm stake, Z = b h² / 6 = 0.05 × 0.05² / 6 = 2.08 × 10⁻⁵ m³
- Stress = 39 / 2.08 × 10⁻⁵ = 1.9 MPa
Even tripled for jolts, that is under 6 MPa, a small fraction of the roughly 100 MPa bending strength of air-dry oak or ash (a recalled handbook figure). So grain does not demand heavy stakes. The weak points are the pockets (their edges crush or split) and a stake that is a loose fit; and tall loads on a side slope are a tipping issue, not a side-board issue (Cart & Wagon Loading).
What You Need
- A flat deck on the wagon frame (Front Axle Pivot for the front end)
- Square-section stakes, hardwood
- Side boards and a tail board
- Canvas or hides as a liner for loose cargo
- A chisel or auger and a mallet to cut the pockets
Method: Build The Sides
Step 1: Mark the pockets along each edge of the bed at even spacing, a metre or so apart.
Step 2: Cut them square, slightly bigger than the stake so it drops in but cannot rock. Reinforce the pocket edges against splitting.
Step 3: Make stakes to fit, with a taper at the foot so they seat.
Step 4: Cut side boards to slide between the stakes, with notches or cleats to keep them from riding up.
Step 5: Make the tailgate a removable board held by cleats or pins.
Step 6: Line the bed for grain, sand or manure, and tuck the liner under the boards.
Common Mistakes
- Stakes tight in green pockets — the wood swells, then splits.
- Gaps in the floor under grain — grain runs out; line the bed or caulk the joints.
- Piling cargo above the sides without tying it — the load, not the sides, then governs; see Securing Methods.
- A tailgate held by one pin — it drops out on a bump.
Safety
Falling cargo when the tailgate comes off
Releasing the tailgate on a loaded wagon can drop or tip a heavy load onto whoever is behind it, and loose bulk can bury a person standing in the bed. Stand to the side when releasing the back, never stand behind a loaded wagon on a slope, and chock the wheels before unloading.
What’s Next
- Learn next: Maintenance & Field Repair — keeping the whole wagon sound
- Combine with: Mixed Cargo Planning — ordering what goes in