With a breast harness on a two-wheel cart, a surcingle passes over the back and under the belly to hold the shafts at the correct height, a belly band under the belly connects to the shafts to stop them lifting, and a back strap runs from the surcingle to the breeching for braking and backing. Without the belly band the shafts can fly up and strike the animal.
Part of Harness & Yoke Making
The belly straps of a shaft harness: what each does, which direction of force it resists, and how they can chafe.
Each Strap Resists A Different Movement
The shafts of a two-wheel cart rest on the animal. If they sit too low they press down; if they lift they swing toward the animal’s back and sides. Three straps manage this:
| Strap | Path | Job |
|---|---|---|
| Surcingle (girth strap) | Over the back, under the belly | Holds the shafts at the correct height |
| Belly band | Under the belly, to the shafts | Prevents the shafts tipping up |
| Back strap | From the surcingle to the breeching | Braking and backing |
The breeching is a strap around the hindquarters. It is what holds the cart back on a descent; see Harness Design.
A note on a wording in the source article: it says the belly band stops the shafts tipping up “when the cart pushes forward on downhills”. Forward push on a descent is carried by the breeching. The belly band resists the shafts lifting, for example when the load is tail-heavy, on a rise, or over a bump. Rig both.
What You Need
- A breast harness or collar harness — see Breast Harness.
- A two-wheel cart with shafts — see Two-Wheel Cart.
- Padded belly straps — the source names friction, sweat and grit as the cause of girth galls.
- Breeching for descents.
Method: Rig The Straps
Step 1: Fit the surcingle. Pass it over the back and under the belly so the shafts rest at the correct height.
Step 2: Fit the belly band. Under the belly, connected to the shafts, so they cannot tip up.
Step 3: Connect the back strap. From the surcingle to the breeching for braking and backing.
Step 4: Check for galls. After work, look under the belly band and surcingle for friction sores, which come from friction, sweat and grit.
Step 5: Make it releasable. Every buckle that holds the shafts to the animal must be one a hand can open quickly, and the handler should carry a sharp knife. Shafts held to a bolting animal drag the cart with it.
Worked Example
How hard does the belly band have to pull when a load sits behind the axle? Assumed inputs, for illustration only: cargo of 100 kg (weight 100 x 9.81 = 981 N), its centre 0.3 m behind the axle, the animal’s support point on the shafts 2.0 m ahead of the axle, and the cart’s own weight ignored.
- Moment of the cargo about the axle: 981 x 0.3 = 294 N m, tending to lift the shaft tips.
- Downward force needed at the animal to hold the shafts: 294 / 2.0 = 147 N, about 15 kg-force (147 / 9.81 = 15.0).
If the same cargo sits 0.1 m ahead of the axle instead, the shafts press down: 981 x 0.1 / 2.0 = 49 N on the surcingle. So a small shift of the load changes the force on the animal’s back by about 196 N (147 + 49), which is why the load is placed with care and the belly band and surcingle are padded and kept flat.
Common Mistakes
- No belly band — shafts rise and can strike the animal.
- Relying on the belly band downhill — use breeching and, on steep descents, a mechanical brake.
- Tight, unpadded girth strap — it causes girth galls.
- Buckles that cannot be opened under load — rig them to be released.
Safety
Shafts that fly up strike the animal; shafts held to a bolting animal drag the cart
Check straps and buckles before every trip, and rehearse the release. Never stand between the animal and the cart wheel or shaft.
What’s Next
- Learn next: Common Harness Injuries — girth galls and how to spot them
- Combine with: Cart Introduction — loading the cart in steps