Lubricate a wooden axle with rendered animal fat (tallow) every day under heavy use, with pine pitch mixed into the tallow for a longer-lasting coat, or with salvaged automotive grease, which lasts months. A well-greased wooden axle and hub can run 300-500 km before the bearing surfaces need reshaping, while a dry one seizes, and the drag from a dry bearing is about three times that of a greased one.
Part of Cart & Wagon Construction
Axle lubrication is the film of fat, pitch or grease between the axle journal and the wheel hub that keeps the sliding surfaces from seizing and wearing.
A Dry Wooden Axle Seizes
A wooden axle turning inside a wooden hub will seize without lubrication. The sliding surfaces heat, char and bind, and the axle wears fast. The parent article lists what to apply:
| Lubricant | Notes |
|---|---|
| Rendered animal fat (tallow) | the most available; reapply daily under heavy use |
| Pine pitch mixed with tallow | more durable, stays in place longer |
| Grease from salvaged vehicles | superior; a single tube of automotive grease lasts months |
| Soap or beeswax | adequate for light loads |
Make tallow by rendering fat (Animal Fat Rendering), and see Axle Grease for greases made from fat or tar. For the pitch, see Pitch Making.
How Much Drag Does The Bearing Add?
The axle’s rubbing torque is μ × F × r, where F is the load on the wheel, r the radius of the journal and μ the friction coefficient of the rubbing surfaces. Divided by the wheel radius R, it is the same as a rolling-resistance coefficient of μ × r / R, which can be compared with the ground’s.
Take assumed figures: a journal of diameter 5.5 cm (r = 0.0275 m), a disc wheel of radius R = 0.30 m, a cart of 500 kg total (weight 4,905 N), and two assumed friction values to show the scale: μ = 0.1 for a greased surface and μ = 0.3 for a poorly greased or dry one.
| Surface | Coefficient μ × r / R | Drag on the cart |
|---|---|---|
| Greased, μ = 0.1 | 0.1 × 0.0275 / 0.30 = 0.0092 | 0.0092 × 4,905 = 45 N |
| Dry, μ = 0.3 | 0.3 × 0.0275 / 0.30 = 0.0275 | 0.0275 × 4,905 = 135 N |
The dry bearing triples the drag, three times the greased value. For comparison, The Wheel gives a rolling-resistance coefficient of 0.03-0.08 for wooden wheels on dirt roads, so a dry bearing adds a drag of the same order as the ground itself. A wheel of twice the radius halves the bearing’s share. The μ values are assumed for illustration; measure by feel, not by these numbers.
What You Need
- Lubricant: tallow, tallow with pitch, or vehicle grease
- A way to lift the wheel — props and blocks, not a jack alone
- A rag and scraper to clean old, gritty grease
- A container and a stick or brush for application
Method: Grease, Check, Re-grease
Step 1: Chock and lift. Chock the other wheels, lift the axle end on a stable prop and slide the wheel off.
Step 2: Clean. Scrape off old grease, which holds grit like abrasive paste.
Step 3: Apply. Work the grease on the journal and into the hub bore, generously and frequently, as the parent article says.
Step 4: Refit and spin. Refit the wheel and linchpin, and spin the wheel by hand. It should turn freely and quietly.
Step 5: Check at the next stop. Feel the hub after the first kilometre: warm is normal, and a hub too hot to hold a hand against is dry or too tight.
Step 6: Re-grease by the clock. Under heavy use re-apply tallow daily; with vehicle grease, inspect it at every service and top up before it looks dry.
Common Mistakes
- Applying grease over dirt — the dirt grinds the surface.
- Too little, too seldom — the bearing runs dry between applications.
- Using a thin oil on a wooden bearing — it runs out; fat and grease stay.
- Never reshaping a worn journal — after the 300-500 km the parent mentions, check the fit for slop.
Safety
Lifted axles and hot fat
A cart propped on a jack alone can drop on a hand or a head; block it and chock the other wheels. A dry or overheated hub can char and ignite, and rendered fat melts and can catch fire if heated near a flame, so melt pitch and tallow over a gentle heat, outdoors, away from dry grass and wood shavings.
What’s Next
- Learn next: Maintenance & Field Repair — keeping the whole cart running
- Combine with: Axle and Bearing Design — bearing materials and pressures