NMFC Class 55 — Auto Parts
Axles and chassis components are heavy, dense parts that ship at freight class 50–55.
Typical class: 55 · Density: 30–55 lbs/cu ft
Shipment Dimensions (inches)
| Class | Density (lbs/cu ft) | Description |
|---|---|---|
| 50 | 50+ | Heaviest, most dense freight |
| 55 | 35–50 | Very dense freight |
| 60 | 30–35 | Dense freight |
| 65 | 22.5–30 | Moderately dense |
| 70 | 15–22.5 | Average density |
| 77.5 | 13.5–15 | Slightly below average |
| 85 | 12–13.5 | Below average density |
| 92.5 | 10.5–12 | Light freight |
| 100 | 9–10.5 | Light freight |
| 110 | 8–9 | Light, bulky freight |
| 125 | 7–8 | Bulky freight |
| 150 | 6–7 | Very bulky freight |
| 175 | 5–6 | Very light, bulky |
| 200 | 4–5 | Extremely light |
| 250 | 3–4 | Extremely light, high value |
| 300 | 2–3 | Low density, high handling |
| 400 | 1–2 | Very low density |
| 500 | 0–1 | Lowest density, highest cost |
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NMFC Class 55 — packaging, handling, and freight class details
Axles and chassis components — front and rear axle assemblies, control arms, spindles, steering knuckles, sway bars, and full chassis frames — move primarily through the heavy-duty truck and equipment parts supply chain. Manufacturers like Dana Incorporated, Meritor (now Cummins), and Hendrickson supply OEM truck manufacturers and the aftermarket. Freightliner, Peterbilt, and Kenworth dealers receive axle and suspension components for truck builds and repairs. The school bus and transit bus markets also generate significant axle freight.
Freight class for axles and chassis parts is Class 50–55. A full rear tandem axle assembly for a Class 8 truck weighs 1,500–2,500 lbs and occupies 30–40 cubic feet — 45–75 lbs/cuft, Class 50–55. Individual axle shafts, wheel hubs, and spindles are denser individually. Chassis frames for heavy trucks are extremely heavy steel weldments that also qualify for Class 50.
Machined surface protection is critical. Axle shafts have precision-machined bearing journals and spline sections that must arrive without scratches, nicks, or corrosion. Any damage to a bearing journal surface makes the axle shaft unusable. Bearing surface areas should be coated with rust-preventive oil and wrapped in VCI (vapor corrosion inhibitor) film for any load that will be in transit more than a few days. Thread protection caps must be installed on any threaded ends.
Heavy axle assemblies require substantial pallets or custom skids. A standard 48x40 stringer pallet is inadequate for a 2,000-lb tandem axle assembly. Block pallets rated for 4,000+ lbs or custom fabricated steel skids are appropriate. The assembly must be positioned so axle ends do not contact the pallet surface — use wood blocks or rubber pads at the housing to support the weight while keeping shaft ends clear. Rate context: heavy truck axle freight pays at Class 50–55 rates. Time-sensitive axle deliveries to dealerships repairing down trucks command premium spot rates.
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