Skateboard

Thin wood veneers are glued into a curved laminate, commonly using hard maple for street boards. The bonded layers share bending loads and help manage the directional nature of wood. Plywood identifies the engineered layered product; wood identifies its constituent, not an additional separate slab beneath it.

Aluminium alloy truck bodies can carry the deck above steel axles. Their geometry converts deck lean into steering. Alloy formulation, casting or forging route and heat treatment affect performance, while the steel axle needs to resist repeated loading within the compact space inside the wheels.

Cast polyurethane forms many skateboard wheels and compressible truck bushings. The wheel must roll, grip and recover from deformation; the bushing controls how the truck leans and returns. These parts use different formulations and shapes, so sharing the polyurethane family does not make their mechanical behaviour identical.

Small steel ball bearings let the wheel rotate around the axle with controlled contact and lubrication. Shields, cages and grease also matter but vary in material. Steel hardness is useful at the rolling surfaces; corrosion, dirt or misalignment can still damage an otherwise hard bearing.

A grip sheet can use a backing carrying bonded abrasive grains, including aluminium oxide in some products. The rough surface helps shoe soles resist sliding across the deck. Other grit chemistries and polymer backings exist, so a visible black abrasive layer cannot be identified precisely by colour.