The bottom of each door section has its own long wheelbase solid aluminium carriage with four wheels that run inside a low threshold base track.
Each wheel is a small work of engineering art. We use nylon type 6-6 for our wheels, a resilient high melting point material that resists degradation due to heat and friction.
Each nylon wheel spins around a 6mm hardened stainless steel shaft on its own set of needle bearings along a stainless steel track.