The vehicles to be profiled are progressed through the underfloor lathe using a capstan and bollard arrangement.
The system will typically consist of:
- Capstan complete with drive motor and reduction gearbox
- Satellite bollards one located at each end of the carshed and one near the capstan
- Two heavy ropes to drive the vehicle in either direction
- Variable speed drive to allow for creeping of the drive unit when the vehicle is close to the under floor lathe.
Using the capstan and bollard system, ropes are attached to the vehicle using an "eye-splice" and chain arrangement.
Each rope is run around the bollard system and coiled next to the capstan. Depending on the direction of travel, one rope is wrapped around the capstan.
An operator stands near the capstan operating the motor while applying pressure to the rope.
Another operator in the pit adjusts the shunting speed via a dial on the console. The machine driving heads have four optical switches that feedback to lights on the console.
When the wheelset is close to central then an amber light illuminates. Once the wheelset is in the correct position a green light illuninates.