WABCO part numbers starting 550
| 550390 | Piston | WABCO | ||
| 550419 | Pin, spring | WABCO | ||
| 550583 | Piston LP with pin and circlips | WABCO | ||
| 550673 | Pins, cylindrical spring (valve, automatic brake) | WABCO | ||
| 550853 | L.p. piston with wrist pin standard size | WABCO | ||
| 550992 | Gasket, 3/4 in OD ring (valve, h-5 air) | WABCO |