| The sulfur acid solution used as the electrolyte in a battery. | |
| A friction reducing bearing that uses a series of steel balls held between inner and outer bearing races, such as in a roller clutch. | |
| The second stroke of the four stroke engine cycle, in which the piston moves from the bottom dead center in the intake valve is closed, trapping and compressing the air/fuel mixture in the cylinder. | |
| And ignition system that uses a distributor, electronically controlled or not. |