was patented in France and Britain at the end of December in 1858 by Devisme. The cylinder is mounted on a pivot that is parallel to the chambers, and the cylinder swings out and down (to the left in most cases). An extractor is fitted, operated by a rod projecting from the front of the cylinder assembly. When pressed, it will push all fired rounds free simultaneously (as in top-break models, the travel is designed to not completely extract longer, unfired rounds). The cylinder may then be loaded, individually or again with the use of a speedloader, closed, and latched in place. The pivoting part that supports the cylinder is called the crane; it is the weak point of swing-out cylinder designs. Using the method often portrayed in movies and television of flipping the cylinder open and closed with a flick of the wrist can in fact cause the crane to bend over time, throwing the cylinder out of alignment with the barrel. Lack of alignment between chamber and barrel is a dangerous condition, as it can impede the bullet's transition from chamber to barrel. This gives rise to higher pressures in the chamber, bullet damage, and the potential for an explosion if the bullet becomes stuck. The shock of firing can exert a great deal of stress on the crane, as in most designs the cylinder is only held closed at one point, the rear of the cylinder. Stronger designs, such as the Ruger Super Redhawk, use a lock in the crane as well as the lock at the rear of the cylinder. This latch provides a more secure bond between cylinder and frame, and allows the use of larger, more powerful cartridges. Swing-out cylinders are rather strong, but not as strong as fixed cylinders, and great care must be taken with the cylinder when loading, so as not to damage the crane. Other designs One unique design was designed by Merwin Hulbert in which the barrel and cylinder assembly were rotated 90° and pulled forward to eject shells from the cylinder. Action Single-action In a single-action revolver, the hammer is manually cocked, usually with the thumb of the firing or supporting hand. This action advances the cylinder to the next round and locks the cylinder in place with the chamber aligned with the barrel. The trigger, when pulled, releases the hammer, which fires the round in the chamber.