In construction, there are three main types of compactor: the plate, the rammer, and the road roller. The roller type compactors are used for compacting crushed rock as the base layer underneath concrete or stone foundations or slabs. The plate compactor, vibrating plate, or tamper, has a large vibrating baseplate and is suited for creating a level grade, while the rammer compactor has a smaller foot. The rammer, or trench rammer, is mainly used to compact the backfill in narrow trenches for water or gas supply pipes etc. Road rollers may also have vibrating rollers. In plates and rollers the vibration is provided by rapidly rotating eccentric masses. In smaller plates the vibration causes a tendency to move forwards, while some larger plates are provided with a directional control. In the rammer the foot is mounted on a sleeve that slides vertically in the leg. Inside the sleeve, a piston is driven up and down by the engine through a reduction gear, crank and connecting rod. Substantial coil springs above and below the piston connect it to the sliding sleeve. The connection between the sleeve and foot is at small angle so that the whole rammer leans away from the operator. The vibrating motion is therefore slightly off the vertical, and this gives the rammer a tendency to 'walk' forwards. The sliding joint in the leg is protected by a flexible bellows.
A ramrod (or scouring stick) is a metal or wooden device used with muzzleloading firearms to push the projectile up against the propellant (mainly blackpowder). The ramrod was used with weapons such as muskets and cannons and was usually held in a notch underneath the barrel. Bullets that did not fit snugly in the barrel were often secured in place by a wad of paper or cloth, but either way, ramming was necessary to place the bullet securely at the rear of the barrel. Ramming was also needed to tamp the powder so that it would explode properly instead of fizzle (this was a leading cause of misfires). The ramrod could also be fitted with tools for various tasks such as cleaning the weapon, or retrieving a stuck bullet. Cap and ball revolvers were loaded a bit like muzzleloaders—powder was poured into each chamber of the cylinder from the muzzle end, and a bullet was then squeezed in. Such handguns usually had a ramming mechanism built into the frame. The user pulled a lever underneath the barrel of the pistol, which pushed a rammer into the aligned chamber.
