The carriage performs a number of functions in the operation of an artillery piece. First and foremost, the carriage holds the cannon in place while being fired, and allows the piece to be aimed. In the case of field artillery, whose mobility is critical, the carriage also allows the piece to be easily moved where it is needed.
The carriage for field artillery consists of two cheeks, bolted together and with the stock. The cheeks support the piece by its trunnions, and in turn rest upon the axle-tree supported by two wheels. The back of the stock or trail rests on the ground. The field carriage dissipates the force of recoil by rolling along the ground, and on firm ground can rear back several feet on firing. On softer ground, the trail tends to dig in, which can cause problems in aiming. The trail terminates in an iron ring called a lunette, which is the means by which it is fastened to the limber. Two pointing rings ahead of the lunette hold a handspike, which provides leverage for aiming the piece. Ahead of the pointing rings are two hooks, around which is wound the prolonge, a length of heavy rope with a ring at one end and a toggle at the other. The prolonge is used to loosely attach the gun to the limber, as when firing while slowly retreating, or for other towing jobs.

A very much simplified parts list is shown here.

6-pounder smoothbore mounted on No. 1 field carriage

The wheels of the carriage are of very subtle design. Their 14 spokes are dished slightly inward to make the wheels more "springy" on rough ground, and the ends of the axle are tapered downward to correct for this angle, so that the base of the iron-tired wheel is perpendicular to the ground. This dishing outward also improves the cornering of the vehicle and has the effect of throwing mud outward and away from the men and horses following the carriage.
The pre-War system of ordnance called for three models of field carriage: No. 1 for the 6 pounder gun and 12 pounder howitzer, No. 2 for the 24 pounder howitzer, and No. 3 for the 12 pounder gun and 32 pounder howitzer. The Napoleon (model 1857 light 12 pounder) used a No. 2 carriage, as did the 10 pounder Parrott and 3 inch ordnance rifles, all with some minor modifications where needed. Wheels for all three of the standard carriages, as well as caissons, limbers and battery wagons, were 57 inches high, and could be easily interchanged. As will be noted, caissons carried an extra wheel, and changing a broken wheel was part of the standard drill for a battery of field artillery.

Limber attached to a Gun Carriage

The limber for field service is basically a two-wheeled cart, simply an axle, with its wheels, and a framework for holding an ammunition chest. At the back of the axle is the pintle hook, on which the lunette on the trail of the gun carriage can be keyed into place.
The result is a four-wheeled cart that pivots on the pintle hook. In theory, the limber chest can be used as a seat for three cannoneers, but after the first few months of the War, it was customary to spare the horses, and cannoneers would ride only when necessary.
The ammunition chest contained fifty rounds of 6-pounder, thirty-two rounds of 12-pounder, or other various quantities of ammunition depending on the cannons in the battery.