A baler is a piece of farm machinery used to compress a cut and raked crop (such as hay, cotton, straw, or silage) into compact bales that are easy to handle, transport and store. Several different types of balers are commonly used, each producing different types of bales – rectangular or cylindrical, of various sizes, bound with twine, strapping, netting, or wire. Industrial balers are also used in material recycling facilities, primarily for baling metal, plastic, or paper for transport.
The common type of baler in industrialized countries is the large round baler. It produces cylinder-shaped “round” or “rolled” bales. Grass is rolled up inside the baler using rubberized belts, fixed rollers, or a combination of the two. When the bale reaches a predetermined size, either netting or twine is wrapped around it to hold its shape. The back of the baler swings open, and the bale is discharged. The bales are complete at this stage, but they may also be wrapped in plastic sheeting by a bale wrapper, either to keep hay dry when stored outside or convert damp grass into silage. Variable-chamber balers typically produce bales from 120 to 180 cm in diameter and up to 150 cm in width. The bales can weigh anywhere from 500 to 1,000 kg, depending upon size, material, and moisture content.
Originally conceived by Ummo Luebbens circa,1910, the first round baler did not see production until 1947, when Allis-Chalmers introduced the Roto-Baler. Marketed for the water-shedding and light weight properties of its hay bales, AC had sold nearly 70,000 units by the end of production in 1960.
The next major innovation came in 1972, when the Vermeer Company began selling its model 605 – the first modern round baler. Previously, round hay bales had been little more than lumps of grass tied together, but the Vermeer design used belts to compact hay into a cylindrical shape as is seen today. In the early 1980s, collaboration between Walterscheid and Vermeer produced the first effective uses of CV joints in balers, and later in other farm machinery. Due to the heavy torque required for such equipment, double Cardan joints are primarily used. Former Walterscheid engineer Martin Brown is credited with “inventing” this use for universal joints.
A bale wrapper is a farm implement for wrapping bales in plastic, for them to turn into silage. The wrapper has a loading arm, much like a bale handler, at the side, that scoops up a bale and places it on the wrapping table. The wrapping table usually consists of two rollers, and four belts which slowly spin the bales while the table itself revolves. As the bale turns, plastic film is pulled through the dispensing unit and wrapped tightly on the bale. When the table has revolved at least 16 times, the bale can be ejected. This is done by a hydraulic ram which tilts the wrapping table, so that the bale can be tipped off. The film is cut and then tied to the wrapper for the next bale. All this is controlled via a computer inside the cab of the tractor.
Round bale handling and transport
Round bales can weigh a ton or more, and are well-suited for modern large scale farming operations such as a dairy with 200 or more cows. However, due to the ability for a round bale to roll away on a slope, they require special transport and moving equipment.
The most important tool for round bale handling is the bale spear or spike, which is usually mounted on the back of a tractor or the front of a skid-steer. It is inserted into the approximate center of the round bale, then lifted up and the bale is hauled away. Once at the destination, the round bale is set down, and the spear pulled out. Careful placement of the spear in the center is needed or the round bale can spin around and touch the ground while in transport, causing a loss of control. When used for wrapped bales that are to be stored further, the spear makes a hole in the wrapping that must be sealed with plastic tape to maintain a hermetic seal.
Alternatively, a grapple fork may be used to lift and transport round bales. The grapple fork is a hydraulically driven implement attached to the end of a tractor’s bucket loader. When the hydraulic cylinder is extended, the fork clamps downward toward the bucket, much like a closing hand. To move a round bale, the tractor approaches the bale from the side and places the bucket underneath the bale. The fork is then clamped down across the top of the bale, and the bucket is lifted with the bale in tow.
Grab hooks on the bucket are a simple and inexpensive tool and method for handling large and small round bales. This is an easy do-it-yourself modification to the tractor bucket. Two hooks are welded to the outside top of a tractor front loader bucket and a 4.3 m logging chain which allows the user to stay on the tractor, grab bales, transport them, stack them and place them out for animals to eat. The advantage of this simple system is that it uses no expensive equipment which must be swapped back and forth on the tractor. This method is safer than some others because the operator can stay in the tractor seat. This allows a small farmer to avoid the costs of extra equipment and not have a separate tractor just for that one function. With a little practice, one can be as quick as the specialized hydraulic bale grabs. This method, developed by Walter Jeffries of Sugar Mountain Farm, also requires less maintenance and is safer than bale spears and clamps. Using this technique bales can be easily flipped from the flat to round facing orientation (often called dinner plate vs tootsie-roll orientations). While the bale is lifted the wrap can be easily removed as well.
It is difficult to flip a round bale so that the flat surface is facing down, and later flip it back up on edge, so transporting many round bales a long distance is a challenge. Flat-bed transport is difficult since the bales could roll off the truck bed going around curves and up hills. To prevent this, the flat-bed trailer is equipped with rounded guard-rails at either end, which prevent bales from rolling either forward or backward. Another solution for this is the saddle wagon, which has closely spaced rounded saddles or support posts in which round bales sit. The tall sides of each saddle, or the bale settling down in between posts, prevent the bales from rolling around while on the wagon. On 3 September 2010, on the A381 in Halwell near Totnes, Devon, UK an early member of British rock group ELO Mike Edwards was killed when his van was crushed by a round bale. The cellist, 62, died instantly when the 600kg bale fell from a tractor on nearby farmland before rolling onto the road and crushing his van.
Round bales can be directly used for feeding animals by placing it in a feeding area, tipping it over, removing the bale wrap, and placing a protective ring (a ring feeder) around the outside so that animals don’t walk on hay that has been peeled off the outer perimeter of the bale. The baler’s forming and compaction process can assist in unrolling a round bale, as it is often possible to unroll a round bale in a continuous flat strip for feeding in the open, or through a feeding barrier.
Silage or haylage bales
A recent innovation in hay storage has been the development of the silage or haylage bale, which is a high-moisture bale wrapped in plastic film. These are baled much wetter than hay bales, and are usually smaller than hay bales because the greater moisture content makes them heavier and harder to handle. These bales begin to ferment almost immediately, and the metal bale spear stabbed into the core becomes very warm to the touch from the fermentation process.
Silage or haylage bales may be wrapped by placing them on a rotating bale spear mounted on the rear of a tractor. As the bale spins, a layer of plastic cling film is applied to the exterior of the bale. This roll of plastic is mounted in a sliding shuttle on a steel arm and can move parallel to the bale axis, so the operator does not need to hold up the heavy roll of plastic. The plastic layer extends over the ends of the bale to form a ring of plastic approximately 30 cm wide on the ends, with hay exposed in the center. To stretch the cling-wrap plastic tightly over the bale, the tension is actively adjusted with a knob on the end of the roll, which squeezes the ends of the roll in the shuttle.
These bales are placed in a long continuous row, with each wrapped bale pressed firmly against all the other bales in the row before being set down onto the ground. The plastic wrap on the ends of each bale sticks together to seal out air and moisture, protecting the silage from the elements. The end-bales are hand-sealed with strips of cling plastic across the opening. The airtight seal between each bale permits the row of round bales to ferment as if they were in a silo bag, but they are easier to handle than a silo bag, as they are more robust and compact. The plastic usage is relatively high, and there is no way to reuse the silage-contaminated plastic sheeting, although it can be recycled or used as a fuel source via incineration. The wrapping cost is approximately US$5 per bale.
An alternative form of wrapping uses the same type of bale placed on a bale wrapper, consisting of pair of rollers on a turntable mounted on the three-point linkage of a tractor. It is then spun about two axes while being wrapped in several layers of cling-wrap plastic film. This covers the ends and sides of the bale in one operation, thus sealing it separately from other bales. The bales are then moved or stacked using a special pincer attachment on the front loader of a tractor, which does not damage the film seal. They can also be moved using a standard bale spike, but this punctures the airtight seal, and the hole in the film must be repaired after each move.
Plastic-wrapped bales must be unwrapped before being fed to livestock to prevent accidental ingestion of the plastic. Like round hay bales, silage bales are usually fed using a ring feeder.