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A baler is a piece of farm machinery that is used to compress a cut and raked crop (such as hay or straw) into bales and bind the bales with twine. There are several different types of balers that are commonly used. Balers are also used in the material recycling facilities, primarily for baling plastic, paper or cardboard for transport to a recycling facility.
The most frequently used type of baler is a round baler. It produces cylindrically shaped "round" or "rolled" bales. The hay is simply rolled up inside the baler using rubberized belts, fixed rollers, or a combination of rollers and belts. When the bale reaches a determined size, the twine or mesh wrap that binds the bale is wrapped around the outside but not knotted. The back of the baler is opened up and the bale is discharged. Straw or fully-dried hay bales are complete at this stage, but if the bale is to be silage, it will also be wrapped in airtight plastic sheeting by another machine. Variable-chamber balers typically produce bales from 48 to 72 inches in diameter (about 120 to 180 cm) and up to 60 inches in width (150 cm). The bales weigh from 1100 lb (500 kg) to 2200 lb (1000 kg), depending upon size, material and dampness.
Early round balers were sold by Allis Chalmers as the Roto Baler. These bales were roughly 16 inches (410 mm) in diameter and 48 inches (1,200 mm) wide. The concept was first pioneered by Ummo Luebbens as early as 1910. Introduced in 1947 and discontinued in 1960, Allis Chalmers was a pioneer in supplying machinery that would form cylindrical bales during a period where rectangular bales were most common.
The modern round baler was designed in 1972 by the Vermeer Company, which as of 2007 continues to produce them.
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 centre is needed or the round bale can spin around and touch the ground while in transport, causing a loss of control.
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 downwards towards 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 lifted with the bale in tow.
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 for round bales to sit in. The tall sides of each saddle, or the bale settling down in between posts, prevent the bales from rolling around while on the wagon.
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 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.
Silage / Haylage large bales
A recent innovation in hay storage has been the development of the silage or haylage bale, which is a high-moisture wrapped round bale. These are baled much wetter than normal round bales, and are usually smaller than regular round 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.
They are placed on a special rotating bale spear mounted on 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 that the operator does not need to hold up the heavy roll of plastic themselves. The plastic layer extends over the ends of the bale to form a ring of plastic approximately 12 inches (0.3 meters) wide on the ends with hay exposed in the centre.
In order 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. In this example wrapping video, the operator is attempting to use high tension to get a flat, smooth seal on the right end. However the tension increases too much and the plastic tears off. The operator recovers by quickly loosening the tension and allows the plastic to feed out halfway around the bale before reapplying the tension to the sheeting.
These bales are placed in a long continuous row, with each wrapped bale pressed firmly up 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 hay from the elements. The end-bales are hand-sealed with strips of cling plastic across the hay opening.
The airtight seal between each bale permits the row of round bales to ferment as if they were in a silo bag but are easier to handle than a silo bag since the bale can just be picked up and hauled away as a discrete package, as opposed to a large open bag which is full of loose material that must be scooped up, and which is fragile and easily damaged by the silage loader. However, the plastic usage is high and there is no way to reuse or recycle the hay-contaminated plastic sheeting, other than as a fuel source via incineration. The wrapping cost is approximately US$5 per bale.
An alternative form of the same type of bale is placed on a pair of rollers on a turntable mounted on the three-point linkage of a tractor, and spun about two axes while being wrapped in several layers of cling-wrap plastic film. This covers both the ends and sides of the bale in one operation, and which is thus sealed 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. The hole in the film is repaired after moving.
For either type of wrapping, the bale must be unwrapped before being fed to livestock to prevent accidental ingestion of the plastic, and are usually fed to the animals using a ring feeder.
Large rectangular baler
Another type of baler in common use produces large rectangular bales, each bound with a half dozen or so strings of twine which are then knotted. Such bales are highly compacted and generally weigh somewhat more than round bales.
Rectangular bale handling and transport
Rectangular bales are easier to transport than round bales since there is little risk of the bale rolling off the back of a flatbed trailer. The rectangular shape also saves space and allows a complete solid slab of hay to be stacked up for transport and storage.
They are well-suited for large scale livestock feedlot operations where many tons of feed are rationed every hour.
Due to the huge rectangular shape, large spear forks, or squeeze grips are mounted to heavy lifting machinery, such as: large fork lifts, tractors equipped with front end loaders, telehandlers, hay squeezes or wheel loaders to lift these bales.
Small square baler
A type of baler which is less common today in some places but which is still prevalent in many countries such as New Zealand and Australia to the exclusion of large bales produces small rectangular (often called "square") bales. Each bale is about 15 in x 18 in x 38 in (38 x 46 x 96 cm). The bales are wrapped with two, three, or sometimes four strands of twine and knotted. The bales are light enough for one person to handle, about 45 lb (20 kg) to 60 lb (25 kg).
To form the bale, the hay in the windrow is lifted by tines in the baler's pickup. The hay is then dragged or augered into a chamber that runs the length of one side of the baler. A combination plunger and knife moves back and forth in the front end of this chamber. The knife, positioned just ahead of the plunger, cuts off the hay at the spot where it enters the chamber from the pickup. The plunger rams the hay rearwards, compressing it into the bales. A measuring device measures the amount of hay that is being compressed and, at the appropriate length it triggers the mechanism (the knotter) that wraps the twine around the bale and ties it off. As the next bale is formed the tied one is driven out of the rear of the baling chamber onto the ground or onto a special wagon hooked to the end of the baler. This process continues as long as there is material to be baled.
This form of bale is no longer much used in large-scale commercial agriculture because of the costs involved in handling many small bales. However, it enjoys some popularity in small-scale, low-mechanization agriculture and horse-keeping. Besides using simpler machinery and being easy to handle, these small bales can also be used for insulation and building materials in straw-bale construction. Square bales will also generally weather better than round bales because a more much dense stack can be put up. Convenience is also a major factor in farmers deciding to continue putting up square bales, as they make feeding in confined areas (stables, barns, etc.) much easier.
Many of these older balers are still to be found on farms today, particularly in dry areas where bales can be left outside for long periods.
The automatic-baler for small square bales took on most of its present form in 1940. It was first manufactured by the New Holland Ag and it used a small petrol engine to provide operating power. It is based on a 1937 invention for a twine-tie baler with automatic pickup.
Bales prior to 1937 were manually wire-tied with two baling wires. Even earlier, the baler was a stationary implement, driven by power take-off (PTO) and belt, with the hay being brought to the baler and fed in by hand. The biggest change to this type of baler since 1940 is being powered by the tractor through its PTO, instead of by a built-in internal combustion engine.
In present day production, small square balers can be ordered with twine knotters or wire tie knotters.
Square/wire bale history
Pickup and handling methods
In the 1940s most farmers would bale hay in the field with a small tractor with 20 or less horsepower, and the tied bales would be dropped onto the ground as the baler moved through the field. Another team of workers with horses and a flatbed wagon with would come by and use a sharp metal hook to grab the bale and throw it up onto the wagon while an assistant stacks the bale, for transport to the barn.
A later time-saving innovation was to tow the flatbed wagon directly behind the baler, and the bale would be pushed up a ramp to a waiting attendant on the wagon. The attendant hooks the bale off the ramp and stacks it on the wagon, while waiting for the next bale to be produced.
Eventually as tractor horsepower increased, the thrower-baler became possible, which eliminates the need for someone to stand on the wagon and pick up the finished bales. The first thrower mechanism used two fast-moving friction belts to grab finished bales and throws them at an angle up in the air onto the bale wagon. The bale wagon was modified from a flatbed into a 3-sided skeleton frame open at the front, to act as a catcher's net for the thrown bales.
The next innovation of the thrower-baler as tractor horsepower further increased was the hydraulic tossing baler. This employs a flat pan behind the bale knotter. As bales advance out the back of the baler, they are pushed onto the pan one at a time. When the bale has moved fully onto the pan, the pan suddenly pops up, pushed by a large hydraulic cylinder, and tosses the bale up into the wagon like a catapult.
The pan-thrower method puts much less stress on the bales compared to the belt-thrower. The friction belts of the belt-thrower stress the twine and knots as they grip the bale, and would occasionally cause bales to break apart in the thrower or when the bales landed in the wagon.
New Holland has invented a machine named the "Stackcruiser", or a stacker. Small "square" bales are dropped by the baler with the strings facing outward, the stacker will drive up to the bales and it will pick it up and set it on a three-bale-wide table (the strings are now facing upwards). once three bales are on the table, the table lifts up and back causing the three bales to face strings to the side again, this happens 3 more times until there are 16 bales on the main table. this table will lift like the smaller one and the bales will be up against a vertical table. The machine will hold 160 bales (ten tiers), usually there will be cross-tiers near the centre to keep the stack from swaying or colasping if any weight is applied to the top of the stack. The full load will be transported to a barn, the whole rear of the stacker will tilt upwards until it is vertical. there will be two pushers that will extend through the machine and hold the bottom of the stack from being pulled out from the stacker while it is driven out of the barn
In Britain (if small square bales are still to be used) they are usually collected as they fall out of the baler in a bale sledge dragged behind the baler. This has various channels, controlled by automatic balances, catches and springs, which sort each bale into its place in a square eight. When the sledge is full, a catch is tripped automatically, and a door at the rear opens to leave the eight lying neatly together on the ground. These may be picked up individually and loaded by hand, or they may be picked up all eight together by a bale grab on a tractor, a special front loader consisting of many hydraulically-powered downward-pointing curved spikes. The square eight will then be stacked, either on a trailer for transport, or in a roughly cubic field stack eight or ten layers high. This cube may then be transported by a large machine attached to the three-point hitch behind a tractor, which clamps the sides of the cube and lifts it bodily.
A simple method of handling large and small round bales can be seen in the article Hay Delivery. This is a simple do-it-yourself modification to the tractor bucket. Two hooks are welded to the outside top of a tractor front loader bucket and a 14-foot (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 fancy expensive equipment which must be swapped back and forth on the tractor. 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 has less maintenance involved and is safer than bale spears and clamps.
Before electrification occurred in rural parts of the United States in the 1940s, some small dairy farms would have tractors but not electric power. Often just one neighbour who could afford a tractor would do all the baling for surrounding farmers still using horses.
To get the bales up into the hayloft, a pulley system ran on a track along the peak of the barn's hayloft. This track also stuck a few feet out the end of the loft, with a large access door under the track. On the bottom of the pulley system was a bale spear, which is pointed on the end and has retractable retention spikes.
A flatbed wagon would pull up next to the barn underneath the end of the track, the spear lowered down to the wagon, and speared into a single bale. The pulley rope would be used to manually lift the bale high up into the air until it could enter the mow through the door, then moved along the track into the barn and finally released for manual stacking in tight rows across the floor of the loft. As the stack filled the loft, the bales would be lifted higher and higher with the pulleys until the hay was stacked all the way up to the peak.
When electricity finally arrived, the bale spear, pulley and track system disappeared, replaced by long motorized bale conveyors known as hay elevators. A typical elevator is an open skeletal frame, with a chain that has dull 3-inch (76 mm) spikes every few feet along the chain to grab bales and drag them along. One elevator replaced the spear track and ran the entire length of the peak of the barn. A second elevator was either installed at a 30-degree slope on the side of the barn to lift bales up to the peak elevator, or used dual front-back chains surrounding the bale to lift bales straight up the side of the barn to the peak elevator.
A bale wagon pulls up next to the lifting elevator, and a farm worker places bales one at a time onto the angled track. Once bales arrive at the peak elevator, there are adjustable tipping gates along the length of the peak elevator. By pulling a cable from the floor of the hayloft, tipping gates can be opened and closed, so that bales will tip off the elevator and drop down to the floor in different areas of the loft. This permits a single elevator to transport hay to one part of a loft and straw to another part.
This complete hay elevator lifting, transport, and dropping system reduced bale storage down to a single person, who simply pulls up with a wagon, turns on the elevators and starts placing bales on it, occasionally checking to make sure that bales are falling in the right locations in the loft.
The neat stacking of bales in the loft is often sacrificed for the speed of just letting them fall and roll down the growing pile in the loft, and changing the elevator gates to fill in open areas around the loose pile. But if desired, the loose bale pile dropped by the elevator could be rearranged into orderly rows between wagon loads.
Usage once in the barn
The process of retrieving bales from a hayloft has stayed relatively unchanged from the beginning of baling. Typically workers were sent up into the loft, to climb up onto the bale stack, pull bales off the stack, and throw or roll them down the stack to the open floor of the loft. Once the bale is down on the floor, workers climb down the stack, open a cover over a bale chute in the floor of the loft, and push the bales down the chute to the livestock area of the barn.
Most barns were equipped with several chutes along the sides and in the center of the loft floor. This permitted bales to be dropped into the area where they were to be used. Hay bales would be dropped through side chutes, to be broken up and fed to the cattle. Straw bales would be dropped down the centre chute, to be distributed as bedding in the livestock standing/resting areas.
Traditionally multiple bales were dropped down to the livestock floor and the twine removed by hand. After drying and being stored under tons of pressure in the haystack, most bales are tightly compacted and need to be torn apart and fluffed up for use.
One recent method of speeding up all this manual bale handling is the bale shredder, which is a large vertical drum with rotary cutting/ripping teeth at the base of the drum. The shredder is placed under the chute and several bales dropped in. A worker then pushes the shredder along the barn aisle as it rips up a bale and spews it out in a continuous fluffy stream of material.
Industrial balers are typically used to compact similar types of waste, such as office paper, cardboard, plastic, foil and cans, for sale to recycling companies. These balers are made of steel with a hydraulic ram to compress the material loaded. Some balers are simple and labor-intensive, but are suitable for smaller volumes. Other balers are very complex and automated, and are used where large quantities of waste are handled.