Heavy equipment machinery

The new Caterpillar G-series wheel tractor scrapers 621G, 623G, 627G, 631G, 637G and 657G have been improved to boost productivity and lower operating costs. The 627G, 637G and 657G tandem-powered machines have new electronically controlled scraper engines that incorporate dual power capabilities, just as the tractor engines do. Each of the new scrapers has a new productivity enhancing operator station, a redesigned scraper bowl with 10 percent more capacity, and the latest electronic monitoring system to simplify maintenance.

All G-series wheel tractor scrapers incorporate Cat’s EU Stage IIIa compliant ACERT Technology engines. The electronically controlled engines feature the Caterpillar HEUI fuel system and comply with current emissions regulations. Each engine is electronically integrated with an automatic planetary powershift transmission to provide maximum power to the cutting edge and high-production haul road speed. The engines ranging from C9 to C15 and C18 provide advanced electronic control, precise fuel delivery and refined air management for outstanding engine performance.

ACERT building blocks include:
Fuel delivery: The multiple-injection process introduces fuel into the combustion chamber in a number of precisely controlled "microbursts". Injecting fuel in this way allows for precise shaping of the combustion cycle. For optimum performance, the multiple-injection process can be tailored for different applications and engine sizes.

Air management: Advanced air management also plays a critical role in reducing emissions. Stage IIIa off-road engines include crossflow heads and wastegated turbochargers. Advantages of wastegated turbos include higher boost levels over the entire operating range resulting in better low-end performance and response. Crossflow heads improve breathing for optimized combustion.

Electronics: The "brain power" for ACERT Technology comes from Cat ADEM 4 electronic controllers. The Cat ADEM 4 can govern fuel delivery and other engine processes with incredible precision. Cat ADEM 4 provides the ability to link machine performance directly with the engine.

The 621G, the 623G and 627G scrapers all use the Cat C15 as the tractor engine. The dual horsepower engine produces net power 246 kW in lower gears and 272 kW in higher gears. Heaped bowl capacity is 17 m3 for 621G and 627G and 17.5 m3 for 623G.

The 631G, 637G and 657G scrapers use the C18 as the tractor engine. The engine in the 630s produces a net power of 345 kW in lower gears and 373 kW in higher gears. The engine in the 657G produces 421 kW in lower gears and 447 kW in higher gears. Heaped bowl capacity for 631G and 637G is 26 m3 and for 657G 33.6 m3.

The tandem-powered 627G and 637G now incorporate the Cat C9 scraper engine for peak performance and high productivity in self-loading applications. The C9 for 627G is a dual horsepower engine with 178 kW while loading and dumping and 198 kW on the haul and return roads. The loading and hauling engine powers 637G for are 198 kW and 211 kW. The 657G features the bigger C15 engine. Dual horsepower capabilities enable the scraper engine to produce more power in higher gear ranges for improved grade-ability and reduced cycle times.

Redesigned operator station enhances productivity
The redesigned operator station promotes efficient operation throughout the entire work shift. A new, adjustable Cat Comfort Cloth Seat includes adjustable armrests, and it swivels and locks in four different positions to provide the optimum operating position in the cut or on the haul. The seat suspension features a self-contained air compressor with a high performance air shock absorber. The revised steering column increases legroom.

The redesigned hood has sloped corners to enhance sight lines. The exhaust is located at the back of the hood for enhanced sight lines to the right of the machine.

The improved scrapers retain the single lever implement control, which combines the traditional three implement levers—bowl, apron and ejector—into one joystick. The operator can raise and lower the bowl and actuate the apron and ejector with the single joystick. On appropriate models, a trigger on the joystick controls the auger or the bail. The transmission hold and cushion hitch switches are incorporated into the joystick as well.

Bigger, stronger scraper bowl
The redesigned scraper bowl increases bowl capacity 10 percent for each machine. The new design also improves draft arm protection and load retention. The low profile design offers less resistance to incoming materials, and cellular construction adds strength and dent resistance to the bowl sides and floor.

The bulldozer ejection system provides constant spreading control while minimizing carryback. A spill guard on the ejector helps retain material and keep it from spilling onto the rear of the scraper.

Designed to reduce service time
The Electronic Monitoring System, EMS III, monitors machine status and provides real-time information to the operator. The system warns of any problems detected by the electronic control modules governing all major systems.

The Caterpillar Electronic Technician service tool easily accesses real-time and stored information through EMS III. The design allows a service technician to diagnose a problem quickly and easily.

Caterpillar has made a number of small changes to the scrapers to improve reliability, durability, and access for service. For example, the implement valve has been relocated from the tractor to the top of the draft tube on the scraper. The change eliminates several hoses and tubes that crossed over the hitch. The result is fewer hydraulic components and connections and improved access.

The G-series scrapers also feature grouped maintenance and service points for simplified routine maintenance. Fluid filters are all spin-on style with the exception of the main hydraulic filter. Spin-on filters decrease maintenance time and reduce the chances of system contamination.

Auger, elevator and push-pull arrangements
Each of the new scrapers is available with an auger system in the bowl, which gives the machine a self-loading capability in material that ranges from free flowing to rock. The auger lifts material off of the cutting edge, conditions it and spreads it evenly in the bowl. In addition, the auger minimizes the production of dust while loading material.

The 623G with an elevator is ideal for windrowing, blending material as well as breaking up vegetation in stripping operations. The elevator lifts material off of the cutting edge, carries it to the top of the elevator, and then dumps the material into the bowl. The operator has variable control of the elevator to match the speed of the elevator to the material conditions for increased productivity. In addition, the elevator reverses for spreading topsoil and unloading cohesive material. The single-pivot elevator design improves the load profile, which allows the machine to achieve consistent payloads.

The 627G, 637G and 657G are available in a push-pull configuration designed for two machines to assist each other when loading. The push-pull arrangement features a hydraulically actuated bail and cushioned plate bolted to the front of the tractor and a hook attached to the rear of the scraper. This arrangement allows a pair of machines to link together when loading. Typically, push-pull scrapers achieve high production and low cost per meter.

http://www.constructionnewsportal.com/construction_article.asp?ArticleID=62

If you agreed with the subtitle, you are rather mistaken. Quite, actually. As a matter of fact, some of the technology experimented with over 40 years ago makes today’s tractor technology seem absolutely stale by comparison.

Experimentation, from the most complex assembly to the most simple and mundane component, is as an integral a part of any farm tractor’s development as the drawing board design itself. The engine, transmission, PTO units, steering, brakes–you name it–of a production farm tractor, all of these went through the trial and experimentation process. Right down to the hidden brackets holding the dash in place. Whether the part was made in-house, or secured from an outside supplier, it went through the trial process anyway, to make sure it was thoroughly compatible with it’s companion parts. If a certain part cracked or fatigued due to a resonant frequency harmonious with part of the rotating or reciprocating mass of the drivetrain at a certain speed or RPM, the offending part/parts were tracked down and changed, modified, or even, in an extreme case, eliminated altogether, to correct the problem. Wear was detected, measured, and compensated for by alternate materials or metallurgical treatment processes. Tractors were abused on torturous test tracks to no end to expose hidden problems that would otherwise come back to haunt the manufacturer once the tractor began bouncing along in plowed fields. Severe ‘test-to-failure’ experiments unveiled problems that, if not otherwise detected, could have escaped the engineering department’s attention, and led to expensive recalls, and retrofits. Occasionally, something would still slip through the experimental detection process, and cause major problems, much to the embarrassment and resultant damage to the reputation of the company concerned. This tended to happen more during times of rapid technological advancement, and the push to bring new merchandise to production to keep pace with the competition. Some new engines and powershift transmissions of the late 50’s and early 60’s fell prey to this reduction in development time. Failures and recalls abounded. One tractor in particular was so bad, that an exchange program was initiated the year following it’s release, where the company gave the customer an entirely new tractor to mount the wheels and tires on from the returned one! This tractor was probably pushed by management through the development stage so fast it never was properly tested before it’s release to the public. Largely to the company’s subsequent regret, embarrassment, and expense. The experimental program of the development stage is there partly to avoid these humiliations. And to bring exciting new technological concepts into the light of day.

The late fifties and early sixties was a time of great excitement and upheaval the world over. The Cold War was at it’s anxious peak. North America was in love with the Kennedy’s. Rock ‘n roll was here to stay. The jet age was upon us, and everything else was trying to keep up. Automobiles sported fins, jet inspired hood ornaments, swept back mirrors, and wrap-around windshields, mimicking the aviation industry. Even missiles were imitated in hood ornaments and steering wheel centers. Yes, we were now not only in a jet age, but a NUCLEAR age. WWII had changed the world forever.

Attempting to keep pace with the rapid change was the agricultural industry. The need for higher quality feed for faster gains and higher milk production was being addressed through biological experimentation and modernized forage harvesting systems. Mechanization was making inroads into feeding systems, also. Farms were becoming fewer and larger. Available farm power was being over-taxed, and the need for more power, speed, and efficiency (remember the jet age?) was distressingly apparent. Well padded from the post war demand for tractors and equipment, the farm equipment industry began to experiment in earnest in the early-to-mid 50’s. The far-fetched experimental tractors the engineer’s fertile imaginations conceived, and their talented hands assembled, were to change the agscape for all time.

Many, many experimental tractors had been produced up until the time line of this article. Most were prototypes; the forerunner of an actual production unit. Some were tried and discarded as useless, unreliable, impractical, too expensive, or so far advanced that they would not be accepted by the consuming public upon release. That was the fiasco that befell the ‘before it’s time’ 1938 Minneapolis Moline Comforttractor project, and no agricultural equipment manufacturer wanted a repeat of that. The remainder of this subject is dedicated to those experimentals that, even built 4 decades ago, still encompassed some such radical technology that it is nearly too much for the public to grasp yet today.

1957 Ford Typhoon

The impressive Ford Typhoon of 1957 was powered by a free piston turbine engine, and boasted a full range powershift transmission. It also sported headlights faired into the hood, a hood scoop, and power steering. The powershift technology gleaned from this experiment was to manifest itself as the Select-O-Speed 10 speed powershift transmission in the 1959 Ford 601 and 801 tractors, and the hood scoop and Select-O-Speed transmission showed up together in the 1961 Ford 6000 model. The Typhoon may have been named after the sleek and imposing mid engine, fore and aft cockpit mahogany speed boat Edsel Ford built in 1929. Unfortunately I can’t produce any more in-depth information at this time about this wild and beastly looking tractor, such as engine manufacturer, HP, RPM, size and weight, etc.., but it is just too extremist to pass over. It does, however, appear to actually be liquid cooled.

The Typhoon’s radical free piston turbine engine

1961 International Harvester HT 340

A dramatic and stylish looking little tractor, the IH HT 340 featured a small turbine engine as it’s powerplant, coupled to a hydrostatic transmission. Common parts with the International 340 tractor likely gave this unit it’s denomination, thus: Hydrostatic Turbine 340. The turbine engine was produced by a subsidiary of IH, the Solar Aircraft Company. Weighing a Lilliputian 60 pounds, it produced a Herculean 80 horsepower. Running at a constant RPM of 57000, it required substantial reduction gearing before it’s coupling to the hydrostatic pump. A marvel of technology, even with the reduction gearing in place, the entire turbine/reduction unit still weighed in at only 90 pounds.

80 horsepower in a 90 pound package!

The tractor’s sleek, high visibility body work consisted of molded fiberglass panels. Obviously a lightweight unit, wheel weights are apparent at both ends to better utilize the capability of this little powerhouse. This tractor was displayed for the first time publicly at the 1961 Tractor Day at the University of Nebraska. It is now in the Smithsonian Institution in Washington. Although nothing tangible came of the turbine technology, which was deemed to lack enough fuel economy for practical application, the hydrostatic transmission technology was to appear in production in 1967 in the IH/Farmall 656 Hydro, and after, in other models of the line. High visibility body work, consisting mainly of a steeply sloped hood, has only in recent years begun to show up in new farm tractors.

1959 Allis Chalmers Fuel Cell Tractor

Departing from the lightweight 80 horsepower IH HT 340 above, this 20 horsepower tractor weighed 5270 pounds, and certainly required no supplementary weight. Here was power of a completely different type. The AC fuel cell tractor used an AC D-12 tractor chassis loaded with 1008 individual fuel cells, fueled by a mixture of gasses, but predominantly propane, which in turn created a current flow. This was channeled through to an Allis Chalmers 20 hp DC electric motor to propel the tractor. Each fuel cell was about one quarter of an inch thick, 12 inches square, and produced approximately one volt of output. In unison, the 1008 fuel cells made an output of about 15KW.

Unconventional, to say the least!

Using the controller at the operator’s left, the four banks of fuel cells could be connected in series or in parallel, thus varying the voltage reaching the DC motor, much like a throttle. Reverse was simply a matter of reversing the polarity of the current through the controller with the crank-like handle. AC was excited by their research, noting that their tractor was twice as efficient as others of the period, the power was derived from no moving parts, it produced no emissions, and ‘ran without a whisper’. Futuristic indeed, and the recent resurgence in interest in fuel cell technology, along with environmental concerns, could still make a fuel cell tractor a reality. This tractor is now in the Smithsonian Institute.

1954 Oliver XO-121

On the tamer side of the experimental tractors was the Oliver XO-121. The engineering department at Oliver was concerned about all aspects of tractor efficiency and operation. While not as futuristic as the power sources described earlier, the experiments of 1953-54 at Oliver were of a more immediately practical sort. The engineering department began experimenting with a simple gas engine, but radical for it’s type, to determine the optimum efficiency available from a conventional gasoline piston engine. Starting with a 4 cylinder Hercules Diesel block, they designed a cylinder head and pistons for it that yielded a 12-to-1 compression ratio. From this compression ratio came the tractor’s name: EXperimental Oliver-121. The completed engine had a 199 cubic inch displacement. Using a gasoline fuel specially formulated for it by the Ethyl Corporation, the XO-121 produced dynamic results, surpassing the similar displacement Oliver 70’s horsepower by an amazing 92 percent, along with a remarkable 35 percent increase in fuel economy. The XO-121’s engine was the subject of a 1954 American Society of Automotive Engineers paper titled, ‘Looking Ahead of Tomorrow in Tractor Engine Design’.

The XO-121’s fuel efficient power plant

Had Diesel powered tractors not made such advances into the agricultural industry, the lessons learned from the XO-121 research could very well have changed farm power for all time. The lessons weren’t in vain, however, as the technology was applied to future Oliver gas powered tractors, cumulating in the 1960 Nebraska testing of the high compression Oliver 1800 gas, which set a record of 13.18 horsepower/hours per gallon of gasoline, a record that still stands today. Originally donated to the Iowa State University for display, where it remained many years, the XO-121 was then in turn given to the Living History Farms, also in Iowa, where it was used-the ultimate goal of industrial experimentation: a usable product of new technology. The Oliver XO-121 is now on display in the Floyd County Historical Museum in Charles City, Iowa.

Oliver Tractor of Tomorrow

This tractor is right out of the Jetson’s TV program. A ‘concept’ tractor, much like the ‘concept’ cars displayed at automobile shows, this tractor sported such features as a nose mounted spotlight (may have ‘steered’ with the front wheels); a glass ‘bubble’ cab that shielded the operator from harmful UV rays; air conditioning, a cigarette lighter, radio, and two way radio; an electrically retractable mounting ladder (again, right out of the Jetson’s); an aircraft Straight Line indicator, and an automatic gate opener. Many of these features would still be considered ‘futuristic’ today.

Outlandish as some of these experimental tractors may seem, the fact that your current tractor may not be turbine or fuel cell powered doesn’t mean that some of the research that went along with these units hasn’t made it’s way into it. So much for looking back, now let’s look ahead; for the sixty-four thousand dollar question: what does the FUTURE hold in store?

http://www.antiquetractorstore.com/articles/artint207.htm

 A tractor is one of the most important investments that any homesteader can make. One of these sturdy, reliable "mechanical mules" will handle any job from tilling a field to yanking a fencepost, and can really ease the newcomer’s transition from urban to rural life ( or help the established farmer raise the productivity of his or her acreage).

Unfortunately, such vehicles cost money . . . often a good deal more than most folks (especially those who’ve just made their move back to the land) are able to afford. Even a medium-sized machine, for example, can easily set its buyer back $10,000 or more . . . and that price doesn’t even include the optional (but often necessary) equipment!

A few years back, however, several farsighted manufacturers realized that a different tractor market was developing . . . one that demanded equipment that wasn’t in line with what the established firms were offering. In short, while the "old guard" continued to design "bigger and better" machines (which had come to resemble construction equipment rather than tractors), the industrial innovators were busy producing smaller work vehicles with diesel engines, big machine capabilities, and lower prices.

Time has, of course, proven that the "little guys" did, indeed, know what a large segment of the public wanted, and the number of manufacturers of smaller workhorses has increased to meet that demand. This year, in fact, there’s a real "bumper crop" of "commonsense compacts" to choose from . . . and there may never be a better time to give the thought of purchasing a new tractor some serious consideration.
LITTLE IMMIGRANTS

As you may have guessed, these mini-machines are—for the most part—imported. In fact, tractors made in Japan alone are being sold (or will soon be available) in the U.S. under no less than 10 different company names! According to a recent issue of Implement and Tractor (the agricultural equipment dealers’ official handbook), Ford—in the past few months—has signed a marketing deal with Shibaura, while John Deere has teamed up with Yanmar, International Harvester with Kumatsu, White with Iseki, and Massey Ferguson and Allis Chalmers with Toyosha! These arrangements will really "fill out" the small tractor field already represented in North America by Kubota, Satoh, Bolens, Suzue, and Hinomoto.

Even the tiniest of the Japanese diesels (which vary in size from 12 to 17 horsepower) are in no way similar to the gasoline-driven, American-made garden and lawn units so common in suburbia today. Instead, the imports are faithfully miniaturized versions of standard-sized farm machines. They have no pretense of beauty, and their outsized drag rods, links, and lifts could even be called grotesque. . . but—pound for pound—the Oriental vehicles are outstanding performers. Most are available in either two- or four-wheel drive, with six forward and two reverse speeds, hydraulic lifts, standard (1-3/8") power take-off, Category 1 three-point hitches, and many other features previously available only on bigger machines. The small diesels can—with little or no modification—even accept a good number of the implements manufactured in the U.S. for the commercial farmer!
LIKE PEAS IN A POD

The specifications for small Japanese diesel tractors—within any given horsepower grouping—read like a checklist for purebred litter-mate pups. In the accompanying table I’ve compared four of the four-wheel drive, 15- and 16-horse-power models that are now available in this country. As you can see in that chart, the overall dimensions and weights of these vehicles differ by only a few inches and pounds.

In addition, all four of these Japanese models have vertical, water-cooled diesel engines (the Kubota with three cylinders, the others with two). Each of the tractors also offers differential wheel locks which (when combined with their four-wheel-drive capability) makes the machines just about mireproof . . . even in that sloppy swale out behind the barn. (In fact, such vehicles are actually used in Asia to plow rice paddies before those flooded areas are planted.) Even the forward and reverse travel speeds are nearly identical from one of the four imports to another, and the small machines can creep along at just over 1/2 mile per hour (slower than many full-sized machines, and an important safety feature when working steep grades) … or race to the barn ahead of a cloudburst at 6 to 8 miles per hour.

Of course, although the mini-diesels cost far less than full-sized machines, you still have to pay for the performance they offer . . . and there aren’t any runts in this "litter" in terms of price. The four small tractors range (on the East Coast) anywhere from $4,055 to $4,295. However, off-season discounts of up to 10% were offered by some dealers in January 1979 . . . and the increased competition in this new market should encourage promotional discounts throughout the rest of the year.
THE TEST OF TIME

If you’re interested in one of the new crop of imported mini’s—but just a little worried about buying from a "new" firm—take heart, because all four of the manufacturers that dominated the mini-tractor market last year (Kubota, Yanmar, Satoh, and Iseki/FMC Bolens) are established Japanese firms with excellent reputations and company histories that go back as far as 90 years! Therefore, it’s a safe bet that the agricultural machinery manufactured by these corporations will be part of our rural scene for a long time to come.
SMALL TRACTORS, BIG PERFORMANCE?

Last spring, when I sold off part of my land and trimmed my farming interests down to three acres of pasture and a half-acre cultivated plot, I traded my 10-year-old Massey Ferguson 135 in for a new 15-horsepower, four-wheel-drive Yanmar 155D. As you can imagine, I had a few misgivings about the deal. After all, the big Massey had built farm roads, bush-hogged acre after acre of overgrown brush, subsoiled pasture, and dragged half-ton logs out of the woods. However, since most of the heavy work around my place was long since done—and seeing as the MF-135 was in need of close to $1,000 in repairs and maintenance parts—I figured that the little machine would be a practical choice. My only real worry was about the kind of performance I could expect from the newcomer.
THE PROOF IS IN THE "PUTTING"

I soon found that the Yanmar’s rear-mounted, belt-driven mower did an excellent job of cutting anything from manicured lawns to standing corn, poke-weed, or small brush. The implement’s three blades are made of 3/16-inch steel, and the belt arrangement is well designed and has proven to be trouble-free. (However, when I "pushed my luck" by attaching a four-foot American-made bush hog, I found that this accessory was a mite more than the tractor could handle … an intolerable vibration developed, and front weights became essential whenever tight turns were attempted.)

Under normal loads, though, the Yanmar has a turning radius of 7-1/4 feet. . . or 5-3/4 feet if the brake is applied to the inside wheel while maneuvering. This short are allows the tractor to mow close to trees and shrubbery, and the machine’s light weight doesn’t compact or scar lawns in dry weather . . . even when agricultural (rather than turf) tires are being used.
ROTOTILLING RESULTS

The Yanmar (which, as I’ve said, is pretty much representative of the other small imported diesels) has enough power in first or second gear (low range) to operate a 42-inch rotovator to depths of seven or eight inches . . . when used on previously cultivated soil. Two passes with this attachment in place are enough to turn corn stubble into a well-tilled bed, while unbroken fescue and clover sod—even on clay loam—can be tilled by traversing the same area three times . . . and increasing the depth of the tines with each successive pass.

That hefty 42-inch rotovator doesn’t seem to strain my Yanmar, either … or cause the excessive engine lugging and smoking that would signal an overload. I am, however, cautious by nature … so I always try to use first gear when tilling, and have the tines turning before I lower them into the soil.

I do occasionally miss my old MF-135’s automatic draft control (which keeps the rotovator’s teeth at nearly the same depth regardless of the ground contour). But, when the area to be worked is fairly level, I don’t find the Yanmar’s lack of this feature to be a significant handicap.
GROUND SPEEDS

It seems that I use third speed (low range) and first speed (high range) on the mini more than any of the other forward gears . . . probably more out of habit than for any practical reason. My Yanmar has a rather abrupt "lurch" between these two gear ranges, which forces me to choose constantly between thrills and discretion. The other three little diesels offer a more gradual transition, however, with the Satoh proving to be the best of the bunch in this respect. (In fact. the Satoh’s slower maximum forward speed is adequate for all off-road work.)
NEITHER RAIN NOR SNOW …

Nothing short of heating the crankcase oil on the kitchen stove would get my ol’ MF-135 running on a frigid winter day. But the Yanmar (as well as the other mini-diesels) has a cold-start attachment that always gets us out of the barn.

On the Yanmar, this system preheats a small quantity of fuel in the air-intake manifold . . . while the other three models have "glow plugs" mounted directly in the cylinders.

And—just to be certain of the glow-plug arrangement’s ability—I drove to a nearby Kubota dealership when the mercury stood at a chilly 6°F. Sure enough, the Kubota B7100 (which had been standing out in the lot all night) fired up right away in the early morning cold.
LIFTING AND POST PULLING

My Yanmar has a lift capacity (at the lower link pins) of more than 750 pounds. However, this capability does decrease quickly when the load is placed further from the fulcrum (the point where the lower links attach to the tractor body). I’ve found that—using a standard boom—the lifting ability of my machine drops to about 300 pounds at a point four feet away from the link pins . . . and down to around 240 pounds when the load is seven feet out.

Unfortunately, wheel weights won’t solve this problem. With 240 pounds at the end of the boom, the tractor’s hydraulic innards emit anguished squeals as the burden clears the ground. The trick, of course, is to keep hefty loads as near the link pins as possible. All in all, I’ve found the Yanmar’s "strength" to be very impressive . . . considering that the tractor itself weighs in at just over 1,100 pounds.
WOOD HAULING

I knew I was taking a chance when I traded my MF for the smaller import, because I had no idea of how large a wagonload the Yanmar would be able to pull. Furthermore, bringing in firewood is a year-round job at my farm, and our woodlot is across a creek and at the bottom of a deep draw!

You can imagine how pleased I was, then, to discover that—in four-wheel drive (low range)—my spunky vehicle could easily haul a third of a cord of hardwood up a 12-percent loamy-surfaced grade. On those rare occasions when the ground is frozen to a depth of just a fraction of an inch, the Yanmar’s tires will tear through the frost and lose traction on the slick undersoil . . . but when the earth is thoroughly frozen (or completely thawed) the mini will really get its shoulders down and pull!
BLADE WORK

When plowing snow or grading, the little imports are limited by available traction more often than by a lack of power. I use a medium-weight, six-foot, rear-mount blade that I originally bought for my Massey Ferguson (the extra width over stock Yanmar equipment is an advantage when dragging or smoothing driveway gravel). The mini-machine usually grabs the ground well enough to handle this full-sized accessory, but the blade must be canted sharply when I want to dig out encroaching grass.
PROS AND CONS

Of course, there are a number of farm tasks that I wouldn’t ask my 155D (or any of the other three mini-diesels) to perform, but the small workhorses have a number of advantages on their side, too. For one thing, a mini-tractor marries the maneuverability of a gasoline-powered riding mower with many "true tractor" capabilities. Maintenance on the imports is far less costly than on large diesels, too, and transporting the machines in for service can be accomplished easily. Tire repairs are particularly convenient . . . since one person can easily lift a mini-tire into the trunk of his or her family car.

Admittedly, the initial purchase price for any of these four lightweights isn’t chicken feed, but few machines worth their salt are inexpensive these days. Furthermore, the mini’s still cost a whole lot less than do "normal" tractors, and they can handle most of the same jobs. . . albeit on a smaller scale.

In fact, the "baby diesels" are so much fun to operate that you might want to buy two . That way, while the rest of your family’s fighting over the first one, you can mosey over to the barn door and sneak off with the other!

http://www.motherearthnews.com/DIY/1979_March_April/The_Marvelous_Diesel_Mini_Tractors

Tractor tire chains come in many of the same models, styles, and designs as other tire chains. Depending on the size and brand of the tractor and tractor wheel, a variety of tire chains can be found.

Like most other types of tire chains, there are many different options available in tractor tire chains. The most popular choice, and the most widely recommended, is two-link spacing with an optional V-Bar. Two link spacing means that there is a cross chain every second side chain link. Basically, it has twice as many cross chains as the four-link spacing, which only has a cross chain every fourth side chain link. The extra chains provide for a more steady, smooth ride and more steering control. The optional V-Bar chains are extremely helpful on ice, hills, and other hard-packed conditions. While V-Bar chains are available in both two- and four-link spacing, they should not be used on pavement since they can damage the surface of the road.

Kubota Tractor tire chains are available in the basic two- and four-link chains. Kubota recommends using tire chains and wheel weights in icy conditions. Even when using tire chains, drivers should still drive at a speed slow enough to maintain complete control of the tractor at all times.

For farm tractors, dealers recommend duo-group cross tire chains. These chains are not connected in the middle, so the pattern does not fall between the tread bars. Duo-group cross chains are recommended for field work, deep tread, off road use, and hilly conditions, making them the perfect choice for farm tractor tire chains.

http://www.articlebiz.com/article/18031-1-choosing-the-right-tractor-tire-chains/