Modern Tire Dealer

DEC 2018

Magazine for the professional tire industry

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Page 73 of 113

A G T i r e T a l k M T D D e c e m b e r 2 0 1 8 72 having to change weight distributions. e exceptions could be heavy implements on the three-point hitch or implements that place large loads on the drawbar such as rippers. ese lighten the front end and may require more front weight. ere are potential problems that can be discarded by the correct tractor ballast. If tractors are under ballasted, there is too much slippage; 5-15% slippage is considered in the normal range with 8% slippage considered optimum. Too much slippage effects fuel consumption, field operating time, and tire wear. Over ballasting also has a potential for problems. is can cause tire failures by tires slipping on the wheel, and lug cracking. It can also cause drivetrain problems, increase soil compaction, and reduce efficiency. James Crouch, national agriculture product manager, Alliance Tire Americas Inc.: It takes a certain amount of weight for a tractor to transfer one horsepower of energy from the engine to the ground — figure 130 to 140 pounds per PTO horsepower for front-wheel assist (MFWD) tractors and 95 to 110 pounds per PTO horsepower for 4WD tractors. at oen requires a little extra weight, which is called ballast. If you have too little weight, your tractor isn't working as efficiently as it should. Your slip increases and you just aren't getting all the power you paid for when you bought that machine. If you have too much weight, your soil compaction increases and your fuel efficiency can be reduced. And if the weight is poorly balanced, you can lose efficiency and experience power hop. Liquid ballast in the tire is a popular way to add weight to the tractor. However, we design tires to be filled with air, not liquid. So when you add liquid to a tire, you're reducing the tire's flexibility and performance, and deforming the shape of the tire. at can lead to irregular wear in the center of the tread, a harder ride, and significantly reduced sidewall flex. From a performance perspective, you're turning a radial tire back into a bias. e bottom line is that if you've paid good money for horsepower, proper ballast is essential to make sure you're getting your money's worth. And if you've invested in radial tires, that ballast should really be achieved with cast iron weights so those tires can perform the way they were designed to. at way, you get the most out of your tractor and your tires. Harm-Hendrik Lange, agriculture tires field engineer in North America, Continental Tire the Americas LLC: e right ballasting for tractors depends on many factors. Generally speaking though, the tractor should be as least ballasted as possible, if the ballast is not really needed. Each pound that needs to be moved forward needs energy during acceleration, creates more energy during braking, creates a longer stopping distance on average, and creates more soil compaction during operation on wet soil conditions. However, there are certain applications and operations where ballasting is needed and reasonable. ose situations can be clustered in two main topics: 1. to prevent an unbalanced situation on the tractor, e.g., when working with a heavy front loader and adding ballast in the rear hitch or on the rear axle, or when using a front ballast as a counter weight for a heavy rear hitch. With higher loads on one end, the maximum speed may be reduced for both the axle and the tires. 2. to make the tractor heavier to transmit more force to the soil, e.g., for implements with lower working speed like a plow where the operational speed is less than 6 mph. Here, all the engine power is transformed into a high torque on the axles, which means high forces in the contact patch between tire and soil. In this instance more weight means better grip for force transmission to the ground – so basically the weight supports the tire. David Graden : operational agricul- ture market manager, Michelin North America Inc.: Depending on the machine's use, improper ballasting will cost more time and money than most would expect. At Michelin, we strongly encourage producers to work towards proper weight distribution of their machine. is should be an all-encompassing solution to maximize traction (which reduces slippage and soil compaction), torque, and fuel efficiency, minimize power hop and road loping, and overall productivity. Further, it is very important to keep in mind each task and corresponding imple- ment can require different ballasts and tire pressure recommendations. For instance, a front-wheel assist machine requires about 120 lbs. per PTO horsepower at 6 mph to fully transfer the torque. Additionally, of the total machine weight, 35% should be on the front axle and 65% should be on the rear axle. Let's say you add a hitch mounted strip till on the back. Now, you have to take into account the weight of the implement, while working in the field, and adjust your ballast weights and air pressures accordingly. Finally, this change only occurs a handful of times per year. Investing in ballast weights that allow you to change quickly and easily CONTINENTAL TIRE'S RECOMMENDATIONS ON PROPER BALLAST Situation Advice Trailer work, spraying, fertilizer work, and crop carrying Try to keep the tractor as light as possible and only use counterweights if needed for re-balancing the vehicle Heavy soil work (till- age, plowing, cultiva- tor work) Use ballast if needed – if during soil work your slip rate exceeds 20%, try to add ballast stepwise and observe how the behavior of the vehicle changes All work – sometimes it is possible to keep a light ballasted status as a compromise This is more so the case if you have less transport work and maximum speeds below 22 mph, because the ad- ditional fuel consumption for the ballast is quite low Easy to attach weights With easy to attach weights for front hitch (or rear hitch for front loader operation), you can easily attach the weight only for the operation when you need it "LESS TRACTION EQUALS HIGHER SLIP, MORE FUEL CONSUMED, GREATER SOIL COMPACTION, ROUGHER RIDE, AND ULTIMATELY A VERY NEGATIVE EFFECT ON YIELD." DAVID GRADEN, MICHELIN NORTH AMERICA

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