Modern Tire Dealer

DEC 2018

Magazine for the professional tire industry

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Page 74 of 113

73 w w w . M o d e r n T i r e D e a l e r . c o m will give you the ability to properly distribute your machines weight for every season. Mark Turner, senior product market- ing manager, agricultural tires, Maxam International Inc.: Ensuring you are using the correct ballasting weight is not always an easy exercise, but ultimately it is one that is worthwhile. Unnecessary extra weight or not enough weight can both lead to higher fuel consumption as well as possible uneven tire wear and thereby increase input costs. Correct ballasting for field work is entirely about ensuring that slip rates are kept in the best window that allows optimum tractive efficiency and drawbar pull. Typical recom- mended rates of slip are 10-15% for 2-wheel drive tractors (2WD) and 8-12% for 4-wheel drive (4WD) or mechanically assisted 4WD tractors (MFWD). e best type and weight of the ballast should be assessed for each implement used and should be added to the front and/or rear to ensure optimum weight distribution between the two axles. e general recommendation for field work is to make sure that at least 20% of the total weight is on the front axle; this ensures good steering response and vehicle control as well as limiting the possibility of an adverse reaction between suspension systems and automatic draught controllers. For prolonged road work applications, a weight split of around 40% front and 60% rear should ensure good vehicle stability and control as well as ensuring that dynamic overload is not excessive when the vehicle is braking. It is also important to remember to alter your tire inflation pressures to suit the new load on the tires when weights are changed. Norberto Herbener , OE applications engineer, Trelleborg Wheel Systems Americas Inc.: For a tractor to perform at its peak capabilities and efficiency, consider the following points. 1. e first point is the correct weight and weight distribution that the tractor must have to transfer power with efficiency. As a rule of thumb, a correct weight ratio begins considering that between 100 to 120 lbs. per horsepower of the tractor is needed. erefore, a 300 hp tractor should weigh approximately 30,000 to 36,000 lbs. is weight will allow the tire lugs to penetrate the soil deeply enough to create optimum grip and acceptable tire-to-soil slippage. e best way to increase a tractor's weight is by adding solid ballast to the axles or on the tractor chassis. 2. e second point is weight distribu- tion. Once the correct tractor weight is defined, the distribution should be 50% on the front axle and 50% on the rear axle for 4WD. For a front wheel assist tractor, the distribution should be between 40-45% on the front axle and 55-60% on the rear axle. If the design of the implement creates a high load on the rear axle (reducing the load in the front axle), the ratio on front-wheel assist tractor should be closer to 45-50% in the front and 50-55% in the rear. For 2WD tractors the front axle should have between 25-35% of the total load. It is very important to measure this weight per axle with calibrated scales --individual per tire

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