J Tractor model J Axle type J MFD Axle Reduction Ratio (if available) J Interaxle Ratio J Recommended Lead/Lag %

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Avis Stokes
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1 CASE IH Service Bulletin FILING INSTRUCTIONS Binder: AG EQUIPMENT BINDER Binder Section: AGRICULTURAL TRACTORS Mach Loc Code: Issued By: PRODUCT MANAGEMENT, RACINE, WISCONSIN, USA Page: 1 of 6 Document No.: EBT SB C/CX NTR SB MX NTR SB MG Supersedes: Date Issued: June 21, 1999 Family: C, CX, MAXXUM, MAGNUM Series Tractors Model: C50; CX50, C60, CX60, C70, CX70, C80, CX80, C90, CX90, C100, CX100, MX80C, MX90C, MX100C, MX100, MX110, MX120, MX135, MX150, MX170, MX180, MX200, MX220, MX240, MX270 Subject: SELECTING TRACTOR MFD TIRE COMBINATIONS BACKGROUND Dealers have been requesting information on how to calculate the correct MFD tire combination, especially if the combination is not listed in the price book. This bulletin is broken down into three distinct areas listed below. CI Terms, Definitions and Examples J What is rolling circumference and interaxle ratios J What is Lead & Lag J Measuring Rolling Circumference of worn/used tires J Lead/Lag Calculations examples R Worksheet J Determine interaxle ratio J Determine Front or Rear Tire desired J Determine Rolling circumference J Rear tire known and front tire needs to be selected J Front tire known and rear tire needs to be selected o Interaxle Ratio Chart I J Tractor model J Axle type J MFD Axle Reduction Ratio (if available) J Interaxle Ratio J Recommended Lead/Lag % Case IH is a registered trademark of Case Corporation Case Corporation. All rights reserved. Service bulletins do not constitute warranty authorization to update units. I

2 Page 2 of 6 o Terms, Definitions and Examples J Rollins Circumference & Interaxle Ratio Rolling circumference is the distance a tire travels in one revolution and plays an important role in the proper setup of an MFD tractor. With an MFD tractor both front and rear tires are driven and both do the work. Since the front tires are smaller than the rear tires, the front tires have to rotate faster to cover the same distance as the rear. This speed difference is accomplished mechanically using gear combinations referred to as interaxle ratios. The tractor manufacturer establishes interaxle ratios. Note: Tire manufacturers publish specification information that lists the rolling circumference of their tires. The same size tire built by different manufacturers may have different rolling circumferences, be sure to use specification information from the proper tire manufacturer. J Lead & Lag The relationship between the front and rear tires is referred to as Lead / Lag and is stated as a percentage. The tractor manufacturer establishes the range of Lead/Lag percentages that will provide the customer with acceptable front tire steering, front tire pulling performance and tire wear. Any tire combination that falls within this range is acceptable. Using tire combinations outside this prescribed range can result in inefficient front tire steering, poor pulling performance and accelerated tire wear. A neqative percentage represents a lag condition and a positive percentage represents a lead condition. L Best performance is achieved with a 0 to +3 % Lead/Lag ratio. The Lead/Lag ratio must always be between 0 to + 5%. J Measuring Rolling Circumference If tire rolling circumference specifications are not available or worn/used tires are being checked, the following procedure can be used to determine rolling circumference. During this procedure, the tractor should be equipped as it operates in the field (weights, tanks, etc.) and with the tires inflated to the correct pressures. 1) Mark the rear tire and ground with a reference dot or line where it touches the ground. 2) Drive the tractor forward so that the tire makes 5 full revolutions, so that the mark on the tire is at the same location, relative to the ground, as it was when you started. Mark the ground in line with the mark on the tire (measure on a hard level surface). 3) Measure the distance between the start and finish marks and divide by 5 tire revolutions. This will provide the rolling circumference of the tire. 4) Repeat this procedure for the front tire.

3 Page 3of 6 J Lead/Lag Calculations examples Lead/Lag percentages can be calculated using the following formula: RC = Rolling Circumference IR = lnteraxle Ratio ( RC front tire x IR ) - RC rear tire X 100 = Lead/Lag % RC rear tire Note: Small tractor tire sizes are used in the below example calculations. Example 1: Acceptable tire combination. 320/75R24 RC = 3310 mm, 18.4R30, R1 RC = 4658 mm ( 3310 x ) x 100 = % 4658 Example 2: Acceptable tire combination , R1 RC = 3174 mm, 16.9R30, R1 RC = 4455 mm ( 3174 x ) _- x 100 = % 4455 Example 3: Unacceptable tire combination, front tire is too small creating a lag condition , R1 RC = 3174 mm, 18.4R34, R1 RC = 4972 mm ( 3174 x ) x 100 = % 4972

4 Service Bulletin EBT SBC/CX , NTR SBMX , NTR SBMG Page 4 of 6 WORKSHEET HOW TO SELECT THE CORRECT TIRE COMBINATION IF ONLY THE FRONT OR REAR TIRE IS KNOWN THE PREFERRED LEAD / LAG RATIO MUST BE BETWEEN 0 TO + 5 %. A. Determine the interaxle ratio for your particular tractor model. (Note: refer to chart on the next page) B. Fill in the known rear or front tire size, brand, and design. Front Rear (Size) (Brand) (Design) (Size) (Brand) (Design) C. With a tire manufactures book determine the rolling circumference (RC) for that particular tire. NOTE: rolling circumference on the same size tire will vary from brand to brand. D. If the rear tire is known and a front tire needs to be selected go to step E. If the front tire is known and a rear tire needs to be selected go to step F. E. Rear tire known and front tire needs to be selected. Front tire RC for front tire lead / lag of 0 %. (rear tire RC) divided by (inter axle ratio) = Front tire RC for front tire lead of + 3 %. (rear tire RC) divided by (inter axle ratio) x (1.03) = Front tire RC for front tire lead of + 5 %. (rear tire RC) divided by (inter axle ratio) x (1.05) = Now use the tire book to find the tires that fall in to the acceptable range and select the one that best meets the customer needs. F. Front tire known and rear tire needs to be selected. Rear tire RC for front tire lead / lag of 0 %. (front tire RC) x (inter axle ratio) = Rear tire RC for front tire lead of + 3 %. (front tire RC) x (inter axle ratio) x (0.97) = Max rear tire RC for front tire lead of + 5 %. (front tire RC) x (inter axle ratio) x (0.95) = Now use the tire book to find the tires that fall in to the acceptable range and select the one that best meets the customer needs.

5 Page 5 of 6 R Interaxle Ratio Chart 0 / 6 0 / 7 0 MXI OOHC/l 1 OHC/ 1255 APL KPH Gearbox to APL KPH Gearbox to APL KPH Gearbox to +6 APL3054 Maxxum (Neuss) MFD Carraro to +5 Maxxum Hi-Clear Carraro to +5

6 Page 6 of 6 Tractor Model Axle Type Interaxle Ratio Recommended Lead/Lag % 84/85 ZF (APL 325 & AP to ) 95 Series Carrao to Carraro (707-STD to & D/8 3-piece Carraro to to / Kramer Mark MKI D/8 3-piece Carraro Kramer Mark II (MKI) +1 to to to (MKI) +1 to Carraro to Kramer to /1390/1490 D/B 3- piece to /1390/1490 Carraro (AE2) to Carraro (AE3) /7120/7210/7220 Dana to /7140/7150 Dana to /7240/ /7220 Dana (N.A. Only to Specialty Axle) 7230/7240/7250 Dana (N.A. Only to /8940/8950 Specialty Axle)

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