Dennis Buckmaster. Agricultural & Biological Engineering. Agricultural & Biological Engineering

Transcription

1 Traction Improvement: Ballasting, Tires, & Inflation Pressure Top Farmer Crop Workshop, 2007 Purdue University Dennis Buckmaster Outline Perspective Ballasting Performance curves Tire selection Inflation Pressures 1

2 Perspective let me confuse you first Tire load affects slip Slip affects pull Axle loads change Pull determines speed Implement draft changes Perspective Draft of implement determines pull Pull alters load balance Load balance determines wheel reactions Wheel reactions alter slip Slip changes speed Speed affects implement draft 2

3 Perspective Key resource: Traction & Tractor Performance. Zoz & Grisso, An ASABE Distinguished Lecture Series paper, presentation, and spreadsheet model. How to read traction plots Efficient Pull Range Max TE Tractive Efficiency Ratio Net Traction Ratio, NTR Peak TE Travel Reduction Ratio Max Pull (slip limited) 3

4 On Magnitude what is 7 out of 70? Tractive efficiency affects Tire wear Fuel consumption Time for the work Machine time Labor timeliness 4

5 On Slip Some is good Optimal level depends on Tires Soil Controlled by Pull/weight ratio Tire selection & inflation Today s focus Excerpts from Zoz & Grisso,

6 Ballasting 1. Choose Tractor Type Getting the most from your tractor. Taylor, Shrock, & Wertz. MF-588. K-State Univ. MF588.PDF 2 Wheel Drive Front Wheel Assist 4 Wheel Drive 2. Identify rated tractor PTO power: 150 hp 3. Select operating speed: 6 mph 4. Select Implement Mounting Towed Semi-mounted Fully mounted RESULTS W/P ratio 94 lb/hp Total Tractor Weight lb Front Axle Percentage 60 % Rear Axle Percentage 40 % Front Axle Weight 8460 lb Rear Axle Weight 5640 lb Ballast Example 180 hp MFWD 5 mph towed implement 117 lb/hp (weight/pto hp) lb total 40% or 8400 lb front 60% or lb rear 6

7 Different soil conditions 1. Peak efficiency is different 3. Max pull is different 4. Optimal slip is 8 to 12% 2 P/W ratio is similar at peak efficiency Different tire pressure & load 1. Efficiency drops off with improper pressure 2. Lower pressure allowed higher pull 3. Higher pull was at lower slip 7

8 Different tire size (with correct pressure) 3. 10% boost due to tire selection 2. Little effect on max pull 1. Little effect on slip Different weight (tire load) & pressure 8

9 Inflation Pressure Best illustrated via example, same 180 hp MFWD 6 mph with towed implement 12,600 lb rear or 6,300 lb/tire R42 has capacity of psi 12,600 lb/axle with singles requires 15 psi Inflation Pressure Not to confuse you, but Same tractor, different make of tire Agribib 20.8R42 (520/85R42) has capacity of psi Pressure calculator considers speed (note more load on rear tires during field action) 14 psi recommended 9

10 Resources Ag Tire sites Dr. Bobby Grisso, VT Traction model with database NE test data database For a limited time only TFCW This presentation Ballast Assistant spreadsheet A couple related articles and documents 10