I am new to the game here running a Volvo 970 with Mulcher with 17.5 Techking Snoplus tires and am having a lot of bounce between 5 and 6 mph.... Does anyone have any suggestions how to get this set up to alleviate the bounce during gravel road maintenance.... Thanks in advance Ed
We run 17.5s at 50-60 psi and go from there you might need more air with the mulcher hanging off I assume the tire are radials I can't find it in a quick search of the brand We have had plenty of tires especially off brand be out of round brand new I have been able to lift the machine and run them in the air against a block and be visibly not round and shake like all get out
Slow Down
I've never ran a machine that was smooth at 5-6mph. I run 6.3-7mph. I adjust that according to success. In regards to bounce. When the machine is bouncing you are going the wrong speed. You may be going too fast. You may be going too slow. But you are most certainly going the wrong speed. You can play with tire psi and change this a little. But each machine will have a speed at which it bounces. I make 3 passes on a gravel road. First two bring material to the center and run 6.3-7mph. Third pass is with blade straight to scatter material and run at 14mph. Your "perfect" speed may vary.
Certain speeds probably put it at a certain hertz (HZ) that causes the bounce. Just like some PTO attachments on a tractor can vibrate at a certain rpm but don't when sped up to the recommended rpm. Just a weird phenomenon.
I guess my problem is getting through the 5-6 mph to get to that 6.3 to 7 since when it starts bouncing, it just gets worse if i try and push through. There must be some opinions on how they should be set such as fronts slightly higher pressure due to added weight from mulcher, front drives 4 lbs lower then rear drives etc.... My example is not from any experience just the way I have set it(I know its not likely correct) but its where I have started... What I am looking for is suggestions that have been come to through experience (Which I have very little).... I did start high and come down in 2 to 4 psi increments with the rear drives and the fronts at the same pressure, and the front drives 3 to 4 psi less with little success. There was a point the other day that I could not go faster then 3 km/h as 4 brought on the bounce, however I tried it on a different road, and it wasnt half bad.... I know I have a lot to learn, and I appreciate the help that those who are willing to share... Its funny how some days things can work amazing, and then the next, I cant do a thing right.... My hats off to the pro's, grading properly is no easy task.... Thanks
Just seems like the nature of the beast, road conditions, material your pushing, the road your on, temp and humidity, and speed, sometimes its just your machine all plays a part, I have messed with tire pressure to try to help curb the bounce but in the end speed is what puts you in a bounce and speed will take it out of a bounce, Cat now has stabile blade that stops the blade from bouncing and leaving a print in your road, they do that with speed control while spreading, so Cat recognizes that speed causes bounce to.
When you have a washboard imprint in the road it is very difficult to get rid of. No matter where you have your pressures set at, the machine will still lope a bit when you drive over it. Extreme tire pressures will make it worse. We run 770G Deere's with 17.5 x 25 Michelin snow plus tires. Tire pressures at 36 psi for rear tires and about 28 to 30 in the fronts. We have Handy Hitch packers on the the rear, and only carry the plow harnesses on the front. the packers only affect things when you carry them, they do not affect ride when the are down in work mode.( Unless you put too much down pressure on them.) Our normal grading speed is 5 mph give or take a bit, depending on conditions. Keeping your rear tire pressures even is crucial. Having one rear tire even a couple of pounds high or low can cause a bounce. The rear wheels on each tandem are chain driven from a central point, and must both turn a exactly the same speed as each other reqardless of tire diameter. When I started running a grader, I was told (on a 2 pass road) to cut about an inch at the shoulder and spread an inch in the center of the road. To keep the bounce out, you need to have some part of the bladed grounded. Municipalities that insist that every bit of gravel needs to be spread over the road surface usually have poor quality road surfaces. When you try to spread too thick, the machine will tend to lope or worse yet, duck walk. Use your articulation, to keep your front wheels a bit toward the center of the road, and when making your second pass try to keep your front wheels a fair distance from the windrow you left on the first pass. I hope that some of this helps. I could type here all day, and many may not agree with my opinions. Don't get too frustrated. I was told by an old operator, that it takes 5 years to make a grader operator, and 10 years to make an expert Good luck
I'd guess running a grader is a continuous learning experience even if you've been doing it for decades.
You got that right, not sure what it would take to be a expert, but there seems to be one heck of a pile of them that never even sat in a grader, lol
Every day I learn something, sadly also every day I am running into things that had worked just fine the other day, but are just making a mess today.... In time hopefully I will have enough things in my bag of tricks when things are not working right, to change it up... Thanks Guys
Absolutely. I learn every day in the cab.
I'm not married to any specific method. Angle change, pitch change, speed change, articulation change. All these are adjusted daily and sometimes multiple times per day. When it's not working, change technique. Somewhere in there is the sweet spot.