Mowing How long do your drive belts last?

[ruffdog]

These are not designed like your car. The mowers have governed speed limiters. Full throttle on your mower is not "wide open" like putting your foot to the floor of your car. Your mower may very well be running harder at 80% than it is at 100% because it must do the same work at a lower rpm. Your throttle setting is just setting the engine speed, not how "open" your intake is or diesel pump output. Your governor does that to maintain the selected rpm.

 

[daugen]

Thanks Ruffdog, but so does my Kubota diesel, but I still won't run it at full rpm.
Why is my diesel lawn mower any different than my tractor?
I'm running the lawn mower at the equivalent of pto speed of the tractor.
I guess we are going to agree to disagree here.
I have 35 engines to tend to; if I had ever had a failure or a problem, I would be so guided.
But I haven't.

 

[daugen]

in hindsight I think I reacted pretty strongly to what BuickandDeere said. Overreacted perhaps. My apologies.
I've been a motorhead for over 50 years, take very good care of my equipment, it's my hobby... ,and for sure understand what lugging an engine means and does.
And if I had been lugging the engine, BuickandDeere would be right.

I always push the throttle all the way to the end, and then bring it back to where the engine note changes. Sure wish garden tractors had tachometers like my tractor.
So I am running somewhere between 80 and 90% throttle, usually closer to 80. And if the grass looks extra thick from lots of rain, I push the throttle up a little bit more, but never ever full throttle. Yes, I understand that is likely governed at 3200 on a 3600 rpm engine. So technically one can't over rev. But you can sure use a lot of fuel at full power. Might be cost effective to a farmer trying to minimize time in the field, but completely unnecessary for a retired guy like me mowing his lawn. A 24hp Yanmar diesel pushing a 60 inch deck has plenty of reserve power.

with sharp blades I bet the cut is better at 12K speed than dull blades at 18k. I can tell they are sharp because the sound is like shredding lettuce, distinctive.
And if the spindles were rotating at approx 3000 rpm at max speed, so they rotate at 2500 rpm at slower speed. Not enough of a difference I'm sure to affect the belts or bearings long term. So I'm not slowing down for that, I'm slowing down to save fuel and for a little less noise. But if I ran at 50% throttle, you bet, likely not very good for the mower, though diesels are pretty tough.

I wonder who has the oldest still operational belt?
my first thought was someone with an old gas powered washing machine, maybe an old pump.

 

[Turbys_1700]

Daugen, my NH 1720 was rated at 23.5 HP at the PTO. This was at around 2250 RPM's or so. The max RPM was rated at 2500. I always tried to keep it at the 540 mark on the tachometer. My new Workmaster is rated up to 2600 RPM's and the 540 PTO speed is set for around 2300 to 2400 RPM's. I can't remember the exact number. One thing that is nice about it is the digital RPM read out. I can get it exactly on 540 RPM's. You can pretty much memorize the engine speed and get within a 100 plus or minus. So in essence you are hitting real close to the 540 RPM mark.

As far as belts go, I ran a Land Pride 5' rear finish mower for 14 years averaging around 70 hours per year. Replaced the belt one time. So far I've run a PRD 7200 Woods going on 9 years with the original belt. Messicks has a price of around $75 for it. Don't know what it's made out of but it has been real dependable. I would think that your 1000 hour mark estimate is pretty accurate. I keep my deck clean and have never replaced a bearing or idler pulley in either unit. Perhaps I'm lucky. I am a grease fanatic.

 

[buickanddeere]

Does the operator's manual say to cut grass at part throttle or full throttle ?

 

[ruffdog]

In the operators manual for the GARDEN TRACTOR mower deck it states the tractor should be at full throttle. It is how they are made. I don't run my big tractor at full throttle either but you are trying to compare apples to oranges.

 

[Turbys_1700]

Does the operator's manual say to cut grass at part throttle or full throttle ?

My operators manual states to run my tractor at 540 RPM...
Does not say anything about throttle...
I'm talking about a tractor...
Every post I have seen you respond to is confrontational...
Why?

 

[daugen]

In the operators manual for the GARDEN TRACTOR mower deck it states the tractor should be at full throttle. It is how they are made. I don't run my big tractor at full throttle either but you are trying to compare apples to oranges.

comparing a gas air cooled zrt to a water cooled diesel tractor, YES, apples to oranges. Comparing a water cooled diesel garden tractor to a diesel CUT, I really don't see the difference. Mfg's want you to run gas zt's full blast because they assume you won't keep the airways clean and you need all the air you can possibly get in there, more rpm equals more air. And because they don't want you to complain that your quality of cut isn't any good when you are mowing at 10mph, they have to set a performance standard for the engine that will handle all conditions. Mower makers don't care how much fuel you use, that's your problem, they just want the mower to cut nicely at least as long as the warranty. Remember this is the same industry that has foisted non greasable bearings on us that my local dealer says typically fail within five years. Wonderful repair business. So my feeling is the full throttle setting as stated in many operator manuals is a guide for what to use to maximize performance of the mower. Not to make it last longer. I just don't need to live life at the max.

My JD X750 is a "little" tractor, a SCUT wannabe, and while I didn't have the need for it, could have been equipped with rear pto, three point hitch, just about everything my big tractor has.
I also think the same issues apply to the commercial mowers JD and Kubota put out, the expensive diesel ones with out front mowers. My older brother has had a Kubota diesel front mount mower for almost twenty years, runs at below full throttle and has had zero problems with it. All I can do is report what I have seen with my own eyes. Your experience may vary and if so, it's just as valid.

My late uncle used to have a Honda Civic with a stick that he would shift into fifth gear before he got to 30mph. How that car lasted, how the engine or trans bearings didn't just leap out of that car, none of us knew. He lugged that poor engine so bad we all cringed. After he died, a relative has now driven the car for another ten years, no longer lugging it, but without problems. That engine was lugged so bad I sure wouldn't have wanted it and I completely agree with BuickandDeere that lugging is bad news.

The operators manual on my car demands that I change the brake fluid every two years. I wonder if anyone who owns this model does that. I just changed mine, glad I did due to accumulated moisture content, but unlikely to do it again for another five years. So I think some of these things can be a little flexible.

 

[4570Man]

I run my mowers including my liquid cooled diesel one at the recommend RPM. The cut quality suffers otherwise. I'm really not worried about engine life. Those little diesels way outlast the rest of the mower. I have had zero problems out of my front mount mower running it hard. Those mowers are just build like tanks. The previous owner managed to crack the transmission case, but I'm guessing that didn't have anything to do with how many RPMs he ran it. I have only had to replace 1 blade spindle. That was a greasable spindle on a JD mower that was greased religiously.

 

[daugen]

Perhaps I'm lucky. I am a grease fanatic.
me too, though buying green grease for my JD seemed a bit much to me...
Just hooked a new air grease gun to my barn compressor and frankly it makes greasing fun.
This coming week I tackle the FEL zerks; pup pup pup pup

My LP finish mower has shields that almost totally block off outside dirt from getting in. I still take them off once in a while and blast out what's in there, but it's nothing like what accumulates under the JD garden tractor mower shields. Surprising amount of junk gets jammed under there, in the pit around the pulley. Seems like they could design that better; they leave it open enough to get an air blast gun in, but open too much to keep the dirt and grass out. It's all one form of abrasive or another so it can't be good long term for belts.