Yep, got another question about using my tractor. I've been dragging an 80lb steel I-beam around some new yard at the farm. It's where an old barn was removed this spring and final graded with a Bobcat. Now I just pull the beam around once a week to keep the soil loose until I drop seed this fall. On my old Craftsman you always had to run at full throttle because there was a fan that kept the transaxle cool. Is it the same with a tractor like the 758? I don't see any fans near the axle so I'm assuming it's ok. Also I read comments about how the hydro's produce plenty of torque at low rpm. What is the general rule with a machine like this?
Always full throttle?
sledmoonman
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It takes 4 times as much energy to double velocity.
Also you are not making the same power at lower rpms, at 1/2 the WOT rpms a 20hp engine might make 8hp.
Then there is the stress placed on things like rods and bearings are greatly reduced at lower rpms. Hard to quantify but a definate factor in engine longevity.
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It's a wet PTO clutch on an x7; you're doing more harm than good by engaging/disengaging at less than half throttle (due to clutch chatter).
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2,409 Posts
Getting a big kick out of this so far. I guess I should never start mine neither as it will be used wrong no matter what. :homer:
Auxiliary hyd and the hydrostatic transmission section are 2 completely different parts of the tractor.
Also, what's the guarantee that your neighbor has any idea what he's doing ? Ask to see his owners manual. Might be enlightening. :thThumbsU
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2,821 Posts
BRB...I'm gonna go out and light the REST of my tractors on fire now since they're all just going to overheat and catch fire no matter what RPM I run them. :hide:
Any of the potential abuses listed limit engine or componant life. It's always situational, but I'm sure the wfm member that hit 3600 hours on his owned since new 318 did not run WOT at all times. Mowing and snowblowing require it, dragging a cart around the yard does not, unless there is a struggle . It's a balance to find equilibrium, if your using the governor at partial throttle you need more, beyond that your adding wear and wasting fuel.
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Agreed. I only run wide open if I am mowing. I'm sure many more Onan powered tractors could make it to 3600 as well, but unfortunately when you consider what kinds of abuses these tractors are built for, it speaks for why they don't quite make it that long.
My uncle has mowed the same 7 acres with his 318 since it was new in 1986. Always runs it at half-throttle. Got about 2500 hours out of the original Onan engine and currently has about 2000 on the replacement Linamar engine which is in for a carb rebuild at the moment. He does take very good care of his equipment. I guess at half-throttle you get just enough of a balance between power and cooling (although I agree it would be much better at wide open). Now that I think about it, I'm surprised it hasn't overheated at half throttle due to all the brush, debris, and garbage that gets mowed over. It mows high nursery grass and brush every week...
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:sidelaugh:sidelaugh:sidelaugh
It's probably not overheated, but it is hotter then it otherwise would be if the the mower drags it down, but if. For me mowing only needs WOT to get a good finish to the lawn due to blade speed. My loader sits at 1/3 throttle, 3300 hours and counting, 400 on the linmar it was a mower tractor before repower and loader conversion. snowblowing is running cool and I think the highest load you can put on an engine, for extended periods. The delay before WOT there is warming the oil and hydro. I warm my tractor while shoveling the edges around my entryways in a couple minutes, then WOT, and out the door I go.
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15,211 Posts
I hate to break this news to the guys who like to run half throttle when mowin & puttin a huge load on the engine..
it is the OIL system that keeps the engine alive for 3000+ hours.. at half throttle (1800RPM) the oil pump is puttin out just half of what it does at WOT (3600 RPM)
at 3600 RPM the pump is puttin out more pressure.. this is what keepin the bearing surface off the crank.. YES it is a film of OIL that supports all the pressure of the rod..
reduce that pressure & the rod bearing can & will score the crank.. it will start this at the outer edges..
it is the OIL system that keeps the engine alive for 3000+ hours.. at half throttle (1800RPM) the oil pump is puttin out just half of what it does at WOT (3600 RPM)
at 3600 RPM the pump is puttin out more pressure.. this is what keepin the bearing surface off the crank.. YES it is a film of OIL that supports all the pressure of the rod..
reduce that pressure & the rod bearing can & will score the crank.. it will start this at the outer edges..
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Wow this turned to be quite confusing. Here's what I know. The transaxle on my tractor does not have a fan on it, so it's cooling is not directly related to engine RPM like my Craftsman was. I always use WOT when mowing or pulling heavy loads. I'll use my best judgment when driving it around, or doing simple light work. 2000 hours? Pfft, that will last me twenty plus years. I'll want a new tractor by then, or be dead...
Also as far as the grass seed. Yeah I got that covered. Thanks though. :fing02:
Also as far as the grass seed. Yeah I got that covered. Thanks though. :fing02:
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321 Posts
Your Uncle in smart, and that is why he has the 318 mowing all those years at 1/2 throttle or about. He doesn't know the word "abuse" like some!!!!!.
We old dudes know the difference between what is good for equipment or other gas operated motors. We don't abuse our highly expensive lawn equipment like the young one who abuse their gas operated equipment, wives, children, in-laws and others.
My 1999 JD 345 with 923 hours has never, never seen the insides of a John Deere dealer repair shop....and never will. At 2400 rpms (mowing range) it has 60 psi on the oil pressure gauge, and goes to 40 psi at idle. AH!, so good for a well kept lawn tractor.
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2,409 Posts
Happens often. Your fine, just use some common sense when using it. This question has only been asked a million times on here and I promise its a split on what's the right way. :fing32:
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321 Posts
I'm laughing so hard, I might hurt something. The oil pump doesn't have anything to do with RPM's. It runs off the crankshaft. And designed to pump oil at startup and beyond. My 1999 JD 345 at 2400rpms has 60 psi. Well enough to lubricate any parts in any type of engine.
Your automobile or truck wouldn't last two days if the oil pump was based on high rpms.
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10,548 Posts
My favorite is what RPM is best to shut the engine off.
Next is what RPM to warm up a diesel in subzero temperatures.
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609 Posts
Always a touchy subject, and always good for a laugh.
All I know is my 445's (same transmission as a new x7 series for this discussion) makes an unpleasant howl when I drive it under load at anything less than 3/4 throttle. So, it's always at WOT or at least close when the tractor's moving. The transmission sounds MUCH happier, and responds better. The hydraulics (FEL and power steering) also work much better at high rpm, when they get full flow and pressure.
I had a 425 (carb engine, similar to a new x710), that had well over 3000 hours on it, still ran great, pto clutch still perfect, transmission still strong. It was owned by a school and had the snot beaten out of it, but fluids always changed on time. The engine and tranny had never been taken apart, except the plastic cam gear replacement. Everything else was worn out, rusty, or broken, but the engine and trans were fine. Front end was so worn out you couldn't even drive in a straight line.
Now, my 140 seems perfectly happy to putter around at any engine speed. The hydro doesn't even groan under load at idle. Different machines act differently. There's not one common part between them, so why should they be operated the same way?
To the O.P.'s last point, your transmission does have a cooling fan. It's the same one that cools the engine radiator, because there is also a hydraulic oil cooler in there that cools the transmission oil. If your transmission is overheating, it will also cause the engine to overheat, and the temp gauge on the dash will go up to the red zone. FWIW, my gauge has only gone to the red zone once, and it was mowing on a hot dusty day and the radiator got clogged. A quick clean-out, and it was back to running cool as a cucumber.
All I know is my 445's (same transmission as a new x7 series for this discussion) makes an unpleasant howl when I drive it under load at anything less than 3/4 throttle. So, it's always at WOT or at least close when the tractor's moving. The transmission sounds MUCH happier, and responds better. The hydraulics (FEL and power steering) also work much better at high rpm, when they get full flow and pressure.
I had a 425 (carb engine, similar to a new x710), that had well over 3000 hours on it, still ran great, pto clutch still perfect, transmission still strong. It was owned by a school and had the snot beaten out of it, but fluids always changed on time. The engine and tranny had never been taken apart, except the plastic cam gear replacement. Everything else was worn out, rusty, or broken, but the engine and trans were fine. Front end was so worn out you couldn't even drive in a straight line.
Now, my 140 seems perfectly happy to putter around at any engine speed. The hydro doesn't even groan under load at idle. Different machines act differently. There's not one common part between them, so why should they be operated the same way?
To the O.P.'s last point, your transmission does have a cooling fan. It's the same one that cools the engine radiator, because there is also a hydraulic oil cooler in there that cools the transmission oil. If your transmission is overheating, it will also cause the engine to overheat, and the temp gauge on the dash will go up to the red zone. FWIW, my gauge has only gone to the red zone once, and it was mowing on a hot dusty day and the radiator got clogged. A quick clean-out, and it was back to running cool as a cucumber.
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3,860 Posts
I guess you didn't read post #2
You can't compare a mower to a car.A car at 10mph has more airflow for cooling.That's why it's "recommended" to run wot for airflow and cooling.Do I always run mine wot,no,pto engauged yes, 90 degree heat yes, 50 degress and no load or light load no.The other thing to remember is the higher rpm keeps the battery charged.
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If the function of the oil pump has nothing to do with RPM, could you please explain why your 345 has 60 psi at 2400 rpm and only 40 psi at idle? :dunno:
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