Green Tractor Talk banner

1 - 20 of 52 Posts

·
Premium Member
Joined
·
1,469 Posts
Discussion Starter #1
Genuinely curious about this...the PTO in lawn and garden tractors is supposed to be engaged under full or at least high throttle, whereas the PTO in SCUTs and larger tractors is only supposed to be engaged at idle.

Does anyone know what the difference is and why it is this way?
 

·
Premium Member
Joined
·
12,288 Posts
Most single cylinder lawn and garden tractors have a problem getting a deck started at anything other than full throttle (when cold). Most lawn and garden tractors use an electromagnetic clutch which isn't harmed by engaging at higher RPM. And as the other poster suggested I suspect the belts are more forgiving than gears (although I believe gear driven decks like on a X700 still suggest WOT engagement)
 

·
Registered
Joined
·
12,341 Posts
Most single cylinder lawn and garden tractors have a problem getting a deck started at anything other than full throttle (when cold). Most lawn and garden tractors use an electromagnetic clutch which isn't harmed by engaging at higher RPM. And as the other poster suggested I suspect the belts are more forgiving than gears (although I believe gear driven decks like on a X700 still suggest WOT engagement)
i forget what speed my x475 calls for-but i still will not start the pto-at WOT--maybe at half throttle-and then i have to play with the throttle to keep from stalling the motor. but after owning a farm tractor myself--and be around other farm tractors all my life-if i would of ever tried starting a mower, baler, or anything at faster than idle--whew-that would of been for the worst whipping i think i would of ever had-for pulling a stunt like that. just wasn't done--same way on my 2520 mcut-nothing on it has ever been started above a idle on it. till this spring when the pto-brake has failed to stop the pto on my 3pt spreader.
 

·
Super Moderator
Joined
·
5,112 Posts
The Deere Operator's Manual for the D100-series machines gives a hint:

"NOTE: Throttle lever should be at full throttle position before engaging mower to avoid stalling engine."

I suspect that if engine stalling wasn't a concern they'd tell you to engage at a lower RPM.
 

·
Registered
Joined
·
758 Posts
I agree with BigJim. I start my 314, 317 & 322 and let idle...1/2 throttle or less... for a few minutes, maybe 5. I then come back to about 1/4 throttle and engage PTO. The engine will slow down, sometimes sputter, and then come to rpm. I THEN go wot. Most clutches also have a braking function, so I disengage at 1/4 throttle also.

The reason: The PTO clutch does not engage 100% the instant you flip the switch...it will slip for a short time. The higher the rpm you engage it, the longer it's going to slip and the more it's going to wear. I bought a well used 314, ran it for 15 years mowing grass and blowing snow and only had to replace the coil because it shorted internally. The clutch surfaces showed wear, but had many years of life/use left. Bob
 

·
Registered
Joined
·
1,846 Posts
I personally think its most likely due to power required to engage the attachment, maybe a bit of operator ignorance coverage too, and Im sure it also depends on the type of system.
Any electromagnetic clutch will slip on engagement some. Tight belts generally dont.

On my 318, I NEVER engage the PTO at full throttle. Thats not good for clutches or attachments.
I usually am at 1/4 throttle or just above.
I do the same on my Exmark.

Sure the engines bog just a bit until the governor straightens them out, but better that than excessive wear on the PTO clutch.
 

·
Super Moderator
Joined
·
2,267 Posts
I like the comment about the gears slamming. Additional, the mass those gears are trying to get moving from a dead rest. ie...a brush hog...heavy blades that it has to get whipping around. Can't comment about a tiller or chipper as I haven't used one on mine.
 

·
Premium Member
Joined
·
12,288 Posts
It's odd that the operator's manuals for the X700-series manuals all say to engage PTO at full throttle and the manuals for SCUT/CUT tractors all say to engage near idle even though that both have similar gear driven PTO mechanisms.

It looks to me like they had the lawn and garden group writing the manuals for the X700 tractors.
 

·
Registered
Joined
·
2,729 Posts
It's odd that the operator's manuals for the X700-series manuals all say to engage PTO at full throttle and the manuals for SCUT/CUT tractors all say to engage near idle even though that both have similar gear driven PTO mechanisms.

It looks to me like they had the lawn and garden group writing the manuals for the X700 tractors.
Biggest difference is the much higher torque available from diesel at idle. Gasses just don't have it. Still I would engage as low as possible, regardless.

Sent from my SM-N910V using Tapatalk
 

·
Premium Member
Joined
·
14,751 Posts
When I owned a 425 , Harleys x595 , and now x738 all called for starting mower deck at WOT..

All the Sub's 2210, 2305, 1026r and now 1025r start mower deck or rear pto at IDLE.
 

·
Premium Member
Joined
·
12,288 Posts
Biggest difference is the much higher torque available from diesel at idle. Gasses just don't have it. Still I would engage as low as possible, regardless.
It doesn't seem to matter to JD. The owner's manuals for both gas (X739) and diesel (X758) say to "move throttle lever up to maximum engine speed" before engaging the PTO.
 

·
Premium Member
Joined
·
13,423 Posts
It's odd that the operator's manuals for the X700-series manuals all say to engage PTO at full throttle and the manuals for SCUT/CUT tractors all say to engage near idle even though that both have similar gear driven PTO mechanisms.

It looks to me like they had the lawn and garden group writing the manuals for the X700 tractors.
Probably the same group of morons that designed the 2018 ROPS :hide:

But seriously 1550 rpms is a hardly an idle IMO, or should I say pretty high.
 

·
Premium Member
Joined
·
13,423 Posts
I like the comment about the gears slamming. Additional, the mass those gears are trying to get moving from a dead rest. ie...a brush hog...heavy blades that it has to get whipping around. Can't comment about a tiller or chipper as I haven't used one on mine.
Tiller's are pretty smooth on start up, at least mine is, but that rotary cutter let's me know.
 

·
Premium Member
Joined
·
7,720 Posts
I start all my PTOs at as low of an rpm as possible. I had my used x485 several months before I got a manual for it. I was starting the PTO at about 1/4 throttle. I did see a need to start the x485's PTO at full throttle, no stalling, just a slight rpm drop. I also throttle down before disengaging any PTOs.
 

·
Premium Member
Joined
·
7,720 Posts
I like the comment about the gears slamming. Additional, the mass those gears are trying to get moving from a dead rest. ie...a brush hog...heavy blades that it has to get whipping around. Can't comment about a tiller or chipper as I haven't used one on mine.
My brush hog always starts out of balance. the swinging blades are never straight out before starting. The whole unit shakes until they swing out and balance. If you ever broke or lost a blade, you know it RIGHT NOW :flag_of_truce: :banghead:

My chipper starts very smooth. Basically a heavy round flywheel with equally spaced teeth bolted to it.

I do not have a tiller, but suspect they start smoothly too :dunno:
 

·
Registered
Joined
·
4,011 Posts
Genuinely curious about this...the PTO in lawn and garden tractors is supposed to be engaged under full or at least high throttle, whereas the PTO in SCUTs and larger tractors is only supposed to be engaged at idle.

Does anyone know what the difference is and why it is this way?

The difference is in the mechanism used to complete the connection. On a lawn tractor, listen to it when you pull up the little yellow knob. It goes "bang" as it pops in immediately as it is a electromagnetic clutch. It is either on or off, no in between. I used to cringe every time I did this on lawn tractors I owned. On SCUT's and above, there is no "bang" as it has a different PTO clutch that I believe is hydraulic. Anyway, it gradually makes contact, much like you releasing the clutch gradually on a gear shift tractor or truck. Think what would happen if you "dropped" the clutch on a gear shift tractor or truck and that is pretty much what happens on a lawn tractor PTO clutch. Remember the older tractors with the lever operated PTO? They used a clutch that you had to engage slowly, just the like the clutch on the transmission of a gear tractor or truck. So when you pull up the little yellow knob on your SCUT and larger, you are getting pretty much the same effect. The knob just engages a slow acting clutch.

Dave
 

·
Premium Member
Joined
·
12,288 Posts
The difference is in the mechanism used to complete the connection. On a lawn tractor, listen to it when you pull up the little yellow knob. It goes "bang" as it pops in immediately as it is a electromagnetic clutch. It is either on or off, no in between. I used to cringe every time I did this on lawn tractors I owned. On SCUT's and above, there is no "bang" as it has a different PTO clutch that I believe is hydraulic. Anyway, it gradually makes contact, much like you releasing the clutch gradually on a gear shift tractor or truck. Think what would happen if you "dropped" the clutch on a gear shift tractor or truck and that is pretty much what happens on a lawn tractor PTO clutch. Remember the older tractors with the lever operated PTO? They used a clutch that you had to engage slowly, just the like the clutch on the transmission of a gear tractor or truck. So when you pull up the little yellow knob on your SCUT and larger, you are getting pretty much the same effect. The knob just engages a slow acting clutch.

Dave
But X700-series tractors have basically the same transmission / PTO clutch drive mechanism as a SCUT yet the operator's manual for those tractors still instructs to engage the PTO at maximum engine RPM.
 

·
Registered
Joined
·
4,011 Posts
But X700-series tractors have basically the same transmission / PTO clutch drive mechanism as a SCUT yet the operator's manual for those tractors still instructs to engage the PTO at maximum engine RPM.

I have no familiarity with the x700 series. Does it go "bang" when you pull up the little yellow knob? If so it does not have the same PTO clutch mechanism as the larger tractors.

Dave
 
1 - 20 of 52 Posts
Top