geared tractor operation question

[ericm979]

This property I bought came with a Deere 5105, which has a pretty basic gear transmission- sycnros only between low range and reverse. I'm going to do some mowing with a rotary cutter. I've driven manual transmission motorcycles, cars and trucks quite a bit but my tractors have been HST. So I have a question:

when you're running a PTO implement do you 1. raise the rpms to PTO speed 2. slip the clutch to get the tractor moving. Or do you use the foot throttle to get just enough rpms to get in motion, like you would with a manual transmission car or truck, and then raise the rpms to PTO speed as you're moving?

 

[Sawyer Rob]

I use option two, with all of my gear drive tractors.

SR

 

[rangerfredbob]

I wing it, mine has a single clutch but I usually engage everything low rpm and up it afterward... mine isn't synchronized but I have the timing figured out where I can shift in motion anyway... just not reverse but I do go up and down gears occasionally...

 

[rScotty]

This property I bought came with a Deere 5105, which has a pretty basic gear transmission- sycnros only between low range and reverse. I'm going to do some mowing with a rotary cutter. I've driven manual transmission motorcycles, cars and trucks quite a bit but my tractors have been HST. So I have a question:

when you're running a PTO implement do you 1. raise the rpms to PTO speed 2. slip the clutch to get the tractor moving. Or do you use the foot throttle to get just enough rpms to get in motion, like you would with a manual transmission car or truck, and then raise the rpms to PTO speed as you're moving?

For mowing or tilliing, It depends a bit on if you have a fully independent PTO with its own clutch, and whether the implement needs to start cutting immediately or if you can accept a partial cut for the first ten feet. And it also depends on how hard the blades are going to have to work to cut whatever it is that you are cutting. There's no way to know all that until you begin to cut. Then you will know very quickly.

Our PTO tractor is a 1957 two-cylinder 30 hp model 530 John Deere. Not as modern as your 5105, but proabably not all that different either. Even those old JDs had some surprisingly modern features - power steering, fully independent PTO, good lights, comfortable seat suspension...and such. Like most Ag tractors, It has separate independent engagement for the PTO. What I'm saying is that the PTO clutch and the transmission clutch are completely separate and either can work independently of the other. Usually I will engage the implement at low RPM and bring it and the engine up to speed while also slipping the PTO clutch. Once the implement is spinning well I will lower it and then begin to engage the transmission clutch so that we can move off doing work right from the start.

Suppose I am bush-hogging saplings, and tall grass, and for some reason need to start was close as I can get backed up against a fence line. Since I want the PTO to be up to speed when it starts to cut the thick stuff, I'll engage the PTO while using the 3pt to hold the bush hog a little bit above the height I plan to cut. Then I'll engage the PTO clutch, rev up engine and the implement's slasher blade, and lower the hog down to operating height. I wait a moment for the dust and cuttings to clear and to make sure that all is working well...which means I didn't hit any rocks or old fence posts that might have been there. If all is good, I'll leave the PTO spinning at full speed, engage the transmission clutch, and move off making a nice even cut right from the beginning.

Every time is different. I like to have the PTO spinning right from the start.

REMEMBER: The PTO drive shaft MUST HAVE either shear pins or a slip clutch in the PTO drive line.
And the PTO also MUST HAVE an over-running clutch. It simply isn't worth risking your tractor and implement to operate without those things.

Like plowing, PTO work is very satisfying. It's what tractors were made to do.
rScotty

 

[ptsg]

Foot throttle is your friend. No reason to slip the clutch to death at high RPMs.

Turn the PTO on, select your preferred gear, release the clutch and increase RPMs with foot throttle. At the end of the run, if you need to change directions, simply let it coast down, change from forward to reverse and vice versa as needed and increase the RPMs again with the foot throttle. This if you're doing short runs.

For long runs, start at idle and just increase RPMs with the hand throttle and at the end just do the foot throttle thing to change directions and you're good to go with minimal clutch slippage.

EDIT: Added a little example of how I do in constant direction changes.

 

[LouNY]

Depending upon what I'm doing if I need the pto at rpm I'll bring the engine speed up after engaging the pto then engage the clutch. It will slip slightly but I'm engaging it rapidly after it starts to pull so it has minimal slippage.
I very seldom use the foot feed throttle, I prefer the hand throttle and leave it set were I need it if, if for some reason I need or want more speed for just a bit I may over ride with the foot feed.

 

[SPYDERLK]

...Snip...

Every time is different. I like to have the PTO spinning right from the start.

REMEMBER: The PTO drive shaft MUST HAVE either shear pins or a slip clutch in the PTO drive line.
And the PTO also MUST HAVE an over-running clutch. It simply isn't worth risking your tractor and implement to operate without those things.

Like plowing, PTO work is very satisfying. It's what tractors were made to do.
rScotty

Hi! Could you develop your thinking as to why a PTO MUST have an overunning clutch? There are some old platforms where load inertia can drive the wheels that I understand "must" would apply, but otherwise?

 

[rScotty]

Hi! Could you develop your thinking as to why a PTO MUST have an overunning clutch? There are some old platforms where load inertia can drive the wheels that I understand "must" would apply, but otherwise?

Sure. Just like you say, it's all about inertia/momentum... or spinning anything heavy and fast.

When the PTO is powered up and doing it's normal job of spinning the implement, all the forces in the PTO transmission are pushing in one direction. The dogs of the overrunning clutch is fully engaged & everything is sweet.

But when the power to the PTO is suddenly reduced for any reason, the stored momentum in the spinning implement tries to turn the PTO transmission shafts in the opposite direction. Like you say, that can drive the tractor wheels and cause an exciting ride for a few feet. But also, reversing the forces like that puts a twist into the PTO shafts as it reverses the loads on the gears.
When you add an over-running clutch into the drive line all this is prevented. The over-running clutch just disengages in that direction and the momentum of the implement cannot drive the PTO transmission backwards.

So what happens without an over-running clutch? Well, without one it's probably better to slow down gradually, and even let the momentum drive the wheels to soak up some of the forces that way. All of that is better than chopping the throttle and then riding the brakes. That risks the twisting forces breaking a shaft or gear.

Either way works. But best way is to just lift the implement while reducing the throttle, and let the over-running clutch do whatever it needs to do while the implement spins down.
Hope this Helps.
rScotty

 

[LouNY]

Sure. Just like you say, it's all about inertia/momentum... or spinning anything heavy and fast.

When the PTO is powered up and doing it's normal job of spinning the implement, all the forces in the PTO transmission are pushing in one direction. The dogs of the overrunning clutch is fully engaged & everything is sweet.

But when the power to the PTO is suddenly reduced for any reason, the stored momentum in the spinning implement tries to turn the PTO transmission shafts in the opposite direction. Like you say, that can drive the tractor wheels and cause an exciting ride for a few feet. But also, reversing the forces like that puts a twist into the PTO shafts as it reverses the loads on the gears.
When you add an over-running clutch into the drive line all this is prevented. The over-running clutch just disengages in that direction and the momentum of the implement cannot drive the PTO transmission backwards.

So what happens without an over-running clutch? Well, without one it's probably better to slow down gradually, and even let the momentum drive the wheels to soak up some of the forces that way. All of that is better than chopping the throttle and then riding the brakes. That risks the twisting forces breaking a shaft or gear.

Either way works. But best way is to just lift the implement while reducing the throttle, and let the over-running clutch do whatever it needs to do while the implement spins down.
Hope this Helps.
rScotty

Good answer but you missed one very important fact.
With an over running clutch installed on pto implements that have a lot of stored momentum these tractors with independent pto are using the built in pto brake to stop the pto turning. Those brakes can be very expensive to repair/replace. Many implements may have one built in, except one of the more common ones used here the brush hog.

 

[rScotty]

Good answer but you missed one very important fact.
With an over running clutch installed on pto implements that have a lot of stored momentum these tractors with independent pto are using the built in pto brake to stop the pto turning. Those brakes can be very expensive to repair/replace. Many implements may have one built in, except one of the more common ones used here the brush hog.

Well, about we can do with PTOs is offer some general principles. There is no standard for how they are designed and controlled. Tractors are individualistic that way.

For the PTO, some tractors have an over-running clutch, with or without a slip clutch or brakes built into the tractor. Many makes rely on some of these being added into the PTO driveshaft. I assume the operator has an idea, or if not we try to tell him what we look for ourselves.

There are also different types of PTOs - like the transmission driven versus a couple of different types of independent ones... Two stage clutches are in some and independent clutches in others. So not all have the same sort of engagement or clutching.

But they all do the same job and have the same things that a person just starting out should look for.
rScotty

 

[DK35vince]

Option 2.
Take off easy then throttle up.
No reason to slip the clutch

 

[ericm979]

From the owners manual and the parts diagram it looks like the 5105's independent PTO does not have an overrun clutch or a brake. I'll keep that in mind while operating it.

 

[ptsg]

From the owners manual and the parts diagram it looks like the 5105's independent PTO does not have an overrun clutch or a brake. I'll keep that in mind while operating it.

Which means the implement won't affect the driving part of the tractor, like how it happens with transmission driven PTOs where it pushes the tractor even with the clutch pedal pressed. You don't really have to worry much about it.

 

[DK35vince]

Which means the implement won't affect the driving part of the tractor, like how it happens with transmission driven PTOs where it pushes the tractor even with the clutch pedal pressed. You don't really have to worry much about it.

Haven't even transmission driven PTO's had internal over run clutch's to solve that problem since the 1950's or 60's.
Far as I know.
My previous tractor (1978 John Deere 850) had a transmission driven PTO. Had an internal over run clutch.
Pto mowers pushing the tractor through the drive line was a non issue, and has been for decades that I know of.

 

[ptsg]

Haven't even transmission driven PTO had internal over run clutch's to solve that problem since the 1950's or 60's.
Far as I know they have.

Nor the Kubota B7000 I had or the little Agria I have now have those. Both were from the 70's.

 

[DK35vince]

Nor the Kubota B7000 I had or the little Agria I have now have those. Both were from the 70's.

Thats what I thought.
The problem of pushing a tractor through the PTO driveline was pretty much solved on most all tractors made for the past 60+ years.

 

[ptsg]

Thats what I thought.
The problem of pushing a tractor through the PTO driveline was pretty much solved 60 years ago.

Sure but there were still made plenty of tractors made without internal overrunning clutch well beyond that time frame.

 

[DK35vince]

Sure but there were still made plenty of tractors made without internal overrunning clutch well beyond that time frame.

Yes they did over 60 years ago.
If you have a tractor from that era it could be an issue.
But the original posters tractors was made from 2000-2007

 

[Quebecguy]

when you're running a PTO implement do you 1. raise the rpms to PTO speed 2. slip the clutch to get the tractor moving. Or do you use the foot throttle to get just enough rpms to get in motion, like you would with a manual transmission car or truck, and then raise the rpms to PTO speed as you're moving?

Eric, I have a 5205 which is basically the same tractor as yours with just a bit more power. When I am bush hogging I engage the PTO by moving the big lever when the tractor motor is idling and the bush hog is up off the ground a bit. Once the PTO is engaged and the bush hog blades are turning, I lower the bush hog, bump the revs up to PTO speed by use of the manual throttle and then let the clutch out normally to drive off, usually in low 2nd or 3rd gear depending on the terrain. The clutch is not really slipping, just being operated in the normal way. I never use the foot throttle when bush hogging. To shut down bring the motor to idle, disengage the PTO and let the motor idle for a few minutes before turning it off. You will find all this is simple to do - don't overthink it.
Regards, Chris

 

[SPYDERLK]

Sure. Just like you say, it's all about inertia/momentum... or spinning anything heavy and fast.

(Snip)

Hope this Helps.
rScotty

Thanks! ... Yes, backfeeding of power from the implement does happen on engine slowdown when there is no overrunning clutch. I have several tractors without this one way feature though, and much prefer their operational characteristic. The ability to slow down the implement with engine braking and to briefly employ the implement as a flywheel has always been a pleasant feature if you live with an understanding of it. Ive seen no evidence of any harm over thousands of use hrs on independent PTO tractors with std gear selected PTO and gear transmission.

In tractors with other drive schemes I believe there is a need for the overrun feature because of some design consideration that requires it to spare combined or omitted functions in differently configured design components. These arrangements seem to often need a PTO brake. What a pain! - although at least with the overrun the stub can be turned one way to line up during coupling.

I appreciate the twist back and forth Torque on driveline components that you mention. I agree this is not an optimal type of situation. Hopefully the occurrences stay comfortably within the system design margin.
Thanks again.