PTO cart

[j.l.holt]

The info I have on the  I-J cart is 350-500  and 375-500. So I have a bigger slot to shoot for.  When I decide which one it will not be a issue to hit it.  Time will tell.

[j.l.holt]

My desire is to pull a baler and mower.  I just don’t know right off how well they will perform at slower rpm speed. Yes, they will turn over easier, but do they run at their peak efficiency.  Turning at 300 rpms is a lot easier than 500. So hitting that gear slot is a must.  Then getting the traction will be a factor.  If the baler labors, will it start to slide the wheels?

[j.l.holt]

If things are just to hard to pull after all the gear work, my only thing to do is buy one of the balers I’v been looking at that is made to pull behind a 20hp yard tractor.  They also make  hay bind style mowers and different rakes.  All set up for the 20hp range of tractor.

[Eli]

I think it will be better to run the baler as close to 540 rpm as you can. You will get more from the fly wheel. The balers I used were to designed to run at like 70 strokes per min.   Eli

[Donn Hewes]

Jl Holt,  Are you planning a home made cart  to pull a baler?   I think all the ground driven baling I have ever seen was only working under the best conditions, with perfect windrows.  possibly the best ground driven baler i have seen is the JD baler conversions out of Ohio?  That is an efficient (as can be for GD) machine.  I am pretty sure I will go to loose hay before I go to the GD baler.  Just my two cents.

[j.l.holt]

Well at this time its just talk.  I’m toying with this just like everyone else.  I know plenty who say they do it all with the horses but they still have the old tractor in the shed for back up.   I’m more incline to build one just for the nay sayers.  That’s the way it is with the logging forwarder I’m gathering parts and pieces for.   It take a good while unless you just go down and buy everything new. But hunting good deals on things is half the fun!

As important as haying on time is..I would say save a buck or two through the year and use the tractor for baling. I know everyone says that it cost to much to just build one to do it,but life is more than money to me. I like to talk over plans with others to hear what they have to say, and how they would do it.

[Eli]

Building, planing, scavenging, and getting it to work is the best part almost as good as using it.   Eli

[j.l.holt]

I started thinking after reading what others were up against when they were thinking about pto cart.  I will have a few parts and enough scrap left from a log forwarder Im pieceing together and thought this would be a good place to use them.

[Ronnie Tucker]

mr holt tell us more about the log forwarder you are building.i would like to try to build one.

[j.l.holt]

well not all on here are interested in this.So in fairness to those who are not ,I do not want to take up all the space it6 would take me to tell you.  As with the alternative Energy systems if you are interested e-mail me at j.l.holt

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

not all the people on here are interested in a forwarder.  So in fairness to them I will not take up all the space needed to tell you. If you are interested e-mail me at jefflholt@gmail.com

 

 

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[j.l.holt]

Not sure why it cut this up but my e-mail is  jefflholt@gmail.com

[Andy Carson]

“What is the added drag of the transmission and is it worth”

I did some reading about this, because I find it interesting as well.  I am not going to be able to give a definative answer, but was able to find enough information to give ideas of the general range of power loss.  The rule of thumb for automobile applications where all gears are lubricated (IE transmission/rear differential) is a 15% power loss from flywheel to the rear wheels, but this varies a lot.  Interestingly, one of the biggest single source of power loss is in the rear differential itself, as the direction of the rotational power takes a 90 degree turn.  Modern hypoid gearsets (the kind that are curved as well as bevelled) increase the total gear contact area and the strength of the differential.  These are common on heavy truck applications, some tractors, and other rear wheel drive applications where strength is important  because of high torque.  The increased contact area in this design also causes more friction and power loss.  Power loss in the range of 6-10% are normal for these types.  Simple bevel gears results in less power loss, assuming they are also appropriately lubricated, and torque is matched to the application.  Power losses from inside a manual transmission range from 1-2% for high gears where input and output rotational speed are identical to over 5% if there are large differences between input and output rotational speed.  Overall, this isn’t alot of power loss, as the direction of the rotation remains the same, and I do agree you get more speed options, which might be important.  In my view, the addition of a transmission does not mean the resulting machine will be 6-20% less efficient than a PTO cart wihtout a transmission.  The PTO cart still has to have a differential, or something like a differential, and this is half or more of the power loss.  I my mind, it might be 1-5% less efficient, depending the transmission.  Not a big deal. 

The concept of speed itself is a very interesting one.  Power (from a physics standpoint ) is force x velocity.  Force in a PTO cart is fixed by 1) the weight of the the PTO cart and 2) the friction coefficient of the traction system.  Gearing can change rotational speeds of PTO shafts, and change torque radiacally, but it CANNOT make more power.  People get that idea from internal combustion engines where when they shift down, the engine runs at a higher RPM, and the engine does indeed make more power at this higher RPM.  Animals do not work this same way.  

This is not to say that there are not “tricks” you can play with reguard to speed and power generation with respect to ground drive systems.  Here’s an example:  Lets say a 800 lb cart moves at 4 MPH spins the PTO shaft at 400 rpm and generates 1 horsepower (This is just for easy numbers and doesn’t come froma real calculation).  If the horses slow to 3 MPH, the PTO will spin at only 300 rpm (which is obvious), but the power also goes down to 0.75 horsepower (power=force x velocity).  Gearing in a transmission can make the PTO shaft spin at 400 rpm, but it will still only have 0.75 horsepower.  In this case, a greater load would just spin the wheels.  An alternate way to overcome this limitation in power at low velocities is to increase the force to match the lower velocity.  If the traction system (IE wheels) is fixed, the only way to do this is by adding weight.  To get back to the example, if an 800 pound cart moves at 4 MPH and generates 1 hp, it needs to weigh 1066 lbs (4/3 x800) to generate 1 HP at 3 MPH.  Big addition in weight…  Adding additional weight sovles many problems and is the driving force behind a lot of these applications.  No wonder one of the main differences between a “heavy duty” Iand J cart and there regular cart is weight.  Twice the weight, in fact. 

Still adding weight (especially the weights we are talking about) is not always desireable, especially in hilly country.  Because power is force x velocity, and the only way to increase force is with weight (assuming you don’t want to play with traction systems), it seems critical that all ground driven work be done at speeds that are as fast as the animals can efficiently walk.  This is a big deal.  Much much bigger for ground drive applications than in other work!  This argues that gears might more useful for changing the PTO shaft speed to accomplish different jobs.  This might be a major attractive feature of gearing.  Similarly, this analysis demonstrates that the gears will not be useful in allowing the same task to be a accompished at a lower forward speed (unless more weight is added to the cart).

I am not sure how much of this was obvious already, but I hope this helps thinking these things through.

[j.l.holt]

I was with you on though,just had not went the extra step as you to explain it to my self that way.  Thank you.  My thoughts run in the direction of the needed traction and no extra weight.  And I think I can build a simple gear change that can be used to run a two different speeds. First being just at 540 for factory recommended speed, and the second around 350 for things like a sprayer.

[Does’ Leap]

well not all on here are interested in this.So in fairness to those who are not ,I do not want to take up all the space it6 would take me to tell you

I’d be interested to read about what you are planning for a forwarder and I’m sure others would as well.

Thanks.

George

[Andy Carson]

Adding traction is a great way to go and calculations show this is critical.  You reach a point of deminishing returns at some point though.  Friction coefficients reach a practical maximum at around 1, which makes good sense to me (this menas the force to drag something is rarely greater than the force to lift it straight up).  Tractor style tires get close to this a 0.7 or so.  Crawler tracks can exceed this slightly, but might add a great deal of complexity and reduced manuverability.  Either are tons better than an auto tire.  calcium in the tires would increase the weight substantially, which I know was not a goal, but if you have that much weight spinning, it would provide somewhat of a flywheel effect, which I would think would be important.

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