JJ and others - Post Hole Digger

[J_J]

So here is a real dumb question JJ. I assume 540 RPM PTO speed is what you get when the engine is cranking - ie maximum top speed. And that most people are probably running there standard PTO at 400 RPM or so unless they are flogging the machine?

I ask because I am looking at this chipper that wants 35 HP and 540 RPMs Just making sure when I don't hit the RPM I am still OK...

Carl, I have the Bearcat chipper shredder, and ;use it on my Kubota B-9200 diesel which has only 22 hp. It does a fine job of chipping and shredding. I also have two speeds on my PTO the other is around 850 rpm. I will look and see what size the pulleys are. I am almost sure the shipper/shredder shaft is turning fairly high. One of the PT owners has modified a chipper shredder . Did a nice job on it.

 

[SnowRidge]

So here is a real dumb question JJ. I assume 540 RPM PTO speed is what you get when the engine is cranking - ie maximum top speed. And that most people are probably running there standard PTO at 400 RPM or so unless they are flogging the machine?

I ask because I am looking at this chipper that wants 35 HP and 540 RPMs Just making sure when I don't hit the RPM I am still OK...

No, PTO speed is typically a little less than maximum RPM. Most machines have a PTO speed mark on the tach. Except for PHDs, and perhaps a few other implements in which fine control is an issue, PTO speed is PTO speed. The operator sets the hand throttle so the tach needle sits on the PTO mark. The only thing I have that I don't run at PTO speed is my PHD.

You can't flog a diesel simply by running it wide open or at PTO speed.

 

[woodlandfarms]

No, PTO speed is typically a little less than maximum RPM. Most machines have a PTO speed mark on the tach. Except for PHDs, and perhaps a few other implements in which fine control is an issue, PTO speed is PTO speed. The operator sets the hand throttle so the tach needle sits on the PTO mark. The only thing I have that I don't run at PTO speed is my PHD.

So now it gets interesting. How do you know if a hydraulic motor is hitting 540 RPM? I mean, My tractor is rated at 18 GPM at 3000 PSI at what I assume is 2800 RPM on the tach. Now this is a huge assumption of specs on my part as there is no documentation on this subject (Guess it is a call to Terry) so maybe someone can correct if I am wrong. So taking my specs and looking at the motor JJ has suggested as an example,

# 8.6 cubic inches per rev. displacement
# 20 GPM rated flow
# 481 RPM max
# 3000 PSI max pressure

It seems Like I could not find the 481 RPM this motor might attain as I am at 18 GPM.

Next question. Why are wheel motors tapered? What is the benefit of this? I get loading if you had a bearing in between the motor and wheel but I do not get why it is tapered.

I have the funny feeling I am really overthinking this project but thanks for all the education guys.

 

[SnowRidge]

So now it gets interesting. How do you know if a hydraulic motor is hitting 540 RPM? I mean, My tractor is rated at 18 GPM at 3000 PSI at what I assume is 2800 RPM on the tach. Now this is a huge assumption of specs on my part as there is no documentation on this subject (Guess it is a call to Terry) so maybe someone can correct if I am wrong. So taking my specs and looking at the motor JJ has suggested as an example,

# 8.6 cubic inches per rev. displacement
# 20 GPM rated flow
# 481 RPM max
# 3000 PSI max pressure

It seems Like I could not find the 481 RPM this motor might attain as I am at 18 GPM.

Next question. Why are wheel motors tapered? What is the benefit of this? I get loading if you had a bearing in between the motor and wheel but I do not get why it is tapered.

I have the funny feeling I am really overthinking this project but thanks for all the education guys.

One way to measure RPM is with an optical tachometer and a white line on the rotating part.

I believe tapered shafts are a safety thing. It's bad form for a wheel to fall off. Tapered shafts allow a controlled interference fit. Straight shafts do not. Also, if the interface between the shaft and hub corrodes, tapered shafts are said to be easier to remove.

 

[marrt]

I'm also interested in the question of determining motor speed. I have 4 spare wheel motors for my 1845. I was thinking of using one of these motors for a phd since I already have a PT 18" auger left over from my 425. For the phd, it really doesn't matter as I can just use the throttle. However, I was thinking of creating a "Universal PTO Power Pack" that I could use with other std. tractor PTO attachments (e.g., shredder). Sometimes you can find tractor attachments cheap on Craigslist. However, used PT attachments are rare and too expensive when new (for me anyway).

 

[SnowRidge]

Harbor Freight has an optical tach for a reasonable price.

The hydraulic motor maker's catalog should have a chart showing RPM versus flow for their motors.

 

[woodlandfarms]

I'm also interested in the question of determining motor speed. I have 4 spare wheel motors for my 1845. I was thinking of using one of these motors for a phd since I already have a PT 18" auger left over from my 425. For the phd, it really doesn't matter as I can just use the throttle. However, I was thinking of creating a "Universal PTO Power Pack" that I could use with other std. tractor PTO attachments (e.g., shredder). Sometimes you can find tractor attachments cheap on Craigslist. However, used PT attachments are rare and too expensive when new (for me anyway).

There ya go! Someone else thinking in my same mental space

 

[J_J]

Carl, and Marrt,

Try and not make this to difficult for your selves. Speed is speed, and is controllable.
whether it is PTO speed from a tractor, or what PT users call their PTO speed. My PT-1445 PTO speed control is manual. others are solenoid controled and run wide open. Both the tractor PTO and hydraulic PTO one can be controlled somewhat by regulating engine rpm. I don't believe there is anything written in stone for PTO implements. For instance, some people run their bush hog mower at low speed, and others run it at maximum. On a hydraulic driven motor, a simple valve will control the flow to the motor and regulate the speed. The valve below will do what you need, but is one way through this valve. It will let you throttle the motor from 0 rpm up to the maximum flow in GPM. You might want to run a small auger fast depending on soil conditions. For something like a 24 in auger for planting trees/shrubs, would run better at a lower rpm. It is simply a choice based on experience and soil conditions, and the size of the auger. I can tell you for a fact that one of those gas augers running wide open with a 12 in auger will rip the auger right out of your hands and it hurts like **** . A hydraulic auger can be reversed, and is a good thing.
Also keep in mind that some augers turn counter clockwise. It all has to do with the gearing in the gear box. A single gear reduction will turn one way, and a double gear reduction will turn the other way. I have one of the augers that turn the other way.
When you hook up your hyd motor, check and make sure the auger is turning in the right direction, You want the teeth to cut into the ground. I have made auger bits that look like a spade bit shaped the size of a 1 gal , and a 3 gal pot. It will sling the dirt fairly fast.

Burden Sales Surplus Center Item Detail

This valve will handle 30 GPM.

 

[J_J]

I'm also interested in the question of determining motor speed. I have 4 spare wheel motors for my 1845. I was thinking of using one of these motors for a phd since I already have a PT 18" auger left over from my 425. For the phd, it really doesn't matter as I can just use the throttle. However, I was thinking of creating a "Universal PTO Power Pack" that I could use with other std. tractor PTO attachments (e.g., shredder). Sometimes you can find tractor attachments cheap on Craigslist. However, used PT attachments are rare and too expensive when new (for me anyway).

Do you mean something like this.

 

[woodlandfarms]

One way to measure RPM is with an optical tachometer and a white line on the rotating part.

I believe tapered shafts are a safety thing. It's bad form for a wheel to fall off. Tapered shafts allow a controlled interference fit. Straight shafts do not. Also, if the interface between the shaft and hub corrodes, tapered shafts are said to be easier to remove.

Whats a controlled interference fit?

Also, JJ you mentioned I would need to have a connector machined? Any chance they allready exist?