Building a 3-point adapter and PTO for Bobcats

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Dameon

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This thread was a good start to a worthy project, but kind of died out and didn't have much information for a DIYer like me.
Surplus Center has this nice set of calculators, but the one referenced in the other thread seems to be AWOL. I needed to calculate what pump would work on a high flow 733 (27 gpm) to output a 540 rpm shaft speed.
I could always go spent $2K on a pre-built adapter/mount, but I don't have $2K to invest in this project. I think I could build a nice setup for $300 or less.
 

antfarmer2

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I bought a nice heavy adapter plate for three point hitch with tow hitch reciever for $270 on ebay have used it on my box blade to reach into the pond for clean out would be a good start no info on a motor but others will
 

jerry

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I bought a nice heavy adapter plate for three point hitch with tow hitch reciever for $270 on ebay have used it on my box blade to reach into the pond for clean out would be a good start no info on a motor but others will
One of the attachment sites I visited, I think it was Skidsteer Attachments had a chart showing the cu inch size of the motor needed at different flow rates. They manufacture the adaptor with a motor mounted on it. Cost was around 2000.
 

jerry

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One of the attachment sites I visited, I think it was Skidsteer Attachments had a chart showing the cu inch size of the motor needed at different flow rates. They manufacture the adaptor with a motor mounted on it. Cost was around 2000.
The site was Skidsteer Solutions
 
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Dameon

Dameon

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The site was Skidsteer Solutions
Thanks for the reply Jerry. The link I posted above references Skidsteer Solutions, but as you pointed out, their solution is VERY expensive. I think I can put something together myself for a fraction of the cost. My main hangup is determining which of the pumps would be suitable for a ~540 rpm PTO drive on a 27 gpm Bobcat.
 
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Dameon

Dameon

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I bought a nice heavy adapter plate for three point hitch with tow hitch reciever for $270 on ebay have used it on my box blade to reach into the pond for clean out would be a good start no info on a motor but others will
AntFarmer2: "I bought a nice heavy adapter plate for three point hitch with tow hitch reciever for $270 on ebay"
That's about what my homemade one cost me. I ordered the blank Bobtach plate from eBay for $95 and bought a local 3-point quick attach adapter for $175. I just welded the two together and it works great. I can't do category 2 implements on my mine though. I saw adjustable 3-point hitches, but no quick attach adjustable. I preferred the quick attach over the adjustable, especially since I don't even have any category 2 implements. I'd have to measure to make sure, but it's possible I could fit a category 2 pin in my adapter.
 

antfarmer2

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AntFarmer2: "I bought a nice heavy adapter plate for three point hitch with tow hitch reciever for $270 on ebay"
That's about what my homemade one cost me. I ordered the blank Bobtach plate from eBay for $95 and bought a local 3-point quick attach adapter for $175. I just welded the two together and it works great. I can't do category 2 implements on my mine though. I saw adjustable 3-point hitches, but no quick attach adjustable. I preferred the quick attach over the adjustable, especially since I don't even have any category 2 implements. I'd have to measure to make sure, but it's possible I could fit a category 2 pin in my adapter.
Good to hear they had the QA too just had to hunt a bit but yours is probley better a little to tight on mine to use some attachments
 
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Dameon

Dameon

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Good to hear they had the QA too just had to hunt a bit but yours is probley better a little to tight on mine to use some attachments
Okay, this thread seems to be getting stale.
Does anyone currently have a hydraulic driven PTO "converter"? If so, can you provide the hydraulic PTO motor specs? Also throw in some info about input gpm and output rpm if available. Thanks.
 
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Dameon

Dameon

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Okay, this thread seems to be getting stale.
Does anyone currently have a hydraulic driven PTO "converter"? If so, can you provide the hydraulic PTO motor specs? Also throw in some info about input gpm and output rpm if available. Thanks.
Due to difficulties in posting to this forum, I'm just going to update my progress in the other forum. For those interested in following my progress, you can view the thread at:
http://skidsteer.info/forum/viewtopic.php?f=2&t=5
Thanks.
 

jerry

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Due to difficulties in posting to this forum, I'm just going to update my progress in the other forum. For those interested in following my progress, you can view the thread at:
http://skidsteer.info/forum/viewtopic.php?f=2&t=5
Thanks.
You will also want to put a bypass hose in with a relief in it so when using something like a brush cutter it can coast rather coming to a immediate stop when the flow is stopped. You could use a overrunning clutch like you would put on a tractor brush cutter for about 40 bucks but will need something in there.
 
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Dameon

Dameon

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You will also want to put a bypass hose in with a relief in it so when using something like a brush cutter it can coast rather coming to a immediate stop when the flow is stopped. You could use a overrunning clutch like you would put on a tractor brush cutter for about 40 bucks but will need something in there.
Thanks for the suggestion Jerry. I got it covered as the flow rate valve also does pressure relief back into the tank.
Flow Control Valve
 

jerry

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Thanks for the suggestion Jerry. I got it covered as the flow rate valve also does pressure relief back into the tank.
Flow Control Valve
The relief and would have to be on the return side of the motor and bypass back to the intake side as when you shut the supply off the motor will operate as a pump from the centrifugal force of the cutter wheel. If the flow control would be on the supply hose only it won't relieve the pressure between the motor and the aux valve or solenoid. I think there are photos of this setup in the media section/
 
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Dameon

Dameon

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The relief and would have to be on the return side of the motor and bypass back to the intake side as when you shut the supply off the motor will operate as a pump from the centrifugal force of the cutter wheel. If the flow control would be on the supply hose only it won't relieve the pressure between the motor and the aux valve or solenoid. I think there are photos of this setup in the media section/
Thanks for the response Jerry.
So you're saying the flow control valve I linked to will not work? It takes flow from the output of the Bobcat, runs it through a control valve, and into the implement. Excess flow (as controlled by the lever on the valve) is redirected to an output on the valve that is connected to the return line to the Bobcat. The most likely way the internal relief valve works is by looping the connection between the implement return flow and the implement source flow... the fluid would just go 'round and 'round until the implement spun down.
Am I missing something?
 

jerry

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Thanks for the response Jerry.
So you're saying the flow control valve I linked to will not work? It takes flow from the output of the Bobcat, runs it through a control valve, and into the implement. Excess flow (as controlled by the lever on the valve) is redirected to an output on the valve that is connected to the return line to the Bobcat. The most likely way the internal relief valve works is by looping the connection between the implement return flow and the implement source flow... the fluid would just go 'round and 'round until the implement spun down.
Am I missing something?
It sounds right, but the relief bypasses guys put in have a one way relief so oil from the incoming cannot go into the out line. Does your valve dump excess pressure from the in line from the bobcat or excess from the attachment? Most relief will only operate in one direction. The few commercial ones I looked at had a bypass also. Try it at lower rpm first to see. With the older cats you could feather it a little at shutdown but the ones with solenoids would be either on or off. I may be way off on this too. Let us know how it all works out, you may have a good solution.
 

jerry

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It sounds right, but the relief bypasses guys put in have a one way relief so oil from the incoming cannot go into the out line. Does your valve dump excess pressure from the in line from the bobcat or excess from the attachment? Most relief will only operate in one direction. The few commercial ones I looked at had a bypass also. Try it at lower rpm first to see. With the older cats you could feather it a little at shutdown but the ones with solenoids would be either on or off. I may be way off on this too. Let us know how it all works out, you may have a good solution.
Not sure why there is a acre of blank space in that last one , that is how my mind works though. Lots of blanks.
 

jerry

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It sounds right, but the relief bypasses guys put in have a one way relief so oil from the incoming cannot go into the out line. Does your valve dump excess pressure from the in line from the bobcat or excess from the attachment? Most relief will only operate in one direction. The few commercial ones I looked at had a bypass also. Try it at lower rpm first to see. With the older cats you could feather it a little at shutdown but the ones with solenoids would be either on or off. I may be way off on this too. Let us know how it all works out, you may have a good solution.
Don't know why there is a acre of blank space in the last one , but that's the way my mind works, lots of blanks.
 
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Dameon

Dameon

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Don't know why there is a acre of blank space in the last one , but that's the way my mind works, lots of blanks.
Yeah, this forum has a few quirks. Some (like the blank space and double posts) are just slight annoyances, but when it dumps a whole post, after I've typed it out, is downright infuriating. I just work around it... normally posting to the other forum and then copy/paste it to this forum.
I'll let you know how I get along with this project.
 

Tazza

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Yeah, this forum has a few quirks. Some (like the blank space and double posts) are just slight annoyances, but when it dumps a whole post, after I've typed it out, is downright infuriating. I just work around it... normally posting to the other forum and then copy/paste it to this forum.
I'll let you know how I get along with this project.
hehe nice one Jerry. You are not alone, there is a lot of nothing going on in my head most of the time too :)
 
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Dameon

Dameon

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hehe nice one Jerry. You are not alone, there is a lot of nothing going on in my head most of the time too :)
I finally got my package from Surplus Center on Friday. I examined everything and it appears as I expected. No suprises there. The adapter adds about 6" to the output shaft length, which was an area I was trying to cut length, not add, so I'll have to work that into my calculations.
Now comes the fun part: how to run my hydraulic lines. I have the Prince Model RDRS175-30. There is a nice schematic here.
This is the drawing I came up with, but I have some concerns:
FlowDiagram1.jpg

1) Do I need to worry about back flow coming out of the line in the EF port into the motor or back towards the PR port?
2) Will this provide the ability for the implement (bush hog) to spin down when I shut off hydraulic flow?
3) Should I run any lines into my "third" connection on the 773? If I understand correctly, that third connection is used for a return-only line into the tank. I could probably just run my PR port straight into that connection, but (as long as it doesn't hurt anything) I'd rather keep the connections to the standard two in case this fabbed implement I'm making mounts to a skidsteer with no third connection.
 

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