Questions on 3pt with pto

techteacher · Apr 26, 2011

I contacted the local hydraulic dealer and he is trying to find me a good but inexpensive pump that will run 540 rpm with 3300 psi. I have a t-250 if that helps. He said he has a motor but when I shut my hydros of it will stop the mower immediately creating a lot of force on the pump and pto shaft breaking something for sure. HE said they make some that free spool but are very pricey. I was thinking about putting an inline slip clutch or overrunning adapter what are some opinions on this.

skidsteer.ca · Apr 26, 2011

All you need is to T the pressure and returns together, with a check valve in the cross over line that won't allow pressure from the loader to escape into the return line.
But when the loaders flow is suddenly cut off and the motor on the 3pt becomes the pump driven by inertia, then the oil coming from the return line on the motor can cross back into the pressure line and circulate through the motor allowing it to wind down slowly instead of being forced to a stop.
If you want to use this for some applications where the motor must be reversed, (ie post hole auger) then you will also need to install a valve that can be closed to prevent flow in either direction in the cross over line and close it for those jobs. A post hole digger turns to slow for inertia to be a problem anyway. But on something like a bush hog you will need this cross over or else you have to install a "motor spool valve" to operate it
Ken

Kermode · Apr 26, 2011

skidsteer.ca said:
All you need is to T the pressure and returns together, with a check valve in the cross over line that won't allow pressure from the loader to escape into the return line.
But when the loaders flow is suddenly cut off and the motor on the 3pt becomes the pump driven by inertia, then the oil coming from the return line on the motor can cross back into the pressure line and circulate through the motor allowing it to wind down slowly instead of being forced to a stop.
If you want to use this for some applications where the motor must be reversed, (ie post hole auger) then you will also need to install a valve that can be closed to prevent flow in either direction in the cross over line and close it for those jobs. A post hole digger turns to slow for inertia to be a problem anyway. But on something like a bush hog you will need this cross over or else you have to install a "motor spool valve" to operate it
Ken

A crossover relief valve will do the same thing but still allow you to run in both directions. An adjustable crossover relief will allow you to tailor it to suit your application.

skidsteer.ca · Apr 27, 2011

Kermode said:
A crossover relief valve will do the same thing but still allow you to run in both directions. An adjustable crossover relief will allow you to tailor it to suit your application.

Kermode
Yes that works also, and I guess you could adjust the relief on the return side to open at a low pressure and get the same effect as my cross over system.
That is kinda a pet peeve on my newer brusher. When I lift the boom I steal the oil flow from the cutter and put it to the loader cylinders.
This cause the cutter to lose momentum as the return flow from the motor comes up to relief pressure before it can cross over, where my home made brusher just keep spinning from the momentum. I can hear the new brusher abrutly slowing when I lift the boom.
So inthe case of the 3 pt pto, I guess it all comes down to whatyouwant to use it for.
Ken

techteacher · Oct 31, 2011

skidsteer.ca said:
Kermode
Yes that works also, and I guess you could adjust the relief on the return side to open at a low pressure and get the same effect as my cross over system.
That is kinda a pet peeve on my newer brusher. When I lift the boom I steal the oil flow from the cutter and put it to the loader cylinders.
This cause the cutter to lose momentum as the return flow from the motor comes up to relief pressure before it can cross over, where my home made brusher just keep spinning from the momentum. I can hear the new brusher abrutly slowing when I lift the boom.
So inthe case of the 3 pt pto, I guess it all comes down to whatyouwant to use it for.
Ken

Finally got it done but I can't post pics photobucket is blocked.

Dameon · Sep 2, 2014

skidsteer.ca said:
All you need is to T the pressure and returns together, with a check valve in the cross over line that won't allow pressure from the loader to escape into the return line.
But when the loaders flow is suddenly cut off and the motor on the 3pt becomes the pump driven by inertia, then the oil coming from the return line on the motor can cross back into the pressure line and circulate through the motor allowing it to wind down slowly instead of being forced to a stop.
If you want to use this for some applications where the motor must be reversed, (ie post hole auger) then you will also need to install a valve that can be closed to prevent flow in either direction in the cross over line and close it for those jobs. A post hole digger turns to slow for inertia to be a problem anyway. But on something like a bush hog you will need this cross over or else you have to install a "motor spool valve" to operate it
Ken

skidsteerca: "All you need is to T the pressure and returns together, with a check valve in the cross over line that won't allow pressure from the loader to escape into the return line."
Hello Ken. I hope you don't mind answering a few questions I have about a similar project I'm working on. I have an ongoing thread here on the forum. Let me know what you think when you get a chance.

Questions on 3pt with pto

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