Hydraulic Motor Help

[kruszert]

Again thanks for the replies,

I am still working on a design for the feed system and it gets more complicated as I go - - - and more expensive. I found a large displacement pump 23.6 cu. in. in surplus center (~$160 anything bigger the price goes way up fast) but it is still too fast at 12.5 gpm. About 122 rpm. Then I need to put in a belt or chain to reduce even further. From what I have read it would be best if the pump ran in its upper rpm range rather than trying to slow way down with the flow control valve. Also I don't want to be able to accidently over speed the feed drum.

dfkrug -- I got the 12.5 gpm off the internet. My tractor is a DK35 all gears - - about 6 years old. I will check the specs. If it is less that would be very helpful. I have added a second aux spool already (tractor had one). I use one for adjustable top link and one for adj side link. My plan is to remove the side link when using the chipper and use those fittings. Since when I use the chipper the tractor is stationary I assumed the full flow would go to the aux spool - - maybe not? Also, I didn't know I could adjust the relief on the aux spool but installing a seperate relief valve isn't that difficult.
I do need to consider a safety system to turn it off.

Design is still in progress.

Reggie

 

[J_J]

kruszert ,

You do know that cu in and pressure determines the torque, so the torque is about constant throughout the rpm range. The load on the hyd motor causes the pressure to develop.

GPM's determine the speed of the motor.

So, determine the torque you need and use a large wheel motor with variable flow valve and control the motor speed with full torque.

If you want even more torque, just use belt and pulley or sprocket and chain at 1:2 or 1:3 reduction and gain more torque, and reduced rpm.

 

[dfkrug]

I found a large displacement pump 23.6 cu. in. in surplus center (~$160
anything bigger the price goes way up fast) but it is still too fast at 12.5 gpm. About 122 rpm. Then I
need to put in a belt or chain to reduce even further. From what I have read it would be best if the pump
ran in its upper rpm range rather than trying to slow way down with the flow control valve. Also I don't
want to be able to accidently over speed the feed drum.

That motor at SurpCntr runs at 1450psi, continuous. Once you pick a motor, go to the manufacturer's spec
sheet in their online catalog and look up the characteristics. You want to pick an operating point somewhere
in the midrange of pressure/RPM; they get very inefficient at the extremes.

If you have an aftermarket AUX valve already, then you are set with a relief, as long as it is adjustable. Full
flow is fine if you are going to pick a motor and gear it down to fit your flow. If you don't want to adjust the
AUX valve RV, and don't use a motor rated at least at 2300psi, then a simple crossover RV like this I recently
used for my hydraulic chainsaw works well, and is not too spendy. Factory AUX valves often do not have their
own RVs because they count on the system RV. My Kioti OEM AUX valve is like that, which required I add an
RV. Also, some hyd motors have an optional RV built in.

I try to simplify the design as much as I can.

 

[J_J]

Do you have 15.8 GPM for the motor you found at Surplus. You said you only have 12.5 GPM, so right away, the motor will run less speed at 123 rpm, and the hyd motor pressure limit is only 1450 psi. Torque, using your 2300 psi would be about 8643 in lbs.

The limb/wood inches per delivery speed is determined by the roller pulling the limb into the chipper.

Otherwise, how fast the wood is moving into the chipper.

You regulate that by the lever on the variable flow valve.

If the hyd motor will run at say 30 rpm, why would you need any more reduction. You might gain more torque.

The wheel motors on my machine can probably run at 1 rpm. We use the hyd pump speed control lever to control the speed of the wheels in our closed loop hyd system.

 

[kruszert]

The 23.6 cu. in. motor runs at 150 rpm at the 15.8 gpm so I figured with my system at 12.5 gpm it would slow down to ~123. I still need to find the factory specs to see if I am running less gpm. As for torque I think I am way over what the right angle gear drive provides so I am not worried about that even if I put in a RV at around 1400 psi. I may actually have to reduce the RV pressure if I go back to twisting the shaft off my feed drum (again).

I do need to look into wheel motors - - I never looked at them.

As for more reduction - - when I try to grind up branches 5" to 6" in dia the tractor has trouble handling them. Usually I cut up this large stuff for firewood but on pine I prefer to just grind it. I was thinking if I could vary the speed down it would go in easier.

Thanks for the suggestions. Still working this out. It is looking like a winter project rather than a quick fix.

Reggie