Hydraulic motor and pump help

[MossRoad]

Then there's this one with one pump...

View attachment 489860

From here:
http://www.colemanequip.com/CASE/Im...PUMP-TO-HYDRAULIC-DRIVE-MOTORS-0DUZ-large.gif

 

[MossRoad]

Then there's this one with one pump...

View attachment 489860

From here:
http://www.colemanequip.com/CASE/Im...PUMP-TO-HYDRAULIC-DRIVE-MOTORS-0DUZ-large.gif

Or is that one pump with two sections, effectively, two pumps?

 

[MossRoad]

Anyhow, I'll be watching this thread. Something to learn. Thanks again.

 

[oldnslo]

Or is that one pump with two sections, effectively, two pumps?

Yes that is one pump housing with two rotating groups or pump sections. Getting more common in skid steers for space savings. Only one inlet or suction line required, one front drive plate,etc. Makes them more compact when you are stuffing 10 lbs. in 5 lb. package.

 

[oldnslo]

So am I better off spending the money for two variable pumps plus a third gear pump?

If your uses are for ground engagement, pulling a cart around, plowing snow, etc. I looked at the JD lawn mower specs and the 300 series run around 5.5 MPH and the 500 series around 7.5 MPH. Average person walks at 3 MPH or more.

I would suspect that plowing snow and pulling your trailer at 2 -3 MPH will be disappointingly slow.

Based on your usage I would look hardest at two variable displacement closed loop pumps and two motors. This would give you the capabilities of traveling faster under low power situations and then slowing down as the load demands like running a zero turn or skid steer.

using 10" sprocket I get 168 RPM at 5 MPH You could possibly use a wheel motor to directly drive your tracks Vs the jack shaft and chain reduction. I believe some of the track type skid steers are driven this way. Might save some space. You would have to check bearing loads and possibly seal protection since this will be in the dirt and mud.

travel speed formula: MPH = (RPM x d)/ 336
RPM of drive sprocket or wheel
d = diameter of drive sprocket or wheel in inches

I found this formulae for converting axle torque to drawbar pull.
T = F x r
T = torque in inch lbs.
F = draw bar in lbs.
r = wheel or drive sprocket radius

 

[Metalburner]

3mph to me is a safe speed. Direct drive is doable since I can give myself the ground clearance rather than doing it through gear reduction. Last question I have, is there a size displacement of motors to look for?

Also since I'm making my own tracks rather than buying rubber tracks, for backyard use I was going to use grousers then for driveway use I was going to make rubber pads to bolt on. What can I use for the rubber that I can bolt on easily?

 

[Metalburner]

Oh and with regards to pulley sizing for the pumps and engine to run the pumps, is there a ratio to go by? Like a 2" pulley on the engine to 5" or 6" on the pumps? I know the variable ones sometimes come with their own.

 

[MossRoad]

I don't know if you know this or not, but a lot of those variable volume pumps that you'll be looking at have a shaft out the front to turn it, and a mount on the back for another pump. That's where you might want to bolt on your pump for your implements and such. Then you only have to drive the one shaft.

On my Power Trac, the drive pump is on the front of the engine and the PTO pump is on the rear. Bolted to the PTO pump is the steering/FEL lift pump. On the newer model Power Tracs, all three pumps are bolted to one side of the engine: Drive pump mounts to the engine, PTO pump mounts to the back of the drive pump, steering/FEL pump mounts to the back of the PTO pump. Makes for a long, but skinny 3 section pump.

 

[Metalburner]

Can you post pictures of that? I can kind of imagine it, but a visual would be more helpful.

 

[MossRoad]

Go to this link and then click on the different views of the pump to see the input shaft and rear mount for auxiliary rear pump mount.

3. cu in EATON 35 DUAL SERVO HYDROSTATIC TANDEM PISTON PUMP