Convert Rear PTO Snowblower to Front Hydraulic

[rswyan]

Well ...... this is getting to be quite the ed-u-ma-kay-shun .....

Also, don't forget to allow for drivetrain power requirements in your calculations. If you use all of your power for the snow blower you won't have any left to drive up the hill.

Yeah .... that's been running across my mind the last day or so as I've been pondering all this ....

There's not much in the way of "hill" here .... there's a pretty gentle grade from the house to the top of the driveway, and the road after that (which I also clear) is basically flat - but I get the point:

If ya use all the HP to drive the pump/motor/blower and ya ain't goin' anywhere ...

Usually I blow from north to south, down the driveway (downhill) - to avoid having snow blow back in my face (wind is often out of the north it seems)

I did some checking on Allied/Buhler's website and found that they make a 60" commercial snowblower that is hydraulically powered for skidsteers. The power requirements are listed as 13 to 22 GPM @ 2000 psi:

Farm King Commercial Snowblowers

Interesting ....

Ran across the following thread by Pks on a snowblower conversion to hydraulic he did for a friend back in 2006/2007 .... but it's leaving me with more questions than answers :

Hydraulic Snow Blower for FEL

.... although he states things were sized for 20 HP, there's a good bit of missing info in the thread : .... the model and exact HP of the tractor (it's a JD and has a model 70 loader on it), and the exact width of the blower (he said it was "only about 44 inches wide" - but the tractor & blower look alot bigger than the single-stage 42" blower that I have for the old Cub Cadet 782)

The one Pks did uses the mid-PTO of the tractor and was designed for an max of 2600 rpm input, with 2000 rpm input typical.

He also said he thought the hydraulic pump and motor were both 2.25 displacement .... the pump is a Prince and the motor is a Char-Lynn apparently .... he was going to get back and post the exact model numbers (along with pics of the pump and drivetrain) ... but never did ...

Claimed that the system was designed for 3000 psi max, but that 1850 psi was the typical operating pressure ...

hydraulic motor coast down circuit. In normal use the check valve is closed, but if the oil flow stops suddenly the hydraulic motor can coast down at it's own speed and not self destruct.

Right - basically it would be plumbed between the return from, and supply to the motor - so that flow from the return line could feed over to the supply side when the pump is shut off, correct ?

Something like this maybe:

3/4" NPT 30 GPM CHECK VALVE 5 PSI CRACKING

It also will not allow reverse rotation of the motor, which can be nice when you want to prevent someone from hooking the hoses up backwards.

Right

 

[rswyan]

Sorry been w/o puter for a while

No worries .... considering the time I'll have available for the next couple of months I'll be lucky to have anything put together to use this season :laughing:

......reading up on this, the only input I have is a system I've seen fabricated similar to what you want ... They had a Prince PTO mounted pump on back running a Commercial Gear Motor on the front snow blower .....

Commercial Gear Motor ?

As in "commercial-duty" gear motor ?

the gear motor displacement was 10-15% larger than the pump as to take up for efficiency loss....giving them basically a 1 to 1 ratio for RPM's.....

Makes sense - considering it sounds like they were using a rear PTO pump (540) ..... to drive a blower that was designed to be driven off the rear PTO (540) ?

My situation is slightly different as you know, since I'm looking at using the mid-PTO - but the principle of upsizing to account for the hydraulic inefficiency so as to be able to deliver the proper rpm would still apply of course ....

Beyond that, the thing I'm thinking is that the larger the displacement of the hydraulic motor, the more torque/force/power it will develop .....

From what I can see, it's definitely a bit of a balancing act to design a system incorporating a pump and motor, figuring out the appropriate flow rate, operating pressure, and delivered force to power an implement to do work - within the constraints of the (tractor) power available.

They tee'd in a PRV and a normally open solenoid (12 VDC power to close valve) at the inlet of the motor for stall control and on/off operation .....

Interesting ...... I wasn't figuring on anything quite as elaborate (solenoid) - figured my "stall control" would be my foot on the clutch

the exhaust from the PRV & SCV was tee'd back in to the line coming out of the motor......

Be interesting to see how that was hooked up ...

The unit worked pretty good but concerns about heat had them alter the hoses larger to reduce pressure drop to run cooler.....

You mean that they altered the hoses larger to increase pressure drop don't you ?

I don't think they needed the SCV as the PTO control on/off on the tractor was sufficient......

Yup - I would think that it should be - as I mentioned, I'm just planning on using the clutch ..... or just flipping the lever for the PTO to dis-engage it ....

the PRV was needed in case of stall to protect the tractor.....

Makes sense ....

Didn't know if this would help but this unit I've seen is basically where you want to be........

Yup - it sounds like it is (where I want to be ....)

Yeah ... it all helps to suss it out in my mind - thanks ! :thumbsup:

 

[rswyan]

I think the 47 HP for (...whatever those displacement, RPM and pressure numbers were), assumes a maximum LOAD, i.e. 47 HP is what you COULD put through it IF you were trying to do that much work.

Yes - I'm sure that you are exactly correct on this - since the above HP requirement is for a specific pressure and flow (22 gpm @ 3000 psi)

And pressure doesn't really develop, except as a consequence of trying to do work (save for frictional losses inherent in the system)

With no snow... maybe a horse power or two just to turn the egg beater and overcome internal friction and losses.

Yup - that makes total sense to me ....

Start feeding it some powdered snow and it loads down, hopefully your tractor's governor keeps up. Load it with a LOT of snow, or heavy slush, say to 20 HP and your tractor would have a hard time, but that is just a limitation of the power going IN.

Exactly.

If you go slow enough you can probably cut into deep drifts and throw them a good long way with 20 HP.

I'm sure that I can (go slow enough) - I have three ranges available and Low really creeps along if you're light on the foot .... but ...

Ideally what I want to do is size everything properly .... and design a system which would be appropriate for the tractor and it's available power ..... so that neither the tractor or the blower is overly prone to stalling ....

I would think that to some extent that can be handled for the tractor with a PRV - and setting it so that it relieves before sucking up all the available HP (of course, available HP will vary - according to the speed the tractor is running at :confused2

For the blower, I would think it would be handled by a combination of correctly sizing the pump and motor - allowing sufficient flow to run the motor at the correct speed for the implement ...... and a PRV - with setting the PRV to an appropriate relief pressure, so that enough pressure can develop to generate sufficient torque to power the implement ....

Does the above make sense ?

This is a bit like the generator question, it might have a CAPACITY of say 15 Kw, but that doesn't mean it will blow up a 15 watt light bulb. Sure the light bulb can't take all the power of the generator, it will only draw 15 watts. The fact that the generator COULD put out 15 Kw is irrelevant to a 15 watt load.

Very true - the only thing is that the situation is somewhat reversed :

I have an entire house to power .... and all I have is a little Honda 2000w generator ..... gotta make sure the wifey don't turn on her hair dryer while I'm flushing the toilet (and causing the well pump to run) :laughing:

 

[wdchyd]

They had a Prince PTO mounted pump on back running a Commercial Gear Motor on the front snow blower.....the gear motor displacement was 10-15% larger than the pump as to take up for efficiency loss....giving them basically a 1 to 1 ratio for RPM's.....

Here's a link to Commercial/Parker Gear motors (same basically as the pumps with a few alterations)..

Parker - 050/051 ASSEMBLED UNITS...

They may have used it for cost/availability cuz it was a pretty good size for displacement......which adds to the cost in other brands of hyd motors....

 

[IceStationZebra]

Right - basically it would be plumbed between the return from, and supply to the motor - so that flow from the return line could feed over to the supply side when the pump is shut off, correct ?

Something like this maybe:

3/4" NPT 30 GPM CHECK VALVE 5 PSI CRACKING

Right

Yep. Sorry my crude drawing didn't come out right, but you've got the picture. In normal use there is no flow through the check valve, but if you close the valve the oil just loops around as everything winds down.

ISZ

 

[rswyan]

Well, it's mid-July and the temperature is forecast to go up to around 90 degrees in the next few days ... so what better way to chill than to think about winter

It's been about 4 years since I started and last posted in this thread, so I guess it's time to resurrect it ... kinda like Lazarus being brought back from the dead ...

I've finally managed to get the shed/workshop cleaned up/out to the point where one could actually work in it ... and I'm itching to complete a number of unfinished or contemplated projects.

This one is a good candidate - since I already have most of the components, so the additional expenditure should be relatively minimal - and because I'm not getting any younger ... and the prospect of blowing snow backwards with the blower on the rear of the tractor makes my neck hurt just thinking about it.

I was thinking about this project last night and was getting all stoked up about the possibility of actually completing it, and then a possible snag hit me:

The Eaton hydraulic pump I have is designed/intended - in terms of rotation - to run off the rear PTO ... and is the mid-PTO on our B2910 rotating in the same direction ?

If it isn't, then I would be faced with sourcing a hydraulic pump ... as well as a hydraulic motor ...

After doing some digging around on the 'net, and checking the way the PTO shaft spins on my MMM (at midnight, in the dark ), I believe it does ...

(I think they both turn clockwise, when considered facing the PTO shafts coming out of the tractor)

If anyone knows different, please give a holler ...

 

[rswyan]

Attached is a rough diagram of the contemplated hydraulics, showing the components. The ones with "Item No." are Surplus Center items, which is where I intend to source them.

I already have the pump, reservoir, and the spin-on filter mount/element. I will use the PTO shaft from my MMM to drive the pump ... but that will require some work to fabricate a coupler to attach it to the pump, since the shafts/splines are different.

 

[rswyan]

I was originally going to build a front mount for the snowblower similar to what Kubota uses for their front blowers ... but now I'm considering just going with a QA mount for the front-end loader.

Having an SSQA for the front-end loader is actually another whole project ... which is being spurred by the prospect of having a additional items to mount/dismount on the front end loader ...

I currently have two items: my 60" Light Materials Bucket and a set of pallet forks.

The snowblower is one additional item and I also want to build a grapple/root rake.

I'll probably source the SSQA bracket assemblies from Titan:

Weld-on Quick-attach Brackets

... and fab up something specific to my LA 402 loader, and use a SSQA plate with a Quick Hitch from Harbor Freight:

3-Point Quick Hitch for Tractors - 27-3/16" Clearance

... welded to the SSQA for the snowblower mount.

 

[J_J]

Do you have the volume and pressure to power a hyd motor.

The HP developed by the hyd motor you select should be equivalent to the HP supplied to the snow blower using the PTO.

The hyd motor also has to turn at about the same rpm.

This is a skidsteer adapter with hyd motor to turn PTO implements on the front.

Skid Steer Powered 3 Point Adapter for Bobcat Low Flow Loaders | eBay

 

[rswyan]

Do you have the volume and pressure to power a hyd motor.

See the earlier discussion in this thread about the Eaton 25503 pump from the Kubota 4690B backhoe I'm contemplating using.

Short answer is: yes, based on the specs of the pump, and considering driving it off the mid-PTO (at a maximum of 2500 rpm) I should have enough volume (around maybe 16 to 20 gpm) and pressure (1500 to 2000 psi)

The HP developed by the hyd motor you select should be equivalent to the HP supplied to the snow blower using the PTO.

I don't understand exactly what that means ... or maybe the significance / ramifications of it aren't entirely clear to me. Using the calculators @ Surplus Center I get the following:

To get 22 gpm out of the pump @ 2500 rpm requires a pump displacement of 2.0 cu in. ... the displacement of the pump I have is 2.05 cu. in.

To get 16 gpm @ 2000 psi requires 22 hp ... the calculator does say that this is for an electric motor and to DOUBLE it for gas motors. I have a diesel so ...

Since I can control the pressure developed (by using an adjustable pressure relief valve) I could do this:

22 gpm @ 1500 psi ... which would require 21 hp.

Flowing 22 gpm with a 9.59 cu. in motor would yield an 530 rpm at that flow rate ...

Going with the next size smaller PTO drive motor - 7.63 cu. in. - 22 gpm would yield 666 rpm ...

Flow will likely be somewhat less than 22 gpm ...

As far as torque is concerned:

1500 psi with 9.59 cu. in. motor would yield 2,291 in. lbs. of torque ...

1500 psi with a 7.63 cu. in. motor would yield 1,822 in. lbs. of torque

Jack the relief pressure up to 2000 psi and we get 3,054 and 2,430 in. lbs. respectively ... probably at less flow rate, since I won't have the hp to drive the pump at that high a flow rate and pressure.

Make sense ?

Thoughts ?

The hyd motor also has to turn at about the same rpm.

The hydraulic motor I've spec'd above should deliver roughly the same rpm as the rear PTO, at the flow the pump will deliver at the maximum rpm I can drive it with the mid-PTO.

This is a skidsteer adapter with hyd motor to turn PTO implements on the front.

Skid Steer Powered 3 Point Adapter for Bobcat Low Flow Loaders | eBay

Thanks - I'll review it to see if it provides any useful info.

Just looking at it though, it has alot more "stick out" than I'd want ... my loader isn't all that powerful in terms of lift capacity, and I'm going to try to mount the blower as close to he pivot pins as possible (hence the idea of the Harbor Freight "Quick Hitch" weld to a SSQA plate)