Convert Rear PTO Snowblower to Front Hydraulic

[Cord]

You can get by with the small resi if you add a oil cooler. The one item that's bothering me with your calculations is the low system pressure. I'd be designing for 2950 psi. Of course, full flow at max pressure will take even more hp.

I mounted a blower on the front of my tractor once. Used a chain drive to drop the pto below the rear axle and then a couple of universal joints and drive shafts brought the power forward. System worked really well and I was really disappointed when I sold the tractor and the new owner didn't want the blower.

 

[rswyan]

You can get by with the small resi if you add a oil cooler.

It just so happens I have a rather nice one that I'm not currently using - has it's own thermostatically-controlled electric fan on it

The one item that's bothering me with your calculations is the low system pressure.

I'm just mulling it over, trying to make sure I've got it fully understooded ...

Building pressure is largely evidence that the system is encountering work (resistance) to be done ... but at the same time in order for the blower to accomplish any real work that would be acceptable it has to operate at a certain speed (flow) ...

In terms of (theoretical) performance, there's probably a sweet spot there somewhere ...

The pressure relief valve I was looking at is adjustable from 1500 to 3000 psi, so I'd have the option of "tweaking" the system to "tune" it.

I can run the numbers using the Surplus Center hydraulic calculators to come up with a pump/motor combination that will deliver more pressure given my horsepower constraints. Going in that direction, requires using a motor with a smaller displacement, to keep the speed that the blower is spinning within an acceptable range (around 500 rpm)

Of course, the problem with that is the potential speed of the blower when it isn't under load but is free-wheeling ...

I'd be designing for 2950 psi.

But the problem with that is the flow you'd get with horsepower available - only around 10 gpm.

At 2000 psi, the flow would be more like 16 gpm ... which is actually doable with the PTO hp available.

Of course, full flow at max pressure will take even more hp.

Exactly ... to get 16 gpm @ 3000 psi you're looking at something in the neighborhood of 33 hp ... which is 50% more horsepower that I have available.

I think a key point that others have made earlier in this thread, is that this an HST tractor we're talking about ... and since I can vary the groundspeed, I can control the load that I'm placing on the blower.

Whether I'd have to slow it down so much that it would be unacceptable is an open question.

We're at the bottom of the Lake Erie/Northeast Ohio snowbelt and we generally don't get a lot of snow at one time. Big snow events usually occur once or twice a year ... if at all. If I lived 20 or 30 miles further north it would be an entirely different deal - since the yearly snowfall might be double of what it is here.

I mounted a blower on the front of my tractor once. Used a chain drive to drop the pto below the rear axle and then a couple of universal joints and drive shafts brought the power forward. System worked really well and I was really disappointed when I sold the tractor and the new owner didn't want the blower.

Yeah ... it kinda sucks when someone doesn't appreciate fine engineering and execution ...

 

[Cord]

Don't worry about matching the gpm and pressure to the engine size. In fact you be off, buy a lot! If you exceed the hp rating of the engine then you'll stall it. That's not the worst because before it stalls you'll back off the load slightly. For example, the drive pumps in my skid steer take almost 200hp to run, but I only have a 89 hp engine. Plus the engine is driving an auxiliary pump that takes another 60hp!

 

[SSdoxie]

Rs, Appears you have put some good thought and research into this. Get-r-done!!.. First get the loader switched to QA, if your going to use QA on the blower versus building a complicated 3pt mount out there, switch the loader to QA first. Don't bother with going to Quick Hitch at the blower, you would have spend $ or time to build a QA mount that or weld on a QA mounting plate, just get a QA mounting plate (which will cost about same as a QH) and weld it to the 3pt frame. Note: buy 3 of them so you can convert the bucket and the pallet forks.
Regards to the hydraulic setup. It looks good, add a cooler - maybe but you will only be using this in winter so some cooling in reservoir will take place. My suggestion is put a temp gauge at the reservoir outlet to pump to monitor it even if you do put the cooler on initially.
Question of available HP has come up. - Pump to motor listed has a close to 4.5:1 reduction, so if pump is consuming 16 HP to run the available motor output is 72HP. Meaning the motor is not going to require nearly as much torque as one might think.
Pump & motor efficiency: 80% is a common term I see mentioned on TBN numerous times. That is the minimum specification any good/known manufacture uses and the minimum (time to repair or replace spec). In the 25+ years I have been working around new and used hydraulic equipment, gear pumps and gear motors, testing of these when new normally run in the over 95% efficiency and don't drop below 90% after 1000 hrs. if fluid changes and filter maintenance done as recommended. This is testing systems designed to run @ 3000 PSI continuous and testing @ 2500 PSI. The last 500 psi they do start to drop off more dramatically.

 

[J_J]

What ever are you thinking.

He only has 30 HP to begin with.

How is he ever going to get the HP you suggested.

You can not develop more than you have.

 

[J_J]

Don't worry about matching the gpm and pressure to the engine size. In fact you be off, buy a lot! If you exceed the hp rating of the engine then you'll stall it. That's not the worst because before it stalls you'll back off the load slightly. For example, the drive pumps in my skid steer take almost 200hp to run, but I only have a 89 hp engine. Plus the engine is driving an auxiliary pump that takes another 60hp!

There is something about your statement that don't jive.

Your total HP is 80.

Gehl SL6635 = 80 HP

Gehl SL6635 Skid Steer - Attachments - Specifications

 

[Cord]

There is something about your statement that don't jive.

Your total HP is 80.

Gehl SL6635 = 80 HP

Gehl SL6635 Skid Steer - Attachments - Specifications

You're right. I got the the drive pump hp wrong. 37 gpm at 5500 psi demands 113hp x 2 pumps = 226hp. View attachment pll_1474.pdf Now, my engine only turns 2500rpm so the gpm is a bit less and thus the drive hp is also proportionally less.

As for the engine hp, well, that's what I get for trying to post with a mobile device. I meant to type in a 80, but missed and got 89. The engine label says 75.

 

[rswyan]

Cord,

Don't worry about matching the gpm and pressure to the engine size. In fact you be off, buy a lot! If you exceed the hp rating of the engine then you'll stall it. That's not the worst because before it stalls you'll back off the load slightly.

Yup ... it's as easy as rocking my right foot ...

For example, the drive pumps in my skid steer take almost 200hp to run, but I only have a 89 hp engine. Plus the engine is driving an auxiliary pump that takes another 60hp!

Well, there ya go ...

Makes sense to me that controlling the loading of motor should make all the difference in the world.

It's possible and, in fact, rather easy to stall an engine by overloading it ... I've done it with our Kubota and a box blade a number of times.

Fail to keep the rpms up and lug the engine and it will quit in a hurry.

Thanks for the input ... and the real world experience.

 

[rswyan]

SS,

Rs, Appears you have put some good thought and research into this.

Thanks ... part of the adventure is acquiring additional understandings ...

I find it enjoyable to learn about things I don't know about ... and to try to figure out solutions.

Get-r-done!!.....

Now we're talkin' ... :thumbsup:

First get the loader switched to QA, if your going to use QA on the blower versus building a complicated 3pt mount out there, switch the loader to QA first.

Yup ... that should be the sequence ... should have done it long ago.

Don't bother with going to Quick Hitch at the blower, you would have spend $ or time to build a QA mount that or weld on a QA mounting plate, just get a QA mounting plate (which will cost about same as a QH) and weld it to the 3pt frame.

Hehehe ... I love it :thumbsup:

... Quick Hitch ... what was I thinking ? :confused2:

LOL ... glad someone is paying attention and thinkin': simpler, less cost, less work, and less weight ... particularly of the "out in front of the pins" variety ...

If ever there was a good example of "overthinking" something, that had to have been it. Thanks for providing me with my dose of humor (and humility) for the day.

Note: buy 3 of them so you can convert the bucket and the pallet forks.

Yup ... actually I'll buy 4 of them ... because one of the other things I've got in the fryer right now is that I'm planning on building a grapple/root rake ... real soon ... may go pick up the steel for that tomorrow.

Regards to the hydraulic setup. It looks good, add a cooler - maybe but you will only be using this in winter so some cooling in reservoir will take place.

Right ...

There was a thread on TBN awhile back about several members that were running hydraulically-powered snowblowers on larger tractors ... one fella was actually concerned about the fluid being too cool ... seems that he could only get it up to around 70 or 80 degrees.

One question I had was what kind of pressures one would see in the return to the tank line, coming off the motor ... seems like that (or the suction line to the pump) would be the place to plumb in a cooler.

My suggestion is put a temp gauge at the reservoir outlet to pump to monitor it even if you do put the cooler on initially.

Yup ... good idea ... will do. Surplus Center has 'em for around $15 or so ... cheap insurance.

Question of available HP has come up. - Pump to motor listed has a close to 4.5:1 reduction, so if pump is consuming 16 HP to run the available motor output is 72HP. Meaning the motor is not going to require nearly as much torque as one might think.

Pump & motor efficiency: 80% is a common term I see mentioned on TBN numerous times. That is the minimum specification any good/known manufacture uses and the minimum (time to repair or replace spec). In the 25+ years I have been working around new and used hydraulic equipment, gear pumps and gear motors, testing of these when new normally run in the over 95% efficiency and don't drop below 90% after 1000 hrs. if fluid changes and filter maintenance done as recommended. This is testing systems designed to run @ 3000 PSI continuous and testing @ 2500 PSI. The last 500 psi they do start to drop off more dramatically.

Thanks ...

Practical, real world experience ... it's invaluable ... :thumbsup:

 

[rswyan]

In terms of SSQA mount plates I'm planning on going with the 1/4" solid mount that Titan offers for the snowblower ... although it's a little heavier than a 5/16" cut-out plate (72 vs 49 lbs) ...

Mostly because I'll be able to cut out and fabricate a SAE 2 bolt mounting point for hydraulic motor on the plate:

1/4" Attachment Solid Mount Plate

It will also give me more surface for attaching other items like brackets for check/relief valves, reservoir, etc.

For my bucket, pallet forks, and the grapple, I'll with go with the 5/16 cut-out plates to save a little weight:

5/16" Attachment Cut Out Mount Plate