Hydraulic snowblower pump/motor calculations.

[dkhntr04]

Hi everyone,

I'm looking for some outside input and proofreading on my calculations for my snowblower project. I am looking to convert my Farm King SB80 80" 540 RPM 3-point blower to SSQA loader mount with hydraulic drive. I am looking to build the hydraulic power pack myself using the mid PTO on my 3720 to power it. Please take a look at my calculations and component selection and let me know if you see anything that doesn't look like it will work. There is a lot more to the project besides these calculations, but please stick to just these for now.The one big question I have is if there will be any issues regarding motor/pump efficiency.

The Parts:

Pump: Surplus Center - 1.74 cu in BORG WARNER S20S15DJ11L HYD PUMP

1.74 CI, 3000 PSI Cont. 3000 RPM Cont.


Motor: Surplus Center - 7.1 cu in PARKER 110A-071-AS-0 HYD MOTOR NP

7.1 CI, 3000 PSI Cont. 3500 PSI Max, 3000 RPM Cont.

The Plan:

Drive the pump off the 2100 rpm mid-PTO on the 3720 either direct mount or by drive shaft depending on what fits. Run the engine at 2723 RPM to produce a 2200 RPM PTO speed. 2200 x 1.74 = 3828 CI/Min (/231 = 15.8 GPM)

Run the blower with the 7.1 CI motor. 3828 CI/Min pump flow / 7.1 CI motor = 539.15 RPM for the blower.

Horsepower: Relief valve set at 3000 PSI. 3000 x 15.8 gpm x .0007= 33 hp required. Surplus Center's calculator says 32 hp. 3720 puts out 35 PTO HP, so I should be good on power.

Torque: The motor is rated for 2915 In/Lbs of torque continuous, 3401 In/Lbs intermittant. The 3720's engine puts out 84.3 Ft/Lbs, or 1011 In/Lbs. 2600 engine RPM / 540 PTO RPM = 4.81. 4.81 x 1011 In/Lbs = 4867.7 In/Lbs of torque at the PTO assuming an impossible 100% efficiency. Assuming 75% efficiency would be 3650 In/Lbs. In the ball park. I ran this blower with a 23hp PTO tractor last year, and it had enough torque to spin a full impeller/blower. I am not concerned with torque, should I be?


Let me know what you think. Thanks:thumbsup:

 

[J_J]

Your tractor only has 44 HP.

Surplus Center - 1.74 cu in BORG WARNER S20S15DJ11L HYD PUMP

That pump takes about 43 HP to develop the potential pressure of 3000 psi.

 

[dkhntr04]

Your tractor only has 44 HP.

Surplus Center - 1.74 cu in BORG WARNER S20S15DJ11L HYD PUMP

That pump takes about 43 HP to develop the potential pressure of 3000 psi.

At 3000 RPM and 21 GPM. I am looking at running it at 2200 RPM and 15.8 GPM.

 

[leonz]

Hi everyone,

I'm looking for some outside input and proofreading on my calculations for my snowblower project. I am looking to convert my Farm King SB80 80" 540 RPM 3-point blower to SSQA loader mount with hydraulic drive. I am looking to build the hydraulic power pack myself using the mid PTO on my 3720 to power it. Please take a look at my calculations and component selection and let me know if you see anything that doesn't look like it will work. There is a lot more to the project besides these calculations, but please stick to just these for now.The one big question I have is if there will be any issues regarding motor/pump efficiency.

The Parts:

Pump: Surplus Center - 1.74 cu in BORG WARNER S20S15DJ11L HYD PUMP

1.74 CI, 3000 PSI Cont. 3000 RPM Cont.


Motor: Surplus Center - 7.1 cu in PARKER 110A-071-AS-0 HYD MOTOR NP

7.1 CI, 3000 PSI Cont. 3500 PSI Max, 3000 RPM Cont.

The Plan:

Drive the pump off the 2100 rpm mid-PTO on the 3720 either direct mount or by drive shaft depending on what fits. Run the engine at 2723 RPM to produce a 2200 RPM PTO speed. 2200 x 1.74 = 3828 CI/Min (/231 = 15.8 GPM)

Run the blower with the 7.1 CI motor. 3828 CI/Min pump flow / 7.1 CI motor = 539.15 RPM for the blower.

Horsepower: Relief valve set at 3000 PSI. 3000 x 15.8 gpm x .0007= 33 hp required. Surplus Center's calculator says 32 hp. 3720 puts out 35 PTO HP, so I should be good on power.

Torque: The motor is rated for 2915 In/Lbs of torque continuous, 3401 In/Lbs intermittant. The 3720's engine puts out 84.3 Ft/Lbs, or 1011 In/Lbs. 2600 engine RPM / 540 PTO RPM = 4.81. 4.81 x 1011 In/Lbs = 4867.7 In/Lbs of torque at the PTO assuming an impossible 100% efficiency. Assuming 75% efficiency would be 3650 In/Lbs. In the ball park. I ran this blower with a 23hp PTO tractor last year, and it had enough torque to spin a full impeller/blower. I am not concerned with torque, should I be?


Let me know what you think. Thanks:thumbsup:

Don't waste you time or money;

The heat and pressure losses from piping will have a huge negative affect



Running the pump on the mid power take off is not making for
happy campers because of the PTO's NEEDED rated rpm.


About your snow blower,

You will be short on power and torque both
unfortunately and you will be spending
money you do not have to spend.

In order to obtain enough torque to do this with your desired set up
you will need a small radial piston motor with a large gear or vane pump
feeding it from a fifty or sixty gallon tank reservoir that you will have
to carry on the three point hitch.



You would be better off purchasing one of the front mount three point hitch kits
from Pronovost that will permit you to mount your blower up front with a front
mounted three point hitch WHICH has a lift cylinder AND a reversing reduction gearbox
to allow you to run a snow clearer or flail mower or a rotary cutter as much as i dislike
rotary cutters.


You will have less money and time in one of the
Pronovost front mount kits for less money and
you will be able to use the front mounted hitch
and front PTO the year round.



If you really really really intent on doing this you should use a large Briggs 2 cylinder gas engine bolted to
the snow blower like the Bercomac snow blower set ups with chain drive as this will be of more benefit to you
as long as your loader can lift it without nose diving.

 

[aczlan]

Running the pump on the mid power take off is not making for
happy campers because of the PTO's NEEDED rated rpm.

Confused here, why would things be "unhappy" when running at 2k RPM? Balance will be critical, but the pump is rated to run at 3k RPM, so it should be fine running at 2k RPM

In order to obtain enough torque to do this with your desired set up
you will need a small radial piston motor with a large gear or vane pump
feeding it from a fifty or sixty gallon tank reservoir that you will have
to carry on the three point hitch.

Why? If he can get 15GPM at 3k PSI he will be pushing 30+ HP on the motor. Also, the rule of thumb is a minimum of 1 gallon of storage capacity for 1 GPM of pump capacity (2 gallons to 1GPM is better). You can get away with less in the winter or when running a oil cooler, but a 50 or 60 gallon tank on a 15 GPM pump is way overkill.
Also, per Pronovost, a hydraulic system putting out 28-39HP needs 28-35 gallons of capacity (yes, Pronovost sells loader mounted hydraulic snowblower kits)

You would be better off purchasing one of the front mount three point hitch kits
from Pronovost that will permit you to mount your blower up front with a front
mounted three point hitch WHICH has a lift cylinder AND a reversing reduction gearbox
to allow you to run a snow clearer or flail mower or a rotary cutter as much as i dislike
rotary cutters.

Why wouldn't he be able do the same with a hydraulic system on the loader?

You will have less money and time in one of the
Pronovost front mount kits for less money and
you will be able to use the front mounted hitch
and front PTO the year round.

What does one of those run? Looks like he will be out $300ish for the motor/pump, lets say $100 for a tank, $300 for lines and quick connects (if applicable), $100 in hardware, $200 in hydraulic fluid and $100 in misc stuff. That works out to $1100. Last time I heard a front mount system was pushing $2000 and you have limitations on how high you can go (ie: you cant take the top foot off of your monster snow pile, you have to chew through the whole thing).

If you really really really intent on doing this you should use a large Briggs 2 cylinder gas engine bolted to
the snow blower like the Bercomac snow blower set ups with chain drive as this will be of more benefit to you
as long as your loader can lift it without nose diving.

So you want to add another motor that has to be started, kept in running order, which cant be tipped very much and requires more of a different kind of fuel... Got it.

Aaron Z

 

[oldnslo]

Mid PTO provides higher RPM for a smaller pump but will require a very large inlet line to prevent cavitation from trying to draw oil from the rear of the tractor to the middle of the tractor.

Ideal solution would be a hydrostatic drive on the blower. This is a closed loop system so all you would need for lines to reservoir is a smaller line for the charge pump inlet and return flow. Down side of this is cost and controlling the hydrostat pump.

Didn't check your calculations but probably figure around 85% efficiency under load on the hydraulic drive.

 

[leonz]

Confused here, why would things be "unhappy" when running at 2k RPM? Balance will be critical, but the pump is rated to run at 3k RPM, so it should be fine running at 2k RPM


Why? If he can get 15GPM at 3k PSI he will be pushing 30+ HP on the motor. Also, the rule of thumb is a minimum of 1 gallon of storage capacity for 1 GPM of pump capacity (2 gallons to 1GPM is better). You can get away with less in the winter or when running a oil cooler, but a 50 or 60 gallon tank on a 15 GPM pump is way overkill.
Also, per Pronovost, a hydraulic system putting out 28-39HP needs 28-35 gallons of capacity (yes, Pronovost sells loader mounted hydraulic snowblower kits)


Why wouldn't he be able do the same with a hydraulic system on the loader?


What does one of those run? Looks like he will be out $300ish for the motor/pump, lets say $100 for a tank, $300 for lines and quick connects (if applicable), $100 in hardware, $200 in hydraulic fluid and $100 in misc stuff. That works out to $1100. Last time I heard a front mount system was pushing $2000 and you have limitations on how high you can go (ie: you cant take the top foot off of your monster snow pile, you have to chew through the whole thing).



So you want to add another motor that has to be started, kept in running order, which cant be tipped very much and requires more of a different kind of fuel... Got it.

Aaron Z

Again his snow blower will require zero modifications.

Most if not all of these snow clearers use rototiller gearboxes
as the tillers also need a right angle drive and operate at 540
R.P.M., with gear reduction and chain drive as do snow clearers.


To the first question, he does not have enough oil in his r
eservoir to do this.

To the second question, many of the remote reservoirs
have a much higher voume than his tractor.

To the third question, he does not have the volume or
high flow hydraulics available. He could purchase
the Pronovost hydraulic drive snow blower system
but why bother when he can purchase the pronovost
front mount three point hitch kit will allow him to
operate his snow blower with no fuss or muss and also
operate a mower if desired or a chipper shredder?

Hydraulic hose and fittings are very very very expensive and
tanks are also very very expensive because they have to be
built properly with a hot oil baffle to segregate the hot oil
away from the cooler oil in the tank.

He will spend less than that on a front mount system that
operates off his mid mount power take off.


As to the last question, he would be better off adapting a
Bercomac unit if he is intent on this path to disaster; The Bercomac
units have been on the market for quite a while.
The Briggs and Stratton motors have been in use for many years
and the gear reduction and chain drive for the engine driven
Bercomac snowblowers have been in use for a while as well.

He would be better off having a welding shop fabricate the frame to
allow him to attach this to his front end loader using a quick attach
forklift kit to carry the snowblower using chain binders to hold it in place,
further the Briggs engines have a presurised lubrication system so tipping
a V twin would not be a problem as they are used on motorised flailmowers
in Europe to mow slopes.


If he breaks a hydraulic fitting or blows a hose under the tractor or
on the loader he will not know it happened until thew system
becomes starved and then the damage is done and
a tractor splitting will be required unless his tractor
has an engine mounted gear pump.


The Pronovost front mount systen for his tractor would
be money better spent for this as he could still use his
blower with zero modifications.

I used to repair and rebuild hydraulics for a living and both
the hose these and these parts are very expensive on a per foot
basis plus the pair of fittings per hose as most hoses have the
disposable fittings which adds to the cost considerably versus
the reusable fittings whch are of stronger construction for two,
four, or six wire braid Aeroquip Hydraulic Hose.


The other thing is if he has snow banks he should be out casting
snow more often anyway as he has an all weather cab.

If neck strain is the issue many folks use rear mount cameras as well as mirrors.

 

[aczlan]

Again his snow blower will require zero modifications.

Please re-read my post. Where did I say that it would? If you are thinking of the pump comment at the beginning, I was talking about his hydraulic pump, not the motor on the blower.

Most if not all of these snow clearers use rototiller gearboxes
as the tillers also need a right angle drive and operate at 540
R.P.M., with gear reduction and chain drive as do snow clearers.

Really... You might want to look at the gearbox on a 2 stage snow blower (such as the OP has). Most have one input and two outputs. Most tillers and flail mowers have a gearbox with one input and one output.

To the first question, he does not have enough oil in his reservoir to do this.
To the second question, many of the remote reservoirs
have a much higher voume than his tractor.

Please re-read my post. I was not saying that he could use his tractor sump as a reservoir, I was saying that he would only need a 20-30 gallon external reservoir, not a 50-60 gallon one like you were suggesting.

To the third question, he does not have the volume or
high flow hydraulics available. He could purchase
the Pronovost hydraulic drive snow blower system
but why bother when he can purchase the pronovost
front mount three point hitch kit will allow him to
operate his snow blower with no fuss or muss and also
operate a mower if desired or a chipper shredder?

Please re-read my post. I never said that he had high flow available. That the whole point of a hydraulic powerpack.

Hydraulic hose and fittings are very very very expensive and
tanks are also very very expensive because they have to be
built properly with a hot oil baffle to segregate the hot oil
away from the cooler oil in the tank.

Wont disagree with you that fittings and hose aren't cheap

He will spend less than that on a front mount system that
operates off his mid mount power take off.

How much will that cost? Worst case, he will be out $2000 making it himself. The only front mount 3 point that I can find prices on is made by Buckeye tractor and they want $2500 for the 3 point and another $1200+ for the subframe.

As to the last question, he would be better off adapting a
Bercomac unit if he is intent on this path to disaster; The Bercomac
units have been on the market for quite a while.
The Briggs and Stratton motors have been in use for many years
and the gear reduction and chain drive for the engine driven
Bercomac snowblowers have been in use for a while as well.
further the Briggs engines have a presurised lubrication system so tipping
a V twin would not be a problem as they are used on motorised flailmowers
in Europe to mow slopes

That's great if you are running the snowblower on a truck, but on a loader where the snowblower could accidentally be tilted to face straight down, it may not be such a good idea.

He would be better off having a welding shop fabricate the frame to
allow him to attach this to his front end loader using a quick attach
forklift kit to carry the snowblower using chain binders to hold it in place,.

IIRC, he has a quick attach on his loader, so that wouldn't be needed.

If he breaks a hydraulic fitting or blows a hose under the tractor or
on the loader he will not know it happened until thew system
becomes starved and then the damage is done and
a tractor splitting will be required unless his tractor
has an engine mounted gear pump.

Or you know if he has a EXTERNAL HYDRAULIC POWERPACK like he is asking for advice on how to setup

The Pronovost front mount systen for his tractor would
be money better spent for this as he could still use his
blower with zero modifications.

As could a hydraulic power pack and a QA to 3 point adapter...

The other thing is if he has snow banks he should be out casting
snow more often anyway as he has an all weather cab.

What if one normally uses a loader bucket and/or blade to push up piles to speed up the process and then pushed back the piles with the blower? Or, what if one has a barn that sheds snow in large piles after each snowfall? Or, what if he doesn't want to be out snowblowing every little bit?
See the thread by grsthegreat for some real life examples of this.

Aaron Z

 

[leonz]

Overheated oil destroys seals quickly and the seals will not last long.


Its his money to waste, I just do not want to see him waste his time or
money as the work has already been done for him where the Pronovost/Hardy front mount kit
will solve these issues for him as he has the midmount power take off system.


In order to generate the torque he needs an axial or radial piston motor to do this and the mid mount PTO
and the Pronovost/Hardy front mounting system eliminates all this to begin with.
As I said it is his money and I have no interest in putting my hand on his wallet.

 

[aczlan]

How much would this magical front mounting system cost? Is my number of $3700+ close?
Is it possible to use a front mount system with the loader on? Most I have seen will not work with the loader on

Why would he need an "axial or radial piston motor" vs a Geroler motor such as the one he linked to if the motor is rated for the same amount of torque?

Downsides to a front 3 point system include:
1. Less clearance
2. A possibility of bending the PTO shaft going to the front if you high center the machine
3. Less lift height
4. Less protection against bending things if you get something stuck in the blower (a hydraulic system pressure relief valve will allow the machine to stop gracefully even if the shear pins do not work properly
5. The ability to reverse the PTO rotation direction if needed to remove stuck objects (assuming that a valve is used)
6. More work to change from a loader mounted plow/bucket to the snowblower
7. No ability to change the angle of attack (ie: tilting the blower up/down) to work at stubborn piles

Aaron Z