Skid Steer Hydraulic Specs

[Spudland_Dave]

Looking at the possiblity of designing a Auxillary Hydraulic system (PTO Pump, Resevoir, etc) which would closely mimic that of a skid steer so I could run attachments like a FEL Mounted Rotary Broom, etc... what would the Ballpark industry specs... PSI, GPM, etc... which encompasses the majority of brands/sizes and allows for the use of the majority of the attachments?

I've recently come across a few smokin deals on Skid Steer equipment and running the Hydraulic Motors associated with them have made me think about gearing up for it.
I want to be as close to "industry spec" as possible so any of the SS attachments would/could work. I hate to design it just for the rotary broom I found and then I find some other "must have" skid steer attachment which wont work....

Thanks for any help.

 

[RickB]

Peruse the spec's for High Flow hydraulic systems of SSL's in the brands of your choice. Major manufacturers have this info on the web. Then you can draw your own conclusions. I would think searching Cat, NH, Case, and Bobcat would pretty well cover it. You probably will end up around 2750 PSI and 25-30 GPM.

 

[radman1]

Bobcat's large frame SS have 20.7 gpm at 3300 psi. Hi-flow 37 gpm. This includes the 220, 250, 300 and 330.

Mid frame SS have 16.9 gpm at 3300 psi. Hi-flow 26.4 gpm. This includes the 150, 160, 175, 185 and 205. The 130 is also considered midsized but has 2600 psi at the same gpm.

 

[Spudland_Dave]

Thanks Radman! I was thinking of trying to be in the 17-ish GPM 3k PSI ballpark...looks like I wasnt too far off..

RickB....the reason why I just didnt bop on over to the JD/Bobcat/New Holland websites is I dont know what physical size SS I should be looking up..What size Skid Steer would typically use attachments such as a 72" Power Rake, 72" Sweepster, Post Hole Digger, 66-72" Snowblower, etc... Essentially attachments that would Physically fit my JD 3520 if they were mechanical drive.

 

[J_J]

Looking at the possiblity of designing a Auxillary Hydraulic system (PTO Pump, Resevoir, etc) which would closely mimic that of a skid steer so I could run attachments like a FEL Mounted Rotary Broom, etc... what would the Ballpark industry specs... PSI, GPM, etc... which encompasses the majority of brands/sizes and allows for the use of the majority of the attachments?

I've recently come across a few smokin deals on Skid Steer equipment and running the Hydraulic Motors associated with them have made me think about gearing up for it.
I want to be as close to "industry spec" as possible so any of the SS attachments would/could work. I hate to design it just for the rotary broom I found and then I find some other "must have" skid steer attachment which wont work....

Thanks for any help.

It depends on the HP you have available.

As an example, if you want 25 GPM and 3000 psi, and that will take 51 HP to accomplish this.

On my case skidsteer, the PTO output is 16 GPM, at 2350 psi, and it uses 25 HP to accomplish this, and the Case skidsteer has a 60 HP diesel.

The below pump will take 32 HP



http://www.surpluscenter.com/item.asp?UID=2009011505570870&item=9-1047-1&catname=hydraulic

 

[skidsteer.ca]

The medium frame loader with 40 to 50 hp have flows in the range of 15 to 20 gpm and pressures between 2500 and 3400 ish Larger 60 to 80 hp machines in the 18 to 28 gpm flows with 2800 to 3500 psi.

Brush cutting, snow blowing and stump grinding , if those are your goals then go with the most pressure and flow you can design with the motor hp you have.
Then buy attachments to match your flow. Our snowblowers use a variety of hydraulic motor sizes to drive the fan at the desired rpm with the available flow Most other skidsteer attachments run fine on 17 to20 gpm with 3000 psi.
Also if you design fo flows over about 25 gpm be prepared to buy attachments rated hi flow which run 20 or 25% more
Ken

 

[SnowRidge]

It depends on the HP you have available.

As an example, if you want 25 GPM and 3000 psi, and that will take 51 HP to accomplish this.

On my case skidsteer, the PTO output is 16 GPM, at 2350 psi, and it uses 25 HP to accomplish this, and the Case skidsteer has a 60 HP diesel.

JJ, when I plug those numbers in the Metaris hydraulic calculator, it gives me significantly different answers. Any idea why?

 

[SPYDERLK]

JJ, when I plug those numbers in the Metaris hydraulic calculator, it gives me significantly different answers. Any idea why?

JJs #s are probably reflective of the power needed to provide those flows and pressures whereas yours are how much HP those flows and pressures will generate... The #s you are getting have to be multiplied by 1714/1500 to see the power the prime mover must provide. Efficiency bites you.
larry

 

[J_J]

JJs #s are probably reflective of the power needed to provide those flows and pressures whereas yours are how much HP those flows and pressures will generate... The #s you are getting have to be multiplied by 1714/1500 to see the power the prime mover must provide. Efficiency bites you.
larry

SPYDERRLK, and SnowRidge

I called the tech at Surplus Hydraulics, and the plug in figures they use are for 100 % of applied power. There is some efficiency lost from engine to pump, and then from pump to motor. The exact figures, I am not sure of. I believe hydraulic efficiency is 85 %. So if you really get into it, you have to take in all the losses to come up with a min HP to power the system. Or, If you work backward such as, you have a pump and motor, you have to compute loses, and match up motor and pump..

Brendon Casey has a hydraulic program that you can plug in different items and pressures, and can see the results of your efforts.

I believe that the 1714 take the 85 % efficiency into account, and Surplus Hydraulics does not.

 

[SPYDERLK]

SPYDERRLK, and SnowRidge

I called the tech at Surplus Hydraulics, and the plug in figures they use are for 100 % of applied power. There is some efficiency lost from engine to pump, and then from pump to motor. The exact figures, I am not sure of. I believe hydraulic efficiency is 85 %. So if you really get into it, you have to take in all the losses to come up with a min HP to power the system. Or, If you work backward such as, you have a pump and motor, you have to compute loses, and match up motor and pump..

Brendon Casey has a hydraulic program that you can plug in different items and pressures, and can see the results of your efforts.

I believe that the 1714 take the 85 % efficiency into account, and Surplus Hydraulics does not.

From the Metaris calculator:

Formula: HP = PSI * GPM / 1714
PSI is gauge pressure in pounds per square inch; GPM is oil flow in gallons per minutes.

Rules-Of-Thumb:
Horsepower for driving a pump: For every 1 HP of drive, the equivalent of 1 GPM @ 1500 PSI can be produced.

Hence the 1500/1714. About 85% efficiency as you have stated JJ.
larry