skattrak 1050 1986

[daddygoose]

Need help. I have purchaed a 1050 skattrak loader and im interested in building a quick attach bush hog for it. It currently has a 9 GPM flow rate. is there a Hydraulic motor out there that will work on a 5ft bush hog, or should i look at changing out the 9 and moving up to 14.5 which is the pump used on the skattrak 1350. I also have the manual with the loader, which i hear is very rare.

 

[skidsteer.ca]

The more flow or pressure or both the hydraulic system has the more horsepower you can deliver to the cutter. 9 gpm is pretty low by todays standards but I guess it really comes down to how much you intend to use it at what kindof performance you expect.
After you have decided which pump specs your going to use, you need to select a motor that will be rated for at least the pressure the system has, and also has the correct volume to give you the desired output rpm at the flow you have. And is capable of running at that rpm.
If you set the cutter up for a 9 gpm pump then later switch to a 14.5 gpm pump, the speed of the motor/cutter will increase by over 50%.
The large pump would be better, but then do you have the engine hp and same cooler capacity, line/hose sizes as the machine with the larger pump uses?
Also what presure does the system run at?
Ken

 

[daddygoose]

The more flow or pressure or both the hydraulic system has the more horsepower you can deliver to the cutter. 9 gpm is pretty low by todays standards but I guess it really comes down to how much you intend to use it at what kindof performance you expect.
After you have decided which pump specs your going to use, you need to select a motor that will be rated for at least the pressure the system has, and also has the correct volume to give you the desired output rpm at the flow you have. And is capable of running at that rpm.
If you set the cutter up for a 9 gpm pump then later switch to a 14.5 gpm pump, the speed of the motor/cutter will increase by over 50%.
The large pump would be better, but then do you have the engine hp and same cooler capacity, line/hose sizes as the machine with the larger pump uses?
Also what presure does the system run at?
Ken

if i stick with the 9 GPM which produces 2150 PSI. do you have any suggestions on which motor to put on a 4 " pto driven bush hog. I was going with a 5 ft untill i found out it was a 9 instead of 14.5 GPM Not sure if the size bushhog makes a difference on what i can do. I just purchased some land with 5 yr old planted pines and the underbrush has never been cut. im hoping that i can clear this with this skid steer.

 

[markplow]

if i stick with the 9 GPM which produces 2150 PSI. do you have any suggestions on which motor to put on a 4 " pto driven bush hog. I was going with a 5 ft untill i found out it was a 9 instead of 14.5 GPM Not sure if the size bushhog makes a difference on what i can do. I just purchased some land with 5 yr old planted pines and the underbrush has never been cut. im hoping that i can clear this with this skid steer.

There are a lot of variables to consider here.. Like if there is a gear box on the mower and all the points Ken made above. Generally speaking, mowing any kind of heavy brush or grass sucks a lot of horsepower. Theoretically you could cut it with about any combination imaginable if you went slow enough, but there are limits to all of our patience.
Some food for thought...
- Take a look at some commercially available mowers for SSL's (just on websites or the such). Find one that is reasonably sized for your machine flow and pressure. Note the pressure and flow ratings of this mower. If you don't find one, that is telling you something....
- Multiply the pressure (in PSI) times the flow (in GPM) and divide by 1714. This should be the HP demanded by the mower. I would then divide this by 0.8 or even 0.7 to account for the losses of the hydraulic system. The resulting number is essentially the HP needed to run the similar mower at max performance.
- Keep in mind you need some HP left over to drive the machine and you don't want to be running your machine at full HP demand for a long period of time. If you operate on hills this demand will be higher. If you operate very slowly on flat ground it will be lower. I would plan on NO MORE than 60% of the max HP of the engine going to the mower.
- Based on the above, does your machine have enough HP? If yes, continue. If no, or if you are very close, you are better off finding another solution. Otherwise you will either be frustrated by how slow you have to go or be killing your machine. In the second case, I would probably look for a small farm tractor to do the job. My gut tells me you are going to be in the second situation. Note that even if you have enough engine HP, you may not have enough hydraulic or engine cooling capacity. If this is the case it will mean that you will only be able to mow in short bursts with stops (engine still running) to let the machine cool itself down. The small Skattraks I have worked with have not proven to be the best cooling machines. Of course the weather makes some difference here, but not as much as you might think unless you plan to mow in the dead of winter.
- If you think you will have enough engine HP, then you can back calculate to find what flow should run your mower at a reasonable speed given your pressure. This is assuming the reference mower from above is very similar in width and general design and does not have a gearbox on it. Since you want the HP demand of the mower to equal the HP above that you calculated, you can use the same equation and just solve for flow instead of HP. i.e. HP needed = Machine pressure * Needed motor flow/1714. Solve for needed motor flow... or... Needed Flow = HP needed*1714/Machine Pressure.
- Then figure what speed you want your mower to spin at... If it was a pto mower with no gearbox, then this is either 540 or 1170. Take the flow from above and divide by the rpm desired. This will give you gallons/rev for the pump. Convert gallons to cubic inch or cubic centimeters or whatever your pump stats are in, and you have the displacement of the motor you need.
If your mower or the reference mower has a gearbox there is another level of calcuation that I won't bore you with (probably already did that well enough).
I hope I wrote this all out correctly... I was doing this in my head while suffering from a bit of insomnia. If I did it wrong you should end up with some really crazy numbers that don't make sense. A good guy at your local hydraulics shop should be able to help you out if needed....
Sorry for the long explanation.... Hopefully it helps me sleep...

 

[daddygoose]

There are a lot of variables to consider here.. Like if there is a gear box on the mower and all the points Ken made above. Generally speaking, mowing any kind of heavy brush or grass sucks a lot of horsepower. Theoretically you could cut it with about any combination imaginable if you went slow enough, but there are limits to all of our patience.
Some food for thought...
- Take a look at some commercially available mowers for SSL's (just on websites or the such). Find one that is reasonably sized for your machine flow and pressure. Note the pressure and flow ratings of this mower. If you don't find one, that is telling you something....
- Multiply the pressure (in PSI) times the flow (in GPM) and divide by 1714. This should be the HP demanded by the mower. I would then divide this by 0.8 or even 0.7 to account for the losses of the hydraulic system. The resulting number is essentially the HP needed to run the similar mower at max performance.
- Keep in mind you need some HP left over to drive the machine and you don't want to be running your machine at full HP demand for a long period of time. If you operate on hills this demand will be higher. If you operate very slowly on flat ground it will be lower. I would plan on NO MORE than 60% of the max HP of the engine going to the mower.
- Based on the above, does your machine have enough HP? If yes, continue. If no, or if you are very close, you are better off finding another solution. Otherwise you will either be frustrated by how slow you have to go or be killing your machine. In the second case, I would probably look for a small farm tractor to do the job. My gut tells me you are going to be in the second situation. Note that even if you have enough engine HP, you may not have enough hydraulic or engine cooling capacity. If this is the case it will mean that you will only be able to mow in short bursts with stops (engine still running) to let the machine cool itself down. The small Skattraks I have worked with have not proven to be the best cooling machines. Of course the weather makes some difference here, but not as much as you might think unless you plan to mow in the dead of winter.
- If you think you will have enough engine HP, then you can back calculate to find what flow should run your mower at a reasonable speed given your pressure. This is assuming the reference mower from above is very similar in width and general design and does not have a gearbox on it. Since you want the HP demand of the mower to equal the HP above that you calculated, you can use the same equation and just solve for flow instead of HP. i.e. HP needed = Machine pressure * Needed motor flow/1714. Solve for needed motor flow... or... Needed Flow = HP needed*1714/Machine Pressure.
- Then figure what speed you want your mower to spin at... If it was a pto mower with no gearbox, then this is either 540 or 1170. Take the flow from above and divide by the rpm desired. This will give you gallons/rev for the pump. Convert gallons to cubic inch or cubic centimeters or whatever your pump stats are in, and you have the displacement of the motor you need.
If your mower or the reference mower has a gearbox there is another level of calcuation that I won't bore you with (probably already did that well enough).
I hope I wrote this all out correctly... I was doing this in my head while suffering from a bit of insomnia. If I did it wrong you should end up with some really crazy numbers that don't make sense. A good guy at your local hydraulics shop should be able to help you out if needed....
Sorry for the long explanation.... Hopefully it helps me sleep...

The Hydraulic motor i found is a 9GPM at 1800PSI with 675 lbs of torque, at 623 RPM's . Witch according to your calculations would require a 12 HP to run. My SSL is a 31 HP kubota. The bush hog does have a gearbox which i plan on using, .

 

[markplow]

The Hydraulic motor i found is a 9GPM at 1800PSI with 675 lbs of torque, at 623 RPM's . Witch according to your calculations would require a 12 HP to run. My SSL is a 31 HP kubota. The bush hog does have a gearbox which i plan on using, .

Sounds like an interesting option. If the mower was set up for a 540 rpm pto, then I guess you'll be spinning it about 20% faster than intended, but that might not work too bad.... I guess you could run at 80% throttle if nothing else although this will take away some of your HP available.. Is the 1800 psi the rated pressure or the max for the motor? Your SSL should put out a max pressure much higher than this, so if it is max you will need a secondary relief valve in the system somewhere. This could be dangerous though as a relief set this much below the machine's relief will probably mean you will blowing over relief a lot. This will generate a lot of heat. I would recommend a max pressure rating for the motor of at least 10% above the machine relief setting. Hopefully that is your case.
Good luck and let me know how this works out for you.
Mark

 

[daddygoose]

Sounds like an interesting option. If the mower was set up for a 540 rpm pto, then I guess you'll be spinning it about 20% faster than intended, but that might not work too bad.... I guess you could run at 80% throttle if nothing else although this will take away some of your HP available.. Is the 1800 psi the rated pressure or the max for the motor? Your SSL should put out a max pressure much higher than this, so if it is max you will need a secondary relief valve in the system somewhere. This could be dangerous though as a relief set this much below the machine's relief will probably mean you will blowing over relief a lot. This will generate a lot of heat. I would recommend a max pressure rating for the motor of at least 10% above the machine relief setting. Hopefully that is your case.
Good luck and let me know how this works out for you.
Mark

the max pressure is 2400PSI. 3.0 cu in, the max pressure if the SSL is 2100

 

[markplow]

The Hydraulic motor i found is a 9GPM at 1800PSI with 675 lbs of torque, at 623 RPM's . Witch according to your calculations would require a 12 HP to run. My SSL is a 31 HP kubota. The bush hog does have a gearbox which i plan on using, .

One more thought... No matter what you do, I'd advise to closely watch your temperatures when you are running this so you don't fry your machine. Watch both the engine coolant temperature and the hyd oil temperature (at the cooler exit). Either one may be your limiting factor depending on conditions, your operating style, etc.

 

[markplow]

One more thought... No matter what you do, I'd advise to closely watch your temperatures when you are running this so you don't fry your machine. Watch both the engine coolant temperature and the hyd oil temperature (at the cooler exit). Either one may be your limiting factor depending on conditions, your operating style, etc.

OK. Sounds like you have this under control. Good Luck!

 

[daddygoose]

One more thought... No matter what you do, I'd advise to closely watch your temperatures when you are running this so you don't fry your machine. Watch both the engine coolant temperature and the hyd oil temperature (at the cooler exit). Either one may be your limiting factor depending on conditions, your operating style, etc.

4 Bolt Ports 1/2" NPT Shaft 1" x 1 3/4" with Woodruff key MG03 Model 3.0 cu. in. displ. 1800 PSI cont. 2400 PSI int. 675 Torque in.-lbs. cont. 936 Torque in.-lbs. int. 9 GPM cont. 9 GPM max. 623 RPM cont. flow & PSI 678 RPM max. no load Shpg. 15 lbs. do you think this is the right motor. does it have enough torque. it's on a 5 ft bush hog . im replacing the top deck with 1/4 " deck to give it a little tougher skin.

 

[markplow]

4 Bolt Ports 1/2" NPT Shaft 1" x 1 3/4" with Woodruff key MG03 Model 3.0 cu. in. displ. 1800 PSI cont. 2400 PSI int. 675 Torque in.-lbs. cont. 936 Torque in.-lbs. int. 9 GPM cont. 9 GPM max. 623 RPM cont. flow & PSI 678 RPM max. no load Shpg. 15 lbs. do you think this is the right motor. does it have enough torque. it's on a 5 ft bush hog . im replacing the top deck with 1/4 " deck to give it a little tougher skin.

Torque is one of the factors of HP, so this should be reasonably in line given you are operating about the same speed as the mower is designed for. Given how a mower is usually used the perception of torque will probably be more influenced by the rotating mass you have (flywheel effect) than by the motor itself. It seems you are fairly in line with the design inputs for this type of mower. Effectively your SSL and motor are replacing an equivalent of about a 25 HP tractor with a 540 PTO which seems to make sense as the size of machine to run this mower. Even though you have more HP availabel than 25, hydrostats and hydraulics are much less efficient at transferring power then a direct drive (pto) hence the comparison to a 25 HP tractor. Of course, as you are demonstrating hydraulics give you lots of options in terms of variability.
My main concern would still be heat. I think you will end up with a rather functional little mowing unit if you can keep it cool. I would suspect hyd oil temp will be your limitation. If you don't plan to run for long periods of time and don't push it over relief very often (i.e. keep a slow enough ground speed), you should be safe in any case. You could get into adding coolers or heat exchangers to the machine or mower, but this opens up another project. Hopefully you won't have to do anything like this.
Often mowing trees requires a lot of turning (zig zagging to get in close and in-between) so this will add to your heat generation and power consumption. You might want to try to find a way to minimize this. My favorite was to use a weed killer to kill the weeds near the trunk of the tree. As the trees get bigger you won't need to do this anymore. ...but now I am into a whole other discussion....

 

[skidsteer.ca]

Torque is one of the factors of HP, so this should be reasonably in line given you are operating about the same speed as the mower is designed for. Given how a mower is usually used the perception of torque will probably be more influenced by the rotating mass you have (flywheel effect) than by the motor itself. It seems you are fairly in line with the design inputs for this type of mower. Effectively your SSL and motor are replacing an equivalent of about a 25 HP tractor with a 540 PTO which seems to make sense as the size of machine to run this mower. Even though you have more HP availabel than 25, hydrostats and hydraulics are much less efficient at transferring power then a direct drive (pto) hence the comparison to a 25 HP tractor. Of course, as you are demonstrating hydraulics give you lots of options in terms of variability.
My main concern would still be heat. I think you will end up with a rather functional little mowing unit if you can keep it cool. I would suspect hyd oil temp will be your limitation. If you don't plan to run for long periods of time and don't push it over relief very often (i.e. keep a slow enough ground speed), you should be safe in any case. You could get into adding coolers or heat exchangers to the machine or mower, but this opens up another project. Hopefully you won't have to do anything like this.
Often mowing trees requires a lot of turning (zig zagging to get in close and in-between) so this will add to your heat generation and power consumption. You might want to try to find a way to minimize this. My favorite was to use a weed killer to kill the weeds near the trunk of the tree. As the trees get bigger you won't need to do this anymore. ...but now I am into a whole other discussion....

Here is some more reading on brushers
http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=10821
http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=2879
The one have have built in the 1st thread now has a open front with the bade tips exposed. (no deck above, blades stickout 4" beyond the deck) This design takes less hp to run as it discharges more.
Currently running on 17 gpm with a 6.2 ci motor volume.
It was originally setup for13gpm with arouns a 4 ci motor. In this configuration I had run it on a 8.5 gpm 553 and it still surprized me on how well it worked.
When I got the machine with the 17 gpm at 3000 psi pump, I was looking forward for the big step up from 13 gpm by 2600 psi and resized the motor to give more torque at the same 540 rpm, but was not left in awe by the difference.
What I have noticed is heavy tall grass is the worst draw on hp. More so then brush. The open deck is by far the biggest performance improvement I have made.
I can't speak for the cooling capacity of the Scat Trac, but it has been a non issue on the NH and Bobcat loaders, but I'm in Canada to so ambient temps are 80f or less usually here too.
If your brush is in the 2.5" dia and under I think the 9 gpm is do able with a 4 ft mower as it does not sound like you will be mowing a lot. How many acrers are you tending?
As Mark said, it will work more as a flywheel while cutting, the motors torque does not apply so much at the moment the blade cuts, but it is what determines how long it will take the cutter to recover the lost rpm after the cut.
Here is a couple vids of fit in its present configuration, note howit discharges grass to the side in the front and the rear sides as well.
http://www.youtube.com/watch?v=CAr2R29UpN8
Here is another cab cam of the 15 gpm Nh 160 mowing mostly 3" minus but some up to 4"
If you listen to the sound you can here the recovery time of the cutters speed. This is now a 6 ft mower with about double the power driving it that you plan on
http://www.youtube.com/watch?v=i0eWNpMYFYk
Ken

 

[daddygoose]

Here is some more reading on brushers
http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=10821
http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=2879
The one have have built in the 1st thread now has a open front with the bade tips exposed. (no deck above, blades stickout 4" beyond the deck) This design takes less hp to run as it discharges more.
Currently running on 17 gpm with a 6.2 ci motor volume.
It was originally setup for13gpm with arouns a 4 ci motor. In this configuration I had run it on a 8.5 gpm 553 and it still surprized me on how well it worked.
When I got the machine with the 17 gpm at 3000 psi pump, I was looking forward for the big step up from 13 gpm by 2600 psi and resized the motor to give more torque at the same 540 rpm, but was not left in awe by the difference.
What I have noticed is heavy tall grass is the worst draw on hp. More so then brush. The open deck is by far the biggest performance improvement I have made.
I can't speak for the cooling capacity of the Scat Trac, but it has been a non issue on the NH and Bobcat loaders, but I'm in Canada to so ambient temps are 80f or less usually here too.
If your brush is in the 2.5" dia and under I think the 9 gpm is do able with a 4 ft mower as it does not sound like you will be mowing a lot. How many acrers are you tending?
As Mark said, it will work more as a flywheel while cutting, the motors torque does not apply so much at the moment the blade cuts, but it is what determines how long it will take the cutter to recover the lost rpm after the cut.
Here is a couple vids of fit in its present configuration, note howit discharges grass to the side in the front and the rear sides as well.
http://www.youtube.com/watch?v=CAr2R29UpN8
Here is another cab cam of the 15 gpm Nh 160 mowing mostly 3" minus but some up to 4"
If you listen to the sound you can here the recovery time of the cutters speed. This is now a 6 ft mower with about double the power driving it that you plan on
http://www.youtube.com/watch?v=i0eWNpMYFYk
Ken

The cuttter is a 5' with a gear box with a stump jumper. i will be maintaing 10 acres of planted pines . the under brush are mostly 1.5' brush and thinner. Im not messing with pines. once i get it cleared , I'll just maintanin it with the SSL. The cutter is a HAUSE with a 40HP gear box. Im cutting the top deck off and putting 1/4" deck plate to beef it up. The front will be left open but do i need to cut the deck back to expose the blades a bit or can i just put a discharge out the side. This particular cutter has an 100% open front and a partial open back. it has the option of a chain guard that pretects from slinging debris. I have seen options of putting a chain guard to keep this debris from being thrown from the cutter.