Hydraulic powered drive-wheel

[Revival Sawmill]

Ok, I'm hoping someone on here knows their way around hydraulic pumps and motors, and can give me some guidance.  I've gotten two diesel railroad power units which have very large hydraulic pumps on them.  This is the tag off one:

I *think* I've matched it to the one in the attached pdf.  I'm hoping the combination of the diesel engine and this pump is powerful enough to drive the bandwheel and a couple parasitic loads (carriage traverse and headrig elevation).  My current problem is that I know NOTHING about hydraulics and can't seem to figure out what sort of hydraulic motor would match this pump and be capable of powering the bandwheel effectively.  It's a 30" wheel, 2" blade, and there will be 3' between the wheels (not planning to cut that wide all the time, but it would be slick to be able to!).  If anybody has some guidance or can even tell me where to start researching, you'd make my day!
Thanks,

[Kbeitz]

One thing you do have to watch is when you run your controls to the hydraulic motor that you need one that will let your wheels freewheel when you tell it to stop.  If not you just might get to see what happens when everything slams to a stop.

[bandmiller2]

Dusty, I'am no authority on hydraulics but I have worked with them for years. My feeling is you have enough engine and pump to run a band mill. There are two common hyd. motor types the piston wobble plate type and the gear type. The wobble plate type tend to be low speed, probably the gear type would work the best. Some gear type pumps can be used as motors they have seals designed for pressures involved. We had an Arial ladder truck that had what they called a hydraulic PTO. It used three similar Hydreco gear pumps one driven from the trans. piped to one used as a motor under the turntable up to another used as a pump on the turntable.  If you can figure the gallons per Minuit of the pump ( its variable depending on engine speed) match it to  a hyd. pump that is motor rated. The best way is to buy it from someone local that will help you with the engineering. You will need to know the RPM of the bandwheel. Frank C.

[Revival Sawmill]

One thing you do have to watch is when you run your controls to the hydraulic motor that you need one that will let your wheels freewheel when you tell it to stop.  If not you just might get to see what happens when everything slams to a stop.

That is an excellent thought, which had not occurred to me at all! Thank you!

Dusty, I'am no authority on hydraulics but I have worked with them for years. My feeling is you have enough engine and pump to run a band mill. There are two common hyd. motor types the piston wobble plate type and the gear type. The wobble plate type tend to be low speed, probably the gear type would work the best. Some gear type pumps can be used as motors they have seals designed for pressures involved. We had an Arial ladder truck that had what they called a hydraulic PTO. It used three similar Hydreco gear pumps one driven from the trans. piped to one used as a motor under the turntable up to another used as a pump on the turntable.  If you can figure the gallons per Minuit of the pump ( its variable depending on engine speed) match it to  a hyd. pump that is motor rated. The best way is to buy it from someone local that will help you with the engineering. You will need to know the RPM of the bandwheel. Frank C.

I wonder if I could just use the second one of these pumps as a hydraulic motor on the bandwheel? I think you're right and I'll have to find someone around here that deals with this type of thing...  My math says that I want the wheels spinning between 600 and 700 rpm... sound right?

Thanks,

[Kbeitz]

Dusty, I'am no authority on hydraulics but I have worked with them for years. My feeling is you have enough engine and pump to run a band mill. There are two common hyd. motor types the piston wobble plate type and the gear type. The wobble plate type tend to be low speed, probably the gear type would work the best. Some gear type pumps can be used as motors they have seals designed for pressures involved. We had an Arial ladder truck that had what they called a hydraulic PTO. It used three similar Hydreco gear pumps one driven from the trans. piped to one used as a motor under the turntable up to another used as a pump on the turntable.  If you can figure the gallons per Minuit of the pump ( its variable depending on engine speed) match it to  a hyd. pump that is motor rated. The best way is to buy it from someone local that will help you with the engineering. You will need to know the RPM of the bandwheel. Frank C.

In my area there is another very common type.  A vane pump.

[Ljohnsaw]

I wonder if I could just use the second one of these pumps as a hydraulic motor on the bandwheel? I think you're right and I'll have to find someone around here that deals with this type of thing...  My math says that I want the wheels spinning between 600 and 700 rpm... sound right?

Thanks,

If you used the matching pump as a motor (assuming the seals are the right type), you would need some sort of flow control/bypass or the "motor" will be the same speed as the pump rpm (2-3,000 rpm?)  Way to fast.

600-700 rpm will give you 4,700 - 5,400 FPM.  For the 2" blade (and if you have the HP) you want to be at the upper end, maybe faster?  I thought I read somewhere that the 2" blades run in the 6-6,500 range.

This could be a pretty high production machine!  I'll be watching...

[Den-Den]

You need to know the flow rate of the pump when engine is running full speed and compare to the volume per revolution of the hydraulic motor so you can calculate the output speed.  I think you will need a hydraulic oil cooler also.

[york]

Bad idea.too complex for a new build-transmit power by belts at first,later can be removed if your sawing ok,then get into your HYD. idea...

[Revival Sawmill]

Thanks!  I've started a build thread, but I'm sticking these design questions out there on their own.
https://forestryforum.com/board/index.php/topic,93309.0.html

[Revival Sawmill]

Yep!  It is starting to sound pretty complicated!! 
I sort of 'fell into' the two diesel motors and hydraulic pumps, and at this point it would greatly simplify my life if I could mount either one of the diesels or the 50 hp electric in a fixed position down on one of the lower carriage rails and just route the hydraulic hoses up to the headrig and driveshaft... I might even end up hanging the hydraulic motor on the front of the headrig and saving myself the clearance between the back of the headrig and the front vertical of the carriage... I'm not even sure how I'd accomplish that otherwise.
Thanks for the input!! Let me know if you think of a way around it!

[york]

There is a mill built in Germany,that does what you want,but big bucks,i have there info,will look for it tomorrow....

[Revival Sawmill]

Thanks York!  I'd love to see how someone else handled it! 
I guess the first thing I really need to know is how many ¿inch-pounds? of torque I need to apply to the driveshaft?  What the heck is an inch-pound?  It can't just be 12x a foot-pound, surely?
Thanks,

[Kbeitz]

One foot lbs = 12.000000427771214 inch lbs.

[ozarkgem]

Direct motor belt drive will be a simpler and cheaper way to go. You will want 50 HP to run the 2" bands. I am sure there is a formula for band HP but I would think 50 would be min to really saw. If you go to the trouble to build I would want the most production I could get out of it. You will need some kind of an oil cooler or a very large tank. 50 gal of hyd oil is around 700.00 bucks here. Not sure how much engine HP you would need to produce 50 hp at the wheel. There is a reason the big mill mfg,s don't use this system. Even a gen set and electric motor would be better. Wire is cheaper than hoses.

[Gearbox]

My concern would be volume of oil needed  and the weight on the carriage . also how are you going to keep the oil below 150 degrees . I am fighting heat on my home built wood processer all the time and I am only running  16 GPM .

[Revival Sawmill]

I guess I could put the electric motor up on the headrig beam, but it's bound to be heavy, and I'm back to the clearance and belt tensioning issues... And I'll have to track down a cheap 3phase generator that I could drag around to power it. 
The only formula for hp I could find came back with 35 hp for the numbers I had/guessed, but even then I'm thinking it meant actual hp delivered to the drive-side bandwheel.
Thanks for the help/feedback!

[ozarkgem]

I guess I could put the electric motor up on the headrig beam, but it's bound to be heavy, and I'm back to the clearance and belt tensioning issues... And I'll have to track down a cheap 3phase generator that I could drag around to power it. 
The only formula for hp I could find came back with 35 hp for the numbers I had/guessed, but even then I'm thinking it meant actual hp delivered to the drive-side bandwheel.
Thanks for the help/feedback!

50 hp diesel motors are routinely used on mills. Some have over 100 hp motors.
I have an 20 hp electric motor and an electric clutch on mine and run it off a 20KW gen set. Works very well. 35 hp  will saw pretty slow on a 2" band. You have to design your mill around the power plant then clearance and weight are not a problem. Look at how WM, TK, Cooks, Baker and others build their mills and get some ideas there. Don't reinvent the wheel. Keep it simple.

[Don_Papenburg]

 Check out Surplus Center.   they have books on fluid power for sale under $30.oo.
call the tech line and they will help you with the book you need for your job.

[bandmiller2]

Dusty, are you planning to mount the diesel and pump on the saw head carriage or festoon hoses to the motor with the engine stationary on the ground.??

[Revival Sawmill]

The plan was to mount the engine on the lower fixed rail of the carriage so it goes back and forth over the deck with the carriage and would only need festooning😜 of hydraulic hoses to allow the headrig to go up and down. Still trying to sort this out in my mind.  Sounds like the 50 hp electric coupled to the drive bandwheel with a belt might be a more powerful/efficient option. And I've figured out how to modify my design to free up the needed clearance.  But that brings up other issues, like how many v-belts does it take to transmit 50 hp? How do you idle/slow the band between cuts with an electric motor that big? Would I have to protect the shaft/bearings in the motor from the side-load of tensioning all those v-belts somehow?  As complicated as the hydraulic system sounds, it might actually end up being simpler.
Thanks,

[Revival Sawmill]

And how do you change band speed for different conditions with an electric motor- change belt pulleys every time?

[york]

OK,the mill i spoke of is the "Serra,Montana MD 90"

http://www.serra.de/index.php?id=128&L=1

[Revival Sawmill]

Cool mill! Looks like they are hanging the power unit and hydraulic reservoir on the back of the headrig instead of down on the carriage? I wonder why they chose hydraulic final drive? Also looks like a 31.5" wheel that's getting pushed by a 30kw/44hp diesel, so 50 hp electric may well be over the line into overkill?
Thanks!

[ozarkgem]

And how do you change band speed for different conditions with an electric motor- change belt pulleys every time?

You don't change the band speed. They are designed to run at a certain FPM depending on what Hp motor you are running. You slow down or speed up the feed rate for different conditions. Different logs take different hook angles also.

[Revival Sawmill]

Really? I've read/seen on the cooks videos about using different fpm for frozen logs/different types of wood?  I guess it makes more design sense to have one permanent set of pulleys on an electric motor and varying feedrate.

So, how many belts would it take to transmit 50 hp from the electric motor to the drive-side bandwheel? I know our chipper has some strange 4-in-1 belt to transmit about 85 hp, but that's shock loaded often and is powering a tremendously large flywheel. Even then it slips occasionally. I'm hoping that bandmills don't need that many?
Thanks,

[Kbeitz]

Pulley and Belt Calculator



http://www.gizmology.net/pulleysbelts.htm

[Revival Sawmill]

That calculator is giving back some very high numbers for the load on the system! I'll have to do some more research.  Looking at similarly sized/powered mills, they mostly use 3-4 belts.

[york]

Search,for the Browning pulley belt calculator....

[Revival Sawmill]

It's also looking like I'd have to adapt an automotive clutch to engage/disengage the 50 hp motor;  All the electric clutches I'm finding top out about 27 hp, and a centrifugal won't do it on an electric motor...  Anyone have any experience with this?
Thanks,

[york]

Cooks big 36 mill still uses a cam over belt tensioner,spelling..   

[Revival Sawmill]

Was sort of thinking about some sort of soft starter and just cutting the motor off between passes, but I'm worried that would still put excessive wear and tear on motor/generator.  Seems like the tensioner would eat belts?

[Revival Sawmill]

What about putting two of the 27 hp electric clutches on a common shaft that's coupled to he output shaft of the electric motor to spread the load?  I could wire them together so they engage at pretty much the same time?

[ozarkgem]

http://www.pittsdistribution.com/pittsclutch-h28.html
This is the clutch I have on my mill. It is still the original clutch from 1985. A 50 hp motor @ 1750 rpm has 150 ft lbs of torque. Mine is rated for 200-300 ft lbs. The drawback is they are pricey.  I would do the cam over or make a slide to move the motor and tighten the belts. I wouldn't worry about disengaging it between cuts.

[ozarkgem]

Pulley and Belt Calculator



http://www.gizmology.net/pulleysbelts.htm

Gives lots of numbers but doesn't say how many or what size belts unless I am not using it right.

[Revival Sawmill]

http://www.pittsdistribution.com/pittsclutch-h28.html
This is the clutch I have on my mill. It is still the original clutch from 1985. A 50 hp motor @ 1750 rpm has 150 ft lbs of torque. Mine is rated for 200-300 ft lbs. The drawback is they are pricey.  I would do the cam over or make a slide to move the motor and tighten the belts. I wouldn't worry about disengaging it between cuts.

No joke those are pricey!!🤑
Those 27hp versions are only a couple of $180-200- I might try doubling up on those before I go to the $1500 option! 😜😉
Do these methods that loosen the belts to disengage not do constant damage to the belts?  How do you ensure you get enough tension on them when you re-engage?
Thanks,

[Revival Sawmill]

Pulley and Belt Calculator



http://www.gizmology.net/pulleysbelts.htm

Gives lots of numbers but doesn't say how many or what size belts unless I am not using it right.

I couldn't get any of those calculators to give me a 'number of belts' recommendation.  But the few I tried out were giving similar numbers for the force applied to the shafts/bearings. Which seemed very high to me!  I wonder how many pounds of force are loaded onto the shaft and main bearings when the blade is tensioned up?
Thanks,

[ozarkgem]

My plan is to start the electric motor with the belts loose and quickly tighten the belts so as no to let the belts rub against the pulley. You will have to build a belt tightener  with adjustable stops so it engages the belts at the same tension each time.

[Don_Papenburg]

On a belt tension system , the belts have a guide that holds the belt in a way that it just misses the pulley and also keeps it from sliding off the pulley .  Engagement is done slowly enough to not shock and fast enough to not smoke the belts.    Move the motor or an idler pulley with a leaver ,an electric actuator ,or a hydraulic cylinder with a restrictor in the engage line to get the proper speed.

[Revival Sawmill]

Ok, so that first motor won't work, now I'm looking at another, but it spins at 3700 rpm instead of 1765 rpm. Is that going to get me more power at the saw once I've slowed the rpms with the different sized pulleys? Or am I better off with another 1765 rpm motor that more closely matches the rpms I want at the drive wheel?
Thanks,

[warren46]

I have a Timber Harvester mill with a 40 HP electric.  It runs three v-belts and has more torque and power than I can ever use even sawing 30" plus wide in oak.  The belts are tensioned using an over center idler pulley.  I recently installed a three v belt that has a backing that makes the three belts act as one.  Works really well.

In my opinion based on the way a 40 HP electric works, 50 hp will be overkill unless you are using something like 6" bands.

[Revival Sawmill]

That's good to hear! 50 hp looks like the biggest motor the generator we got could possibly start, and I was starting to worry it might be 'underkill' based on some of the comments 🙄

[ozarkgem]

I have a Timber Harvester mill with a 40 HP electric.  It runs three v-belts and has more torque and power than I can ever use even sawing 30" plus wide in oak.  The belts are tensioned using an over center idler pulley.  I recently installed a three v belt that has a backing that makes the three belts act as one.  Works really well.

In my opinion based on the way a 40 HP electric works, 50 hp will be overkill unless you are using something like 6" bands.

Warren
    What size blades do you run on the TH?   thanks  Jim

[warren46]

[/quote]
Warren
    What size blades do you run on the TH?   thanks  Jim
[/quote]

I run 1 1/2" .055 1" pitch 10 degree bands.  I can never detect any slowing of the motor.

Electric motors produce the full horsepower when loaded so the maximum torque is at the maximum horsepower point on the rpm curve.  On an internal combustion engine the maximum torque point is lower than the maximum horsepower so when an internal combustion engine is loaded to produce the maximum torque is is putting  out less than maximum horsepower.  An electric motor will deliver more power to the band at maximum load then an internal combustion engine with the same horsepower rating.

[ozarkgem]

I have a 20 hp electric on mine. Electric is the only way to go. I didn't know if you ran 1 1/2 or 2" bands.

[bandmiller2]

Electric will punch far above its rating, it is ideal mill power, especially in an enclosed building. My band mill runs 1 1/2" bands along with a hydraulic pump on three phase 15hp. I have all the power I need. Be Leary of pacific rim electric motors, they won't put out like ours. Frank C.

[Wintergreen Mountain]

I  have a TURNER band saw mill that I bought new without the gas engine from Bill Turner in up state NY.. I mounted a 17 GPM hydraulic gear motor on the mill head. the engine is a 51 HP VW diesel out of a VW rabbit. The pump is a 14GPM Vickers pressure compensated piston type. Two 1" hyd hoses, 60 ft long drag or sling between the power unit and the sawmill.


The mill disengages and the engine idles down with a key chain remote control that I took  off a wireless control winch.

I have sawed about 42000 B/F and it works better than I expected

Leon

[47sawdust]

Leon,
That is a great set-up.Nice job.