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 | shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin 
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2004-01-16 74205
I am setting up a traditional circular sawmill. Right now the log carriage is moved by a system that tightens two flat belts that can turn a 12" diameter drum clockwise and counter clockwise. Wrapped around this drum are 6-8 turns of steel cable. It's like a winch where both ends of the cable can pull in opposite directions. The cable then extends in both directions to the ends of the mill tracks, goes through a pulley at each end and then back to the log carriage on top moving it in two directions. I want to get rid of this dangerous flat belt system and move the log carriage with hydraulics. That way I can stand farther than 3ft away from the blade as set up now ( :-0 ). I have drawn a simple schematic and placed it on my pic #6. The red arrows show the cable drum. The cable and log carriage are also shown.
I would like to keep the cable and drum and turn the drum with a hydraulic motor and two way valve. I can mount the hydraulic motor directly to the end of the drum's 1" shaft. I'm thinking the valving would be similar to that used on a log splitter so I can turn the drum in both directions. I don't think I'll need super force, maybe 200 lbs at the carriage. I think my Kubota's hydraulic system should produce much more pressure than I'll need? I have no experience in this but expect that hydraulics will give me no feedback as to the amount of pressure I'm applying against the sawblade which should be limited. Is there a way to control the maximum pressure at or near the valving and yet have good flow below that pressure? If I just constrict the flow of fluid it seems that I can still build up max pressure. I think I'll need about 100 ft lbs of torque from the motor and it should have a range of 0.1 - 1.0 turns per second. This would give me a carriage speed of 3.7 - 37 inches per second. Does this torque and speed sound reasonable for a hydraulic motor?
If any of you guys with hydraulic experience could comment, I would appreciate it.
Dave
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 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada 
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2004-01-16 74206
Dave, I take a stab at it, I've designed & built several mills over the years, although they were all thin kerf bandsaw mills, not circular blade rigs, the principle should be the same.
First of all I'm not sure you are going about things the easiest way with your cable setup, it sounds like a maintenance nightmare, constant fiddling, and potential problems with the multiple passes of cable on the drum.
IMHO, the drive might be better accomplished using a pair of 'donut' spare tires run with really low air pressure, to cause a groove or depression in the centerline of the tread, but not with multiple loops of cable around it, the rubber tire should give you more grip than you will need. Besdies this method allows the use of readily available spindles with good bearings (the rear axle of a front-drive car or van is a perfect donor). Tension is obtained, and maintained, by small hyd. cyclinder pushing one spindle out and back as needed.
All tension values are determined by a simple pressure gauge in the hydraulic circuit. The higher the pressure, the more the tension.
The valve is similar to that used for a splitter, but in the case of a motor they are a little different style. The lever is a rotoating lever, like a hand on a clock, when you move it off the center point and let go it stays there. A "pressure compensated adjustable flow control" is what you want though, it will maintain a set flow rate regardless of variations in the rest of the hydraulic circuit. Again, a pressure gauge will allow you to learn how much force is required, and then be able to repeat it subsequently.
Your Kubota will surely provided enough force, but I doubt it will provide the amount of FLOW rate you will need. I would suggest a PTO pump, they have a 1 3/8" 6 spline hole in the center which slips on the output shaft directly. Big volume units are probably in the $500 range.
Another option if you have a 2 speed PTO is to make a mount for your 3pth and mount a free-standing pump there and drive it with the PTO at 1,000rpm setting and gear it up to 2,000rpm using a timing chain for a truck motor.
As for hyd. motors, they are usually rated in inch/pounds, a pretty big motor is going to make about 4,800 inch/pounds. Twelve inch/pounds is one foot/pound so 4,800 inch/pounds is 400 ft./pounds. However a motor of that size would need about 20GPM at 1,500psi. As I said this is WAY beyond the output of almost any tractor, let alone a CUT.
The speed you are looking for is going to be best obtained by gear reducing the motor speed since slow speeds are not great for producing torque, it would be easiest to run the motor at 100 RPM and use a reduction, or change your drive system to accomplish the same thing.
Best of luck. ....
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-16 74216
Thanks Murf, The drum/winch is already in place from the old setup and actually works pretty well. I'll just be getting rid of the belt system that used to turn it.
I think my 3130 puts out almost 9 GPM but that's a long way from 20. The guy I bought my backhoe from had a PTO pump and tank but I couldn't get him to throw it in on the deal. He had mounted the hoe onto his FORD 2N which was way too small for the weight of the hoe. For counterweight he had 500 lbs of weightlifting dumbells hanging with ropes off the front axle and grill. It was a sight to behold! The front end was still floating. I'm getting off track here but I will think about how I might gear a faster motor down. I suppose it will require a parallel shaft.
Dave ....
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 | TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2004-01-17 74261
This sounds like a real interesting application that might get me away from my usual theory stuff. I don't have enough time to get my mind around the idea right now and maybe more later if that's useful. For the moment, the site below goes to a set of hydraulic formula that can solve some of the problems. I fish through them later and see what I might solve.
If a basic open center system is used there's going to be the problem of controlling flow to control speed. There's also the problem that pressure is developed by the load rather than the pump and the load changes. Off hand, I think there are enough specialty valves to solve the problem. Flow can be proportioned. Different flows and pressures can be created in various parts of a system and I think held constant but it does take specialty valves.
It'd be interesting to me to think about it and maybe the results would be useful but it should be kept in mind that I'm an amateur w/o and engineering background. Wish I knew of a web site that describes the various types of valves available. ....
Link: Formula from Precision Power Inc.
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-18 74350
Thanks Tom, I will look that website over later tonight. I probably didn't discribe the project on the best detail. I should say that the cable winch system is "factory" and was the part of the carriage drive system that works pretty well. It has spiral cuts across the surface that the cable lays in and can wind side to side as it feeds cable to/from the carriage.
I was away all day yesterday making venison summer sausage. Four of us got our venison together and butchered a pig (two weeks ago) for a 67%/33% venison to pork mix. We had 180 lbs of meat total. It took about 4 hours to grind, mix the spices and stuff the casings. Today we are going to smoke it (drink beer) so that should be fun. Thanks again, Dave ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2004-01-18 74353
Now that sound like a real good reason to be away for the Board. Our neighbour usually goes a bit south to where he grew up and brings back deer that feed in corn fields down there. It makes better sausage than our bush fed deer here but any is better than none. Other neighbours went north and brought back four caribou between two of them. Another neighbour went as well haven't heard how he did. Anyway we're likely to be knee deep in caribou sausage around here and it is really out of this world. Oh boy is that stuff (vension included) good!
I think Murf is far more up on these sorts of applications than I am, and I may say some really dumb things. I imagine that there are ways other than hydraulic motors for doing things and some may be better applications.
I imagine you'll be wanting to run a carriage foreward at a constant slow speed with managed pressure and have a higher reverse speed. I'm not sure if you're thinking of using a variable displacement motor to manage the speed with a constant flow or a fixed displacement motor and manage the flow externally. I think either are feasible. I should reread Murf's comment carefully but I think he pointed out that very slow speeds from motors are not very efficient and I that's true far as I know.
The formulas on the site solve for flows required to produce given output HP and required input HP as well. Some overall efficiency assumptions are required. I forget if there are formula that go to torques directly or if you have to do your own conversions. I'd probably start off thinking about it in terms of the force needed on the carriage and required speed to get HP and then work backwards to the motor through any gearing and drive losses. I may see what I can come up with. One advantage of a pto pump is that more of the engine's power can be put into a pump than from most tractor hydraulics. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2004-01-19 74447
In rereading Murf's comment in detail I see he addressed most everything and far better than I could. There is valving that will manage flow/speed and pressure but getting flow that would produce enough torque directly might be a problem at low rpm's.
I'll take a stab at some numbers. If the effort is really butchered than I'll hear about it and that's the way we all learn. If I've got it right, 1HP is moving 550 lbs. in 1 second. So in terms of the carriage, moving 200 lbs. 37" in a second is something under 2 HP, which is a fairly modest requirement. Strictly in terms of flow, 2hp at 1500 lbs. is under 3 gpm. That might seem modest requirement but as Murfs points out, torque is the problem. If 200 lbs. is needed at the outside of the drum, larger torque is needed at the smaller input shaft. Of course, a problem with these formulas is that pressure isn't independent and can't be selected arbitrarily. Pressure is developed by the load and a good question might be what pressure at the pump would develop an acceptable load on the saw blade.
I hope this starts an orderly way to think about it in not too many words--for both me and other people. I noted Dennis provided what I think amounts to a 'cyber jail' and I think that's useful. I sometimes think I should have my own category titled something like 'useless ignorant theory groping' for my more self-indulgent efforts. As I say, it's how I learn. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2004-01-19 74451
Dave, the real problem with running a hydraulic motor is the basis by which they operate requires a minimum amount of flow.
They are best explianed as a 'hydraulic water-wheel', the hydraulic flow causes an impeller to spin. The faster (within reason) it spins the more efficient it is. Sort of the wet version of traction, if your vehicles wheels are spinning you have a very inefficient drive, if they connect to the ground there is little loss, the same is true of a hydraulic motor, the impleller must be spinning at the same speed as the hydraulic fluid passing it or there will be BIG losses.
I misunderstood the cable setup being 'factory', the norm for this sort of application is a heavy roller chain around the track and fixed to the carriage, the motor then direct-drives it via a sprocket on the output shaft.
Tom's effort at the power requirement calculations are close, but they do not include the various losses. In a hydro-static drive system the power losses from heat alone can be substantial, up to 50% is not uncommon.
Best of luck.
....
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-19 74459
Murf, when I say factory, I'm probably talking about something that was cutting edge for the 1930s or 40s. :-)
I got the 100 ft lb torque requirement by assuming the force I could possibly exert on the carriage by pushing it by hand (~200 lbs). If the pulleys and cable are lossless then I still need that 200 lbs of force at the drum. The diameter of the drum is one foot which creates a torque moment arm of 6 in. The torque applied to the drum by the motor has to be 200lb X 0.5 ft = 100 ft lbs or 1200 in lbs as Murf previously converted. (Sorry if this is obvious)
It's starting to look like the problem is to find the amount of gear reduction that would allow the drum to turn in the speed range I need and yet be in a good range (speed and torque) for an economical ($$$) hydraulic motor.
Any comments are appreciated.
Dave
....
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-19 74460
I found one manufacturer’s website (White Hydraulics, link below) that seems pretty informative. For one of their motors (CE120) they show that for a flow rate of 6 gal/min and a pressure of 2000 lbs this motor will produce 1800 in lbs of torque at 173 rpm. I’ll want to run the drum between 6 and 60 rpm (the 6 rpm is probably more important than the 60) and the motor looks like it’s most efficient at between 50 and 400 rpm so it seems that for this motor I would need at least a 10:1 gear reduction. There is nothing special about this motor it was just the first one on their product list. I have no idea yet of the cost. ....
Link:
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2004-01-19 74461
If your method of construction is anything at all like mine you will try an existing product in a new application as opposed to re-inventing the wheel. In terms of gear reduction, the simplest way to do it (IMHO) would be to have a hydraulic motor drive a small standard transmission from a rear wheel drive vehicle. These days that means a Toyota, Nissan (Datsun), or Mazda/Ford Ranger pickup. These trannys are a dime dozen at the wreckers and offer a good spread of gearing from deep reduction (1st gear) to even overdrive sometimes. If you want a real spread of gear choices put two together end-to-end, with one as a 'range selector' and the other as a gear box you will have a super low end and a big range up to 1:1 plus possibly O/D or even double over-drive.
I gather from your description that the torque calculation was based on sawing a log with you providing the 'push power'. If so then it will not be too far off, but verify what your 'push-power' is by pushing a bathroom scale against a (sturdy) wall in order to 'calibrate' your 'test results' LOL.....
Most high torque hyd. motors run between 100 - 250 rpm (max.) so I think you should concentrate on gear reduction, maybe the trannys I mentioned above would be easiest if not pretty, at least as an experiment. To achieve 100:1 reduction with gears and chain would involve several reductions, you couldn't do it in a single run. As an added challenge you want a spread of 10:1 in the speed you achieve, that will not be realistic using a motor either, it will have to be done with gearing. A motor that makes peak torque at 200 rpm will not be very good at 20 rpm.
Best of luck. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2004-01-19 74462
Dave, check out the Danfoss website (link below) for more information on the motors, etc. in the "Produsts" area then click on "Orbital Motors".
In the section "Distributors" you will find listings for several 'fluid power' specialists in wisconsin, they will (I'm sure) be able to offer very detailed & specififc information about the best route for you.
Best of luck. ....
Link: Sauer Danfoss
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-19 74464
Thanks Murf,
If I can't get the high RPM range that's ok. I will just have to wait a bit longer for the carriage to return. This will NOT be a mass production mill. :-)
Yes, it was an estimate of my "push power." When the flat belts I talked about in the first note would slip, it was easier to just hand push the log through. So I'm confident of being in the ballpark on required carriage force. ....
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-19 74471
I agree about getting expert help for this project. There is a custom hydraulic shop where I work in Rochester MN so I was planning on stopping there soon to talk. Mostly I wanted to pick your collective brains a bit so I could make some sense when I do stop.
Dave ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2004-01-20 74522
It's shaping up to a good discussion from my perspective but I've got to keep my stuff shorter. A custom shop would be able to recommend a pump and related gadgets and also address working pressures. It might be good to think about how you want to operate it because that would affect the application. Figuring if you want variable speed feed, fast reverse and 'smart load' might be good. Smart load might be something like stopping the feed if the saw blade binds. A bunch of fancy stuff could be done.
A summary of what we've got might be along the lines that theory and practical need to be separated. Theoretically, the whole thing could be done entirely hydraulically. The tractor hydraulics likely have enough power. However, you probably wouldn't want to pay for it. Torque can be amplified hydraulically as well as mechanically and there are many types of motors. Piston types work OK down to around 10 rpm and cam-lobe types go down to 1 rpm. Keeping costs realistic likely excludes everything but gear motors and those kind of crap out around 100 rpm so mechanical torque amplification likely is needed. I'd be surprised if the shop recommends anything else.
I've sort of lost track if the tractor's going to run the saw blade. If it does, the power required has to be added to that required for the carriage. Including losses (thanks Murf) the hydraulics are unlikely to require more than 4 hp but it could be an issue depending on log and blade size if the tractor's going to run both. There are losses other than just the motor but 80% overall efficiency is a common rating for gear pumps and gear motors are about the same. ....
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-20 74532
Tom, I don't think I said it but yes, I was planning on hooking the arbor up to the PTO. It came with a PTO setup. I think my L3130 has about 28? PTO hp. I THINK that this will be enough because my dad bought an old Belsaw sawmill that had very similar size and geometry to this one. We powered it with a Ford 9N (23 HP?) running a long flat belt hooked to a pulley on the arbor shaft. All the carriage power also came off the arbor shaft with secondary belts (like this one does right now).
So, my backyard engineering tells me that if the hydraulic power losses running the carriage are reasonable compared to straight mechanical losses of the old belt system I should be OK. If it takes 20 HP to hydraulically run what might take 5 HP mechanically, then I probably should look elsewhere for power. I do have another power option but right now it seems more complicated. ....
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-20 74534
One thing that's confusing me about these hydraulic motors is the "stall torque" rating at 1 RPM. Referring the the chart on the White hydraulic website I posted earlier it says that at 1 RPM this motor still has 1653 in lbs of torque. Doesn't this imply that I would have more than the 1200 in lbs I'm calculating at anything over 1 RPM? ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2004-01-21 74611
G'Morning:
I took a look at the CE120 specs on the site. I think the 1 rpm stall torque is basically how big a load the motor move at startup. I think (emphasis on 'think') I've also hear it called 'starting torque as a percent of theoretical' torque. It's basically what it'll get moving and doesn't mean the motor is intended to operate at 1 rpm.
I note the CE120 tables do spec operation down to 7-rpm. I forget what the input rpm needs to be but I don't think a motor should be operated below its speced range. There may be heating problems anyway and the application might benefit from an oil cooler. Maybe these motors would be suitable depending on rpm requirements.
The basic idea in matching a motor to an job (more think emphasis) is that the torque has to be sufficient to move the load and the flow is a given to move it at the right speed and the motor has to operate within designed parameters. Torque curves in table are fairly flat across flow and of course they increase with pressure. RPM is fairly flat but declining across pressure and of course increases with flow. I think what works is to find a cell that is a decent fit and then apply pressure control and flow control devices to get the right performance--and there are always losses.
An additional complication is that the tractor pump has it's own overall efficiency. Flow from the pump is not independent of the working pressure. There'd be some assumptions that flow and pressure control devices would operate within the limits of the tractor pump at a given engine rpm--likely pto rpm.
That's enough emphasis on 'I think' for one day I think. Hope it helps organize your thoughts. I know mine are a bit more organized after trying to think it through. ....
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-21 74616
Thanks Tom and Murf for your input. I too have been able to better organize my thought process with this discussion. I'm thinking this is somewhat analogous to running an electric motor under a load from a home generator. The generator/pump has a limited output (current&voltage/flow&pressure). As the load on the motors increase, to maintain RPM the generator/pump has to increase the voltage/pressure differential across the motor input&outflow while maintaining current/flow.
A big difference between the two might be the high frictional losses in the hydraulic hoses, valves etc. vs. relatively low electrical resistance in wires and switches. A DC system would probably be a closer match to hydraulics than AC. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2004-01-21 74617
Tom is right about the starting moment of the motor, the reference to 1 rpm is meant to give you a maximum amount of torque under which the motor will start turning, anything above that it will 'stall', in other words NOT start turning.
As for sizing, there is a range of motors that will work, it just depends on your particular a) budget, some of them can be big $$$$, b) needs, and c) wants.
For instance if you will never be cutting large or knotty logs, just small softwood then you may be able to get buy with a marginally adequate motor, if on the other hand you will be cutting big knotty green hardwoods, then you will want a little extra capacity built in to the system.
The overall design of the system must also be factored into the selection process, that's why I suggested you talk to some fluid power people. For instance yoiu may be forced to go to the next larger pump if you have a lack of cooling capacity to keep a smaller unit from over-heating it. On the other hand, if you have a shortage of flow you may be forced to go to a smaller motor.
The trick to sizing a hydraulic motor is to get one big enough to do the job adequately, but not so big that you waste flow and therefore the energy to produce it.
Best of luck. ....
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-01-21 74619
Murf, I have no real hardwoods on my land. I will probably be cutting only white and red pine. Green white pine saws like butter and is really fun. Red pine is a bit harder but not too bad either. Also the sawblade is only 48" so I'm really limited to logs about 22" or less. This small blade is the big reason you can get away with a power source under 30 HP. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2004-01-21 74621
I'm quite familiar with them, I built a cross-cut (chop-saw) using the same setup for firewood production at the farm a few years back. It is a good setup.
For the life of me I cant figure out why people fiddle around with those bandsaw mills, those little blades save you little wood, but the cost and maintenance is ridiculous compared to a circular blade. I've designed and built a few but I wouldn't have one myself.
Best of luck.
....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2004-01-22 74690
Sounds like the ideas are coming together pretty well--yes, electrical metaphors for fluids almost always work and vise-versa. The hydraulics shop guys likely will come up with several workable alternatives.
One alternative might be a variable speed feed. I keep thinking that might be a good idea since the loads likely will be pretty variable with different log sizes and types. The speed likely would vary a bit with load due to volumetric efficiencies of both the pump and motor. But that 'bit,' might not be too desirable if it means sitting around waiting for a slow feed that is suitable for large logs to barely work the blade on small ones and take all day to do. Ironically, a cheap motor with low efficiency might be desirable if losses could be tolerated.
A variable displacement axial flow motor with high efficiency could manage such a feed but one that'd do the job might be pricey. I've heard of 3-speed motors but I don't know much about them.
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-10-12 98167
After some time now I'm going to finish this project. I've replaced all the rotten wood parts with steel so the basic mill will be ready to go soon. I still need to buy the hydraulic motor to run the sawmill carriage and have found a suitable candidate with low rpm and high torque made by Prince.
I will need about 50' of hose to plumb everything. Because this is a stationary application I realized that I do not really need flexible hose but could use some kind of piping that would look neater and probably be much safer (no hoses to trip over).
So here's my question. The max pressure the motor will take is 1500 lbs psi. Would normal black pipe and fittings be able to take this pressure? I've only used it for natural gas lines prior but thats only a few lbs pressure. Any other ideas out there?
Dave
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 | yooperpete
Join Date: Jan 2004 Posts: 1413 Northern Michigan 
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2004-10-12 98168
NPT fittings will leak at 1500 psi. If you hard plump it use hydraulic tubing and make bends with a pipe bender. Get a tool to make a flared fitting connection or use compression style fittings if you don't want to bother with flaring. Put rubber isolation dampeners to support the tubing so the vibration, etc. doesn't cause stress failure. Hydraulic hoses may be easier. ....
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| shortmagnum
Join Date: Nov 2003 Posts: 848 Wisconsin
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2004-10-12 98173
"Hydraulic hoses may be easier."
And possibly cheaper. Our local Fleet Farm store sells 1/2" hydraulic hose at $27 for 192" long with NPT fittings. It would only cost about $100 for everything. ....
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| shortmagnum
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2004-11-10 100143
This past weekend I installed the hydraulics for the sawmill carriage. I found a low RPM, high torque motor from White Hydraulics. The valve is the same as you would use for a log splitter so it can reverse the direction after the cut. I did buy the hoses rather than using pipe. I don't need very much flow so the tractor is just idling to give good flow with a pto pump.
I cut 3 or 4 logs with it. The mill still needs some adjustment but I should be able to tune it pretty well in a few more hours of playing around.
Dave ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2004-11-10 100149
Dave, do yourself a favour and put a "pressure compensated adjustable flow control" between the pump and the direction valve. They are not expensive, probably about $100 or less.
This will allow you to maintain a constant flow rate to the motor regardless of the pressure in the rest of the system. It also allow you to have an infinitely adjustable range of speed on the motor from shut off to fully open and anywhere in between and will maintain that regardless of changes in the system.
Best of luck.
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| shortmagnum
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2004-11-10 100155
Thanks Murf, I think that would take care of the problem of the carriage feeding a bit too fast when the log is not yet up to the blade then slowing when the blade starts to cut and the pressure builds. You can feed slower, but the valve is very sensitive when it's just slightly open.
Dave ....
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 | beagle
Join Date: Jan 2004 Posts: 1333 Michigan
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2004-11-10 100158
You may also want to consider a motoring spool instead of the log splitter spool you are now using. A motoring spool is open nuetral allowing the motor to free wheel in the nuetral position avaoiding the sudden stopping when then flow is shut off, and also allows for good control of motor speed, as long as the spool capacity is balanced with the pump capacity. The jerking you have now could be from an in-balance between the pump and spool capacity in your present set-up. ....
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| shortmagnum
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2004-11-10 100161
Beagle, I think the valve has about twice the capacity of the pump. Plus I'm running the pump as slow as I can so there is a definite mismatch of valve and pump capacity.
Dave ....
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| beagle
Join Date: Jan 2004 Posts: 1333 Michigan
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2004-11-10 100166
An option to Murf's suggestion would be a lower capacity motoring spool. The spool wouldn't open the flow as quickly if the ports were smaller. I think you would find you have a lot better control over your motor speed, and a smoother operation.
The capacity of the motor should also be balanced with the spool and the pump. The better all the component's flow capacities are balanced, the better your control will be. ....
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