Hello everyone. Is it true that piston pumps requre less power to run than gear pumps ?.And if they do ,is that allot less power or ?. I mean lets take example as one gear pump with power output same as piston pump,would they both be able to run with same kw engines or not ?. I don't know how to phrase this question better,i am not really good at english .... Also if hydraulic pump maksimum power output is 100kw,what would be required diesel engine kw to be able to run that pump ?.Are we talking about 110-130kw diesel engine,or much more ?.
Hydraulics are typically 80% efficient
In regards to HP/KW I get lost in the math. In regards to pumps, variable displacement typically run through closed center valves whereas gear pumps are associated with open center. The pumping losses are negated by the style of valve employed. That said, the gear pump is delivering 100% of capacity per revolution. It's designed to run at rated rpm. The variable displacement by comparison delivers lesser amounts at lower rpm to reduce load on engine but maintain delivery per demand and accomplish work. The VDP is a winner
Variable displacement pumps usually have load sensing (a design trait) that makes them respond to the load put on them to get max. efficiency and performance while keeping the engine in the optimal RPM range. A gear pump you usually need to manually lower the output at the valve to avoid stalling the engine with too much load where a VDP will automatically lower the output to keep from stalling the engine. You can still stall an engine with a VDP though. VDP's are more fussy about the cleanliness of the oil. The basic formula is 1HP for each GPM at 1500 PSI for electric motors. I'm not sure the formula to convert to internal combustion engines but there are several HP calculators and formulas online. VDP's are more efficient and there are ratings of the different pumps online as well.
@Welder Dave Can i use those calculators online to calculate my pump power output ?.I don't need them to be 100% accurate ofc. And can those calculators be used both for gear and piston pumps ?. Could you maybe share link for one of those online calculators ?.
Your best bet if you need 100% accuracy is to go to an established hydraulic shop where they can calculate everything from the exact pump you will use. The manufacturer will have all the design and engineering data for their pumps as well.
I don't need anything 100% ,not even close. I don't understand why is this so complicated ,all i ask is if there is difference in power requirement to run piston vs gear hydraulic pump. These online calculators can show hydraulic pumps power kw output ,based on pressure,flow and efficiency. So lets take example,using this calculator,its in bars and liters/min,i couldn't find one with psi and gallons. Hydraulics calculator – calculate hydraulics Hydraulikrechner - einfach Werte eingeben und sofort berechnen - Volumenstrom, Verdrängungsvolumen, Drehzahl, Drehmoment, Differenzdruck, Leistung und Fördervolumen einer Zahnradpumpe www.hk-hydraulik.com So anyway option 1: Gear hydraulic pump at 2000rpm 450 liter/min (119 gallons) at 170 bar (2500psi) ,equals 150kw.Doesn't matter if its 130-160kw,i don't need anything accurate 100%. Option 2: Piston hydraulic pump at 2000rpm(variable or not ,don't matter to me) 300 liter/min (80 gallons) at 250 bar (3600psi) equals 149kw.Again don't care if maybe its 130-160kw ,no problem. So we have 2 different pumps,that at full power equals +-150kw ,right ?. Will one of those pumps require smaller diesel engine to run ?.Or they both require same powerfull diesel engine to run them,at max power output. And if they do require different sized diesel engine,is that difference idk +- 50 kw ,or 100kw ?. If piston pump needs 200kw diesel engine to run it,then gear pump will need 250kw ?.If there is difference ,and if its only +-50kw diesel engine,then to me it's all the same either i use gear or piston pump.
A piston or gear pump is going to operate anything hydraulically. The difference is going to be performance of what you are running. Some implements are going to need GPM and others will need PSI, or both. It may help if we knew what you are trying to build? You also have to consider the peak HP/torque curves of your engine.
Another difference is that a large displacement gear pump won’t last long at anything over 3000 psi. A piston pump will work fine at 6000 psi. I would say for lower output low pressure a gear pump would be cheaper and work well. Anything over 2500 psi and over 30 gpm I would go with a piston pump. Would you consider a vane pump just to confuse things more?
An engine for a gear pump system has to be sized for maximum flow and pressure. Flow X Pressure/1714 X Efficiency% = HP. An engine for a variable displacement piston pump can be sized a bit smaller since the pump provides high flow at low pressures and low flow at high pressures. Add in HP limiting controls to the pump and engine size can be further reduced. IME, (43 years with excavators), 170 HP with gear pumps gave considerably less performance than 170 HP with variable displacement piston pumps with HP limiting.
A piston pump is more efficient. Basically the same comparison as a conventional internal combustion engine compared to a wankel, the wankel seems like a great idea, but it's hard to seal, just a like a gear pump is hard to seal the ends, whereas cylinders are easy to machine precisely and seal. I can't find figures, but I'll guess gear pumps are around 80% and piston pumps are 90-95% efficient. But there are other factors as well, especially when the pump size approaches the max the power unit can produce, gear pump can be set with torque limiting controls etc. that produce the pressure needed and drop the flow if HP/torque is limited.
The only downside to an axial piston pump is - more moving parts and may require the reservoir to be mounted somewhat higher than the pump or it may require a charge pump to supply the main pump
And axial piston pumps are more expensive than gear pumps
@BSAA65LB Thanks that's some good information there. @Vetech63 Hi,well i need these information for 2 projects to say...1st is screw type wood chipper for my farm,and 2nd project is wheel loader with flail mower. 1st project i didn't yet started so can't say much about it,only collecting informations for now,i might use hydraulics or mechanic drive of screw ,idk yet...have no idea which way to go xd. 2nd project wheel loader,i already made it to work to say ,mulched almost 2 hectares of some wild bush , with no malfunctions some 2 months ago.But i am not happy with hydraulic pump,it's weak and i have plenty of engine power left,or to say,not used .... Diesel engine for screw type wood chipper i plan to use from combine,i have 1 in my garage,75kw at 2200rpm,no turbo.Will yet to find on internet what size of screw will be enough for that engine... Diesel engine on wheel loader is 260hp ...so its starting point that can't be changed.I use 210cm wide (+-7 feet) flail mower from my farm that i used with my tractors,and it is powered by 2 hydraulic piston motors from track drive from 50ton excavator.(drum of flail mower is driven on both sides). These are hydraulic motors i used on flail mower,size A2FE107.RPM of drum on flail mower is not in question,i target 2000rpm,with larger pump it will spin faster,i will reduce it on pulleys easy and cheap. http://www.hydpump.com/pdf/A2FE.pdf
There's a reason engineers have to take a lot of math classes... Basically hydraulics is going to be limiting, mechanical drive is going to be easier and better for most raw power uses. For instance, I've never seen a wood chipper that is not powered hydraulically because there is no reason to use hydraulics, the drum wants to turn full power, full speed all the time. Now the feed rollers can be run hydraulically because it allows governor control and reversing, so there's reason to use hydraulics, plus it's not a large power requirement. Even looking at large hydraulic components off an excavator final drive, or a combine hydrostat, those are not designed to handle large HP for long periods. Both are more incidental loads on the engine than main loads.
Yes one option it is to be mechanical drive,i would probably use semi truck differential instead of hydraulic pump and motor,plenty of power,but will see yet... What about wheel loader ?,can't go mechanical there .I need larger hydraulic pump.And based on those hydraulic motors i have and diesel engine,idk how large can i go with pump ...
I miss read about your needing 100% accuracy. I think you need to figure out what flow and what pressure will work the best for your intended use. Then you figure out how much HP the engine needs to turn the pump without taxing it too much. It sounds like you have an abundance of HP though. You need to talk with a good hyd. shop and they can help with the calculations you need as well as the most suitable pump. There isn't a simple answer. I wouldn't think a wheel loader has the best transmission for a flail mower. I'm also not sure what type of flail mower you're referring to? Some flails are good for thick grass and weeds and light brush while others are designed for heavier brush and mulching.
Some of your applications might need some inertia and hydraulic powered systems don't have unless you put a flywheel with
When it comes to just fluid pump-there are some interesting concepts-Roper-gear, Blackmer Vain, And then there is a rather odd one that I have only seen two of, built in Stockton California some- time back in the 40's-50's named Richmond Pump. It is a sphere on roughly 35* from each-shafts. it required 25 hp to drive it. Were mounted originally under a farm delivery fuel truck. I used them to build self contained slip tanks for bulk 10x40 and 15x40. These pumps would move a mass amount of oil-I don't remember the volume compared to other pumps of size but considerably more. Richmond Pump went out of business in the 60's IIRC--trivia. Anyone ever see one of these?
@Welder Dave No abudance,i wan't to use as much as i can of the engine power,if i can use last breathe of that engine ,all on pump power,i will use it,even if engine will die in 2 years ,not care,engines are here sold on price of scrap iron.So i want to use all 260hp of that engine,but i guess some of that hp need to go for moving the loader,so lets say 200hp all for the pump.Questions is how big of a pump i can put there ?.As i say ,this existing pump on loader is too small .... Btw mine flail mower is for heavier brush and mulching type,i used it with my tractors for few years,it can handle 2-3 inches thick wood no problem. @cfherrman What inertia u mean ?,for screw type wood chipper ?.
You have something spinning and you put a load to it, some applications the hydraulic motor isn't enough to keep it going, sometimes you need a flywheel to keep going. I have no idea if you need one or not.
Hmm i think i understand what you mean ...well drum of flail mower is pretty heavy,it's like flywheel.
If you want to basically have 200 HP driving as big of hyd. pump as possible on a mulcher type flail mower you're going to need a much bigger hyd. tank and a really good hyd. oil cooler if you want it to last. There isn't simple answers to what you're looking to do. You need to design a complete system from the tank to the flail mower. Maybe a single drive motor could provide the needed power and require less flow than 2 drive motors?
I have hydraulic tank specially for pump that is driving hydraulic motors,and large oil cooler from 50t excavator.That's a must in hydraulics where some hydraulic motors are used. About 2 motors,well i bought them because price was affordable,and i use 2,because my flail mower have drive belts on both side,left and right.I thought why 1 when 2 is better ,also 2 of those motors can produce more than enough power ,my only problem is hydraulic pump .... I was looking on internet for more information with my problem,i found that piston variable pumps operate in closed loop hydraulic system.Is that necesarily ?,can i use that pump type with my open loop system ?.
If you are going open loop you should go with a regular pump, price can't compare
If you use an open loop(open centre) then your variable piston pump will run at full stroke all the time which will wear it out prematurely
Davidov, ok, you have a 260hp engine but the engine has multiple functions to drive which all requires engine power, loader arms and power to the wheels. The power use for these needs to calculated. Let's say for arguments sake it's 100hp then the hydraulic system for the mower is 160hp. Pump size, the pump displacement should be the same as the hydraulic motor/ motors, ie, a 100cc pump drives one 100cc motor or two 50cc motors. Using smaller motors /motor diminishes the torque and creates a lot more heat, just like driving a vehicle up a steep hill in top gear. Next thing is rotor speed and how fast you want it to spin. In my experience 1600rpm is sufficient but others may differ so once you gather this info you can make a decision. My preference for calculating motor and pump sizes is to use the metric system, the size in cc's is the oil required for 1 rotation and times engine RPMs give you the flow rate. Cc's times psi divided by 600 gives you the required hp IIRC
This is where a good hyd. shop would be a tremendous asset to help you design a system. Using random components off of other equipment may just complicate things, especially if you don't have all the critical specs. of the components you plan to use. I don't know if things like track motors are designed for continuous duty at their max. pressure and flow limits, etc.? These are all things you need to know.
@56wrench So what is determining that pump stroke in closed loop system ?.So for my open loop i should use non variable piston pump ?,or gear pump.But i checked on internet,there is piston variable pumps designed for open loop systems.Idk how that works .... @Tones Yes,my current pump i used is 133cc at 150bar pressure only,and motors are 2x 107cc ...i had to set rpm (i think they are +-2000) over belt pulleys.That pump is very weak for that mulcher head,no doubt about that.Also i don't use loader arms,they have large hyd. pistons that from small flow will take forever to operate.So i installed separate hydraulic distributor on loader,40liter/min flow,and i lift and lower flail mower head using small seperate hydraulic cylinders.But honestly i don't use that often,when i set height i rarely change it much.I mulch wild bushes and shrubs like type,not huge trees .Flail mower head is not in front of loader,but on side,right side.So i can mulch in 2,3 or more levels(by lifting and lowering),not directly from the ground level ,or to say,all at once.That's why this way is much easier on machine,and i don't need crawler,hydraulic drive.1st speed from loader transmission is perfect. @Welder Dave I will go to hyd. shop too,but most of them won't make me design unless i buy from them parts ...and they sell new motors,new pumps ...those cost thousands of euros.I am trying to make something cheap,to work.And i almost made it,all i see as problem now is weak pump,and i try to figure out what is maxed out pump i can install on machine.Ofc i also need to consider transmission auxulary drive limits.But this exact same transmission from my loader is used on many others,larger ones,with engines 300-340hp and they have larger hydraulics pumps and operate on higher pressures,actually some of them have i think piston pump as main pump. @Tones Also i forgot to mention,my loader factory engine was 150-155hp.So yes ..his main hydraulic pump(this i am using now) if i use some online calculator was taking at peak 70-90kw from it.Or u can check also,maybe i made mistake somewhere .133cc,150 bar,1500rpm. And plus loader have 2 more hydraulic pumps,one for powering hydraulic distributor,ok that one take tiny amount of power,but other one is for steering,that one is not small pump,not at all. I am sure,100%,that loader in first gear when it is mowing freely over ground,is not taking more than 20-40 engine hp for that operation.Otherwise factory would add larger engine from start.And this engine i added on it ,260hp.Is from larger loader ,that uses same exact transmission,but ofc ,larger pumps,larger machine,more tonnage,larger bucket ....
So you are saying that your loader at full throttle or to the floor in first gear is the speed you cut at ? The reason I ask is because if you throttle back the engine no longer has 260 hp and your mower will slow down depending on rpm. A wheel loader with fixed gear speed and torque converter is probably one of the hardest machines to run a mower on because the engine rpm changes constantly.
Closed loop is different than closed center. Open loop and open center, and closed/closed are typical, but not the same thing. Closed center vs open center refers to the valves and pump design, loop refers to whether the oil goes back to the reservoir, or circulates between the pump and motor without going through the tank. Closed center hydraulics have to turn the pump flow on and off somehow, so are better for something like an excavator that has various functions that need to be precisely controlled. Your mulcher is a more specific function, and one that will take a large and relatively fixed part of the engine HP, so open center valves is not such a big problem, you'll turn the valves on once and run for minutes or hours even. You do not have to use closed center valves on this if you already have closed center piston pumps and motors, you would control the pump directly on and off and the output would have no feedback to the control system. Possible/practical/advisable? only because it's a dedicated pump to a dedicated load. That's assuming the other hydraulics are run off the original loader hydraulic system. Or a smaller auxilary system. If you're trying to run all of this off one new big pump, you're in way over your head, and most of our heads also.
The way I understand this is he is looking for a dedicated pump to run the flail mower only the loader has separate systems for steering and arms and he is asking what size hydraulic pump he would be able to run with about 160-180 hp available for that just to error on caution to not stall the machine and he is using track drive motors from a large excavator to run the motor. First I’d want to make sure the size of piping and hoses are large enough to provide adequate flow not just pressure and that your pressure relief is set properly as far as what size pump you would have to get some one on here who works on that regularly I’m more of using what I have available and modifying from there
I’m not sure what the current technology is, but years ago, variable displacement pumps were usually pressure and flow compensated. There was a compensator valve that controlled the angle of the swash plate inside the pump thereby adjusting the pump output as the system demand continuously changed. One method you could consider would be to use the hydrostatic drive pump and motor off a combine harvester or similar equipment and control the speed/on-off with an electric actuator or small hydraulic cylinder. Are there any used equipment dismantlers nearby?
@Mobiltech Yes,well not really full throtle ,more like 80-90% of engine rpm i was using all the time,it works fine like that.As i say i mulch in 2 passes,no need to do everything at once. @56wrench It's not bad idea,i was thinking about it.But yes,not many parts for sale from those combines,and when i did find some pump or motor ,they were ussualy smaller than what would i need.Combine harvesters are much lighter machines than 45-55t excavators.
you're mistaking the weight of the machine for the HP rating and duty cycle. I'd guess an excavator final drive is nowhere near the HP of a combine transmission (that can climb hills at some speed). An excavator final drive is an excellent use of a hydrostat, it can run a acceptable speed at lower displacement through the motor, and at full displacement can produce adequate torque. You're not going to use that function though, you just want raw HP. 56wrench, that's exactly what I was thinking. You don't have to engineer the whole variable output control system to make bigger piston pumps work for this use. If the engine has 150hp available, then the hydraulic system just needs on and off, and a way to ramp up the motor speed slow enough to not break anything, appropriate relief valves. The transmission is not as ideal as if it was a hydrostat, but if your lowest gear at full speed is acceptable, then a hydrostat is not needed.
@Delmer It's not really final drive,i think.It's 2x hydraulic motors that mount on final drive,Rexroth a2fe107 model.It's exact model on picture.And on second picture it's what i mean by final drive motor.I don't think these motors have any problem runing all the time,or to say to power flail mower all day long.Good hydraulic oil temperature,viscosity,quality oil fitering...don't see why would they not last long.On excavator its even worse,how many times in 1 day are they being powered,forward,backward ...i think that put more stress on motors. https://www.interempresas.net/FeriaVirtual/Catalogos_y_documentos/3145/A2FE.pdf Well anyway,i think i will get good results with just larger pump,and yet piston norma,piston variable,or gear ,still don't know which type to search for.Ofc hydraulic hoses i will replace for larger diameter,as to not affect the flow of oil.
You need to know the max. flow the motors are designed for and the pressure in order to size a pump. If they typically need 3500 PSI or more a gear pump might get ruled out right off the bat. The motors may be high torque low speed so getting the RPM required might not be very efficient because you'd need a higher GPM pump to get the speed you required. A higher GPM pump would need more HP, more cooling and larger lines. You also lose efficiency (and power) using drive belts off the motors. A big advantage with hyd. drive is there's a built in relief compared to mechanical drive. It would be worth your while to pay a few hundred bucks to have a hyd's. specialist help you design a system. It would really suck to build something only to have it not perform as intended or have major issues that weren't considered. You need a pump and all the other associated hyd. parts. A shop would be glad to help you design it if you were going to be buying a pump and all the other components you need. It's not a simple thing you're trying to do.
I posted on link above specs of those motors. 107cc,4000rpm(4400max),350bar/5000psi and some 420liter/110 gal/min.In my opinion it doesn't matter specs of the motors as long as they are higher than those of the pump.I run those motors just fine with small gear pump,and my power limit was my pump,not motors. Every mulcher head,or flail mower have belt drive from motors,i didn't see one yet that have directly attached motors to the rotor.
Like was previously mentioned if you want to run 3500 or more PSI you'll likely have to use a piston pump. Maybe a vane pump but I don't know what pressures they run. There is a good video on you tube explaining the difference between open and closed loop systems. You're going to need high capacity filters with high flow hyd's. I've seen flail mowers and such with direct hyd. drive. With a belt drive you'll also need to know how much side loading the motors are designed for. In the past I've seen motors not recommended for side loading. May not be an issue with the motors you have.
1.4 tons can be maximum side load on drive shaft about 1 inch from housing.I think that is more than enough for me. I have 2 large filters on return line before reservoir ,they are in total 500 liter/min capacity,both of them.Also i added safety by pass valve in case they can't handle the flow ,so nothing goes boom. About pressure,i look at it from different way,idk if i am correct.Piston pump can produce high pressures ,but flow not really ,well ofc they can but pump would be really large,and expensive. On other side gear pumps produce high flow and low pressure ,but smaller dimensions of pump. Now using calculators for hydraulics online,just as example,it's same to me if i use gear pump 500 liter/min at 170-180bar or piston pump 250 liter/min at 350 bar ...their peak output power is more or less same. Am i right ?.
You will need some pretty large lines to run 500 lpm
It's not problem lines ofc,but it was only as example.
The hydrostatic pumps i am thinking of would be found on NH TX66(mid 1990’s) combines or the bigger JD combines or other similar size machines. They were designed to handle 250 engine hp and the bigger ones off newer combines should handle more than that
There's another thing that comes into play when running any hydraulic driven mowers and that is pressure spiking which track drives don't suffer from so much. On closed loop systems with a hydraulic transmission pump set at 6000psi spike pressures can top 20,000psi but only last millie seconds. These spikes hammer the guts of the pump and motors. I found all this out when I was running a forestry mulcher and the pump went to lunch at 1700hrs from new. The replacement pump I had the pressure set at 4800psi which was still working properly when I sold the machine at 6500hrs. Davidov; how are you going to plumb the hydraulic motors?
You need the right combination of pressure and flow to get the motor at the proper RPM. Higher pressure and less flow may be better than higher flow and lower pressure. Flow gives the speed but pressure gives the torque. If it spins fast but powers out easily it won't be very efficient. Commercial mulchers have done a lot of R&D to figure out the right speed and torque requirements. It's best to have some kind of safety/overload protection built in.
On the contrary Dave, pressure creates heat which then turns into a loss of power. Running a higher flow can be turned into inertia and using enough pressure to keep the production up. Most commercial manufactures IMHO wouldn't know their ass from their elbow and run on 100% BS, a fact I have proved many times.
I was thinking in general terms, that's why I said you need the right combination. If you use a smaller size gear pump to get the speed but it doesn't have enough pressure the mulcher will power out too easily. Too much pressure does create more heat and may cause damage to other components. There are some good mulchers that have it figured out. I've said all along it's not a simple thing he's trying to design and talking to a hyd. shop would be a good idea. Another thing to consider is how balanced the cutter shaft needs to be. I know on higher speed flail mowers for grass and heavy weeds if they aren't balanced can vibrate themselves to death. Something like a rototiller not so much but I don't know at what RPM balancing becomes important. He mentioned 2000 RPM.
@56wrench I checked on internet,and all the results i am getting for NH tx66 are tandem gear pumps. Some other pump i found that looks like piston pumps,were from TX68 models,but their splines on shaft don't match what i need.I have friend of mine who is also farmer and owns tx66,will ask him what pump he have on his machine. @Tones I didn't do much about hydraulic plumbing my self,but i had help of 2 mechanics,1 of them works on hydraulics on excavators and loaders.If u mean how are motors connected on loader,well they have just 3 lines in total,1 is pressure line,1 is return line,1 is case drain. Hydraulic pump that is powering flail mower have it's own oil tank,oil cooler,oil filtration.Oil under pressure goes directly towards motors,no hydraulic distributor in its path,nothing.There is some pressure relief valves only and i think that's all.Return line goes trough oil cooler,oil filtration and back into reservoir,i think its in that order. So high flow,low pressure is not bad idea ?,gear pump low pressures or piston ?..As i have 260hp diesel engine,i could use some 170-180hp(130-140kw) for powering main hydraulic pump for flail mower.That would be some hydraulic pump gear type with flow of 450-500lit/min(120-130 gal) at 170-180bar (2500-2600psi) ,or piston pump 250 lit/min (65-70 gal) at 350bar (5000psi). And vane pumps ,i was checking them earlier today on internet,they are something between gear and piston,which was mentioned here also.Some loaders have those pumps factory instaled.Little more max working pressure,slightly less flow,but same smaller casing, unlike piston pumps.I could use them also,it's not out of option ofc.
Yeah that magical 2000RPM number, more bs. I dialed the rotor speed back to 1600 RPM which added more torque in turn added more production and a whole lot less bearing problems. To summarize, changed from a 100cc motor to 2 63cc motors which then gave a total size of 126cc all fixed displacement, driven by a 100cc pump equaling 250lpm at 2500 engine RPM, reduced pressure from 6200psi to 4800 psi, rotor speed reduced from 2000RPM to 1600RPM. Production went up,costs went down.
Ur mulcher head rotor is driven on both sides also ?.
Davidvo ,there's 2 ways of plumbing multiple hydraulic motors on one circuit. One is to run the feed line from the carrier to the first motor the return then goes to the 2nd motor with the return going to the carrier. This then sets the motor RPM as if there's only 1 motor. 2nd way is to T the feed and return lines to each motor thus doubling the size of 1 motor which is what I did as per previous post.
Yes. Also helped to get enough belts on to coup with the extra power without making the overall width bigger which was important for the select clearing is was doing.
Yes sorry..my english is not best.If u mean't on that about plumbing motors,then yes,currently they are now T connected. I will look into some piston or vane pumps,just to see what i could find,with what specs ,etc ...main problem would be ofc pump shaft diameter and number of splines,bolt holes orientation,those needs to match.Will talk to some hydraulic shop to see what are their opinion.If they try to sell me new parts,they are useless to me. Also forgot to mention about Screw type wood chipper,hydraulic drive would be bad idea for sure.I talked with some mechanic in my area,he say cheapest and easiest solution would be to try using semi truck rear axle differentia...i think that would be overkill for what i am planing to make.Well,anyway will yet see about that,need to look more into it.
IMO Danfoss make some of the best hydraulic transmission pumps being the 90 series. They come in different sizes and spline shaft arrangements to suit. The on/off can be controlled by cable or electric. Pumps come with a SAE standard fit (bolt pattern and spicket).
Just a thought on vane pumps. They don’t handle shock loads very well. A shock load may break vanes
Slower RPM for more torque makes sense with the added bonus of longer bearing and component life. I don't know if there are cushion valves that work for hyd. motor applications that would reduce shock loads on the pump and rest of the system.
Yeah, I fitted an Stauff accumulator to overcome that problem. It lasted 5 hours then blew the bladder. Oh well. Still have it here if you want it. postage only
Now that you mention accumulators that's what graders can use to cushion shock loads. Maybe there's something better for hyd. motor applications??
Do the track motors you’re using have built in brakes. If so you will have to remove those. Are they 2 speed motors or single speed.
I've seen high pressure accumulators, just have to buy the right specs
@Mobiltech I don't think that they have brakes,written on this pdf link ,it say that they only have pressure relief valve (without pressure boost facility).Also 1 speed.
It was the best Stauff had from a very reputable company.
What was the max psi rating? How much nitrogen was in the bladder?
How is the speed of the drum being monitored or estimated? Some sort of tachometer or by ear? Perhaps the pressure gauge display used on a skidsteer rotary mower is there to inversely correlate rotor rpm? The HP calculators described in this thread put the currently installed 107cc gear pump at 120-135hp consumption. We want to dump another 60hp (+50%) into the flail so can't we try a 150cc gear pump to see what happens? We are using salvaged parts so perhaps some trial and error is in order.
Hello.I thought at first u ask about project screw type wood chipper xd,was confused little... No problem,anyway yes,those guys,mechanics,that worked with me used tachometer to check speed of rotor with no load.I do plan to add pressure gauge on pressure line towards motors just to monitor at what pressure are they working while mulching. Pump is 133cc on loader right now,low pressure type,gear,2300psi. 107cc are hydraulic motors,piston type,fixed displacement,2 of them. I do plan to search for either gear pump +-200-240cc,lower pressure ,or piston pump +-130-150cc higher pressure.I mean maximum power output of both pumps would be more or less same.
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Interesting. I run a 40gpm pump off a 30hp Kubota. Relief is 3000psi. According to that equation, I'd need like 60hp.
You are not getting 40 gpm at 3000 psi, probably 10 at 3000 if your lucky
When i used to check flow and pressure, max flow is at low pressure and dropped off the closer to relief pressure. At relief pressure the flow will be zero.
The pump definitely doesn't bypass that much!
At 3000 psi I'm sure it can plus it's not bypassing it's also compressing fluid
Uh, fluid doesn’t compress
No, it doesn't. Just need to keep in mind of the pressure of normal operation, might be a few hundred psi, and not factor relief pressure.
From my experience, piston pumps generally do require less power to run than gear pumps, but the difference isn’t huge. Piston pumps tend to be more efficient, so they can achieve the same output with less energy, which can make a difference when you're looking at long-term use. But if you have a gear pump and piston pump with the same power output, they should both work with similar engine sizes.
From my experience, piston pumps generally do require less power to run than gear pumps, but the difference isn’t huge. Piston pumps tend to be more efficient, so they can achieve the same output with less energy, which can make a difference when you're looking at long-term use. But if you have a gear pump and piston pump with the same power output, they should both work with similar engine sizes. For a 100 kW pump, you’d typically need a diesel engine around 110-130 kW, depending on the system’s efficiency and load. I’ve used gear pumps in the past, and Northern Hydraulics always had great options to choose from when I needed to replace or upgrade my pumps.
What are you wearing?
G’day boys . So I have bought this Mulcher for my 2017 Hyundai 14 tonner. I began testing it and it’s making a horrible noise when it winds down . What’s causing it any ideas ? Cheers Morty
I am unfamiliar with your attachment but pics and description are terrific. You say the horrible noise starts when you stop the implement. Without hearing it. I would guess the rotating mass continues after you close the flow. In the motor, should be an anti-cavitation valve. This keeps the motor from becoming a pump and blowing itself up. It takes oil from the B port and directs it to the A port. It does this through a restricted passage to help slow the implement without a sudden stop which break all the expensive things. Again this is based on NOT HEARING WHAT YOU'RE DESCRIBING. But to be safe, I'd advise a filter service on your hydro circuit and to inspect the filter media . Make sure you have no debris and no sparkly bits. Also , very important, make sure that the case drain line is clear and smooth with no kinks or obstructions. Good luck
Thanks heaps mate. Spoke with diesal Hydraulic mate he said undo the case drain hose ( into a bucket or something) spin it up and see if it still does it disconnected from the circuit. And if there’s tons of oil pump is rogered! Would a pump like that be easy to replace ? Rob
Its not a fair test. Not really. It will tell you if the motor is worn out. Case drain is for cooling and lubricating oil. If you remove the hose from the machine to the implement and cap the end from the machine, you can shove a piece of rubber hose like old heater hose or whatever on the nipple of the motor. Clamp it securely. Start the machine, have the hose empty into a bucket. When you spin up the implement, you're looking for a trickle to a steady light flow. What you don't want to see is heavy flow or surging. When you stop the implement, you shouldn't see any more flow. That oil should shuttling between A & B Rule of thumb, the flow from case drain should not exceed 10% of motors rated flow. This would require you to find the flow rate of your motor. Reach out to the mfr. of the mower or the motor if you can find the tag. Hope I didn't muddy it up too much, good luck
Oh yeah YouTube of course silly me .
That's anti-cav working. Wouldn't lose any sleep over that. I still suggest checking the filter whenever adding a motor circuit to your machine. That will catch trash before it hurts your machine.
Unfortunately there is no tag or identification on the motor?!!
Oh really???!!! It sounds horrible
Out of curiosity, I engage the foot throttle to run the unit. ( if put my heel down it will spin in reverse, does this sound ok to you). Depending on the Hyundai, can I set it to turn on and stay on ? Possibly ? Thanks son much for your help mate .
You have to consider all the rotating mass and weight driven off that motor. Then you suddenly stop the flow, if you didn't have anti-cav, the motor would revert to a pump, with no place to send the oil, it would either snap off or blow a hose. There are things you could do if it's that concerning. You could set up your drive with a Sprague clutch or something along those lines. You could throttle down prior to shutting down. Some things cost nothing, others want to break the bank. Good luck with whatever you choose.
You should be able to set your option behavior to hammer mode which would be one way flow. In shear you have bi-directional flow. While its not terrible, you don't want to reverse flow when at speed , that would definitely contribute to a hurt motor.
Every thing that funwithfuel has post here is absolutely on the money. The hydraulic motor looks very similar to a Rexroth bent axis FM series. Is there a tag on the opposite side to were the casedrain hose is? If there is from memory the first 2 numbers are the motor size in cc, thats the amount of oil required for 1 rotation.
If the unit can be run in reverse rotation then there is not a crossover check valve installed Would highly recommend adding one if the unit needs to spin one direction only
Thanks tones heaps mate .
That’s where I’m a bit concerned I’ve done damage to the pump if I have run it in reverse a few turns ? Anyway . Fun with fuel reckons I may be overthinking it. But you can never be too Safe with these types of pressures .
In order to stop confusion, the hydraulic motor isn't a pump. The pump is what drives the hydraulic motor from the opposite end of the curcuit By bringing the engine to an idle then stopping the mower will help with the longevity of the hydraulic system. Doing the opposite on startup will also help. Where abouts in Oz are you based?
Because of the open loop curcuit you should be OK but don't go from 1 direction to the other at full noise.
In between Byron bay and mullum mate on the coast.
I removed the case drain and it seems its All fine in that department. Would you set work mode to crusher or breaker?
Looks as close to perfect as you could ask for. As for setting, I would go breaker or hammer. Depending on what you folks call it down there. But ideally you want one way flow without the possibility of reversing all that weight while rotating. Thats a pretty cool attachment, thanks for sharing it.
Know the area well, the bloke who bought my machine was just inland from Byron, spent quite a few months working it for him on a development he was doing at Coorabell.
Thanks mate for your wise and measured counsel. It’s deeply appreciated.
Thats a good one. Im dying over here.
Yeah right Coorabell know it well . Rich ppl..unlike me ..
Tones I’ve just had a clarification with porters (Hyundai Brisbane) and old mate said the oil flow on “crusher” is 150lpm. “Breaker” 110lpm. But he said you’d want to clarify the specs for the pump as he’s seen a million times blokes cranking up the power and blowing the pump no problem. Question is how would I get info for this pump with the info I have ? Cheers mate Morty Ps funwothfuel he said that noise is anti cav he believes . Cheers
What make and model mower is it? Is there a plate underneath the motor? The numbers in the pictures will be casting numbers and not revelant to the motor size. I guess you bought it used, has the previous owner got any info to help identify it? Flow makes speed, RPMs, it's pressure that can destroy motors. To give an example the AHWI mulcher I owned had a 63cc Rexroth motor which was rated good for 6000rpm, ran similar flow to yours and spun at around 2000rpm ,⅔s below maximum. I think you're safe on the flow side.
Mort Check your mail box, top rh corner of your screen
Forgot to ask you mate on my 7 tonne Takeuchi TB070 it has these some kind of heat resistor set up. Have you seen this before know what it opened the dump to tank! Way better
There's a great auto electrician in Ballina but don't have any contact details. However if you contact the bloke who had the repair business on the western side of the Pacific Hwy near the BP service centre has it. As of a month ago his phone number was still painted on the building. You maybe able to get it using Google Maps with the 360 view. Good to hear the mower sounding better.