HYDRAULIC GEAR PUMPS EXPLAINED!

[@Kevin-rc5ec]

Dear AvE, your videos have kept me interested in engineering and thus lead me to my degree. You are just the best. Thanks for putting all the work you do into these videos, man!

[@notsure7060]

Good work m8. Gratz on your degree =D

[@MuffinManUSN]

Cheers to that. Very cool you found that inspiration

[@flyingjeep911]

Same story with me but ima machinist 🙃

[@StealthPlatypus1]

I absolutely love these kind of videos. Nothing beats the hands on explaining. Please keep these up!

[@coreyregier5546]

I'm in first year HET and we just started taking little hydraulic pumps apart last week to measure the displacement and whatever, good timing for this video! Also, I think that's cool that you can flip the input shaft around in case your pump needs to be driven the other way.

[@mehmetalikocak3843]

Aliminyum , ana gövdeyi ters cevirmesi gerekir , yön degişikligi için

[@srednadahlberg]

Impeccable explanation! And I love how you stress the flow/pressure distinction.

[@petermof]

As someone who lives in a former colonial outpost, the easiest way to tell imperial fasteners in my garage is by the rounded heads from using metric tools on them...

[@AndyHullMcPenguin]

Another well tested method. Eyeball the fastener, and select the tool you are absolutely certain will fit it.. if you selected metric.. it will be imperial... and if you selected imperial it will be metric. Uncanny.. works every time for me.

[@charredskeleton]

If it's an American car either might fit, if it's a Japanese car metric tools will fit but you hands won't!

[@apuuvah]

Hey... let's all switch to metric! And let's put the steering wheel on the left side as well, while we're at it!

[@MichaelSteeves]

11/16 wrench on a metric bolt. Never change AvE...

[@scarface3131983]

ha..it is a crapsman wrench tho

[@sthenzel]

Just 0.46mm too large, doesn´t matter that much on 12.9 bolts, they´re hard stuff. If the Crapsman dies on it, who cares?

[@duramax78]

Wasn't a wrench it's a torque device....lol

[@XC2long4u]

I use 3/4 for 19mm and 5/8 for 16 all the time, call me a rebel.

[@Scofflaw_k10]

it's 11/16 of the proper torque

[@doibing9856]

I've never even considered engineering until i came across your channel a couple years ago. Glad you can share joy of machining with us common folk.

[@davidheaton7740]

I like the cavitation talk. Ive seen the end results of water cavitating a diesel injection pump quite a few times. They love to send steel glitter all through the fuel system as the pump detonates slowly.

[@fergusoddjob]

Got a university report on gear pumps and was getting bored of my tutors long winded vijeos without any swearing. Glad I remembered you made a video on these!

[@JordyValentine]

Hahaha, I laughed way too hard at the click of the tourque wrench. I'm guessing you tourqued it to FT (fucking tight)

[@TINRFD]

Jeff from elderly iron has the same torque wrenches...

[@marccrocker1908]

me too lol

[@GunFunZS]

It took some learning growing up to stop at that click before the fastener said "Ting", and my knuckles chimed in.

[@underourrock]

FFT. That's Full Fucking Tight, for you. Any tighter and you get stripping.

[@ddd228]

GOOD-'EN-TIGHT. Yah .

[@kdknitro]

Your hydraulic videos is how I discovered you, your infrared heat gun trick is worth its weight in gold. Keep up the great info.

[@pauldavidson6321]

The ISO code on the pump body is stamped "P " for pump or "M" for motor , Motors also usually have a case drain port.it would appear someone has swapped the rotation group to change direction. You have a pump in this clip as indicated by the seals on the thrust plates ,a motor is bidirectional and the thrust seals seals are figure 8 shaped .

[@dukeman7595]

You have a great deal of knowledge telling the difference between the two. You should have a KZbin channel.

[@pauldavidson6321]

@@dukeman7595 I run a hydraulic repair business.

[@ronroberts110]

Glad you mentioned cavitation. Put your hand underwater and move it from one side to the other really fast. A vacuum pocket will form behind the hand that you can easily see. There's no air in there, but it is a cavity. I have also seen the inlets being pressurized to reduce cavitation. The highest I saw was 100-PSI, and that was on a 3000-PSI system. Great vidya, my friend...

[@ownedpatrol]

Just picked up a little scrap honor pump from work that I'm gonna disassemble and attempt to fix. Your videos definitely helped get me interested!

[@mehmetalikocak3843]

Aliminyum ana gövdede çizik varsa o pompa ölüdür , bogaz keçesi yada gözlüklerde, keçelerde problem varsa belki kurtarırsın pompanı .

[@HennerZeller]

I never really thought about the details of a gear pump and falsely assumed that the oil goes through the middle part, but had been wondering how it would do that as the cavity is pretty small there. Doh. That the oil goes _around_ the outer diameter makes much more sense. #TIL. Your vijeos are a source of interesting information. Skookum as frick. Thanks!

[@tomcummings3471]

never thought about it until seconds before he was explaining it, but I too assumed the flow would go through the middle. which makes absolutely no sense in retrospect

[@MIGASHOORAY]

N

[@TimpBizkit]

I always imagined the closing in teeth would pressurise the oil (although the oil doesn't change in volume very much at all unlike with compressed air) with some leakage but yes going around the outside makes more sense.

[@hamppid1alfathponphydrliqe60]

Henner Zeller

[@miguelash886]

I made the same assumption

[@marklowther2133]

The cut out pieces on the gear side of the bearing holder only allow oil to escape back out into the side of the pump that it came from. Because the groves don't break into where the bearings are. The groves on top do look like they allow the high pressure oil into the bearings. I think this makes sense because if the oil was flowing in and out of the bearings it would not be at as high a pressure. Also I love your channel, and I wish I had lecturers like you at uni.

[@dukeman7595]

I learned more in 10 minutes regarding the workings of a hydraulic pump/motor than I ever did watching KZbin videos.

[@WatchWesWork]

I love how you go into detail on how to verify that it's a metric bolt and then you wail on it with an 11/16 wrench. You can't script gold like that.

[@ZerokillerOppel1]

Celeb reply here!! Sorry it took me 4 years to notice...

[@anger806]

I am a mechanic for a company which specializes in truck mounted material handling loaders (primarily logs) ran completely by a gear pump mounted to an eaton pto on the underside of the truck transmission and driven by the input shaft of the transmission, typically when we see symptoms of a tired pump we only replace pumps, not disassemble and repair. This vidjayo defintely helped me understand a little more of the witchcraft that goes on inside these pumps

[@NeilvanGeffen]

You're a knowledgeable man! And i'm glad to learn something new from you every video!

[@babunaidu7670]

Hydaraulik relef valve

[@babunaidu7670]

Relef valve experience

[@lanwickum]

Those pumps are designed to wear into itself. The gears eat into the housing at break-in making its own clearance. You will always see wear in the housing. The wear is on the low pressure side. High pressure pushes toward low pressure. If the wear goes past the housing locating pins to the high pressure side it is worn out. If you replace the bearings, you reset where the gears are at in the housing and you have internal leakage. Thanks for the vid, sorry my comment is a year late.

[@HonzaZalabak]

Hello. Is it possible to buy these bearings as spare parts?

[@moeshouse575]

Moe7404. i worked industrial hydraulics for 20 years. now retired. that demo was the best that subject could EVER be done. the part about pump or motor is a point that even a lot of people that work on them dont even understand

[@neilcarrie3396]

I to work in the hydraulics industry and it does catch a lot of people out. What he stripped down was actually a pump tho because of the 2 different sized ports and the kidney plate seal only sealing off the high pressure side. Some pumps like commercial brand actually run a full seal around the shaft like a motor has but the ports are the give away.

[@mattzze98]

Ist a one directon motor wich needs the sealing only on the higpressure side an a lekage flow from the bearings spots to the Tank side The actuator is labeld as a Motor also Greetings from germany

[@keithcarpentersr.4353]

Moe Shouse I have an old backhoe and not really any power or force when I’m using the backhoe part. Would it be a bad pump?

[@davidbuschhorn6539]

It's a lawnmower supercharger.

[@Avram42]

Does that mean it force-feeds grass into the blade?

[@davidbuschhorn6539]

Like how I put USB cords into the plugs. "God damn it! TAKE IT!"

[@kumarkartike4638]

+Dav5id Buschhollll

[@dirtydish6642]

Put my 48 Ford 8N into a tree stump, cracking my loader pump case earlier this year. Had to self learn everything you just showed. This filled in some lingering gaps of knowledge from that day.

[@WheelH0rseC101]

i feel ave knows me, i do roll my own smokes and can kickstart a harley

[@BrianB14471]

but are you female?

[@WheelH0rseC101]

was that aimed at the od female in the crowd then? didn't notice that xD

[@apuuvah]

Quit smoking, roll a joint and switch to enduro (dual sport).

[@pzozack07]

I was always under the impression that hydraulic motors had the same size ports on either side, so that the motor would spin the same speeds in either direction. Then hydraulic pumps normally had the larger size for suction and the smaller size for pressure, depending on the application.

[@gotjuggling]

Only positive displacement pumps create flow. Centrifugal pumps create pressure. Correct me if I'm wrong, but I'm fairly certain, and this makes intuitive sense when considering the high clearance provided in most impeller pumps, and the low clearance in positive displacement pumps like gear pumps or reciprocating pumps.

[@tomthumb3085]

I can’t believe that it’s almost six years since I first watched this video. It’s still great to watch now. Thanks.

[@sp1nrx]

So hydraulics are the big boy version of wimpy pneumatics? :-)

[@Agar4Life]

"Before I was rudely interrupted by the truth" has to be up there with one of your best lines. Copyright it quick before it becomes a US presidential campaign slogan.

[@DasGrinch]

I keep waiting for the day when I'm going to need something I learned here at work. I work in the wireless internet industry, so there's not many hydraulic pumps and such, but some day!

[@anthonydurantine2292]

Think you should find some vajayos that’s apply to your needs friend

[@tomconner9695]

What drives hydraulic pump and the pump creates pressure, that pressure is determined by the circuits resistance to the flow of the oil passing through it, where that occurs determines the nominal (required) pressure, and the max or stall pressure. The resistance in the lines orifice fitting filter or valve will determine nominal pressure (the pressure that occurs in the lines when the force driving the pump meets the opposing force (friction) enough pressure builds up to either overcome the resistance or bypass the circuit through the relief valve, of the system is functioning as intended then the H/F starts to transfer the pumps mechanical input to the motor, (pressure and flow) setting the motor into motion and the fluid into the return line.

[@Hizone1]

This video given me the exact knowledge that I need to know now a days for my project. Lot of thanks for uploading such a brilliant effort.

[@ericesoteric1884]

Upon seeing the Craftsman wrench, I had to go into the toolbox for the crucifix and hold it up to the screen. Thoroughly shaken, I then called my Snap-On dealer for further support.

[@marcellemay7721]

How many easy payments did that cost ya?

[@ericesoteric1884]

+Marcel LeMay Lmao! touché brother.

[@Obsidian0Knight]

yeah and when she breaks and the guy doesn't show up for a month. fuck that! nawh any way if hes like most of us here hes probably got at least 4 11/16" wrenches. Plus the ones hes had to fuck up to change that one hose jammed up at the back to the valve body some some obscure obsolete machine.

[@JerseyTom]

some would say the real measure of a man is how many combination wrenches he has cut in half and/or welded into funky angles

[@droy333]

Haha "click". Totally torqued to spec like a boss.

[@evansveilleux5168]

Very clear good views,explanation,and comprehensive language;as much as vocabulary,u can tell the speaker knows what’s an hydraulic component

[@promenacegaming5402]

I just had to rebuild one of these on my PTO for my wrecker, and damn. This knowledge is great.

[@ve2vfd]

Many Fire Engines use a gear pump attached to an electric starter motor as "primer". The gear pump is used to create a vacuum in the body of the main rotary pump (with the help of a little spritz of oil on the gears) to get the air out of it and flood water into it (from a the tank, a hydrant or a pool/pond). The gear pump is also used to test for leaks in the pump and manifolds valves by creating a vacuum which must be maintained when the primer it turned off (which is why the main gauges go into negative pressure on the panel).

[@Gu1tarZer0]

I love how you can explain shit better in a few minutes than 3 weeks of high school ever did..

[@goose300183]

Absolutely. I am not any kind of engineer, and I learn a lot from his vids. He drops gold nuggets of information without even knowing it sometimes I think.

[@dnsmithnc]

They might have explained it just as well in high school but, at the time, you no interest or little experience in the topic. That is, the teacher's ability to teach isn't that much different from AVE but you, with your age and experience, are different.

[@villijs33321]

That's because in high school teacher are only theorists they have no idea how stuff works in real life ...

[@Mmouse_]

Do you have any examples of cavitation damage? I'd like to see what that looks like up close.

[@mortenhartvigkristiansen7760]

It Kinda looks like it has been sandblasted ;)

[@marklowther2133]

bloximages.newyork1.vip.townnews.com/energy-tech.com/content/tncms/assets/v3/editorial/d/b3/db3ca91e-0637-11e6-97cb-dffd69c367a4/57163b7e13c8d.image.jpg?resize=300%2C400

[@johan.mp4]

... and a bigger version bloximages.newyork1.vip.townnews.com/energy-tech.com/content/tncms/assets/v3/editorial/d/b3/db3ca91e-0637-11e6-97cb-dffd69c367a4/57163b7e13c8d.image.jpg?resize=1200%2C1600

[@aglaycock1]

If you google cavitation damage you will see all sorts of damage pics from props, pumps, impellers etc. It is quite a fascinating failure mode.

[@AndyHullMcPenguin]

If you have access to an ultrasonic cleaner (and who doesn't)... pop in a bit of tinfoil and clean it to death.. Tiny holes will appear, caused by cavitation. Also check out -> --lmh.epfl.ch/page-57977-en.html--

[@GlawberOliveira]

I was so pumped for this video

[@farmertyler8087]

Had to re build a couple of those last winter, i had absolutely no idea how they worked but somehow the re builds went good

[@DoRC]

Very interesting. From the automotive mechanic side is always throught it squeezed through the middle. This makes more sense now that i see you explain it.

[@ericwolf5874]

I always wondered about the IN's and OUT's of a Hydo pump.... and now I even know the in-between's.

[@bryanb7918]

quick question on the backup plate for that lip seal, how exactly does it work to make that 15psi seal hold up to 3000psi? does it just add force back on the lip to keep it from folding over? the reason I'm asking is because my truck has an 87 cummins diesel engine from a Komatsu excavator and they are equipped with a rotary pump with a front lip seal. now normally that lip seal is no big deal because it's just sealing a low pressure vane pump inside the injection pump itself, and is usually only fed up to 12 psi or so. But when people go to bumping up the pumps it gets to be necessary to start upping the pressure of the fuel supply to help keep the pump supplied with fuel and keep the dynamic timing working. But upping the inlet pressure starts to leak past the seal at around 18psi. so what I'm asking is, can you send me a drawing or make a quick video of how that backup plate on the seal is keeping that much pressure in so I can some how make my truck go faster and not fill the crank case with diesel fuel? lol thanks in advance!

[@pauldavidson6321]

The seals don't seal anywhere near 3000 psi ,he's wrong about that 50 to 150 psi is considered high in a pump or motor, the rotation group of the pump directs all high pressure flow to the outlet port it's only a small amount of bypass leakage that gets to the shaft seal to lube the bearings ,heat is far bigger problem for an engine mounted pump like yours, we fit Viton shaft seals to cope with that ,I've had 30 years experience working in the commercial hydraulic industry BTW.

[@4speed3pedals]

I wish I would have watched this 6 years ago. I now understand why a Melling oil pump for a small block Chevy has the pressure relief valve and how it controls bearing pressure and yes, it dumps into the crankcase. It contains no o-ring so the design is simpler and works for the needed pressure. KUDOS! As an aside, modern engine machining now uses plateau honing with deep scratches and a finish that is smoothed for the piston rings to seal "against" and the ring seal is the oil, not the pressure. You want no contact between the 2. This is why modern pistons rings live longer. Better seal, less emissions, more power, longer life. Rediscovered by the diesel crowd that make extremely high horsepower. Can you say RVK meter?

[@dummyduhast]

Excellent, I have been trying to figure out why my pump wont build pressure and heats up quickly, after reversing the rotation I didn't get the excess fluid diverter in the correct orientation, works great now, thanks!!!!

[@leehodge2415]

he hydrulic lessons are worth the patreon, the boltr's are gravy. thx for welcoming us into your shop, sorry about the occasional riff raff

[@Ironfist2211]

"You're gonna have schmoo blasting in your face like last Saturday night" --AVE Fukken pure gold buddy

[@mattzze98]

@6:50 the seal needs only one lip to seal the second seallip is for dust. The Most Motors have a leakeoil port the Port is for reversal use in this case the motor can only be used in one direction

[@bobiggins8027]

how are you so fucking good at explaining things, you need to write books and force them upon us all

[@JonathanSchattke]

cavitation is not from boiling, but from moving a surface in contact with the fluid faster than the speed of sound of the fluid.

[@nelumbonucifera7537]

That doesn't sound right - the effect should be dependent on the vapor pressure of the fluid. The bubble collapse does occur at the fluid's speed of sound, though.

[@squareroots3931]

+Hans the speed of sound is different in all materials.

[@marccrocker1908]

@hans the speed of sound waves differs among different materials. high density materials transfer concussion waves faster than low density materials, hence the speed of sound is faster in water than it is in air. grade 4 science ftw

[@fawzanna]

let's do some math, speed of sound in air 340 m/s , a pump gear diameter 25 mm (a big pump )and so 340 /(3.14 *.025) * 60 = 259 872 rpm if you divide that by 1500 rpm or 1800 rpm you find that it is around 173 ~ 144 fold just saying .

[@marccrocker1908]

@fawzan if I'm reading this correctly I think your reasoning is flawed. you're assuming speed of sound in air, at sea level, through the gear. what's flowing through the gear is oil under negative pressure. as AvE said the oil can boil, now I'm not an inganeer or a math magician, but it stands to reason that the density inside the gear is very different from oil at 1 atmosphere of pressure. now I have been wrong once or twice, and could very well be again, but my previous point was to explain "speed of sound of a fluid".

[@rsedivy2]

I am a comp sci student with literally zero experience in anything mechanics related, yet I still enjoy the hell out of these vijayos

[@ActionMax09]

Om Gosh Ave... You have a video for everything. What is it that you do for a living? You're a genius.

[@jiaan100]

A year and a half of engineering classes: the video

[@Syncubus]

I'm rarely offended by AvE's language, but I find it surprising for him to use the N-word at 0:27, almost directly after the language disclaimer!

[@MelvinWillikers]

Inwards and outwards?

[@BriarHood]

it's the owtwords I'm worried aboot.

[@gerhardtoxopeus8574]

dick not nick

[@StefsEngineering]

Totally agree, using words like inwards and outwards is totally out of place and uncalled for in a disassembly review.

[@kyloren8236]

N words and out words

[@marv42dp]

Caught myself copying your hand movements while explaining some very techy stuff to a customer. Thanks! ;-)

[@Obsidian0Knight]

oh and the bearing cut out bits are also to ensure there is flow of new oil past the bearings to keep them cool and lubricated. I dunno if you can get your hands on a variable displacement piston pump, but them things are pretty cool as far as pumps go. we use them in our manlifts for the drive circuit.

[@sv55492]

Great video! Could you possibly do a video of the internal workings of a hydraulic pump/motor and how it transitions between the two functions? Thanks!

[@ALegitimateYoutuber]

After hearing you talking about pressure and flow, I wish you would do a few videos just on the basics. Kinda like what you would see in those old education film from like the 40's. Because without a doubt you're knowledgeable enough to get the info right, and I feel you would easily be able to put it all in layman terms.

[@mythril4]

I use used small pumps on drills or mounted to a motor to function as a viscus fluid pump. If you ever filled a transmission from the bottom of a vehicle, this will make sense. At low pressure, these will pump 140W oils no problem. Another fun point of using these as viscus fluid pumps, flip your motor or drill into reverse and it changes the direct of the fluid (put too much in scenario). Yes at low pressure a battery operated drill will run these with no issues.

[@lourdesamykupusamy4314]

I appreciate your clear explanation and good reasoning.you are professional. Thankyou for sharing without holding any secrets.

[@MikeEdwardsful]

I actually just watch this because it's entertaining and interesting. I don't think I'll ever be using a hydraulic gear pump in my life. But I'll be damned if I don't say that I enjoy the shit out of your videos.

[@jhjbeckett1]

Sir, you have a way of breaking down high end knowledge to my level. Also, I can't stop saying chooch or skookum. Thanks!

[@jamesdaniels9882]

Your videos helped me fix my ingersol-rand impact now its helping me understand pto’s that i work with daily better. You got one for everything dont ya

[@a__duck]

This is awesome , im taking a hydraulic design course right now so this is at a perfect time!

[@wayne5607]

I was looking for a repair video on hydraulic pumps and you came up! VERY COOL! I love your videos! Thanks!

[@ooo_Kim_Chi_ooo]

As a Double E I love this channel!

[@sparkythawelder]

If I'm not mistaken sysyemic pressure does not change the vapor pressure of a liquid. Vapor pressure is effected by temperature. I think what you meant to say was that as systemic pressure drops and converges with the vapor pressure of the oil it will begin to boil causing the pump to capital. Keep up the good work man I love your videos.

[@TomsLife9]

just gotta torque the bolts down, "click!" goes the box wench call that a "one grunt" torque spec

[@samlau7948]

Hahaha! AvE's ikea table: torque the bottom screws two grunts, try wiggling it until it choochs

[@kylebarg880]

"metric grade 12.9" but then goes on to use an imperial 11/16" wrench.

[@gregadams558]

Nice catch.

[@MrAwoodrow]

It's not 12.9 in size, it's a rating for the strength of the bolt. It was a 17mm bolt, the 11/16" is close enough..."for the girls he goes out with"

[@martinus9755]

When all you have is an 11/16 every nut looks like it's about to get fucked.

[@Avtovaz21057]

the plate with the seals in is teh specticle plate, and some pumps have a grub screw in them that has to be changed too when changing the rotation of the pump. Not sure why, but when i turned the rotation of a pump at work i fulled a truck gearbox up with hydrolic oil threw the pto LOL! thanks for the vid, i didnt know what the bits did on the specticle plate

[@Lazarus7000]

I learn so much useful stuff from these videos. Shortly after you cause me to develop the question "how does something that, by definition, when it is working, is always in a pressurized oil bath, come to experience failure?" you answer the question.

[@chromauk]

cavitation demonstration failure! for shame +AvE you shoulda demo'd a beer bottle breaking. fill 2/3 with water after carefully disposing of the contents. Get a firm grip of the shaft, your aiming for purple over pink here. and with the flat of your palm slap down hard on the bell end! Do it over your designated Art receptacle as the back-pressure from the shock wave causes cavitation and the bottom of the bottle decided to come apart at the seams causing a fair amount of mess. It might not work well with the first bottle but by the time you've disposed of the contents of the twelfth bottle you should be cavitating like a champ. the more science you do, the more lightheaded you become. Fear not, this is a normal side effect of conducting the experiment.

[@mannyfernandez7028]

know what?youre my favorite youtuber from now on..more power to your channel.

[@ta420nk5]

Great video, your ability to explain relatively complex workings is second to none. I was going to ask your option on a brand of tool the other day and bam there it was, what do you think about porter cable?

[@brianmalambo6483]

Very loud and clear, thanks for sharing this information

[@ryanbarbolt3691]

This is so true, and so many people miss this, you have to have a stoppage to create pressure. The pressure is what does the work, but you need resistance. Almost exactly the way electricity works oddly enough.

[@soaringkhaled]

You know what ... to your surprise I have a bachelor degree in mechanical engineering , I remember studying what you said in college .. but I suppose only now I've completely understood what was going on :)) ... Thank you

[@realbeef6538]

Hey man, I hope you see this. I just wanted to say I love your videos. Very fun and educational. Some of the best entertainment on youtube. Chooch.

[@MohaMMaDiN55]

I love you man. I never seen such an explanation like this for gear pumps. neither in books.

[@HerraTohtori]

Hang on, now. Pumps most definitely create a pressure (or rather a pressure differential); that's how they make the fluid move within the pump. The resulting flow applies pressure on the fluid ahead of it, and the whole line of fluid moves as one. Behind the pump, fluid from a reservoir is pushed forward into the pump either by cohesion, or by atmospheric pressure, or by the pressure of the pump being directed back to the reservoir in a closed cycle - either way, it's always a pressure differential that creates a flow. All fluids always move from high pressure to low pressure. If they don't move, then the pressure is constant. However: When the flow is unimpeded (ie. there's no load on the system), the pressure in the system doesn't build very high, only up to what is required to get the fluid moving at exactly that flow rate. Hydraulic pumps usually have a limited speed in order to not rev themselves to death in an unloaded state, so the flow rate doesn't climb insanely high (this is also probably in order to avoid pressure spikes from hydraulic ram effect from the fluid's inertia when the flow is abruptly stopped). In other words, when the pump is running unloaded, it's only working against the backpressure provided by the resistance of the fluid flowing through the system - this is usually quite small but measurable pressure, caused mostly by the viscosity of the fluid. When you start to restrict that flow rate by putting load on the system (like actuating a cylinder or putting resistance on a hydraulic coupling or motor), then the actuator itself produces backpressure to the system. This is when the system really starts to output work to the external world, and this is also generally when you start to hear the engine running the hydraulic pump make a different, more strained kind of sound - it's because the load on the engine is increased, because now it has to work against the increasing backpressure to maintain the fluid flow and to keep providing pressure for the actuator. So what you're saying kind of makes sense, because the flow rate and pressure typically have an inverse relationship - the higher the flow rate, the lower the pressure, and when you're exerting a higher load on the system, the pressure spikes and the flow rate is reduced and, eventually, halted as the actuator backpressure becomes equal to the pump's outlet pressure (pressure differential is equalized so there's nothing driving the flow). So it *superficially* seems like the pump running without load only "creates" flow, and the load - the stopping of the flow - is what "creates" the high pressure. But this doesn't mean the pump doesn't generate pressure - it does, or rather more accurately the pump creates a *pressure differential*. That's the primary mover of the system. Flow always the result of a pressure differential in the system, and flow is also the nature's way of equalizing pressure in the system. It's just that the pressure in the system is *dynamic* and *dependent on the load* on it. The pump is still what generates the pressure that makes the system work at those high loads. At high loads, the pump starts working harder to match the backpressure. I think one confusing thing here is that fluids in hydraulic systems are practically incompressible, so you don't really see the relationship between pressure differentials and flow. Pressure pulses also transfer through the system at speed of sound in the hydraulic fluid, which is why the fluid starts flowing throughout the system very very fast when pressure is applied at the pump end. A pneumatic system using a gas (usually air, sometimes nitrogen in fancy systems where you need to maximize consistency at different temperatures by minimizing the effects of something like condensation of water vapour in the air) as its working fluid, however, will give you a very different impression of how it works, but it makes it more apparent how pressure, compression (density), and flow are interconnected (and temperature, if you want a full thermophysical analysis of the system). But even though the difference between pneumatic and hydraulic systems appears very large, they actually work with the exact same principles. With pneumatics, pressure always comes with compression, and flow becomes a more apparent mechanic as pressure equalizer. That's why, in a pneumatic system, the pump is called the *compressor* - but it doesn't "compress* the air. The compressor is a *pump* that creates a *pressure differential* that drives air from the environment into a reservoir or tank, which - if the flow is obstructed - will then build up the pressure as more and more air is driven into it and compressed. The same things fundamentally happen with hydraulic fluid, but because of its properties, the compression is negligible and almost impossible to demonstrate.

[@sivalley]

Pumps DO NOT create pressure! The pressure you see in a system is derived from the one factor you are missing in your understanding: headloss. ALL fluid systems; be they gasses, fluids, or in some extreme cases solids, have headloss caused by every component in the system except for the pump which adds WORK to the system. Even the smoothest bore pipe has headloss, that is it has a NON-ZERO value that is very small. (See also Carnot Cycle) It is the TOTAL headloss of a system that gives the measurable value we call pressure. The amount of headloss in a system component is directly proportional to the friction coefficient of said component times the volumetric flow rate of the fluid. Pumps also need Net Positive Suction Head (NPSH) to prevent cavitation and the amount of suction head varies with the system fluid's vapor pressure, temperature, and physical VERTICAL distance from the fluid source. In a closed loop system (like a car's coolant system), NPSH comes from the thermal expansion of the fluid. Conversely an open loop (as almost all motor driven pump hydraulic systems) suction head comes from the column fluid height in a tank open to atmosphere since the suction line is 2-3 pipe inside diameters (i.e 1/2" line would be 1 to 1-1/2" inches) from the bottom of the tank and why manufactures specify a MINIMUM fluid LEVEL in the supply tank. The reason you hear the motor straining under load in a hydraulic system is because of the use of a virtually incompressible fluid. All the fluid is doing is transferring a static force (work) from the motor via the pump rotor and fluid to the device under load. If the load is a ram, the appearance of pressure rising in the system is because the load on the ram is applying a force against the incompressible fluid as more fluid is forced into the system. A hydraulic motor is nothing more than an infinite set of small rams in the same way a gear is a set of infinite levers. In gaseous systems a compressor is indeed compressing a fluid, this why they ARE CALLED COMPRESSORS! Gasses all follow the same general principal of Ideal Gas Law/Boyle's law hybrid: P1V1=nRT=P2V2 Where P is the STATIC pressure of a system in ABSOLUTE units (i.e. 1 atm=14.7 psia=0 psig), V is volume, n is a fluid coefficient, N is the specific quantity of the gas, and T is the temperature of the gas. For example in an air compressor at the end of a suction stroke (piston is Bottom Dead Center [BDC])P1 is 14.7 psia and V1 will be 1 ft^3, if we then compress it to 0.1 ft^3 the pressure in the cylinder at its highest point (Top Dead Center [TDC]) the pressure will now be 147 psia. If you look at the equation above again, n is constant because it is a property of air in this case, R has not changed (assuming a 100% pressure tight cylinder), therefore T HAS TO RISE because we added work to the system by compressing the air. This is why compressor discharge is HOTTER than the inlet; the volume of the working cylinder is constantly changing adding work to the gas being compressed. This phenomenon is known as HEAT OF COMPRESSION and it works in both directions. If you have a high pressure gas and release it to a lower pressure region(atmosphere for example), the cylinder will get colder as the previously rejected heat of compression is re-absorbed (this is a major principle in how refrigeration works). But because fluids are essentially incompressible this is why they are favored for work where direct electric motors are not suitable, otherwise a pneumatic system would require MASSIVE compressor/reservoir arrangements to do a similar amount of work. Comparing a gaseous system to a hydraulic system is an incompatible analysis because you are dealing with two DISTINCTLY different phases of mater. As a personal request, please do NOT attempt to pass off "a full thermophysical analysis of the system" as an understanding of thermodynamics centering on heat transfer and fluid flow until you have taken such courses. I would be glad to assist you in getting a better and functional understanding of these subjects if you ask.

[@danalex2991]

Only hydrodynamic pumps create pressure differential within the pump . Positive displacement pumps which most hydraulic pumps are ,create only flow .

[@HerraTohtori]

sivalley 1. for a fluid to start moving, a force needs to be applied to it. 2. A force distributed over an area is called pressure. In this case, the pump creates a force over the diameter of the outlet, which, ah, *forces* the fluid ahead to move. This is pressure. But since the pressure in a closed system (ignoring things like pressure differentials from gravity gradients) is the same on every side, adding pressure to a fluid line not only makes the fluid move, the same pressure is applied to the sides of the lines, and to whatever actuator is at the other end of the line. 3. From this we already know that any pump that makes fluid flow *has* to exert pressure on the fluid. This fact is independent from the pump type. The flow we can see is the effect, while the cause is the pressure. 4. There is no such thing as suction... 5. The ideal gas law (pV = nRT) can be used as an approximation for any fluids, it's just not particularly good for things like liquids. This is because in ideal gas, particles don't interact with each other at all, and only interact with their environment with elastic collisions with the container walls. In a fluid, you have to take into account the increased interaction (bounds) between molecules, which are what makes the fluid practically incompressible. That said, you *can* approximate it with ideal gas law - by assuming the volume remains constant. This is also called an isochoric process, in which only the temperature and pressure of the fluid change in measurable amounts. And yes, of course the temperature of the working fluid increases when it's pressurized. This happens in both hydraulic and pneumatic Also, things like specific heat capacity will be different in real substances than in ideal gas. And things like phase transitions (cavitation) can happen depending on the enthalpy of vapourization, if the pressure drops too low. With a hydraulic or pneumatic system, the work done by the working fluid is generally W = ∫ p dV integrated over the cylinder's volume change from minimum to maximum; this is the work done to expand the fluid against the load on the cylinder. This actually works the same whether you're dealing with an incompressible hydraulic fluid or an expanding gas - the only thing you really need is pressure that is enough to overcome the load on the cylinder. Hydraulic motors are a bit more interesting as they are basically a positive displacement pump in reverse, but fundamentally they are still just the rotary counterpart of a hydraulic cylinder and can be solved in a similar way (though the equation may look different). 6. I know basic thermophysics pretty well. I just didn't feel like elaborating all that much on my initial comment because KZbin in general is not a great platform for discussing such things. I simply wanted to point out the seemingly obvious fact that all pumps *have to create pressure* in order to force fluid to flow. Dan Alex Positive displacement pumps differ from dynamic pumps in that as long as you can maintain the RPM, they produce a constant flow rate, whereas with dynamic pumps the RPM and flow rate are not directly coupled. So with a dynamic pump, you have to spin it at certain RPM to get the fluid flowing at certain rate *at a specific load*, but if the load increases the fluid flow will slow down even if you keep the pump running at steady RPM. To restore normal flow rate you'll then have to increase the pump RPM. With a positive displacement pump, however, the flow rate depends on the torque you can apply to the pump to maintain the constant RPM. Since the RPM of positive displacement pump is generally kept constant, this means that the torque must be dynamic (corresponding to the load). So the pressure created by the pump to push fluid through the lines and work the actuator depends on the torque that is being used to run the pump at a given moment. With no load on the system, you need minimal torque on the positive displacement pump to create the pressure needed to maintain steady flow rate. In other, the head loss is small. As the load increases, the increasing backpressure (or head loss) starts to slow the fluid flow, and the response to that is to ramp up the torque, which makes the pump's outlet pressure increase so that it can keep pushing fluid through the lines and into the actuator. But the pump *has* to produce pressure on the outlet to get the flow going. The flow is an effect, not the cause. Saying that pumps do not generate pressure would be the same as saying that a car's engine doesn't make the wheels spin, it just makes the car move and the wheels spin as a result of them being in contact with the road. It's skipping an important step - how does the car get moving, which is analogous to asking "how does the flow get moving" in a pump.

[@HerraTohtori]

+sivalley 1. No. Force is not the same as work. A force is measured in Newtons. Work is measured in Joules. A force is what pushes on things and makes them accelerate. Work is a way to express the changed energy state of the system - ie. the *work done by the force*. In thermodynamics, work can also be any energy change in the system, like a temperature change - or a volume change, like in hydraulics. 2. You're confusing the definitions of pressure (force per area) and work (result of force, or pressure in this case). With no other load, the pump works to make the hydraulic fluid move in the lines. This is accomplished by applying a force (pressure) to the fluid at the pump's outlet. This is what *makes the fluid move*. Also, yeah, hydraulic systems aren't strictly speaking closed systems. If there's no load on the system, the fluid flows through the pipes and out an opening at the end, into the reservoir. But when the hydraulic actuator is engaged, it *is* a closed system... on one end you have the actuator (like a cylinder) and on other end you have the pump. What do you think the pump does when it *pushes* fluid into the actuator (the hint is in the wording of this question)? 3. Pressure is not even close to being the same thing as work. Static pressure does absolutely no work, for example. Pressure only does work when it's associated in moving something, like when the volume of the container changes. 4. True, in colloquial use there are both suction and cold, but in precise physical terms, these are just a low pressure zone being filled from high pressure zone, and heat transfer from higher temperature (like a human body) to lower temperature zone (environment or a frozen consumable you just took out of the freezer), and it feels "cold" to your senses. But the use of colloquialisms does nothing to improve the physical understanding of the world; to do that you sort of have to be able to process them as what they really are. By all means there's no problem with using the terms in everyday language, but when you use them in physical context, there's bound to be some confusion. Well, engineering lingo has its own nuances, I'm sure they use "suction" routinely and have a precise definition for it, if it works it's good enough I guess. 5. Ideal gas law is an approximation that doesn't absolutely apply to absolutely anything. In real life, depending on the accuracy you need, you have to take into account lots of things even for gases: The angular momentum of the particles, their degrees of freedom (depends on their symmetry), their diameter and mass distribution, the small forces happening between the particles, etc. etc. Ideal gas applies only to a substance known as *ideal gas*; it was just discovered that most gases in most situations behave close enough to ideal gas that the approximation is still useful. If you add correction terms for forces between particle, you end up with much better state equations which can be used for almost anything. For liquids, the biggest change you need is make the volume invariable. Of course that's no longer the "ideal gas law" as we know it then, but more like the "ideal fluid law" - except that with fluids, the difference between real fluids and ideal fluid are much bigger. For example, ideal fluid has the viscosity of zero, which would mean it should provide no head loss at all when you're pumping it through the hydraulic lines at zero... but we all know real fluids all have this property, so you have to, ah, exert a pressure to the fluid to keep it flowing. The equation I posted is correct when you're looking at the work done by fluid inside hydraulic cylinder when pumped in at some pressure p; the work is the pressure causing the cylinder's volume to increase. The flow rate (dV/dt) defines the *power* of the hydraulic cylinder, ie. how *fast* it can get that work done (dW/dt). This is no different from a closed cylinder with expanding gas inside - only, because the fluid is incompressible, the only way to expand a cylinder filled with fluid is to either heat it (which causes a pressure increase caused by thermal expansion, which then does work) or to pump more liquid in. But to pump more liquid in, you need *pressure*. Which is provided by the pump. If the pump can't produce enough pressure (ie. overcome the head loss), then the fluid doesn't go into the cylinder and the cylinder does not do work. Everything grinds to a halt at this point when the *pump cannot produce enough pressure* to maintain the flow. The difference between a dynamic pump and a positive displacement pump here is that a dynamic pump can keep on spinning even when it can't maintain the flow. A positive displacement pump on the other hand slows down and stops when torque becomes too small to maintain the flow, so the simplest way to fix that is to increase torque. But you can only increase torque up to a certain point depending on the motor providing that torque. 6. Posting misconceptions or simplifications from the internet does not make you right either. They may even be *useful* simplifications in terms of teaching the *functionality* to the operators - field engineers - of the equipment, but it doesn't make them physically true. Since there is a direct relationship between the pressure and the load applied to the hydraulic system, it may be simpler to just say that the pressure is "caused" by the load, but that's not true. Even if the pressure is *dependent* on the load, that's not what *pressurizes* the system. For a viscous fluid to keep moving, a pressure needs to be applied to it. This is what the pump does with no load. The flow is the effect, pressure is the cause. This is fundamental basic physics. It's analogous to pushing an object on the floor when there's a resistive force (friction) trying to slow it down - you need a continuous push to keep it moving. In terms of fluids, the viscosity is analogous to friction, and the pressure is analogous to viscosity. Naturally, the pump only starts really working when load is applied to the hydraulic system, but all the pump does is produce a pressure exceeding the head loss (backpressure) from the system, *in order to maintain positive pressure to keep the fluid flowing into the hydraulic cylinder* or through a hydraulic motor or whatever actuator is providing resistance to it. Saying that a pump doesn't create pressure is an absurd and needless complication. Of course the pressure in the system depends on how much load the pump has to deal with, but the *pump is what provides the pressure* that the hydraulic cylinder needs to do work. My car analogy wasn't perfect, but demonstrates the similar kind of backwards thinking as saying that the pump doesn't provide pressure, it just "makes the fluid move". A better analogy would be to say that the engine/transmission doesn't provide torque, it just provides rotation for the wheels and that's what moves the car. You're ignoring the fact that you absolutely need pressure to move fluid around even in a no-load scenario. Just like you need torque to make the wheels of a car rotate. You need to ask yourself, what does the pump do that *makes the fluid move*, hmm?

[@HerraTohtori]

***** Of course pumps create flow. How do they create flow?

[@sc0tte1-416]

I've been in the logistic industry for about 18 years in various positions, so I've operated a crap-ton of different material handling equipment over the years. Something I've noticed with electric forklifts is the older (I'm talking electric trucks here) is the pump would always operate at one speed, ie balls-to-the-wall, no matter how much action you selected on one of your levers. I'm guessing the excess oil was being diverted back to the res via your valve block, but that's a bit redundant. The newer machines seem to not only have control-by-wire, but the pump only works as much as required, none of that sudden motor noise when you just want to move something by a hair.

[@deuceandguns]

Mostly unrelated note. Cavitation also kills wet-cylinder diesel engines when the incorrect antifreeze is used. Many good old diesel engines died of this due to new inexperienced owners.

[@rhunter3406]

That's why all new diesels run OAT coolant similar to dexcool where they already have the proper additives in them. In glycol systems you need DCAs which you also have to ad in when changing it, its kind of like the whole gear oil with anti slip additive already in it nowadays, because way too many people were fucking it up.

[@MindCrime550]

just stumbled upon this channel, 2nd video in. I knew right away this guy is smart and funny. Keep up the good work!

[@MG-it9mw]

Very education and accurate. This helped me to understand the K46AC transmission. Thanks

[@buttonman6262]

You explain things brilliantly. Any chance you could you could get to England by tomorrow and teach my auxiliary course?😩

[@adamdebowski2037]

What a great video. Hands down #1 key takeaway is the wife underwear joke 😂

[@poongkyelee2068]

It is really fascinating to see the inside of the gear pump!! Thanks for the video

[@TheFalconJetDriver]

I love how you explain the details. In a previous life I installed CNC machining center’s one client was Worthington pumps. They built hydraulic pumps with herring bone meshing gears. Later on in life I flew airliners and on the MD DC- 9 airplane the engines Pratt and Whitney of course JT 8-9 the hydraulic pumps where variable displacement pumps that used a wobble plate to adjust required pressure. I really enjoy your videos. May ask what is your background as in what did you do for a living? You have a wonderful understanding of so many subjects. 😁🛫

[@wgm-en2gx]

Thanks for the explanation. I've mistakenly thought that the pump moved oiled through the mesh of the gears. The first thing I thought when you opened it was how does the oil move through such a close mesh. Now it makes perfect sense that it doesn't and in retrospect it was a little stupid to think that it did...

[@TheRealPOTUSDavidByrd]

So pressure is torque and flow is horsepower. Gotcha. Thanks for all the videos! I've learned a lot!

[@ecseymour3]

you should do one on a piston pump works, and explain how the charge pressure is created and control (Parker valve). awesome video

[@dustyroads834]

I work on PC-400 excavators. They have a dual set variable displacement piston pump. To stop cavitation they build the pump with a centrifugal primary pump on the inlet side to somewhat pressurize the oil before the piston section. I thought that was a good idea to make up for a lot of bad ideas that Komatsu has.

[@dwaarf]

Nice vid. There is one more way to say what way should the pump turn. You just check how the seals on the sealing elements are fitted. The high pressure part is divided from the low pressure so just by telling which part is which you can tell if the pump is cw or ccw.

[@creativejunior7060]

I also got this pump and i made it into a powerful pressure washer. Thank you so much

[@roscoepcoletrain2716]

thank you so much for your help, u taught me so much I needed to know if a pump could run either way all I have to do is flip the gears wow thanks again

[@giar9124]

thanks for helping my hangover with your soothing video

[@mb2k100]

The odd lady here

[@1hdsquad]

But do you kickstart a Harley?

[@TheBaconWizard]

How odd are you, exactly? :p

[@red00eye]

Can you suck start a Scania?

[@DCsk8rgoelz]

+

[@TerryPullen]

Welcome to the boy's club.

[@a_Gláir]

I just see that you`ve mounted the seals directing the flow from gallery to the inlet. Maybe that is because I have an oil linking in the motor axle, once I have done quite opositte.

[@garym8348]

Thanks man. Very in-fkn-formative. I had to replace the oil pump in my car about 20 years ago and for whatever reason I thought about gear pumps and watched your vid. Great job, good info.. Thanks again.