How does GPM Translate into Work Getting Done?

[TableRocked]

So as I'm still wrestling with the "ideal" TLB setup for me, aside from a beefier frame on the "construction" TLB models, I noticed the hydro pump has a significantly greater output than what comes with similarly sized "non construction" Kubotas.

Assumptions:

1. My Kubota won't be worked daily, just part time playing
2. A few seconds quicker dig or lift times doesn't matter to me
3. I plan to run a rock breaker, finish mower, Brush Hog RTH 72" tiller, front HD grapple for stacking rocks, and rear hyro thumb
4. Plan to dig multiple foundations, septic runs, and water/power access trenches

My questions:

How does more GPH translate into benefit for me? Can I lift more because of increased GPH? Do I have increased breakout force for digging because of an increased GPH output?

 

[BotaDriver]

GPM is speed. GPM increases with machine RPM. Most of us do loader work at less than full speed as they hydros get a little touchy when you're at full speed. Force is by pressure, and you'll find that you'll have 95%+ of full pressure at idle. My machine's pressure does not change at all with RPM. I have full pressure at idle.

Look at the machine specs, that will tell you what you can do. Particularly the lift forces. TLBs don't really do anything faster, but they do tend to lift more than machines of similar size. You're focusing on the wrong specs. Look at lifting specs. GPM of the hydro does not equate to work. Backhoes in particular have limiters on the various functions as it's a single cylinder doing the work. TLB specs are combined. The L45 has 2 pumps on it, one dedicated to the swing of the backhoe. They have separate ratings for the steering, the backhoe swing, and the loader/rest. Each is its own rating and adding them together is worthless.

L45 Hydro Specs....
11.8GPM Loader/backhoe & remotes
6.6GPM Backhoe Swing
6.6GPM Power Steering

 

[lsmurphy]

I'll disagree with the above.

If you have a system that requires 22gpm and a pump that produces 11gpm you will only get half the work done.
You will also have a pressure drop as the pump cannot supply the demand.

The pressure control valve is what equalizes and protects the entire system.

 

[BotaDriver]

I'll disagree with the above.

If you have a system that requires 22gpm and a pump that produces 11gpm you will only get half the work done.
You will also have a pressure drop as the pump cannot supply the demand.

The pressure control valve is what equalizes and protects the entire system.

Define 'System' as you're seeing it? The question was not that he needed a certain flow rate, it was that he needed certain work done. GPM does not translate to work done. I can put a 30 GPM pto pump on the 3800 to up its specs, but it certainly doesn't translate to being able to do more work. The loader will still lift it's rated spec unless I up the pressure. The bucket still holds its same volume, and the travel rate of the tractor is unchanged.

The only thing that GPM has to do with is when running independent attachments. Most SSQA attachments will work with 11GPM hydraulics as a lot of older bobcats had about that flow. Unless there is a specific attachment (there are some) that require super high flow, the GPM rating is moot, and will yield no additional production.

 

[lsmurphy]

He asked a theoretical question, did he not?

My statement stands.

What is his system? Is he increasing the demand of his current pump? I have no idea what he is doing, he did not say.


Let's assume that he wants to add a log splitter attachment and the cylinder he wants to use requires 22gpm to operate at a specified speed, he only has a 11gpm pump.

What do you think the outcome will be?


Pressure and volume are two completely different things.


You can go to HD or Lowes right now and buy a 3000psi pressure cleaner......here's the down side......2gpm and it will DO NO WORK........it's a POS.

Now, you want a machine that will do work? look to one that at least puts out 4gpm.

In fact my machine puts out 2200psi at 4gpm ........less psi yet does MORE WORK.

 

[DonDC]

I can't answer your question about GPM vs work done but I think you will find that a TLB will do anything that a similar regular tractor will do plus a little more and will be a better choice for a lot of digging and lifting. The backhoe is frame mounted and in my opinion stronger then an add on system. I have an L35 TLB and it get work done quite well. Yes a bigger TLB would sometimes be nice when you reach the force limits but if you take it a little slower and smaller bites, you get the same work done but it takes a little longer. I have put nearly 400 hrs on my L35 since I got it last year and I am very happy with it. I have cleared 3 acres of 4 to 8 inch trees and brush plus dug foundations with no problems. I am glad that I did not go for a heavier TLB because my machine is smaller and lighter for trailering. I have a 10,000 lb trailer which leaves me about 1000 lbs margin for safety or if I need to carry an additional piece of equipment. The backhoe removes fairly easily and I can then run any type of 3pt equipment. This may not be what you require but it is everything that I need.

 

[Bulldog]

The higher the GPM the more functions you can do at ine time.

ex. Digging with the backhoe and you are needing to hoist, croud, and curl all at the same time. This is where high GPM will come into play. Lets say one system is 22 gpm and the other is 11 gpm.

22 gpm using 3 functions gives 7.3 gpm for each

11 gpm using 3 functions gives 3.7 gpm for each

I know this is a very basic example and not exact but it gives a easy way to look at it. The true TBL will allow you to get more done because it will be much faster. Not only faster but it will be smoother to dig with. It will act more like a full size backhoe.

 

[moog]

Your front end loader is sized for your tractor. When you get into rear remotes and implements some rear implements require a certain gpm to operate properly. For a very poor example you wouldn't want to try to use a implement that required 40hp and 13 gpm on a 32hp tractor that delivered 7gpm.

 

[BotaDriver]

So as I'm still wrestling with the "ideal" TLB setup for me, aside from a beefier frame on the "construction" TLB models, I noticed the hydro pump has a significantly greater output than what comes with similarly sized "non construction" Kubotas.

The Pump is actually about on par with similar sized machines. The primary pump for attachments is 11.8GPM. Compare that to a L4240 that has 9.8GPM. The L45 has a 2nd pump that is for the swing of the backhoe only; when added to the primary pump, and the steering pump, you arrive at the larger number.

Assumptions:
[*]My Kubota won't be worked daily, just part time playing
[*]A few seconds quicker dig or lift times doesn't matter to me

All of Kubota's loaders are sized to the tractor and there is not much difference in speed between them. Some of the Grand L kubotas and loaders are faster than the TLBs in lift and lowering speed.

[*]I plan to run a rock breaker, finish mower, Brush Hog RTH 72" tiller, front HD grapple for stacking rocks, and rear hyro thumb

Are you looking at PTO powered or Hydro powered? PTO are much cheaper and utilize the full power of the tractor whereas the Hydro units are limited by the pump. Which rock breaker are you looking at and what GPM does it require? I found several sized for the backhoe in the 45hp range that are fine w/ 11.8GPM

[*]Plan to dig multiple foundations, septic runs, and water/power access trenches
My questions:

How does more GPM translate into benefit for me?

Doesn't seem to matter except for the rock breaker

Can I lift more because of increased GPH?

No

Do I have increased breakout force for digging because of an increased GPM output?

No

 

[BotaDriver]

The higher the GPM the more functions you can do at ine time.

ex. Digging with the backhoe and you are needing to hoist, croud, and curl all at the same time. This is where high GPM will come into play. Lets say one system is 22 gpm and the other is 11 gpm.

22 gpm using 3 functions gives 7.3 gpm for each

11 gpm using 3 functions gives 3.7 gpm for each

This is not exactly the case. Open center hydro valves when activated to a certain point no longer provide any flow to downstream valves. The return line from the active valves is dumped to the tank. A backhoe typically can perform multiple operations though I have seen instances of machines when using a 3rd function that nothing happens. Backhoes also because they use a single cylinder for most functions have restrictors on each one as sending the full flow to it would make it work entirely too fast. Loader functions are shared by 2 cylinders on most machines so the flow is half as fast since it's feeding 2 cylinders. Of course cylinder diameter comes into plays as well, but that would just be overly complicating the current discussion.

 

[Lil Foot]

The higher the GPM the more functions you can do at one time.

You took the words right of of my mouth…. or in this case, my fingers.

 

[Bulldog]

This is not exactly the case.

I was trying to keep it simple and to the point.

The more flow you have the great use you can get from your machine. That I have seen Kubota backhoes don't have a system where the operator can set the priority for the flow like what full size machines do.
This is where a good operator can get more out of a machine than a novice operator can. Learning how to feather the controls and put the power where you need it is a must.

 

[BotaDriver]

I was trying to keep it simple and to the point.

This is where a good operator can get more out of a machine than a novice operator can. Learning how to feather the controls and put the power where you need it is a must.

I agree. It's not always a yes or no as to what a machine can or can't do; more often than not it's if the operator knows the machine well enough to accomplish the task. Someone on one of the forums made a comment about an old man being able to accomplish just about anything with a single bottom plow on an old 2wd machine, particularly removing stumps with one.

And to the original question at hand; are there certain tasks that you are wanting to accomplish one time, or are you in business and will use the machine for customer jobs? Is trailering and thus weight an issue? You can get a TLB to tackle all of your tasks and then sell it to get a 'normal' machine afterwards? You will be able to keep all implements for the replacement machine while not having to keep more tractor than you need. Also often suggested is obtaining an older/larger Case machine to accomplish your work and then obtaining CUT for maintenance / upkeep. There are many solutions to your question, having more information would help everyone narrow down your choices.

 

[TableRocked]

I agree. It's not always a yes or no as to what a machine can or can't do; more often than not it's if the operator knows the machine well enough to accomplish the task. Someone on one of the forums made a comment about an old man being able to accomplish just about anything with a single bottom plow on an old 2wd machine, particularly removing stumps with one.

I will have a few thousand trees to cut down and stumps to remove

And to the original question at hand; are there certain tasks that you are wanting to accomplish one time, or are you in business and will use the machine for customer jobs? I'm not using this for business, just clearing land for a 3 to 5 acre garden, soil prep, erosion control, landscaping, retaining wall construction.

Is trailering and thus weight an issue? I don't plan to have it leave my property. It will need to navigate dense forest, so I figured the full size TLBs from case are both out of my price range and too big.

You can get a TLB to tackle all of your tasks and then sell it to get a 'normal' machine afterwards? Oh, and my wife will not likely let me buy and sell....buy and keep is her preference, so I'm trying to get a machine that will meet but not overmeet my needs for future gardening, livestock work, foundation work for another morton building, ect. Plan to keep for rest of my life (40 years or so).

And thanks so much to everyone for the responses and information. I'm still not sure I'm 100% understanding all the points, but it does make a little more sense now what I should be considering.

 

[MtnViewRanch]

If you have thousands of trees to remove on 3-5 acres, I would think they can't be all that big. You can buy a Case 580TBL with 7000 hours on it, warn, but not warn out for about $10k. That what most people consider a warn out machine will dig circles around any of the Kubota TLBs. My suggestion would be to look at a CUT and a used excavator. That IMO would be what would work the best for you and not cost all that much more than what you are currently looking at.

I think you would find that having 2 separate machines to work with works very well.

Good luck.

 

[BotaDriver]

If you have thousands of trees to remove on 3-5 acres, I would think they can't be all that big. You can buy a Case 580TBL with 7000 hours on it, warn, but not warn out for about $10k. That what most people consider a warn out machine will dig circles around any of the Kubota TLBs. My suggestion would be to look at a CUT and a used excavator. That IMO would be what would work the best for you and not cost all that much more than what you are currently looking at.

I think you would find that having 2 separate machines to work with works very well.

Good luck.

Indeed, buy the Case, use the hell out of it, then turn around and sell it when it's need has been fulfilled for almost what you paid for it. It's a win win. It's cheaper than the TLB, far more useful / powerful, and then get a nice new utility tractor that you'll keep for decades. Keeps all of the wear and tear on the sold equipment.

 

[Stubbyie]

My opinion--others may disagree--too much overthinking on this subject.

GPM = $: the more you pay the more GPMs you can buy.

The kicker is that unless you want to run supplemental hydraulically-driven attachments or implements, the GPM on a tractor loader backhoe (TLB) is immaterial, within some general constraints. The manufacturer has engineered the system to work within its design limits.

Sidenote: a frequent posting in this forum is the relative speed at which Kubota backhoes operate. Some call it jerky. Mostly it's just getting used to your machine. Many owners posting here have said they keep the machine throttled down to prevent high-speed banging-clanging mistakes (like a fast swing that whacks something not seen). Very few posters here use their machines in a high-production environment where seconds per cycle translate to serious dollars.

If you want to run supplemental equipment (rock breaker, hydraulically driven front-loader bushhog) you probably need a high-flow skid loader or one of the relatively rare TLBs with high-flow capabilities.

If you buy a name-brand construction-level TLB (Kubota, Ford New Holland, Case, JCB, Deere) that has an integral frame-mounted backhoe unit you will be able to do more work than you want too: you'll give out long before the machine on any particular job.

Trouble arises when an aftermarket (typically 3-point mounted) backhoe unit is attached to a tractor. The PTO-driven pumps are often marginal.

Now, back to the $ mentioned above. You'll always find some job you need a bigger machine for. Instead, concentrate on spending your money on the size machine that will do 80% of your desired work. The other 20% either won't matter, you'll find a way around it, or you can rent the bigger machine for a day every couple years. Basically, buy all you can afford. You should be able to get your money back upon reselling if you later choose.

Personally, ours is the handiest thing on the place and has become our go-to machine when the other 'bota is left in the shed.

Please post back your thought process, purchase decision, and how you choose to proceed so we may all learn.

 

[TableRocked]

Stubbie, thanks for the explanation and I couldn't tell from your posting, what model did you say gets all the work while others sit in the barn?

If I understand you correctly, if I purchased a Grand L and added a backhoe, it would be a PTO driven backhoe different than what the construction TLB from Kubota then offers?

 

[Bulldog]

if I purchased a Grand L and added a backhoe, it would be a PTO driven backhoe different than what the construction TLB from Kubota then offers?

A Grand L with a backhoe is not the same as a TBL. If you get the Grand L make sure you get a subframe mounted Backhoe instead of a 3pt type.

My $.02, instead of buying a backhoe for the tractor look at getting a mini excavator. They will outwork a tractor mounted backhoe 10x over. For about what the BH cost you should be able to find a good used mini x in the 7K - 8K lb range.

Another plus to a mini x is that it's always ready to dig. You never have to worry with mounting or dismounting a backhoe. You have a machine that's made for digging and that leaves you tractor free for other task. It's a win win for me but that's just my opinion.

 

[DonDC]

I am fairly sure that Stubbie has an L35 TLB