Loader Getting Weak With Use?

[hagrid]

That is the big downside to these glorified lawn mowers.

@Soopitup, trade current toy tractor for a B, L, or any of the real tractors, plz.

 

[TheOldHokie]

@Soopitup, trade current toy tractor for a B, L, or any of the real tractors, plz.

Go big or go home

Dan

 

[MapleLeafFarmer]

I've noticed that my loader has less lifting power at the end of the day.

When the tractor is cold (not ran) and I start it running at idle I have no problem lifting the front loader ( 2023 BX23S).
It's very slow, but it has no problem lifting and curling the bucket.
Once I've ran it for a while at idle it doesn't want to lift the bucket at all.

Can you clarify your statement above?

are you talking about unloaded lift speeds / capacities or loaded.

I would suggest you make a loaded lift test.

In the morning on startup load 500# of something you know the weight of like 10 50# bags of sand or whatever you know is about 500 pounds. Then at end of day do same cycle test from ground to max height and back with same weight in the bucket.

Would love to hear what the cycle time (seconds takes from ground to full height and back) of both tests is.

 

[Soopitup]

Let me clarify here; I'm not trying to do any work with the tractor at idle.
I also don't have a problem with the tractor capacity.

*My tractor idle is usually 1500 RPMs, sometimes drops to 1400. Drop has no effect on lifting capacity.*

When I want to use the tractor I go out to the garage, start the tractor and let it idle for a few seconds to a minute, depending on temp.
Because the bucket is on the ground I have to raise it to move the tractor. I leave it in idle and raise the bucket a few inches and idle out of the garage. The tractor has no trouble raising the bucket at this point (idle, cold fluid).
Then I rev it up and do whatever work needs to be done. RPMs Depend on what I'm doing, but I don't run it below 2500 RPMS.
When I'm done I let it idle for a few minutes, then back it into the garage.
While doing this (idle, hot fluid) I noticed if I had worked the tractor hard it could barely lift the bucket, sometimes not at all.
The hydraulics I'm used to is large heavy equipment. It doesn't have this problem.
I wasn't sure if this was normal for a small machine or not (I don't have any experience with small stuff).
If there is a problem I want to know now so I can get it in to service.

After hearing everyones advice I'm guessing there isn't a problem, but I'm going to confirm, just in case.
Won't be hard to do.

there's nothing wrong with it. Normal for that tractor. That tractor's hydraulic pump is TINY in regards to flow. The pump has a pair of gears inside of it which mesh together and are "sealed" at the ends between the gears and housing. When the fluid warms up to operating temp (which, btw is roughly 100 deg above ambient temp), the pump parts expand and the amount of leakage between the gears and also between the gears & the housing increases. Because the pump is so tiny, any leakage is felt by a loss of hydraulic power.

Yeah, I was paging through the WSM last night and I noticed how small the pump was.

@Soopitup, trade current toy tractor for a B, L, or any of the real tractors, plz.

Everything on here is a toy. Even that machine that Dan posted.
The shit I used to operate/work on would pull that around like an empty trailer.

Use the right tool for the job. I'd be stupid to grab my sledgehammer to nail boards together.
Those are all too big for what I need. Even the B.
I almost bought a B, and at first I was afraid I was going to regret getting the BX.
After seeing how the BX fits in my yard (and in my garage), and what it does to my yard, I'm glad I didn't get the B.

Go big or go home

Dan

View attachment 115571

HA!
That's medium at best.

 

[TheOldHokie]

Let me clarify here; I'm not trying to do any work with the tractor at idle.
I also don't have a problem with the tractor capacity.

When I want to use the tractor I go out to the garage, start the tractor and let it idle for a few seconds to a minute, depending on temp.
Because the bucket is on the ground I have to raise it to move the tractor. I leave it in idle and raise the bucket a few inches and idle out of the garage. The tractor has no trouble raising the bucket at this point (idle, cold fluid).
Then I rev it up and do whatever work needs to be done. RPMs Depend on what I'm doing, but I don't run it below 2500 RPMS.
When I'm done I let it idle for a few minutes, then back it into the garage.
While doing this (idle, hot fluid) I noticed if I had worked the tractor hard it could barely lift the bucket, sometimes not at all.
The hydraulics I'm used to is large heavy equipment. It doesn't have this problem.
I wasn't sure if this was normal for a small machine or not (I don't have any experience with small stuff).
If there is a problem I want to know now so I can get it in to service.

After hearing everyones advice I'm guessing there isn't a problem, but I'm going to confirm, just in case.
Won't be hard to do.


Yeah, I was paging through the WSM last night and I noticed how small the pump was.




Everything on here is a toy. Even that machine that Dan posted.
The shit I used to operate/work on would pull that around like an empty trailer.

Use the right tool for the job. I'd be stupid to grab my sledgehammer to nail boards together.
Those are all too big for what I need. Even the B.
I almost bought a B, and at first I was afraid I was going to regret getting the BX.
After seeing how the BX fits in my yard (and in my garage), and what it does to my yard, I'm glad I didn't get the B.



HA!
That's medium at best.

The loader should raise an empty bucket at idle speed.

Dan

 

[GreensvilleJay]

idle ..... what RPM is your idle ?
My 5 year old BX23S can idle at 1200,1600,1300,1400 even 1000. Don't know why it can vary and one day may actually try to read the WSM but I KNOW that under 2000 RPM the hydraulics are 'weak', same as the drivetrain. I assume that's the nature of the beast. As I've mentioned before , every pump has a minimum RPM and graphs to show GPM vs RPM.From what's been posted here , idling a diesel is not a good thing.
I start the beast up, get 2000 RPM THEN drive out of the garage and off to the jobsite, 2500 for a few minutes ,then 3500 going down the road. Unlike others though , when I'm not using the tractor I shut it off as diesel is almost $2 a litre and no good reason to waste fuel.

 

[Soopitup]

Idle is 1500 RPMs.
I know the hydraulics are weak at idle.
That's not the question.

The question is the difference in hydraulic power at idle between cold/warm and hot.

 

[TheOldHokie]

idle ..... what RPM is your idle ?
My 5 year old BX23S can idle at 1200,1600,1300,1400 even 1000. Don't know why it can vary and one day may actually try to read the WSM but I KNOW that under 2000 RPM the hydraulics are 'weak', same as the drivetrain. I assume that's the nature of the beast. As I've mentioned before , every pump has a minimum RPM and graphs to show GPM vs RPM.From what's been posted here , idling a diesel is not a good thing.
I start the beast up, get 2000 RPM THEN drive out of the garage and off to the jobsite, 2500 for a few minutes ,then 3500 going down the road. Unlike others though , when I'm not using the tractor I shut it off as diesel is almost $2 a litre and no good reason to waste fuel.

Idle is 1500 RPMs.
I know the hydraulics are weak at idle.
That's not the question.

The question is the difference in hydraulic power at idle between cold/warm and hot.

That's what a pressure gauge will tell you.

Dan

 

[Soopitup]

That's what a pressure gauge will tell you.

Dan

Yes
Need to order a few things.
I plan on checking pressure and comparing loads at full throttle too.

Already worked 40 hours since Sun night and going back for more tonight.
So I'm decompressing this evening. No work.

 

[PaulL]

My old BX always lifted the loader at idle, no matter how warm. Sounds weird to me to suggest that a BX after it's warm can't lift the (empty) loader when at idle.

 

[leveraddict]

ive never experienced this problem on my BX23S.

 

[leveraddict]

there's nothing wrong with it. Normal for that tractor. That tractor's hydraulic pump is TINY in regards to flow. The pump has a pair of gears inside of it which mesh together and are "sealed" at the ends between the gears and housing. When the fluid warms up to operating temp (which, btw is roughly 100 deg above ambient temp), the pump parts expand and the amount of leakage between the gears and also between the gears & the housing increases. Because the pump is so tiny, any leakage is felt by a loss of hydraulic power.

Secondly, since the pump is so teeny tiny, and the flow rate is so little, at idle they're very, very weak. You have to increase the engine speed in order to make the pump develop any pressure and flow. That is the big downside to these glorified lawn mowers. They're not really "tractors" per say, although they have all the features that a larger tractor does, just scaled way down.

Brand new ones that I dealt with on dealer lots were all like this. All the BX's were/are the same way.

Running at idle speed also tends to reduce coolant flow through the radiator and reduces airflow across the radiator, both can lead to overheating. Increase the engine speed. It's not gonna hurt anything but your ears, use ear plugs if it bothers you.

The BX is the best glorified lawn mower I ever had the pleasure of running!

 

[GreensvilleJay]

My BX23S is the best little tractor , and it'll NEVER have a mower deck on it !

 

[ve9aa]

My BX will definitely lift the loader at idle (hot or cold).........i wouldn't normally expect it to do a lot of real "work" at these RPM's but for sure it'll lift an empty bucket.

Have you done your 50hr service yet?

Make sure you clean the hydraulic screen. Some pix I've seen online of screens look downright scary. Others (like mine) had a few traces of silicone goop not worth worrying about.

 

[TheOldHokie]

There has been a great deal of opinon and frankly bad physics and principles of hydraulic pump operation expressed here. So let me try to illustrate the actual physics and hydraulic operation with a little high school science class style laboratory demonstration.

This demo is conducted using my L3901 which was at a chilly 48F when I started it this morning. The test demonstrates that maximum regulated pump discharge oil pressure is the same at 900 RPM engine idle speed and 2500 engine RPM regardless of the oil temeperature. There is nothing special about this pump or these results - they are indicative of the pump design and operation across the full lineup of Kubota SCUTs/CUTs

The Test Rig

I have connected a 3000 PSI test gauge to one of the work ports on an auxiliary valve. If I operate that valve it will deadhead the pump against the gauge and the gauge will register the discharge outlet pressure at the pump.

T


Test 1

With tractor started and oil still at 48F I set engine speed to idle @ 900 RPM and operate valve to deadhead the pump, I can hear the pressure relief valve open and gauge pressure spikes to 2200 PSI which is the specified relief valve setting. The pump is producing flow which is being unloaded to tank via the relief at a regulated 2200 PSI to prevent damaging the pump

Test 2

Wih oil still at 48F the engine speed is increased to 2500 RPM and the valve is operated to deadhead the pump. Same result - pressure spikes to 2200 PSI, relief valve opens, and pump unloads to tank at same pressure.

Test 3

Tractor is allowed to run until oil warms up to roughjy operating temperature. With engine set to 900 RPM valve is operated to deadhead pump. Results the same - pressure spikes to 2200 PSI and relief opens to unload flow to tank at regulated pressure and prevent damage to pump.

Test 4

With oil still at the same operating temperature the engine speed is increased to 2500 RPM and valve is operated to deadhead pump. Results are the same. Pressure spikes to 2200 PSI, relief valve opens to unload hot oil flow to tank at regulated pressure and protect pump from damage,

 

[lugbolt]

Your pressure readings are right in line with that tractor. On the BX's, the pump is so small that it simply cannot flow enough oil to build enough pressure to to into relief at low idle speed. I wish all the BX's had this same style pump, but they can't. The BX's don't hold much oil in them, and there's no cooler to speak of other than that funny little fan on the driveshaft. Thus, if we are running against relief all the time, the oil heats up faster than it can be cooled, so the pumps on the bx's are sized accordingly, to keep them out of relief at or near idle speed. This helps keep the oil cool. Remember this is an open-center system, it doesn't have any type of flow control or flow divider. This design also keeps the build cost down, it's pretty simple for the most part. Cost is a concern on homeowner style tractors.

This is where the L series is what some call a "real tractor". BX's and B's have small pumps and don't flow much, particularly at idle speed.

Flow is affected by the displacement of the pump (gpm) which is directly related to shaft speed. If the shaft speed is low, pump output is going to be low. Depending on the amount of restriction in the system that the pump feeds, there may or may not be much pressure-again depends on the restriction. Restrictions are the valves, hoses, fittings, cylinders, motors, etc. Pressure is the sum of restrictions. If the restrictions flow more than the pump puts out, say a hydraulic motor can flow 1.5gpm, and the pump can only supply 1gpm, assuming no leakage at the motor or the pump, the motor will rotate but pressure will be low, resulting in low motor torque. But as RPM of the pump shaft increases (which is proportional to engine rpm), the pump puts out more fluid, yet the restrictions stay the same, so pressure rises, motor torque increases and since flow also increases with rpm the motor speed increases as well. Same principle with a cylinder. More flow=faster cylinder, more pressure=more cylinder force.

At idle the pump doesn't make much flow, and the restrictions from the cylinders aren't enough to make much pressure. Increase the engine RPM, flow goes up, restrictions stay the same so pressure rises to close to and maybe into relief pressure and thus the cylinder's force rise-giving you more hydraulic power. As engine speed increases, driveshaft and cooling fan speeds increase as well, resulting in more air flowing across the fins of the transmission, thus aiding on cooling. But since BX's have tiny pumps, at idle they just don't make much flow therefore not much pressure. Increasing the RPM increases flow AND pressure, up until it exceeds the relief valve's set pressure.

 

[TheOldHokie]

Your pressure readings are right in line with that tractor. On the BX's, the pump is so small that it simply cannot flow enough oil to build enough pressure to to into relief at low idle speed. I wish all the BX's had this same style pump, but they can't. The BX's don't hold much oil in them, and there's no cooler to speak of other than that funny little fan on the driveshaft. Thus, if we are running against relief all the time, the oil heats up faster than it can be cooled, so the pumps on the bx's are sized accordingly, to keep them out of relief at or near idle speed. This helps keep the oil cool. Remember this is an open-center system, it doesn't have any type of flow control or flow divider. This design also keeps the build cost down, it's pretty simple for the most part. Cost is a concern on homeowner style tractors.

This is where the L series is what some call a "real tractor". BX's and B's have small pumps and don't flow much, particularly at idle speed.

Flow is affected by the displacement of the pump (gpm) which is directly related to shaft speed. If the shaft speed is low, pump output is going to be low. Depending on the amount of restriction in the system that the pump feeds, there may or may not be much pressure-again depends on the restriction. Restrictions are the valves, hoses, fittings, cylinders, motors, etc. Pressure is the sum of restrictions. If the restrictions flow more than the pump puts out, say a hydraulic motor can flow 1.5gpm, and the pump can only supply 1gpm, assuming no leakage at the motor or the pump, the motor will rotate but pressure will be low, resulting in low motor torque. But as RPM of the pump shaft increases (which is proportional to engine rpm), the pump puts out more fluid, yet the restrictions stay the same, so pressure rises, motor torque increases and since flow also increases with rpm the motor speed increases as well. Same principle with a cylinder. More flow=faster cylinder, more pressure=more cylinder force.

At idle the pump doesn't make much flow, and the restrictions from the cylinders aren't enough to make much pressure. Increase the engine RPM, flow goes up, restrictions stay the same so pressure rises to close to and maybe into relief pressure and thus the cylinder's force rise-giving you more hydraulic power. As engine speed increases, driveshaft and cooling fan speeds increase as well, resulting in more air flowing across the fins of the transmission, thus aiding on cooling. But since BX's have tiny pumps, at idle they just don't make much flow therefore not much pressure. Increasing the RPM increases flow AND pressure, up until it exceeds the relief valve's set pressure.

Ah I knew someone was going to tell me the BX pump is somehow different. It is not.

Please stop all the hand waving and your fundamentally bogus hydraulic analysis. Get this very basic hydraulic principle in your head.

It does not matter how little or big the pump is. When a fixed displacement pump is deadheaded and ALL output flow is cut-off outlet pressure will build to extremely high pressure that can permanently damage the pump. That is a fundamental hydraulic principal governing fixed displacement pumps of ALL sizes. You have to have a relief in the circuit or the pump will literally self destruct if deadheaded.

Now back to "the BX is different" idea. There are thousands of BX owners with backhoes out there. For the benefit of all of the hydraulic deniers this is a simple demonstration.

With the tractor fully warmed up stop the engine and disconnect your backhoe loop. Plug a gauge into the tractor side backhoe supply line, start your tractor, set engine to idle, and read outlet pressure.

Your pump will be deadheaded and you will see pump relief pressure (2000+ PSI) at the outlet. In that state and at that engine RPM the relief valve on a BX is unloading roughly 1.5 GPM of flow to tank to prevent damaging the deadheaded pump.

Be nice to the tractor and dont let it run deadheaded like that any longer than it takes to get a pressure reading.

Dan

 

[hagrid]

Be nice to the tractor and dont let it run deadheaded like that any longer than it takes to get a pressure reading.

Quite agree. Lawn mowers aren't accustomed to that type stress.

 

[Soopitup]

Quite agree. Lawn mowers aren't accustomed to that type stress.

Dunno man, there's some pretty ferocious lawn mowers out there....

I finally got around to checking this.
It confirmed my "butt dyno" feeling.

-3000 PSI gauge teed into the backhoe power beyond (not the backhoe power feed).
-Tested loader lift and up curl as well as my third function running off the loader power beyond. All 3 had the same results.
-Cold was approx 60*. Started, drove out of the garage and stopped. Hooked up gauge and ran tests.
-Hot was after running the loader for an hour plus. Dug into some pretty hard soil, stalled many times against a tree stump and too many roots. Not that hot out but definitely gave it a workout.
-I also checked with the backhoe power beyond disconnected and the gauge attached to the hose. I only did idle and max, got the same readings.

Cold pressure readings

-Idle (approx 1500 RPMs) 1100 PSI
-2000 RPMs 1600 PSI
-2500 RPMs 1650 PSI
-3000 RPMs 1700 PSI
-Max (3500 RPMs) 1800 PSI


Hot pressure readings

-Idle 600 PSI ( I did a double take when I saw this, definitely explains the weakness)
-2000 RPMs 1500 PSI
-2500 RPMs 1600 PSI
-3000 RPMs 1630 PSI ( rough estimate, gauge only has 100 PSI increments)
-Max 1690 PSI " "


To head off some questions.
-My tractor has 125 hours as of tonight.
-Replaced hydraulic fluid and filter with Kubota parts, cleaned pickup screen (wasn't that dirty) at 50 hour service.
-Fluid level is good.
-Hoses were warm to the touch, not excessively hot.
-No unusual noises.

 

[Soopitup]

Guage setup if anyone is interested.