My loader won’t stay up?

[MAArcher]

Personally I think a gauge is essential equipment for anyone working on actractor. But I am wondering what the problem is that you are planning on using ot on.

Dan

I’ll use it to test the pressure in the system to see if I’m reaching proper PSI. Trying to verify if my perceived lack of power is an issue or not.

 

[GreensvilleJay]

Once you get your gauge setup, also buy several known, calibrated weights, say 100#,200#,500#. Using them and a digital stopwatch you can assess the overall tractor's performance at various RPM levels. Be sure to record air temperature, humidity as well as hydraulic oil temperature.
PSI is just one factor in the 'power problem'.

 

[MAArcher]

Once you get your gauge setup, also buy several known, calibrated weights, say 100#,200#,500#. Using them and a digital stopwatch you can assess the overall tractor's performance at various RPM levels. Be sure to record air temperature, humidity as well as hydraulic oil temperature.
PSI is just one factor in the 'power problem'.

I didn’t even think of temp. Would there be a noticeable performance difference in loader performance between a 70 degree day and a 95 degree day? This is the first time I’ve worked the loader this hard in such hot temperatures.

when was a kid I had a Yamaha rz350 motorcycle. Two stroke. There was a very noticeable difference, lots of power loss on hot days, it was like two different bikes between summer and fall.

 

[GreensvilleJay]

Yes, heat IS a factor. Every car/truck with an automatic tranny has a cooler in that system.
As for how much heat affects your tractor's loader performance.I don't know as Kubota probably doesn't publish that data. I do know that adding an 'oil cooler' on a custom built rig made a HUGE difference. I suspect skidsteers have them.Most if not all 'heavy equipment' will too .
'performance' is based on the 'system', so LOTS of factors are involved, have to look at everything not just focus on one.

 

[William1]

If... you want to 'hold something up', that is what a hoist is for. Lifting with a tractor should only be done when there is an operator in the seat and the engine running.
Some loaders and many BH have 'transport pins'. that are inserted before the engine is shut down to 'lock in place the loader or BH. But even with them in, I'd never recommend depending on them to hold something in the raised position.

A hammer will remove a nut from a bolt. But it is the wrong tool for the job. A wrench will drive in a nail but it is the wrong tool for the job.

 

[MAArcher]

If... you want to 'hold something up', that is what a hoist is for. Lifting with a tractor should only be done when there is an operator in the seat and the engine running.
Some loaders and many BH have 'transport pins'. that are inserted before the engine is shut down to 'lock in place the loader or BH. But even with them in, I'd never recommend depending on them to hold something in the raised position.

A hammer will remove a nut from a bolt. But it is the wrong tool for the job. A wrench will drive in a nail but it is the wrong tool for the job.

It was holding a board being glued against the side of a cement block building. No weight other than the bucket. Just a one time thing. Sometimes you have to do what you have to do to get things done.

 

[TheOldHokie]

I didn’t even think of temp. Would there be a noticeable performance difference in loader performance between a 70 degree day and a 95 degree day? This is the first time I’ve worked the loader this hard in such hot temperatures.

when was a kid I had a Yamaha rz350 motorcycle. Two stroke. There was a very noticeable difference, lots of power loss on hot days, it was like two different bikes between summer and fall.

No - this is not an internal combustion engine.

The lifting power of the loader is strictly a function of hydraulic pressure.

If the system is operating correctly the system will develop the maximum pressure as limited by the relief valve regardless of temperature.

If pressure is lower when hot something in the system is leaking pressure. Places that can happen are the pump, the conyril valve, or your cylinders.

The first pressure test you should make is at the inlet to your loader valve. Disconnect that hose and connect the gauge to the end. Start the tractor and pressure should immediatly rise to the maximum specified in the WSM. Your pump is maxed out and unloading to tank via the internal relief so try to limit the length of the test to 30-60 seconds. A little longer is OK but you dont want to run it for an extended time in that state.

Dan

 

[unioncreek]

It’s either leaky cylinders or valves.

 

[GreensvilleJay]

re:
The lifting power of the loader is strictly a function of hydraulic pressure.

Not 100% true....
You can have 1800 PSI ( say the design spec ) and loader won't lift 500#s..... due to leaky seals, worn spool or HOT oil ( it 'thins out... )

 

[TheOldHokie]

re:
The lifting power of the loader is strictly a function of hydraulic pressure.

Not 100% true....
You can have 1800 PSI ( say the design spec ) and loader won't lift 500#s..... due to leaky seals, worn spool or HOT oil ( it 'thins out... )

I dont think you gave that enough thought.

How do you get that pressure if the seals are not holding it? Pressure is a measure of the force being applied and Mr Pascal says its equal throughout the fluid and in all directioms. If theres 1800 PSI of force being applied to the face of the piston it will lift the rated weight regardless of any leakage around it or the viscosity of the oil.

When tHe leakage gets excessive it bleeds some of that pressure off and thats when you lose lift force. When that happens you see it on the gauge.

Dan

 

[TheOldHokie]

It’s either leaky cylinders or valves.

The only way it could be a cylinder is if the leak Is external.

Dan

 

[GreensvilleJay]

I dont think you gave that enough thought.

With a leaky seal ,some of the oil will flow around the ram and reduce the force it can produce. the greater the leak, the less force you'll have
I KNOW that's true for the master cylinder in a 57 Willy pickup. After having it professionally rebuilt was hauling 3/4t of garden soil down the hill into Dundas. Lost all the brakes,with steady pressure,pedal went to the floor.Only by manually doing what 'ABS' does now did I save the truck , the load and me.

It'd be interesting if someone would remove their seals from their cylinders and see what happens.

 

[TheOldHokie]

I dont think you gave that enough thought.

With a leaky seal ,some of the oil will flow around the ram and reduce the force it can produce. the greater the leak, the less force you'll have
I KNOW that's true for the master cylinder in a 57 Willy pickup. After having it professionally rebuilt was hauling 3/4t of garden soil down the hill into Dundas. Lost all the brakes,with steady pressure,pedal went to the floor.Only by manually doing what 'ABS' does now did I save the truck , the load and me.

It'd be interesting if someone would remove their seals from their cylinders and see what happens.

Mr Pascal says no. If the system (gauge) pressure is measuring 1800 PSI that force is being applied to every square inch of the walls of the containing vessel. Since the piston is part of that containing wall it is being pushed outward at 1800 PSI and will act with that force regardless of any flow that may be bypassing at the edges.

Dan

 

[GreensvilleJay]

Mr Pascal wasn't in the truck with me for a harrowing 7 minutes and while his science may seem solid,same group of guys say bumblebees can't fly and you can't fly faster than the speed of light.
I'd like Mr pascal to explain the no brakes that I had.

 

[TheOldHokie]

Mr Pascal wasn't in the truck with me for a harrowing 7 minutes and while his science may seem solid,same group of guys say bumblebees can't fly and you can't fly faster than the speed of light.
I'd like Mr pascal to explain the no brakes that I had.

Mr Pascal was right by your side and the master cylinder was doing exactly whst he says and exactly what I am trying to explsain to you.

When you pumped the brakes you produced a burst of FLOW that despite the bypassing fluid resulted in a momentary spike in cylinder pressure. A gauge would show rhat.

That pressure spike activated the brakes and slowed you down. Then the pressure bled off and cylinder lost force. A gauge would also show that. that.

Lets revist the start of this discussion. You asserted a gauge could show 1800 PSI hydraulic pressure but the cylinder would not act with that force because it had leaking seals. That is simply not possible as explained by Mr Newton, Mr Pascal, and a while lot of other people. If the gauge is measurung 1800 PSI fluid (gauge) pressure that is the magnitude of the force acting on the piston leakage or not.

Dan

 

[Henro]

The way I would look at it is that in Jay’s example, the master cylinder isn’t really a cylinder. It’s more like a hydraulic pump providing pressure to cause the cylinders at the brakes to extend, causing the brake shoes or pads to push against a drum or disc.

It would be the cylinders that cause the operation of the brakes that are analogous to cylinders on a loader. And the master cylinder is not really a cylinder, but rather a pump which supplies pressure to the system.

That’s my take on Jay’s example anyway…

 

[TheOldHokie]

The way I would look at it is that in Jay’s example, the master cylinder isn’t really a cylinder. It’s more like a hydraulic pump providing pressure to cause the cylinders at the brakes to extend, causing the brake shoes or pads to push against a drum or disc.

It would be the cylinders that cause the operation of the brakes that are analogous to cylinders on a loader. And the master cylinder is not really a cylinder, but rather a pump which supplies pressure to the system.

That might take on the question anyway…

My take is Jay is missing the obvious

Gauge pressure in a hydraulic system is a DIRECT MEASUREMENT of the force being applied to all surfaces inside the container. That measurement is as accurate and reliable as the instrument used to obtain it.

The piston in a cylinder is part of the hydraulic container and it sees the same applied force as the gauge and transmits that force to an external load via the rod.

Its just that simple. No need to complicate the analysis with discussions about bypassing seals, hot oil, leaky brakes, bumble bees that cant fly, or Enstein's theories of relativity....

Dan

 

[Henro]

My take is Jay is missing the obvious

Gauge pressure in a hydraulic system is a DIRECT MEASUREMENT of the force being applied to all surfaces inside the container. That measurement is as accurate and reliable as tje instrument used to obtain it.

Its just that simple. No need to complicate the analysis with discussions about bypassing seals, hot oil, leaky brakes, bumble bees that cant fly, or Enstein's theories of relativity....

Dan

I know, but he did give an unrelated example involving a master cylinder, and in my mind was considering the master cylinder in the vehicle as a “cylinder” when it actually is a hydraulic pressure source.

Others may be confused by this as well, so it can’t hurt to focus on it briefly.

 

[TheOldHokie]

I know, but he did give an unrelated example involving a master cylinder, and in my mind was considering the master cylinder in the vehicle as a “cylinder” when it actually is a hydraulic pressure source.

Others may be confused by this as well, so it can’t hurt to focus on it briefly.

I started to go your route earlier but decided it only confuses the issue.

Fluid pressure determines the force the system is producing and that is what the gauge is measuring.

Stop - end of analysis.

That should not confuse anyone.

Dan

 

[DustyRusty]

I dont think you gave that enough thought.

With a leaky seal ,some of the oil will flow around the ram and reduce the force it can produce. the greater the leak, the less force you'll have
I KNOW that's true for the master cylinder in a 57 Willy pickup. After having it professionally rebuilt was hauling 3/4t of garden soil down the hill into Dundas. Lost all the brakes,with steady pressure,pedal went to the floor.Only by manually doing what 'ABS' does now did I save the truck , the load and me.

It'd be interesting if someone would remove their seals from their cylinders and see what happens.

Mr Pascal wasn't in the truck with me for a harrowing 7 minutes and while his science may seem solid,same group of guys say bumblebees can't fly and you can't fly faster than the speed of light.
I'd like Mr pascal to explain the no brakes that I had.

Mr. Pascal here to explain to you why you lost your brakes after the master cylinder was rebuilt. To start with, we need to know the knowledge base of the person rebuilding the master cylinder. I know of many mechanics (nowadays referred to as automobile technicians) who have been rebuilding both wheel cylinders and master cylinders for decades and have been doing it incorrectly for decades. I will start with the correct method first and continue this dialog further down in the page.
1) Remove master cylinder, disassemble, and inspect for pitting or rust. If pitting or rust is found, rebuilding isn't recommended, so replace master cylinder. It replacement isn't available, have the cylinder bored and a new sleeve installed.
2) Assuming the number 1 is rebuildable, then hone the interior of the master cylinder with a 2 or 3 stone hone using brake fluid as a cutting lubricant. Once the cylinder is properly honed, clean the interior of the cylinder with a brake cleaning solvent. Next step is an absolute must! Take the cylinder to the sink and wash the cylinder with dish washing liquid and a bottle brush. This step will remove the microscopic metal filings that are still in the microscopic grooves from honing.
3) Using brake assembly fluid or the brake fluid that you will be using in the braking system, assemble the master cylinder paying particular attention to how all the parts go together as when they were removed.
4) Install master brake cylinder in a vise with the outlet ports so they are accessible. In stall brake bench bleeding adaptors into the outlet ports and attach bleeding hoses. Using the provided clips that come with the bleeding kit place the hoses low into the cylinder. Fill cylinder with the brake fluid of choice and using a #2 Phillips screwdriver slowly push on the piston in the cylinder observing the bubbles coming up from the hose(s). Continue bench bleeding until there are no bubbles coming from the hoses. The bench bleeding is now complete. Install the master cylinder cover and remove from vice.
5) Install rebuilt master cylinder onto the vehicle and secure with originally removed hardware and connect brake lines to the master cylinder.
6) Moving to the drivers seat position, check the free travel of the brake pedal which should be 3/4"-1" and adjust is necessary.
7) Move to the farthest brake in the system, usually the right rear, bleed brake cylinder with the assistance of a helper. Bleed the brake until you see clean clear fluid coming out. Add additional brake fluid to the master cylinder as necessary during the bleeding process. I will assume that you understand how to bleed brakes to remove all air from the system. Continue to the left rear brake and repeat the bleeding procedure, then the front right and finally the front left.
8) Now that you have bled all four and did a final top off of the master cylinder, position yourself in the drivers seat and push on the brake pedal as hard as you can to check the condition of the steel brake lines. Better to have a line brake in the shop than on the road. Brake lines rust from the inside to the outside, and visually the outside of the brake line might appear to be good, but the inside will have rusted.
9) Take the car for a road test and make sure that it stops in a satisfactory manner. If not, bring the car back into the shop and remove all 4 wheels and inspect the brake linings or pads. Adjust as necessary after inspection. Road test again for satisfactory braking of the vehicle.

Now, had your mechanic used the above procedures, you wouldn't have lost your brakes. He might be a good mechanic, but we all know that sometimes when you have jobs waiting to get done, proper procedures are many times not done or not done properly. Most likely you had air trapped somewhere in the lines. Trapped air many times will eventually migrate back to the master cylinder if the master cylinder is the high point of the system.
Should you need further instruction or explanations, I will be happy to enlighten you.
Thanks,
Mr. Pascal