My Tractor Forum banner

81 - 100 of 107 Posts

·
Registered
Joined
·
525 Posts
Discussion Starter #81


Still a bunch of little issues to address and some welding to do, but this is a really exciting day.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
47 Posts
even if you have the FEL arms bottom out with the stops, you have remember the curl cylinders can add static presser in the system also. I have seen cylinder with velocity fuse built in the fitting to help with this but will offer other problem.
 

·
Registered
Joined
·
1,625 Posts
To the OP your loader looks great. As for all this debate in your thread I am heavily siding with Grandpa Jay's design. I would take his loader all day long over my OEM 45 loader.
 

·
Registered
Joined
·
525 Posts
Discussion Starter #84
I have had the chance to use the loader some and I love it. I shimmed the relief valve and increased the pressure from 950 to 1250 psi. That made a huge difference but I would still like some more lifting power. I am considering two modifications:
1. Upgrade from 1.5" to 2" lift cylinders. I wish I had bought 2" to start. Originally I was going to use this on a 318 and was interested in speed for lifting light loads like snow and mulch. Dumb mistake!
2. The other mod I'm considering is to move the lift cylinders mounts down the tower about 6-8" That should make a difference, but I don't have a good feel how much it will really matter. Any comments would be great.

Option 2 is free since I have some left over steel. Option 1 will cost about $250.
 

·
Registered
Joined
·
4,096 Posts
Going to 2-inch rams will slow down the speed but increase the force. Tudor will have to comment on the change of mount position. I don't think it will make any difference myself.
 

·
Premium Member
Joined
·
2,373 Posts
Lowering the cylinder mounts will help the lift capacity, but the lift height will be reduced also. Now that you know it value as a work tool, why not invest in an auxiliary pump.
 

·
Moderator
Joined
·
22,114 Posts
I just went through the whole thread. There are no dimensions pertaining to the geometry of the loader, or specs for the hydraulics, for me to work with.

Mods to the current geometry are a "rob Peter to pay Paul" type of scenario. What you gain for one aspect, you will lose somewhere else. The trick is to make gains where you want and lose where the penalty is survivable while maintaining those aspects that are acceptable.

In this case, lowering the base of the cylinders on the posts will gain lift capability at ground level and cost lift capability at the maximum lift point, but you want to do that while keeping the same low and high positions of the ends of the arms. How much lift can be gained depends on the result of some number crunching.

Changing from 1.5" cylinders to 2" cylinders will gain 56% of payload capability with a speed reduction of . . . 56%, if no other changes are made. (Same stroke length, same pump.)

Costs:

- To adjust geometry - time and material. (And some number crunching.)

- To replace cylinders- Price of two cylinders and a pump (or you lose time with every lift over the next umpteen years). The time is negligible for changing out the components.

Between clearing snow from multiple driveways, excavating, and moving various materials from place to place, my GT probably averaged about 4,000 lifts of varying heights per year over a 22 year span. (3 lifts per minute from grade is not uncommon when piling snow to max height.)

Information request.

- The c-c distances between the 4 pin holes in the arms.

- A-B - Where A is the arm to post pin and B is the cylinder base pin on the post.

- A-C - Where C is the cylinder rod pin on the arm.

- A-D - Where D is the bucket pin on the arm.

- B-D

And the retracted pin c-c distance on the cylinder - B-C.

There are two triangles, ABC and ABD

Also, for the hydraulics, bore and stroke of the lift cylinders, and the pump displacement and engine to pump drive ratio.
 

·
Premium Member
Joined
·
2,373 Posts
I shimmed the relief valve and increased the pressure from 950 to 1250 psi.
Your using the charge pump; did you know that increasing the charge pressure reduces tractive force (but only if the two happen together).
 

·
Moderator
Joined
·
22,114 Posts
Your using the charge pump; did you know that increasing the charge pressure reduces tractive force (but only if the two happen together).
:confused:

Okay, you have my attention. How so?

It won't be the first time that I have had difficulty grasping the concept behind what should be an obvious point. The lesson that I received on additive pressures is a case in point. Although I now have it securely locked down, it was not easy for me to absorb the concept when first presented for some reason. :00000060:
 

·
Registered
Joined
·
525 Posts
Discussion Starter #90
Correct that I’m using the hydro. I don’t know the gpm, but can probably find
It. I’m traveling for work for a few days so it will take a little while to take the measurements.
I’m using 1.5” x18” lift cylinders now.


Sent from my iPhone using Tapatalk
 

·
Premium Member
Joined
·
2,373 Posts
:confused:

Okay, you have my attention. How so?

It won't be the first time that I have had difficulty grasping the concept behind what should be an obvious point. The lesson that I received on additive pressures is a case in point. Although I now have it securely locked down, it was not easy for me to absorb the concept when first presented for some reason. :00000060:
Funny, I thought that might perk your ears up, lol. It's simple; charge pressure is present on both ports of the hydrostat pump. Since the motors torque is base on pressure drop; the higher the high and the lower the low makes the most torque; and since the high is limited by the physical envelope (protected by relief valves), raising the low reduces the torque. One time, we serviced a pump that was used on a submarine; sea pressure was introduced around the pump to maintain it's max pressure, weird stuff.
 

·
Moderator
Joined
·
22,114 Posts
Ah-ha! Additive pressure strikes again! Same concept, different application.

Thank you for the lesson, good sir.

That is weird with the submarine pump, unless the seawater is for cooling.
 

·
Registered
Joined
·
3,362 Posts
Funny, I thought that might perk your ears up, lol. It's simple; charge pressure is present on both ports of the hydrostat pump. Since the motors torque is base on pressure drop; the higher the high and the lower the low makes the most torque; and since the high is limited by the physical envelope (protected by relief valves), raising the low reduces the torque. One time, we serviced a pump that was used on a submarine; sea pressure was introduced around the pump to maintain it's max pressure, weird stuff.
Not sure I quite get it. How does shimming the relief valve from 950 top 1250 raise the pressure on "low" port of the motor?... It makes sense that if the high is fixed and you raise the low, the pressure drop (which results in torque) is lower. But I dont get how the charge pump output changes the "low" port pressure.... can you please elaborate?
 

·
Moderator
Joined
·
22,114 Posts
Keep in mind that the high (relief) pressure for the implement lift system is not sustained. At most, it will last for a few seconds only and settles back down to the regulated charge pressure when the valve is re-centered.

To your question, in a normal system, a pump draws fluid from a reservoir and sends it to a motor which dumps it back to the reservoir after doing work. The return trip to the reservoir is unrestricted so, for our intents, there is zero pressure. If it takes 1000 psi to do the work, the pressure differential across the motor is 1000 psi, that is 1000 psi in and 0 psi out.

A hydro is a closed loop system, meaning that the fluid moves from the pump to the motor and back to the pump to start the cycle over again. But pumps and motors leak internally through the clearances necessary to allow moving parts to, well, move. A charge pump is added to ensure that make-up fluid is always available to replenish that which is lost through the internal leakage.

The charge fluid then becomes the supply for the pump. Unlike a reservoir with its nominal zero pressure, the charge system is pressurized to something higher, usually regulated by the charge pressure control valve, sometimes known as a charge relief valve, which maintains a constant pressure which is overridden by the pressure for raising implements or steering.. Under normal circumstances, the pressure can be as low as 50 psi, or as high as 280 psi, depending on the setting for the particular hydro. I'll pick 100 psi for this discussion.

So now we have a supply pressure of 100 psi entering the pump from the charging point in the low pressure side of the closed loop. If the motor requires 1000 psi to do work, and the return is at 100 psi, the pressure differential is 900 psi which will develop less torque than 1000 psi. Should the loader be lifting a max load that requires 900 psi, the charging system will also have 900 psi and the pressure differential is only 100 psi for doing work. Not much work is going to get done at 100 psi differential.

Fortunately, the big hydros found in GTs capable of loader duty have hydros that can operate at higher pressures, negating much of the pressure differential lost due to high charging pressures, and it is a rare occurrence when a hydro is called on for high performance moving of a GT while simultaneously lifting a max payload.
 

·
Red Plaid is Timeless
Joined
·
975 Posts
Now switch the real world operation discussion over to charge pump volume output. IIRC, the chart on my JD400 Sundstrand (now Sauer Danfoss) In-Line 15 shows a flow maximum of about 4.5 gpm with the tractor not moving. When moving and under significant load the excess flow available for implement use can drop below 1 gpm. When I had the loader on the onboard pump, it worked pretty well until I started to move. Then implement operation slowed waayyy down.

This may not be applicable to the Tuff Torq K91.
 

·
Moderator
Joined
·
22,114 Posts
Now switch the real world operation discussion over to charge pump volume output. IIRC, the chart on my JD400 Sundstrand (now Sauer Danfoss) In-Line 15 shows a flow maximum of about 4.5 gpm with the tractor not moving. When moving and under significant load the excess flow available for implement use can drop below 1 gpm. When I had the loader on the onboard pump, it worked pretty well until I started to move. Then implement operation slowed waayyy down.

This may not be applicable to the Tuff Torq K91.
Right on, grandpajay! And that right there is why I recommend a dedicated auxiliary hydraulic system for a loader on a GT . . . consistency of flow.

The K92 (I can't find specs for the K91) charge pump has 50% more displacement than the charge pump on the Sundstrand, but it has a slower maximum input rpm resulting in up to 6 gpm flow. With the higher flow rate, the issue that grandpajay referenced is not quite as bad as with the Sundstrand, but the flow will still vary with the load on the hydro.
 

·
Registered
Joined
·
4,096 Posts
I have a 445 with a JD 40 loader on it and it is as fast as any FEL I have ever used using the onboard pump. I am trying to imagine a situation where I am using the FEL and at the same time making big corrections with the steering wheel and running the bucket up/down at the same time. Usually, I am driving into a pile of something and at that time the bucket is usually flat on the ground and the speed of the tractor is about 3 mph or less. What could I be doing that would cause a huge drop in available pressure? I can see backing away from the pile as I lift the bucket but even then I would not be making any huge turns or hydraulic loads on the system. On the old four-port steering valves like on the early 318's I can see the problem but not on a 5-port with 1000 to 1200 psi. If it were me I would try it with the onboard pump first and then if it isn't up to your needs add the aux pump as Jay did. Just my opinion.
 

·
Moderator
Joined
·
22,114 Posts
I have a 445 with a JD 40 loader on it and it is as fast as any FEL I have ever used using the onboard pump. I am trying to imagine a situation where I am using the FEL and at the same time making big corrections with the steering wheel and running the bucket up/down at the same time. Usually, I am driving into a pile of something and at that time the bucket is usually flat on the ground and the speed of the tractor is about 3 mph or less. What could I be doing that would cause a huge drop in available pressure? I can see backing away from the pile as I lift the bucket but even then I would not be making any huge turns or hydraulic loads on the system. On the old four-port steering valves like on the early 318's I can see the problem but not on a 5-port with 1000 to 1200 psi. If it were me I would try it with the onboard pump first and then if it isn't up to your needs add the aux pump as Jay did. Just my opinion.
Not a situation that you are likely to come across in your locale, but we get snow, and lots of it.

Run up to the snow pile with a full bucket until the tractor stops. Apply enough forward drive to keep the bucket tight to the pile and raise the bucket to max height. The bucket may only lift 6', but this technique can push the snow to over 8' high under the right conditions.

In the process, too much forward drive on the hydro can force the bucket into the wall of snow hard enough to pop the relief valve while trying to lift.

Result, limited torque delivery by the hydro due to the high pressure applied by the charging system at implement relief pressure. The tractor won't even spin the tires on the snow until the loader controls are centered.

Note that the power steering has no bearing in this scenario, and the same can happen when piling dirt in the summer. You just can't get the same height with dirt. I've tried.

It does take some careful control on the drive to achieve the desired effect. My snow pile goes across behind my garage, and if necessary up along side the garage. It can be as little as 24' long, or as much as 76' long by the end of winter if straightened out. It measures over 14' wide at the base and 7' high if I put the tractor up on top to level it out.
 

·
Registered
Joined
·
4,096 Posts
Wow! You're right about not having that experience! The only similar thing down here might be moving sand or gravel but I would never raise the bucket to full height with it loaded unless putting it into a truck and then only as I approached the truck. I remember one of my 318's with hand control and how it could become an issue when loading the bucket and maneuvering the tractor at the same time.
 

·
Moderator
Joined
·
22,114 Posts
My MF12H also had the hand control, and with that particular task, the steering wheel was not part of the process thus freeing up that hand for the drive. Since the tractor only moves a couple of feet until the nose is against the snow bank, that's no big deal.

Even so, it's still a lot more comfortable with the fine control available with the foot pedal on the MF1655.

You do tend to get a lot of experience and learn a few tricks when moving snow in quantity with a GT loader. Tricks that often can be used when moving dirt or gravel, maybe not as effectively, but still transferrable, and you definitely learn how to control the cutting edge angle of attack. I never use the float position except to relax the hydraulics when I shut the engine off. Of the roughly 4000 hours of loader work under my belt in the past 40 years, over 60% has been accumulated moving snow flakes.
 
81 - 100 of 107 Posts
Top