Well..I have more "seat time" in now that the rain has stopped and I'm getting to know the PT fairly well. Indeed letting up a bit on the treadle going up a steep slope with the PTO running does help..the time I stalled it I did just the opposite(guess I thought I was running the Farmall!)....so far my approach is...if cutting grass the throttle is wide open and I control the speed to match the terrain. When using the bucket I have the throttle a little over half way for light loading and wide open for any heavy work(like today...repairing the dirt lane..some digging & pushing, etc). and now I find myself thinking at night...hmmm, what can I do with it tomorrow! /forums/images/graemlins/confused.gif
Proud new owner..................422 arrived today
- Thread starter MuncyBob
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J_J
Super Star Member
- Joined
- Sep 6, 2003
- Messages
- 18,952
- Location
- JACKSONVILLE, FL
- Tractor
- Power-Trac 1445, KUBOTA B-9200HST
I am sorry, but I just added my input to the subject of stalling, not to anyone in particular.
Clarke
Silver Member
I took a look at the plumbing diagrams that came with my PT. They make no sense to me. Took a look at the actual plumbing you are right the wheels on each side look to be in series but the two sides are parallel setting up a situation where you can get more flow to the side with least resistance. I notice on my machine the left front wheel is the dominate wheel going forward. The flow must reverse to go backwards so one of the rear wheels are dominate. Feeding hydraulic pressue in series seems like the first wheel to get the full force of the fluid would be the most powerful wheel the second in line would get the energy thats left. The only work I do with the PT that I notice the lack of traction is when I am using the loader. All in all the PT has enough wheel power for me. With the technology we have today I think the wheel motors could be all in parallel with a rotation sensor on each wheel and some kind of proportioning valve that could be closed to the spinning wheel to divert hydraulic power to a wheel with better traction No basis for this just my opinion.
sg
sg
Bob999
Platinum Member
<font color="red"> I took a look at the plumbing diagrams that came with my PT. They make no sense to me. Took a look at the actual plumbing you are right the wheels on each side look to be in series </font>
I looked at the manual that came with my 1845 and it does not appear to me that the wheel motors are plumbed in series. Rather it appears that each motor gets its supply direct from the pump.
In thinking about it (and I am not an engineer) I don't see how a series arrangement could work. It is a combination of pressure and flow of the hydraulic fluid that turns the motor. The pressure that the motor "sees" is the difference in pressure between the inlet side and the return side. If a second motor were plumbed in series the first motor would see very little pressure and have very little power.
I looked at the manual that came with my 1845 and it does not appear to me that the wheel motors are plumbed in series. Rather it appears that each motor gets its supply direct from the pump.
In thinking about it (and I am not an engineer) I don't see how a series arrangement could work. It is a combination of pressure and flow of the hydraulic fluid that turns the motor. The pressure that the motor "sees" is the difference in pressure between the inlet side and the return side. If a second motor were plumbed in series the first motor would see very little pressure and have very little power.
SnowRidge
Elite Member
<font color="red"> (Took a look at the actual plumbing you are right the wheels on each side look to be in series but the two sides are parallel setting up a situation where you can get more flow to the side with least resistance.) </font>
Disclaimer: Before we bought our Power Trac, I knew almost nothing about hydraulics--now I know a little more than nothing. /forums/images/graemlins/tongue.gif
But I am learning. On the PT-425, at least, the two sides are fed from separate ports on the pump. I don't know what the internal plumbing of the pump looks like. There may be some sort of proportioning arrangement, or they may simply be fed in parallel. It may also be that a single port simply can't handle the maximum output of the pump by itself, thereby forcing a sort of limited slip differential action between the two sides.
Edit: Big goof above. The feed is from one port via a tee. No proportioning action at all.
But no matter what, the machine will always have at least one wheel on each side in contact with the ground. From my experience, the machine will move as long as one wheel has traction. I have had a couple of occasions when I was in wet sloppy stuff on one side and dry ground on the other. So far, I have not gotten myself stuck, and I haven't experienced wheel spinning on one side.
Edit: It does look like it would theoretically be possible for one side to spin leaving little pressure for the other side. Anyone ever experience this?
SnowRidge
Disclaimer: Before we bought our Power Trac, I knew almost nothing about hydraulics--now I know a little more than nothing. /forums/images/graemlins/tongue.gif
But I am learning. On the PT-425, at least, the two sides are fed from separate ports on the pump. I don't know what the internal plumbing of the pump looks like. There may be some sort of proportioning arrangement, or they may simply be fed in parallel. It may also be that a single port simply can't handle the maximum output of the pump by itself, thereby forcing a sort of limited slip differential action between the two sides.
Edit: Big goof above. The feed is from one port via a tee. No proportioning action at all.
But no matter what, the machine will always have at least one wheel on each side in contact with the ground. From my experience, the machine will move as long as one wheel has traction. I have had a couple of occasions when I was in wet sloppy stuff on one side and dry ground on the other. So far, I have not gotten myself stuck, and I haven't experienced wheel spinning on one side.
Edit: It does look like it would theoretically be possible for one side to spin leaving little pressure for the other side. Anyone ever experience this?
SnowRidge
Clarke
Silver Member
Looking at my 425 the wheel motors are fed from two ports on the pump into a tee which then feeds the wheel motors. The maual that came with the machine shows the front wheels in series and the back wheels in series. I am not a hydraulic anything but the diagram sent could not work and is not even close to whats on the machine.
sg
sg
SnowRidge
Elite Member
<font color="red"> (In thinking about it (and I am not an engineer) I don't see how a series arrangement could work. It is a combination of pressure and flow of the hydraulic fluid that turns the motor. The pressure that the motor "sees" is the difference in pressure between the inlet side and the return side. If a second motor were plumbed in series the first motor would see very little pressure and have very little power.) </font>
OK, here's how it works--the same as electrical current.
When the two wheel motors are in series, the pressure divides across the two motors, provided they have equal traction, which in turn will provide equal resistance to flow. Assuming they do, and using 2,000 psi from the pump for the example, the motors would see the following:
Motor 1: 2,000 psi in -- 1,000 psi out
Motor 2: 1,000 psi in -- 0 psi out
Note that each motor "sees" 1,000 psi, which is the difference between the input pressure and the output pressure.
This is similar hooking two six volt light bulbs up in series and hooking them to a 12 volt battery. Each light bulb only sees 6 volts.
If one of the wheels loses traction it will try to spin. It's resistance drops and the pressure differential across the motor drops accordingly. As long as the other wheel doesn't lose traction, the slipping wheel will spin no faster than the wheel with traction because wheel speed is limited by flow rate, not pressure.
The wheel with traction is now providing all the resistance and therefore determining the rate of flow. Since they are in series, the flow in each wheel must be identical.
Looking at this, it seems to me that each wheel motor must be able to handle at least half the output of the pump. Under normal operating conditions, it seems that the motors are pretty much loafing along, which should make for a long life.
SnowRidge
OK, here's how it works--the same as electrical current.
When the two wheel motors are in series, the pressure divides across the two motors, provided they have equal traction, which in turn will provide equal resistance to flow. Assuming they do, and using 2,000 psi from the pump for the example, the motors would see the following:
Motor 1: 2,000 psi in -- 1,000 psi out
Motor 2: 1,000 psi in -- 0 psi out
Note that each motor "sees" 1,000 psi, which is the difference between the input pressure and the output pressure.
This is similar hooking two six volt light bulbs up in series and hooking them to a 12 volt battery. Each light bulb only sees 6 volts.
If one of the wheels loses traction it will try to spin. It's resistance drops and the pressure differential across the motor drops accordingly. As long as the other wheel doesn't lose traction, the slipping wheel will spin no faster than the wheel with traction because wheel speed is limited by flow rate, not pressure.
The wheel with traction is now providing all the resistance and therefore determining the rate of flow. Since they are in series, the flow in each wheel must be identical.
Looking at this, it seems to me that each wheel motor must be able to handle at least half the output of the pump. Under normal operating conditions, it seems that the motors are pretty much loafing along, which should make for a long life.
SnowRidge
SnowRidge
Elite Member
<font color="red"> (Looking at my 425 the wheel motors are fed from two ports on the pump into a tee which then feeds the wheel motors. The maual that came with the machine shows the front wheels in series and the back wheels in series. I am not a hydraulic anything but the diagram sent could not work and is not even close to whats on the machine.) </font>
One tee seems to be the feed for all four motors, one is the return. I believe the diagram is accurate, but just doesn't indicate physical locations. We are assuming--incorrectly, I think--that the bottom two motors in the drawing are at the front. I believe they represent a side, instead. It's too bad the components aren't better labeled.
It would be really nice if the Power Trac manuals contained more information. A theory of operation section would be a big help. Rumor has it that they are rewriting the manuals. Maybe we'll get something better.
SnowRidge
One tee seems to be the feed for all four motors, one is the return. I believe the diagram is accurate, but just doesn't indicate physical locations. We are assuming--incorrectly, I think--that the bottom two motors in the drawing are at the front. I believe they represent a side, instead. It's too bad the components aren't better labeled.
It would be really nice if the Power Trac manuals contained more information. A theory of operation section would be a big help. Rumor has it that they are rewriting the manuals. Maybe we'll get something better.
SnowRidge
Bob999
Platinum Member
Snowridge--Thank you for an excellent explanation.
Yardscaper
Bronze Member
- Joined
- Oct 20, 2003
- Messages
- 93
- Location
- St. Louis, MO
- Tractor
- Polaris ASL 300, 1959 Economy Tractor
I have a 1430 as well, and have only had problems making it up hills for 3 main reasons.
1: Poor traction
2: Oil loses viscosity and therefore can not pull machine up hill ( this happens on my 2445 all of the time, has never occured on the 1430 as of yet)
3: One instance that I had was that some of the silicon that PT uses to seal the hydraulics had broken free and had gotten caught in the hydraulic filter. The machine will make a very high pitch sound and will struggle to even creep up the hill while manipulating it using the steering cylinders.
Other than that the machine does fine for us. It does seem that the wheels are set up to where the front two are plumbed on a tee and that the rear two are the same. This is most noticable when you have the machine 'hung up' by being at the maximum frame oscillation, thus having the right front wheel and the left rear wheel off of the ground and spinning. The machine will not move until one of those wheels receives traction.
On side slopes, I have used the machine on slopes that are hard to even walk on just to make it to a remote area. At times you do have to turn up the hill to keep all four wheels on the ground. This is very dangerous and should not be done on a regular basis. I have flipped a 1425 in the past. It occured on a side slope with a hidden log in the brush. Just righted the tractor, added some oil, and away we went. No structural damage at all! /forums/images/graemlins/cool.gif
It is good to know that I am not the only crazy one out there!! /forums/images/graemlins/grin.gif /forums/images/graemlins/tongue.gif /forums/images/graemlins/wink.gif
1: Poor traction
2: Oil loses viscosity and therefore can not pull machine up hill ( this happens on my 2445 all of the time, has never occured on the 1430 as of yet)
3: One instance that I had was that some of the silicon that PT uses to seal the hydraulics had broken free and had gotten caught in the hydraulic filter. The machine will make a very high pitch sound and will struggle to even creep up the hill while manipulating it using the steering cylinders.
Other than that the machine does fine for us. It does seem that the wheels are set up to where the front two are plumbed on a tee and that the rear two are the same. This is most noticable when you have the machine 'hung up' by being at the maximum frame oscillation, thus having the right front wheel and the left rear wheel off of the ground and spinning. The machine will not move until one of those wheels receives traction.
On side slopes, I have used the machine on slopes that are hard to even walk on just to make it to a remote area. At times you do have to turn up the hill to keep all four wheels on the ground. This is very dangerous and should not be done on a regular basis. I have flipped a 1425 in the past. It occured on a side slope with a hidden log in the brush. Just righted the tractor, added some oil, and away we went. No structural damage at all! /forums/images/graemlins/cool.gif
It is good to know that I am not the only crazy one out there!! /forums/images/graemlins/grin.gif /forums/images/graemlins/tongue.gif /forums/images/graemlins/wink.gif