PT-425 PROS & cons??

[J_J]

Re: PT-425 PROS & cons??

The rate of turn is caused by the maximum articulation of the tractor, which remains unchanged.

OK, I will try and see if this works. If the wheel width is 54 in, and if you use the formula for a circle, the distance the outside wheel travels is 339 in, or 28.25 ft. if you increase the wheel width to 59 in. The distance that the outside wheel travels is 370.25 in, or 30.87 ft.

I computed the circumference using 54 in as the first radius, and 59 in as the second radius. If this not correct, some one please correct.

Circle
Area = πr2
Circumference=2πr
r = radius

 

[ddonnell]

Re: PT-425 PROS & cons??

In my head, I'd agree with Kent that the machine itself still travels the same path with wheels either way. In the reversed setup, the outside (away from the tractor) edge of the inside tires would actually scribe a tighter circle and the outside edge of the outside tires would scribe a larger circle. If you measured the turning radius from the articulation joint, I'd bet it's the same either way. It depends on your definition of turning radius and from what spot on the tractor it is measured from. Probably not a huge difference in an open area but with a front mounted mower rather than a mid mounted mower like a ZTR, would the increased width make mowing around a tree tougher i.e. would the inside wheels hit the tree sooner than if they were tucked tighter to the tractor? My guess is that they would and would therefore require more "jockeying" to mow tight to the tree. If you could pivot the front of the tractor around the obstacle and swing the rear of it out, sort of like a tail dragger plane, then it wouldn't be a problem. But it won't so I think it would take a little longer to mow around something (well, maybe not a redwood) with the wider stance. Probably not worth all this wordiness but what the heck.

 

[KentT]

Re: PT-425 PROS & cons??

OK, I will try and see if this works. If the wheel width is 54 in, and if you use the formula for a circle, the distance the outside wheel travels is 339 in, or 28.25 ft. if you increase the wheel width to 59 in. The distance that the outside wheel travels is 370.25 in, or 30.87 ft.

I computed the circumference using 54 in as the first radius, and 59 in as the second radius. If this not correct, some one please correct.

Circle
Area = πr2
Circumference=2πr
r = radius

Your math is correct, IMO the problem is with your original premise. The body of the tractor will move in the same circle, but the tires will not. You're saying radius (r) and calculating circumference, BTW....

The inside tire will not be starting at the same location, nor will it follow the same track it would if the wheels were not reversed. It will turn in a tighter circle. If the body of the tractor begins the circle from the same point, the inside tire will turn a circle 4" smaller in diameter while the outside tire will turn a circle 4" larger in diameter. The body of the tractor itself will move in the same circle, as determined by the angle that the tractor is articulated.

The difference in the turning radius -- not circumference -- is the whopping 2" of change in the position of the outside tire... the difference in diameter is twice that, or 4"....

Technically, radius is the distance from the center to the outside of the circle, while diameter is twice that -- the length of an arc that goes across the center of the circle, or twice the radius.

In actual use, I found it is only detrimental to the use of the 48" rough cut mower, where it is now wider than the cut and it will mash things down in about a 1" or so strip on the uncut side. I simply reverse direction, rather than driving in circles and it tends to stand this material back up (that it just mashed down) and then cut it off... The snow/dirt blade is wide enough to where you just angle it slightly less. The 60" finish mower still cuts wider than the track. Using a bucket, it is typically not an issue unless you're trying to just skim a shallow cut off the material -- in that case the tires are wider than the bucket and tend to ride up on each side of the cut. However, most of my use has been pushing into the material only deep enough to fill the bucket, and not trying to use the bucket to cut and level an area -- i.e. using it as a loader and not a dozer...

I've found no real noticeable difference in the maneuverability in the woods, but significantly increased stability going across slopes. I comfortably go on slopes that I wouldn't even consider before. Here's some pics, especially the ugly stitched panoramic views, that show my challenge. My limitation now is wheel motor torque to climb these slopes when the hydraulic oil is hot...

Tidying Up, June 23-26, 2006

I'm considering doing a "permanent version" of Stray's proposed mod, using 4:1 hydraulic manifolds and plumbing the wheel motors independently to get more torque, while sacrificing speed. I don't need to be driving 8MPH on these hillsides anyway...

 

[MossRoad]

Re: PT-425 PROS & cons??

O.K. Here's my thoughts...

If you put wider tires on it:

1. The turning radius, measured from the centerline of the tractor will not change.

2. The inside turning radius, measured from the inside of the tire tracks will decrease.

3. The outside turning radius, measured from the outside of the tire tracks, will increase.

If you put taller tires on it, but not wider tires on it, nothing will change. You will, however, have to be concerned that if you go with too tall of tires, the front and rear tires will hit each other when turning the unit too tight.

 

[BobRip]

Re: PT-425 PROS & cons??

Kent, have you change to synthetic oil (20W50) in your transmission yet. That helped me tremendously. I would try that before the major replumbing. With the replumb if one wheel slips, then most of the power/torque will go to that wheel. Sorry to be off topic here.

 

[KentT]

Re: PT-425 PROS & cons??

Kent, have you change to synthetic oil (20W50) in your transmission yet. That helped me tremendously. I would try that before the major replumbing. With the replumb if one wheel slips, then most of the power/torque will go to that wheel. Sorry to be off topic here.

I'm running Amsoil 20W50 in it... over $200 worth! If the replumbing gives me the torque I need, I'd even consider putting 4 flow restrictors, if needed, to prevent all the fluid from going to one wheel when it spins. I really don't think spinning will be that much of an issue, since I've also loaded all my tires -- another "not recommended" practice according to Tazewell... The final resort would be new higher-torque wheel motors, or move up to a newer PT 425 that has them, but both of those alternatives would cost serious $$$...

 

[BobRip]

Re: PT-425 PROS & cons??

I'm running Amsoil 20W50 in it... over $200 worth! If the replumbing gives me the torque I need, I'd even consider putting 4 flow restrictors, if needed, to prevent all the fluid from going to one wheel when it spins. I really don't think spinning will be that much of an issue, since I've also loaded all my tires -- another "not recommended" practice according to Tazewell... The final resort would be new higher-torque wheel motors, or move up to a newer PT 425 that has them, but both of those alternatives would cost serious $$$...

I had not thought of the restrictors. Good idea. I am really curious how well this works both from a degree of difficuly and how much improvment you get in sticky situations. I am seriously considering upgrading my wheels motors if and when I get a failure. If such should occur at over 1000 hours, it might be a reasonable economic decision. Does anyone know if you have to change the mounting holes. If seems there is an adapter plate required. I like the length of the 422 versus the 425 and would just as soon spend a little less money upgrading it as buying a new machine. I probably should consider a filter on the hydraulic reservoir cap to maximize life.

 

[FOURTEEN]

Re: PT-425 PROS & cons??

Your math is correct, IMO the problem is with your original premise. The body of the tractor will move in the same circle, but the tires will not. You're saying radius (r) and calculating circumference, BTW....

The inside tire will not be starting at the same location, nor will it follow the same track it would if the wheels were not reversed. It will turn in a tighter circle. If the body of the tractor begins the circle from the same point, the inside tire will turn a circle 4" smaller in diameter while the outside tire will turn a circle 4" larger in diameter. The body of the tractor itself will move in the same circle, as determined by the angle that the tractor is articulated.

The difference in the turning radius -- not circumference -- is the whopping 2" of change in the position of the outside tire... the difference in diameter is twice that, or 4"....

Technically, radius is the distance from the center to the outside of the circle, while diameter is twice that -- the length of an arc that goes across the center of the circle, or twice the radius.

In actual use, I found it is only detrimental to the use of the 48" rough cut mower, where it is now wider than the cut and it will mash things down in about a 1" or so strip on the uncut side. I simply reverse direction, rather than driving in circles and it tends to stand this material back up (that it just mashed down) and then cut it off... The snow/dirt blade is wide enough to where you just angle it slightly less. The 60" finish mower still cuts wider than the track. Using a bucket, it is typically not an issue unless you're trying to just skim a shallow cut off the material -- in that case the tires are wider than the bucket and tend to ride up on each side of the cut. However, most of my use has been pushing into the material only deep enough to fill the bucket, and not trying to use the bucket to cut and level an area -- i.e. using it as a loader and not a dozer...

I've found no real noticeable difference in the maneuverability in the woods, but significantly increased stability going across slopes. I comfortably go on slopes that I wouldn't even consider before.

AND THE WINNER IS: (drum roll) 'KentT' for the most insight into the question of "What happens when I go in a circle with my wheels reversed??"!!

Indeed, the articulation does not change, so the PT travels and turns just the same, except that at maximum articulation the inside edge of the inside tire is a few inches closer to the center. This is not a significant problem in any way, and the advantages of the wider track far outweigh any slight change in tire placement! The added stability is truly amazing!



PS: Sorry I haven't posted for a while, but for several months now a neuromuscular disorder has prevented me from fully opening or closing my hands, and from lifting or pushing more than 10#. So PT usage is just too painful.

 

[MossRoad]

Re: PT-425 PROS & cons??

Sorry to hear of your physical troubles... Glad it hasn't affected your sense of humor! What's the prognosis on your hands, if I may ask?

 

[JD-Beach]

Re: PT-425 PROS & cons??

Fourteen, sorry to hear about your health related issues. We'll all hope and pray for your speedy recovery. ... We're glad your back.

JD