Traction Power Trac Traction
- Thread starter duane
- Start date
PTRich
Gold Member
Sometimes you can make one wheel spin faster than the three other wheels under certain conditions when applying excess pedal power.
PTRich
PTRich
Sedgewood
Platinum Member
MChalkley<font color=red> As I understand it, from talking with several of the folks at PowerTrac, they use two series circuits, each driving two motors. I'm pretty sure the PowerTrac circuit drives the front and rear on the same side, and I'm certain that each circuit drives one front wheel and one rear wheel.</font color=red>
It's not really clear from the drawing in the manual but I get the idea that the front motors are in parallel with each other but are in series with the rear motors, which also are in parallel with each other. I should go look at the tractor to verify this some time.
It also feels in a seat-of-the-pants way like torque is reduced progressively with the number of wheels spinning and that increasing pedal increases torque (which can give one a surprising bit of acceleration if the tires "hook up" at full pedal). I'll have to give this some closer attention in future to see if these seat of the pants observations are indeed right.
It's not really clear from the drawing in the manual but I get the idea that the front motors are in parallel with each other but are in series with the rear motors, which also are in parallel with each other. I should go look at the tractor to verify this some time.
It also feels in a seat-of-the-pants way like torque is reduced progressively with the number of wheels spinning and that increasing pedal increases torque (which can give one a surprising bit of acceleration if the tires "hook up" at full pedal). I'll have to give this some closer attention in future to see if these seat of the pants observations are indeed right.
MChalkley
Elite Member
- Joined
- Mar 27, 2000
- Messages
- 3,239
- Location
- Eastern Virginia
- Tractor
- EarthForce EF-5 mini-TLB (2001)
Sedgewood - <font color=blue>It's not really clear from the drawing in the manual but I get the idea that the front motors are in parallel with each other but are in series with the rear motors, which also are in parallel with each other.</font color=blue> Is this the sort of manual that has removable pages you could fax? I'd sure like to see a copy of the diagram, especially if they've got a hydraulic schematic. I doubt it's a simple combination of parallel and series circuits. If it includes any sort of parallel circuit at all, most of the advantages of the series circuit are compromised. On the other hand, if there's priority valving or something like that involved, that would be different. But, then, it also wouldn't really be a parallel circuit anymore, either...
<font color=blue>It also feels in a seat-of-the-pants way like torque is reduced progressively with the number of wheels spinning</font color=blue> this could certainly be true, but I'm not sure how you could tell, unless it's from the wheels still getting traction not having enough power to turn <font color=blue>and that increasing pedal increases torque</font color=blue> this should definitely not be the case - it might give the appearance that torque is increasing, because of the centrifugal force of the spinning wheel, or something, but it should have less true torque. The only way I can think of that this wouldn't hold true is if there's also some sort of sensing circuit similar to the one in the EarthForce machines involved.
When I talked to the PowerTrac factory folks, one of them several times alluded to the "valves" that control the flow to the wheel motors. But, the "valves" I saw were simply distribution blocks. And when I asked the president of the company, who is also the founder and primary designer, if there was a valving mechanism in the "drivetrain" to control the flow to the motors, he said no, that it was series circuits. At least, that's my recollection of the conversation - not infallible, I'm afraid...
<font color=blue>It also feels in a seat-of-the-pants way like torque is reduced progressively with the number of wheels spinning</font color=blue> this could certainly be true, but I'm not sure how you could tell, unless it's from the wheels still getting traction not having enough power to turn <font color=blue>and that increasing pedal increases torque</font color=blue> this should definitely not be the case - it might give the appearance that torque is increasing, because of the centrifugal force of the spinning wheel, or something, but it should have less true torque. The only way I can think of that this wouldn't hold true is if there's also some sort of sensing circuit similar to the one in the EarthForce machines involved.
When I talked to the PowerTrac factory folks, one of them several times alluded to the "valves" that control the flow to the wheel motors. But, the "valves" I saw were simply distribution blocks. And when I asked the president of the company, who is also the founder and primary designer, if there was a valving mechanism in the "drivetrain" to control the flow to the motors, he said no, that it was series circuits. At least, that's my recollection of the conversation - not infallible, I'm afraid...
Sedgewood
Platinum Member
MChalkley <font color=red>I'd sure like to see a copy of the diagram, especially if they've got a hydraulic schematic.</font color=red>See attachment. Sorry, no schematic, I wish there were one but this plumbing diagram is all they've put in the manual.
<font color=blue>It also feels in a seat-of-the-pants way like torque is reduced progressively with the number of wheels spinning</font color=blue><font color=red> this could certainly be true, but I'm not sure how you could tell, unless it's from the wheels still getting traction not having enough power to turn </font color=red>That is probably what my pants sense.<font color=blue>and that increasing pedal increases torque</font color=blue><font color=red> this should definitely not be the case - it might give the appearance that torque is increasing, because of the centrifugal force of the spinning wheel, or something, but it should have less true torque.</font color=red>This part I'm unsure of and need to observe more closely but it seems that the tractor finally starts to move after I've added pedal.
<font color=blue>It also feels in a seat-of-the-pants way like torque is reduced progressively with the number of wheels spinning</font color=blue><font color=red> this could certainly be true, but I'm not sure how you could tell, unless it's from the wheels still getting traction not having enough power to turn </font color=red>That is probably what my pants sense.<font color=blue>and that increasing pedal increases torque</font color=blue><font color=red> this should definitely not be the case - it might give the appearance that torque is increasing, because of the centrifugal force of the spinning wheel, or something, but it should have less true torque.</font color=red>This part I'm unsure of and need to observe more closely but it seems that the tractor finally starts to move after I've added pedal.
Attachments
Sedgewood
Platinum Member
MChalkley, I think now that I look at the diagram again that I have misread it. #19 is a return line and connects to #17, rather than the supply line I thought it was going from front to rear. So it looks like all wheels may be in parallel with some modifier at the #3 Splitter Block Manifold. Or perhaps front wheels are in parallel with each other and with rear wheels, which are in series. There's a fuzzy bit in the memory bank from the flurry of my visit to PT, something about series/parallel wheel motors that is innovative and gives traction to all four wheels.