PT422 on hilly terrain

[BobRip]

If I try to creep, it just stalls. The wheel motors don't spin. My best torque is with the petal about 1/3 to 1/2 down. I have tried lots of things and this is the best option. This hill is not very big, so it is not much of a problem. Oh, I can also steer back and forth and this helps. I can work my way up slowly with left and right steer while applying the pedal.
Bob Rip

 

[RegL]

</font><font color="blue" class="small">( If I try to creep, it just stalls. The wheel motors don't spin. My best torque is with the petal about 1/3 to 1/2 down. I have tried lots of things and this is the best option. This hill is not very big, so it is not much of a problem. Oh, I can also steer back and forth and this helps. I can work my way up slowly with left and right steer while applying the pedal.
Bob Rip )</font>


That's my experience also. I think the transmission anolagy and what we are calling torque is not quite right. I'm not an expert, but I bet if you took a hydraulic motor(ie. wheel motor), the more volume and pressure you applied to it's input the more torque there would be at the output. Trouble is, when that motor is under heavy load(steep hill and good traction) it takes a lot of HP on the other end to keep all four motors digging. so like Bob says, it's a balancing act. Enough treadle to keep the wheel motors from stalling and not so much to make the engine stall.
Reg

 

[ernemats]

I also have a 422 with the 48" mower , about 6 years old and 850 hours on it. I mow some rather steep areas up to 25 degree slope, I usually mow cross slope. Mowing up hill with the mower running is a problem especially if the hydraulic fluid is hot, so I will mow down hill or cross slope most of the time. Mowing cross slope at anything over 20 degrees feels like maybe this is too steep to be doing this but I have never had any problems, and sometimes the tractor will sort of slide sideways a little, not much. I will take the power trac a lot of places I would never go with a normal tractor.

 

[BobRip]

There is also leakage (bypass, blowby, whatever you want to call it) around the motor and backwards through the pump. When the fluid is hot this leakage increases and torque decreases. If there were no leakage it would work much better at stall conditions. I use synthetic oil (Mobil 1 20W50) and it has been a big help. No system is perfect of course.

A bigger gasoline engine, bigger wheel motors and a bigger pump to drive the motors helps. The 425 has all of this. However, I have only one short hill where this is a problem. The other area that I get stuck in is a swamp and and no wheeled vehicle should go there.
Bob Rip

 

[SnowRidge]

<font color="blue"> A bigger gasoline engine, bigger wheel motors <font color="red"> and a bigger pump <font color="blue">to drive the motors helps. The 425 has all of this. <font color="black">

I didn't realize the tram pumps were different. I thought the PT-422 and PT-425 used the same pumps. If the pumps are different, it sure could explain a lot. I had a number of talks with PT about the differences between the two machines, and they never mentioned any pump differences.

I had a hard time understanding the large price difference between the two. Maybe the pump is a big part of it.

 

[BobRip]

I don't know about the bigger pump adding much cost, but it sure adds value. Actually without the bigger pump I think you would still get the torque, but your top speed would drop by 1/3. Someone has done that on TBN.
I would surely pay the difference between the 422 and 425 if I were buying a new machine. But of course a lot of this depends on your use. There are people here who love the 180, and compared to a riding mower, I can see why.
I continue to like the 422. The Mobil 1 is a factor, but more importantly is operating experience and techniques from this site. Intially I was getting stuck once a week. The wiggle walk on hills and big ruts solved a lot of that and experience helped too. Whenever you think the machine is not doing what it should, ask questions or do searches and there will probably be an answer.

Take care and buy a 425.

Bob Rip