Videos of New PT425 Arriving/Unloading

[Gravy]

I don;t understand the concept of the operator sitting sideways on the mining tractor. What is the advantage?

Kent may have a better answer, but I'll make a stab at it.

Underground coal mining follows the seams. If I understand it at all, seams are really long, kinda wide, and not very tall. I met a miner last year who mentioned spending 15 years in 42" tunnels before he moved up to taller spaces. The driver doesn't sit crossways - he lays down crossways. That keeps him low so he doesn't remove parts of his head on a low hanging obstacle. Being crossways leaves more length for the cargo bed.

Coal mining is weird.

 

[Clumber]

Kent may have a better answer, but I'll make a stab at it.

Underground coal mining follows the seams. If I understand it at all, seams are really long, kinda wide, and not very tall. I met a miner last year who mentioned spending 15 years in 42" tunnels before he moved up to taller spaces. The driver doesn't sit crossways - he lays down crossways. That keeps him low so he doesn't remove parts of his head on a low hanging obstacle. Being crossways leaves more length for the cargo bed.

Coal mining is weird.

Thanks Gravy. The recent mining events this year has given me a better appreciation of strip mining.

It would seem that it would be awkward to operate a treadle in that position not to mention front attachments. Weird!

 

[J_J]

Some of the drivers in the mining cars sits side ways because he can see fwd and backward better than a face the front position. I don't think the cars turn around, so the cars go in pushing, and come out pulling.

 

[MossRoad]

Thanks guys, I will try the both feet approach. I had experienced the sudden speed change thing.

So, the treadle is really a single direction flow valve. Pressing the right foot causes flow in foward direction, pressing harder increases the flow to the wheel motors which move the tractor forward faster. likewise for the left foot opposite direction... Using both feet to hold posistion on a slope or slow foward decent, pressing left foot more than the right seems to infer hydraulic flow in both directions, more so to the reverse direction providing a breaking action. Or is the left foot pedal also forcing the right pedal up causing reverse flow only to slow the effect of gravity on the tractor?

Also, Kent, I don;t understand the concept of the operator sitting sideways on the mining tractor. What is the advantage?

The treadle pedals are all one piece of steel with a pivot point just offset of the middle. When you push one pedal the other one has no choice but to go up and vice versa. It is a rocker. Under the center console between your feet is one hydraulic valve. Centered, the tractor goes nowhere. To the right it goes forward. To the left it goes backwards. The more you open the valve in one direction, the faster the tractor goes and vice versa. However, you need to understand that the flow to the wheel motors does not go through that valve. All that valve does is control an internal mechanism in your variable volume pump that provides the movement to the swash plate in the variable volume pump. The variable volume pump is what supplies the flow to the wheel motors. The swash plate sits inside the pump in a neutral position, spun by the engine constantly. When you change the angle of the swash plate it pumps fluid to one side of the pump. You center it, no pumping. Angle it in the other direction, pumping in the other direction. The more severe the angle, the more fluid to the wheel motors. Also, you will find that if you need more power to the wheels, you need to go slower and put less pressure on the pedals. Sounds weird, but here's how that works. High flow = less pressure. Low flow = more pressure. So you will find that you can go fast like a sprinter but if you need to do work you need to slow down like a weight lifter.

Older PTs like mine have a cable connected to the treadle that pushes and pulls a lever on the outside of the variable volume pump. Newer models like yours have a pump with the external lever replaced by an internal valve, which is operated hydraulically by your foot control.

You should search TBN for variable volume pump or swash plate and do some reading to really understand how your PT works. It is quite interesting and a good thing to know what is on the other end of those foot pedals. :thumbsup: Hope that helps. :laughing:

 

[MossRoad]

Also, Kent, I don;t understand the concept of the operator sitting sideways on the mining tractor. What is the advantage?

Think of driving down a really long, low, dark tunnel. The tunnel is only wide enough for the machine. You have to go in and out and in and out of that tunnel all day without turning around. Your neck would get pretty sore, yes? So you sit sideways and half the day you look left and half the day you look right.

 

[MossRoad]

Some of the drivers in the mining cars sits side ways because he can see fwd and backward better than a face the front position. I don't think the cars turn around, so the cars go in pushing, and come out pulling.

What J_J said! :laughing: :thumbsup:

 

[ponytug]

Their mining equipment makes the PT equipment look like Tonka toys, but they have prices to match;

The driver is facing up the page.
Specifications here: 10,000lbs lift, built in fire suppression system...
LT6540

All the best,

Peter

 

[MossRoad]

If you look at this picture, you can see a silver crank arm on the top of my variable volume pump. There is a cable connected to the end of the crank that goes all the way up to my treadle pedal.

 

[MossRoad]

If you look at yours, there is no crank arm. There is a box on top of the front of the pump with hoses connected to it. Those go to the valve that your treadle pedals are connected to.

 

[MossRoad]

Also, I mentioned that the treadle is slightly offset from center. The longer arm is on your right foot and the shorter is on you left foot. At least that's the way mine is. You can see it in this picture. I think it is so that there is more control and range of motion in the forward direction, which you use more often and to leave a place for your left toes to sit when you are mowing. Why keep them angled up on the pedal for mile after mile of lawn?