For you tractor guys

[cassandra and sara's daddy]

http://m.wimp.com/powertractor/
Old meets new


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[geronimotwo]

hey vern, what's that fancy green plow attachment that you've got there?    

[RoadKingLarry]

The steam tractor would have had even more of an advantage if it had the original steel wheels.
HP is nice but torque is king.

[Sergeant Bob]

I watched a 123 HP Reeves (huge steam tractor) drag a big 4wd tractor around like a toy one time. Raw torque!

[MillCreek]

Wow!

[vaskidmark]

Got to 0:44 and said "This is not going to end well for John Deere."

Then all I could think of was "Too easy, Drill Sergeant!  More, Drill Sergeant!"

stay safe.

[230RN]

Wow.  Made me remember from High School Power Lab that the torque from a steam engine is pretty much the same throughout the RPM range, but especially at the low end.

Something that's always bothered me is that the way they mount tractor tires seems backwards.  Looks to me that you would want the "V"s in the treads to climb UP on the dirt, not cut down into it.  This video brought that up in my mind again.

Terry

[K Frame]

Not at all surprised.

The torque on those steam tractors is monumental.

[MikeB]

Part of it is torque. A bigger part of it is weight. The old steam machine more than likely has a huge weight advantage.

[geronimotwo]

Something that's always bothered me is that the way they mount tractor tires seems backwards.  Looks to me that you would want the "V"s in the treads to climb UP on the dirt, not cut down into it.  This video brought that up in my mind again.

with the tires mounted "backwards" the tread tends to scoop out the dirt.  mounted correctly they push the dirt to the sides and it tends to "lock in" with the rest of the soil.

in all fairness to the jd, the tow chain is attached lower on his tractor which will take some of the weight off his wheels.  i was surprised that the steam rig was able to overcome going backwards, it must have a heck of a clutch.  i'm wondering what the weight difference is between the two.

[Tallpine]

i was surprised that the steam rig was able to overcome going backwards, it must have a heck of a clutch. 

No clutch on steam engines 

[charby]

No clutch on steam engines  

http://www.smokstak.com/forum/showthread.php?t=26875

Some did

[bedlamite]

Biggest issue is traction. The angle of the bar connecting bar is lifting the JD and increasing the weight of the steam tractor. Also, the JD is set up for sled pulling, where building momentum is a big factor and speed wins. Something like this with a level connecting bar would pull that steam engine around the track, and it has a lot less power than the JD in the video.

[230RN]

No clutch on steam engines  

Yup.  No clutch.

You just open the valve and apply 200 psi of steam to a 12" diameter piston (113 square inches) and you get 22,600 pounds of piston thrust... even at zero RPM.*

Yes, that's more than 10 tons.

That's why you can get this kind of wheel-spinning (~1:10):

https://www.youtube.com/watch?v=QqyUVqi3fOg

Terry, 230RN

*  These are more-or-less typical numbers for a smallish steam loco.  Dunno what the diameters and pressures are for a steam tractor, but this illustrates the principles.

PS.  This wheel-spinning can also apply to diesel-electric locomotives, too, since electric motors also have torque at zero RPM.  I once saw a diesel-electric spin its wheels on the tracks just northwest of the Valmont Power Plant east of Boulder CO and when  I looked later, I found gouges in the tracks where the loco had been.

[230RN]

Addendum.  For your (and my) amusement.

Steam torque and locomotive wheel slippage.  Slight grade, heavy train.  Longish, but last half (6:19 and following) shows details of the valve linkages working and the chuffing of the cylinder exhaust steam blown up the stack to increase fire draft.

https://www.youtube.com/watch?v=VZdURcRjEXM

Gives meaning and substance to the phrase, "He's just slipping his wheels."

Also illustrates how static friction is greater than slipping friction.   

Don't know why they didn't use the sandboxes.

[K Frame]

On an episode of Top Gear some years ago they did a race from London to Edinburg using the tops of 1947 technology -- a Vincent Black Shadow, a Jaguar XK120, and Jeremy Clarkson in a steam locomotive.

At one point they're doing close to 70 mph in the locomotive and they got several bursts of wheel spin.