[AT] RE: Vintage tractor pulling advice

[Steve W.]

> >A favorite scene of mine at a pull at the Nebr State Fair was when
the huge,
> >supercharged tractors got a sled loaded with concrete blocks skewed
on the
> >track.  They couldn't get it straightened out with tractors so they
brought
> >in the real muscle...two huge pulling horses, who got the sled
straightened
> >out as if they were moving a couple hay bales.  I love old tractors
and have
> >little affection for horses, but the big draft animals really do
appeal to
> >me.
> >
> >Rog
>
> I wonder how many horsepower they where?
>
> Which brings up a side question about horsepower..  When did they
start
> the massive cheating on horsepower ratings?  I have an old Case VAC
that is rated at well under 30 HP and I have a newish lawn tractor that
is rated at 26.
> The Case can pull pretty much anything I ask it to, or make a mess out
of
> the ground trying.  Lets just say that the lawn tractor must be using
much
> smaller horses...
>
>
> --Matthew
>
>
Matthew,
the big difference is the method of rating that HP. Your VAC was rated
using drawbar HP. The LT is rated using brake peak HP. They are both
real numbers BUT the different methods make the numbers entirely
different.
Current marketing ethos shows that sheeple shop by HP numbers. So the
current trend in marketing is to use the maximum numbers for a given
engine/motor. Doesn't seem to matter that those numbers mean nothing in
reality, they just sound good. The test for your Case was done by
actually hooking it to a weight system and pulling with it till it
achieved 5-10 percent wheel slippage. Then it was connected to a dyno
and the PTO was rated by loading it until the engine started to drop
below 540 rpm at the PTO. The LT on the other hand was tested with a
bare engine spinning into a dyno and the number given is the spike given
when the engine is loaded until it stalls. In reality that engine would
probably relate to about 8 HP if tested the same way as the VAC. It's
kind of like the current ratings of electric motors. They use the
maximum amp draw that the motor uses just before it stalls from the
load. That is why a new compressor motor is rated as 5 peak HP when one
the same size but rated in the 60's would be 2HP or less.