Confused about power

[chadincolo]

</font><font color="blue" class="small">( Tractors are a lot different. Since they run so slowly, power-to-weight ratio is a pretty useless statistic. )</font>

Actually, power to weight ratio is one of the most important specifications for some applications. If you are planning on pulling anything, digging with the loader, you NEED weight. My main tractor is around 50 hp, and weighs somewhere in the 10,000 pound neighborhood (don't know exactly since I dumped the fluid out of the rear tires, was right about 12,000). The thing is, pulling a ripper or pushing with the front blade, it needs more weight if I give it full throttle. The little B7100 here at work on the other hand, just needs enough weight on the front to keep it on the ground with the bush hog on the back.

As a chore tractor, power to weight doesn't mean much, as a work tractor, pay close attention to power to weight.

 

[have_blue]

Chad,

Using power-to-weight ratio (P:W) for a tractor is a catch 22.

If you add weight to a tractor, the P:W goes down! If you lighten a tractor, the P:W goes up, but pulling power goes way down.

What I am saying is, instead of judging by P:W ratio, we should judge by power AND weight. Both should be appropriate for the implements a given tractor is expected to pull.

 

[Bob_Skurka]

Bob, I've been sitting back here watching, and I have to say that I think you and Chad are BOTH right but are probably splitting hairs on the defintions and really probably agree, but your agreement depends on the application.

Generally for the small tractors that we play with (a typical CUT) here on TBN, I would side with your points. For larger AG tractors, I would suggest that Chad probably hits the nail on the head. But you are talking about general useages and Chad is talking about ground engaging use, and that is probably were the basis of division is.

The only thing with what Chad wrote that I would disagree with, and this ONLY applies to CUTs is that heavy weight is needed for FEL work. To that point I would say PROPER BALLAST and BALANCE is far more important than absolute machine weight. I can site examples of lighter tractors that have greater FEL capacities than heavier machines to prove that point. But again, I am referring to CUT size machines that are really jacks of all trades, the machines that are used for mowing the lawn, tilling a garden, blowing snow, digging post holes and moving dirt and mulch around our 5, 10 or even 40 acre mini-estates.

My preference for an "all around" tractor for homeowner general use is typically a light to medium weight tractor with removable ballast. I'm willing to give up a bit of traction since I don't "pull a plow" and especially since my tiller doesn't seem to even need me to be in 4wd. I'd rather not rut the yard and have the lovely Mrs_Bob scream at me if I run a heavy piece of equipment across the lawn. I've found that most people who maintain their property really don't gain any advantage from owning a heavy tractor, that probably explains much of the popularity of the Kubota B series light weight tractors. Now if you want to log the woods (pulling really big trees, not dragging 8" to 12" trees) then weight is good. If you actually use a plow, then weight is your friend. If box blade work is a major task, then weight is good.

Define your uses, use that to figure out what weight tractor is best. Most people are probably BEST served by going to the light or middle weight range machines (assuming they are not type who NEED weight).

 

[Spiffy]

I didn't remember posting to this thread!? /forums/images/graemlins/confused.gif /forums/images/graemlins/grin.gif

Kidding, I see "chadincolo". /forums/images/graemlins/smile.gif

Anyway, just to add something productive, I think Bob nailed it with defining the uses.

I'm more familiar with ag than the 20-30HP CUTs I think are in question here, but if FEL is the main thing in question, again balance would be the answer. Barring that, pure weight can make up some difference, however, dont forget tires can be filled or weights can be added where ever needed.

On the same note [probably mentioned earlier and I missed it], weight plays in with tire design on pulling power vs. turf damage.