[AT] Horsepower Question

[charlie hill]

Ben,  I'll add a little to my one word answer.   See if you can find the 
Nebraska Tractor test data.  It's available in book form and maybe online. 
You will se the weight (as tested) of the tractor and the drawbar pull. 
You'll see that all wheeled tractors will pull a fractional portion of their 
weight.  It is usually in the 80 or 90% range if I remember right but always 
something less than the weight of the tractor.   There were a few crawlers 
tested that actually pulled slightly more than their weight but only by a 
small amount.

I haven't looked at the data lately.   I hope I remembered it right.  As for 
the pulling tractors, specifically the high horsepower, unlimited types, I 
don't know they might pull more than their weight.  Has anyone ever seen 
data on drawbar pull of pulling tractors?  Someone has certainly thought to 
hook a load cell to a puller by now.

Charlie

--------------------------------------------------
From: "Ben Wagner" <supera1948 at gmail.com>
Sent: Wednesday, October 06, 2010 8:23 PM
To: "Antique tractor email discussion group" <at at lists.antique-tractor.com>
Subject: Re: [AT] Horsepower Question

>  On 10/6/2010 11:47 AM, Will Powell wrote:
>> Ben,
>>
>> You said:
>>
>> "So in reality, horsepower is not really the important number; torque and
>> RPM is what matters?"
>>
>> The Torque and the RPM are variables in the HP calculation... Tourque and 
>> RPM matter based on their application.
>>
>> High HP low torque = Light engine, good for lawn mowers, automobiles, 
>> race cars, airplanes, usually high ware, shorter service life. Cheaper to 
>> build?
>>
>> High Tourqe, Low RPM = Heavy engine, good for Trains, Tractors, Trucks, 
>> excavating equipment. Applications that welcome weight for pulling or 
>> pushing. Low wear, long service life. More expensive to build. (more 
>> metal)
>>
>>
>> The other factor that makes things different between a lawn tractor and a 
>> farm tractor is weight...
>> The main measure of a tractors pulling strength is related to its 
>> weight... Try pulling a 1 row plow with your 20hp lawn tractor......
>>
>> Regards,
>>
>> Will
>>
>>
>> ----- Original Message -----
>> From: "Ben Wagner"<supera1948 at gmail.com>
>> To: "Antique tractor email discussion 
>> group"<at at lists.antique-tractor.com>
>> Sent: Wednesday, October 6, 2010 10:17:32 AM
>> Subject: Re: [AT] Horsepower Question
>>
>> On 10/6/2010 10:00 AM, charlie hill wrote:
>>> Ben, the lawn mower engine is rated in gross hp with no drive train 
>>> load.
>>> The tractor engine is rated at net hp, either at the wheels or the PTO.
>>> There may well be some fudging on the lawn mower engine as well. Also, 
>>> HP
>>> is torque in ft/lbs. times RPM. You can make hp with high rpms and low
>>> torque or high torque and low rpm. Your tractor is high torque and low
>>> rpm. that is what allows it to move a load easily.
>>>
>>> Charlie
>>>
>>> --------------------------------------------------
>>> From: "Ben Wagner"<supera1948 at gmail.com>
>>> Sent: Wednesday, October 06, 2010 9:00 AM
>>> To: "At"<at at lists.antique-tractor.com>
>>> Subject: [AT] Horsepower Question
>>>
>>>> Here is a puzzler that maybe someone with a better knowledge of
>>>> engines can answer. I was asked this question, and had to announce
>>>> that I needed to look it up. What better place than the AT Mailing?
>>>>
>>>> I have a Super A with four cylinders, producing c. 20 HP.
>>>>
>>>> I have a lawnmower, with an engine that says it is also 20 HP, with 
>>>> only
>>>> two cylinders.
>>>>
>>>> What is going on? Is this two different measures of HP? Or has
>>>> technology improved that much? What makes a little two cylinder "small
>>>> engine" have the same HP as four cylinder "tractor" engine.
>>>>
>>>> Thanks,
>>>> Ben Wagner
>>>>
>>>>
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>> So in reality, horsepower is not really the important number; torque and
>> RPM is what matters?
>>
>> Ben Wagner
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> Thank you, everyone, for your replies.  I will have a better
> understanding know of the horsepower issue now, so I think my friend
> will have his answer.
>
> As for the weight in pulling power, is that why in tractor pulls the
> classes are defined by weight?
>
> Thanks,
> Ben Wagner
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