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Re: Re[2]: Air compressors

Subject: Re: Re[2]: Air compressors
From: LeChevet <>
Date: Wed, 10 Apr 1996 18:14:03 -0400
At 16:23 4/9/96 -0500, BBRANDT@TCMAIL.FRCO.COM wrote:
>Jon writes
>> The HP ratings that Sears uses are false advertising in my opinion. I 
>>notice that their 5 HP model has a maximum current draw of 14.7 amp @ 120v 
>>-the same as my 3.5 HP unit.  I short, the MAXIMUM input power on their 5 
>>HP model is a bit over 2 HP.  How they rate the maximum output at 5 HP is a 
>>true feat of wonder and a violation of the basic laws of nature!  I also 
>>notice that they do this same trick on most of their power tools.
>Sears quotes the max hp developed by their motors *at stall*. While this is 
>a legitimate rating it hardly reflects the true capability of most tools. It 
>works great with a table saw because as you bog the motor down in cutting 
>heavy material the hp increases to stall but a compressor or sander or other 
>tool that does not go to stall is considerably overrated by this method.
>Just my $.02
Jon Replies:
Understand what Sears is doing and how they rationalize the ratings.  An
analogy (although slightly hyperbolic) would be to claim my 1984 stock
Cavalier SW develops 1450 HP.  [This is peak HP developed during "rapid
deceleration" - yeah, the brakes absorb the power.]  However, no one in
their right mind would sell the car as a 1450 HP car with a little footnote
explaining that SAE HP is not being discussed.  Your point concerning the
table saw is well taken, but peak HP ratings have no place on a power tool
that is expected to perform continuous duty.  As I remember, power tool
makers use to use the "stall torque" as well as HP in sales literature.
These numbers mean something, both for table saws and compressors.

My point is that Sears' "peak HP" is of no practical use when it comes to
determining how much capacity the tool has, but is a nice advertising
gimmick.  Sears may be correct and have the blessing of their legal
department to advertise this type of HP, but they have lost me as a power
tool customer.     

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