• Horsepower and Watts

  • General discussion about railroad operations, related facilities, maps, and other resources.
General discussion about railroad operations, related facilities, maps, and other resources.

Moderator: Robert Paniagua

  by 1st Barnegat
This is an extention of the discussion at NJT Rail that morphed into one about horsepower and watts. You can pick up the start of the thread here: http://railroad.net/forums/viewtopic.php?t=20212
Bill West wrote:"Watts are not uniquely metric..."
Well, close. Engineer James Watt (no, not the railroad kind) created a four-fold improvement in the power of the then-stationary steam engine (which were used to pump water out of mines) and found a way to compare its capability to that of the horses it replaced. Watt's unit of power was "horse-power." Details at http://www.spartacus.schoolnet.co.uk/SCwatt.htm

The railroad connection is via a Richard Trevithick, who, in the UK in February 1804, "produced the world's first steam engine to run successfully on rails." Steam locomotives at last! Quoted from: http://www.spartacus.schoolnet.co.uk/RAtrevithick.htm

Rating engines by horsepower continued through the steam engine era. (For stationary, non-railroad engines, begining before 1763 in the UK. For American steam locomotives, begining c. 1825 and lasting into the 1940s. I do not know the duration of UK steam locomotives, but I do know they preceded ours.) This usage predated the discovery of electric power (battery power at first) by 1800. Battery reference from: http://www.ideafinder.com/history/inventors/volta.htm

Now with batteries there was a need to quantify electric power, which as Irish said, was named after Watt in his honor in 1889 (and volts were named after Volta), as repeated below for convience.
Irish Chieftain wrote:The Watt came into being back in 1889...
So there has always been only one unit of electric power, the watt, and it was incorporated into the metric system. There is no USCS (inches, pounds, gallons..., see http://www.engineeringtoolbox.com/uscs-d_940.html) equivalent, and really no need for one. Watts are commonly used here for electric power along with USCS units for most everything else. You can convert USCS units to metric here: http://www.engineeringtoolbox.com/unit- ... d_185.html

  by jkrail
There are 746 watts to a horsepower.
746 watts = one horsepower.

Jerry Kelley

  by pennsy
Hi All,

You might also add: Volts times Amperes equals Watts.

ie; E x I = Power. E is in volts, I is in amperes, Power is in Watts.