My bad. Forgot to state "at 1 ft."

"Ermalina" wrote in message
...
John wrote:

Who's going to sit there and figure out that a 180 lb man standing (?)
on
the end of a 24" breaker bar will deliver 90 ft/lbs of torque? What if
you
needed only 75 ft/lbs? Do you know the formula to determine that you'll
have
to stand on the breaker bar at 10" from the center of the nut?

It's not rocket science, but neither is changing a lawn mower blade. If
you
need to, rent/buy a torque wrench.

"Ermalina" wrote in message
...
iBuyMinis wrote:

Taking off the blade is easy, it's torquing it down to ensure
that it does not fly off is the difficult part.


"torquing it down" difficult?

1. You know your weight in pounds.

2. You know the length of the wrench in feet.

3. You know the desired torque in foot-pounds.

It's neither rocket science nor brain surgery.

A 180 pound man, standing at the end of a horizontally-oriented 2 foot
breaker bar so that the force is applied vertically produces a torque of
360 ft-lbs (not 90).

Technically, Torque = R X F, the crossproduct of the displacement and
force vectors. So, as long as the force is applied at a 90 degree angle,
the torque is simply the force multiplied by the distance from the pivot
point. That's about as simple a "formula" as you can get.

How hard is it to determine that if you want to produce a torque of 50
ft-lbs (the recommendation for my mower) that if you weigh 180 lbs, then
apply your weight fully (stand or whatever) between 1/4 and 1/3 ft (3 or
4 inches) down the length of the breaker bar? No need for great
precision. Like I said it's neither rocket science nor brain surgery.