Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Other Topics => Topic started by: shooter on February 11, 2022, 05:14:54 pm

Title: help with pulleys
Post by: shooter on February 11, 2022, 05:14:54 pm
I’m stuck, I can’t formulate a search string to get me where I want to be  :BangHead:
I got this far (image).  The left bottom pully is the driven 2 “ rated 1750RPM 5HP
I got the RPM’s down to 70 but I’m clueless on what the HP did, if anything.
 
Thanks
dave
Title: Re: help with pulleys
Post by: PRR on February 11, 2022, 06:23:44 pm
The HorsePower ideally stays exactly the same.

In practice every 10:1 of gearing will suck-off 5% to 50% of power as friction. High-ratio gearing is lossy and/or real costly. Yes, past 10:1 you may prefer 2-stage, as you have done to get 20:1. (Also to avoid 12-foot wheel and 45-foot belt.)

Car gears may be well-made and can be found cheaper than new. Two first-gear transmissions and a rear-axle run close to 70:1. There was even a production lawn-tractor which ran a belt to a box to a cut-down 1950 Plymouth axle.
Title: Re: help with pulleys
Post by: shooter on February 11, 2022, 07:09:28 pm
Thanks, was guessing it stayed the same but one of the hemisphere's wasn't havin it!  :laugh:
so 5HP minus losses it is!
working toward substituting an electric motor driven water pump with a 4 stroke.  I don't have the electric pump yet, planning stage!
Title: Re: help with pulleys
Post by: PRR on February 11, 2022, 10:24:04 pm
> substituting an electric motor driven water pump with a 4 stroke.

Engine?

A 5 horse utility engine is liable to be rated at 3600RPM. At 1800RPM it may be under 3 horses. Engines driving slow grunt-loads may need a lot of step-down. In fact historically this was part of the rush to Diesel-Electric drive on railroads. "Gearing down" with motor connections is less lossy than most gear systems.
Title: Re: help with pulleys
Post by: shooter on February 12, 2022, 06:35:34 am
the engine is 8hp, currently on my snow thrower but it's a problem child, has been for 5yrs now.  the water pump is driven by either a 1/4HP or 1/2HP electric, need to visit Lowes for conformation.  It's an irrigation type, not a 30' well pumper so load should be minimum.
I do have a 2:1 gear head that I used for a elevator to haul 4X8 sheets up 2 stories when I did the barn roof.


Step-down is what keep hanging me on what HP did in my example.  I know there is a force multiplier when stepping down, just not
what force.
i'm still paying off the laundry room remodel so it's be a couple months before I can put pieces together for testing to see what snags the real world has
Title: Re: help with pulleys
Post by: kagliostro on February 13, 2022, 11:05:42 am
Quote
I know there is a force multiplier when stepping down, just not what force.

Look here

(https://i.imgur.com/3WBD1MJ.jpg)

if you use an rpm reductor (pulley or gear the difference stay on different friction) what you will obtain will be to move your load in a slower way, but then you will be able to move a higher load

ideally (if you leave friction from compute) if you use a 10:1 rpm reductor, you'll obtain to moltiply for 10 times the load, but at a 10 times lower speed (power stay always the same)


Franco
Title: Re: help with pulleys
Post by: shooter on February 13, 2022, 11:53:39 am
thanks Franco, torque was the part I was getting hung up on.


if I freeze the water and slide it over ice the horse will be happy  :laugh:
Title: Re: help with pulleys
Post by: kagliostro on February 13, 2022, 12:57:02 pm
Quote
if I freeze the water and slide it over ice the horse will be happy

 :laugh: :laugh: :laugh: