HP rating for pulleys

[stuckmotor]

Spyderlk,
I hadn't thought about adjustable pulleys. Thanks.

 

[SPYDERLK]

also most gasoline small engines are over rated in the Hp they produce, (if you noticed many no longer rate the power in horse power),

(it is my understanding the way the old system worked was to use a brake and to get the max HP, that meant to kill the engine, by over load),

in the past, one could usually safely replace a gasoline engine with an electric motor in the 1/2 to 2/3 range and usually no have any problems,

or if one was replacing an eclectic motor it was normally suggest you double the gas engines HP,

so I really doubt if you engine can continue to run and produce the 13 HP, most likely it really only has the ability to produce about 6 to 8 true horse power,

(one quick example is a generator, say a 13 HP engine is used to run a generator, most are only about 5500 watt normal out put generators (alternators actually), a horse power is said to be, 745 watts, take that 5500 and divide by is 7.3 (horse power), yes I know there is some losses, but 5.7 HP in losses, I doubt it,

https://www.google.com/search?num=1...-1.1.0....0...1c.1.42.serp..1.0.0.rYnzlbsZI1s

The story is:
A 13 HP rated gas engine will put out 13HP and thats all. It starts to slo quickly if you load it beyond that. ... Whereas, a ~7HP rated electric motor will put out 7HP all day, but if you call for more it will just draw more current and barely slo down while putting out the extra power. It will finally buckle and stall when you ask for too much, but the buckle point will be nearer 14HP than 7. It costs tho. The elec will ride right thru a brief overload that would buckle a gas, But it wont sustain a near 2x overload for very long w/o burning up.

 

[LD1]

Yep. HP is HP. A measure of how fast work can get done.

It really ticks me off the lawsuit that has caused mfg to quit listing HP. How the heck are you supposed to size things like hydraulic pumps??

 

[Tractor Seabee]

Yep. HP is HP. A measure of how fast work can get done.

It really ticks me off the lawsuit that has caused mfg to quit listing HP. How the heck are you supposed to size things like hydraulic pumps??

BTU/HR/Minute,/Second, Calories/second, kilowatts, watts, joules can all be converted to HP. There are conversions on the internet. I have a package on my computer that converts any like measurement to the others.

Ron

 

[LD1]

Yea, they can all be converted if given the info. Anymore all you see listed is cc's and torque. Both of which are useless when trying to size a hydraulic pump.

 

[Tractor Seabee]

Here is an explanation for your bedtime reading:

cc to torque to hp Conversion Update! - MovingSnow.com

Ron

 

[LD1]

Nothing new to me in any of that.

You cannot find the HP based on only the cc and/or the torque. He made the assumption that the torque raring was at 3600 rpm. Bit I am betting its at a lower rpm, cause torque is likely highest around 1500-2000 rpm, so that larger number I am betting what its rated at.

The article also said that there were a lot of variables, and this would get close. That's true. Lots of variables. And close might not be close enough when trying to size an engine to meet the spec of a hydraulic pump.

Regardless of how close we can get with guessing based off of a torque rating, the fact is....it was a lot simpler to buy an engine based on HP. And only way to do that now is to know what the torque is at the operating rpm of the engine. And not whatever the peak torque is at a lesser rpm.

 

[Tractor Seabee]

Nothing new to me in any of that.

The article also said that there were a lot of variables, and this would get close. That's true. Lots of variables. And close might not be close enough when trying to size an engine to meet the spec of a hydraulic pump.

Have you figured out what HP your pump requires? Only about half the pumps in Surplus Centers catalog have HP ratings. Of course the HP required is more dependent on the actually load developed not the pump max capacity as the charts show. RPM, Pressure, and GPM all play in the game as this link shows: Hydraulic Oil Pumps - Horsepower Required

 

[LD1]

Have you figured out what HP your pump requires? Only about half the pumps in Surplus Centers catalog have HP ratings. Of course the HP required is more dependent on the actually load developed not the pump max capacity as the charts show. RPM, Pressure, and GPM all play in the game as this link shows: Hydraulic Oil Pumps - Horsepower Required

pump efficiency is also a factor for sizing. Pump MFG's dont need to give me a HP requirement. Thats what the formula is for.

I am not sizing anything at the moment. Just pointing out that since most small engines dont list a HP, it makes it more difficult for people to properly size. Knowing the peak torque the engine makes does nothing to help determine its power at operating RPM. Sure, you could figure the HP at THAT rpm, but it will likely be lower than where the engines peak power is, and lower than where the engine is designed to run.

So unless they start giving the torque rating "at peak power rpm" and then listing what that RPM is, there is no way to properly size a hydraulic pump to match. But then again, if they gave the torque rating "at peak power", might as well just give us the darn HP.