Coupling or belt drive ? - Crunch time !

[Veggiefuel]

Hi everyone,

The guys in the fab shop where I work have finally agreed to build the base for my Changfa generator assembly.
I have been bouncing back and forth between belt driving or direct driving the ST-5 head.
I have about 2 days to finalize my decision.
There are pros and cons to both.

BELTS:
- The Changfa comes with a 3 groove drive pulley installed on the flywheel
- Belts are easy to align and install
- I can run the engine at 1500 RPM and drive the head at 1800 rpm.(Perhaps quieter and longer engine life)

COUPLING:
- needs a custom coupling adaptor ($400 approx.)
- simple layout (other than alignment shims)
- Compact
- Quiet

The Changfa has an electric starter, so hand cranking is usually not a concern.

Input from owners of direct drivers and belt systems would be most appreciated.

Cheers,
Veggie

[Stan]

Sorry Veggie, don't have the required qualifications with direct drive but I've read where they occasionally need replacement, at least the flexible part.  What's the price comparison between replacing the flexible part (forgot the proper name) on a direct drive setup, and the price of a replacement belt(s) drive?

Could be a consideration.
Stan

[listeroidsusa1]

A limited slip coupling from a bush hog makes a fine coupling. This is the coupling that mounts on the gearbox of the brush cutter to connect the drive shaft. They work well and are reasonably priced. They have a rubber biscuit in the center and have 2 steel halves that are spring loaded to the rubber disk. The one on my bush hog is rated for 100 hp @ 540 rpm.

[mobile_bob]

i don't know which changfa you are planning on useing, but

there is something to be said for running at 1500rpm, they are a bit quieter and get a bit better fuel economy

personally i like direct drive, makes for a tighter package, in my opinion
and less to have to adjust, once setup it stays put
but you are stuck with 1800rpm if you in need of 60hz
1500rpm if you are on the other side of the pond for 50hz

bob g

[jtodd]

I built mine with a direct coupling - less parts to eat limbs.  The downside, as noted, is that the engine has to run at 1800 RPM.  However, this is already de-rated from the 2200 (?) RPM that provides peak horsepower.  Very compact package, though.

I even have a spare coupling left over.  It's a clever design - uses nylon (PVC?) 1/2" rods as "fuses" that shear if load imbalance occurs.  Made for an ST-10 sized coupling (42mm) and I don't know if the Changfas have different sized pulley hole bolt-downs, but it mated up to a Changfa 195.  I ultimately went with a spider-gear type connector, because I got a really good deal on it from George.

Pictures here:  http://www.loligo.com/projects/changfa/pulley/

$130 plus S&H.  It's just collecting dust in my garage. 

JT

[TimSR2]

Go belt drive if it is a standby set and ultimate efficiency is not the #1 priority. Belts are cheap and suck up misalignment and diesel power pulses. Vee belts provide lots of 'fudge factor', at the expense of some efficiency.  Your single cylinder diesel will shred your expensive direct drive coupler but it is no match for a single B series belt on large pulleys.  Direct drive will be only 5 percent more efficient and probably will require more repair. YMMV.

[Stan]

First you have to create an account with listerenginegallery.com (top right corner of every thread)  then set up your album then upload a picture.
Then you click on the picture to make it bigger, and then right click on it.  Then you select "copy image location" (just click on it)
Then you come back and post a message with the javascript stuff found when you click on the little icon with the image of a computer screen on it (second from the left above the winky icon).  Dont touch the mouse, just do a ctrl+V and the image location will be pasted in the middle of all the javascript.
Your done.
Stan

[NoSpark]

So what RPM did you decide on?

[mobile_bob]

it looks like he is going to go with 1800rpm and give it a whirl
nice looking pulley btw

Henry is going to end up with a really sweet genset in the end
his attention to detail is second to none in my opinion.

very nice to have a fellow 195 lover even if his is a DI engine,, 

looking forward to getting his consumption numbers.

bob g

[Veggiefuel]

Thanks for all the input you guys,

I settled on the belt drive configuration.

FYI: A motor slide base for a 256T electric motor frame fits the ST-5 generator perfectly.
It allows for easy adjustment of the belt tension. (Only $65 at my local electric motor supplier).

For me this was the simplest configuration. The Changfa 195 already had a drive sheave, so the only thing I needed to buy was the motor slide base and the sheave for the ST-5 head.

The engine will be running at 1500 rpm and should still produce enough BHP to drive the ST-5kw.

I will post pictures when I get the unit assembled.

Cheers,
Veggie