idler pulley location & tension

[mike90045]

I need to abandon the "Loosen the mouning bolts and slide the engine" to tighten the drive belt scheme, and instead, want to use an idler pulley with spring tension, to keep it tight. 

My question is, how should the tension be applied, to the belt as it departs the drive pulley (flywheel), or as it departs the alternater pulley (arrives at the flywheel) ?

My alternator pulley is on the side opposite the starting handle & fuel pump.  (listeroid 6-1)

Thanks,
   Mike

[veggie]

If you are using a serpentine belt, you have the luxury of running the idler on the inside (grooved) or the outside(backing) of the belt.
An inside tensioner should be ribbed if possible, an outside tensioner should have a flat surface.
Tensioner should be located on the "slack" side of the belt.

veggie

[mobile_bob]

Henry and i were just discussing this the other day, we came to the consensus
that the tensioner probably is more effective mounted closer to the drive pulley than it would be closer to the driven pulley.

reason being, considering the physic's involved you can direct more of the tensioners effort to keeping the belt in contract with the drive pulley which is preferable with a single cylinder engine, and also not have as high a side load presented to either the engine or the genhead. (as opposed to mounting between the two)

another consideration is the flywheel being a plain surface likely is the slipper compared to the more commonly grooved genhead pulley, if there is going to be a chirp it is more likely at the flywheel to belt interface than from the belt to gen pulley interface, so having the tensioner up close to the flywheel ought to keep the belt in better contract.

additionally the idler being closer to the flywheel can be done so that the belt angle is improved from the flywheel to the generator, improving the degree's of contact on both but particularly the generator  pulley.

fwiw
bob g

[Lloyd]

I need to abandon the "Loosen the mouning bolts and slide the engine" to tighten the drive belt scheme, and instead, want to use an idler pulley with spring tension, to keep it tight. 

My question is, how should the tension be applied, to the belt as it departs the drive pulley (flywheel), or as it departs the alternater pulley (arrives at the flywheel) ?

My alternator pulley is on the side opposite the starting handle & fuel pump.  (listeroid 6-1)

Thanks,
   Mike

Always on the slack side as close to the drive pulley as possible. I posted a link to the GATES drive software which is a free download on this site somewhere, but I can't find it at this moment..asaid I will post it to this topic.

Lloyd

[Tom Reed]

Hi Mike,

I can see how your mount in the bottom photo will be a problem with engine to generator belt alignment.



This is what I did and it works flawlessly for 5 years now.

[mike90045]

With the house getting wrapped up next week (I hope) and rain coming too, I have to get the generator on line this weekend, and will likely fab up something to press the outside of the ribbed belt, to increase the wrap on the alternator pulley.  I just need to think about a way to do that.   

Today I got some spacers (oak planks from flooring) under the engine rails so the steel won't be pounding on the concrete and turn it to powder.  Then to torque everything back down, prime the fuel lines again, and spin it up.  I'll load it down with a 2x4 to clean the pulley groves out - much of the grove is obstructed with yak putty, or something.

And the shaft of the factory fuel tank ball valve is leaking, so I guess it's time to locate a new thing-a-mabob to shut the fuel off at the tank.

Tom - what does "I can see how your mount in the bottom photo will be a problem with engine to generator belt alignment." mean ? 
I can do fore-aft to adjust tension, and I hope that the side-side alignment will be good enough to not need any adjustments.  I got the square taper washers from Mc-Master Carr, to get better bolt pressure to the tapered I beams, so locking the engine to the frame slots should be OK.

Mike ( now full time in Willits, in a shack by the Skunk Train tracks )

[mike90045]

This is what I did and it works flawlessly for 5 years now.

May have to take that on next summer !

[SteveU.]

Ahh. I forgotten Mike that you got one of the later groove machined flywheel engines. Try a hand held wire brush for cleaning instead with the engine runnong. Wear a face shield and expect to get bristle peppered.

Read back and take the advice to put the tensioner on the slack side of the DRIVING pulley (your flywheel) instead of at the gen head.
Here's why. When you are coming off the acceleration power stroke event into the de-acceleration period it will whip a loop/hump of slacken belt wrap backwards up around the driving pulley. Kinnda' like whipping a hump down a garden hose. When pulley diameter distance/RPM/and event cycling all synchronize with the next power cycle event is where your micro-slippage will occur.
Lister SOM systems with V belts were using V belt stretch and V groove dig in to even this out all out. Poly groove belts do not have any usable stretch tensioning or compressible ribber depth to do this. Why the need for a spring arm tensioner then when on applications with cycling loading/unloading events.

Hope this helps
Steve Unruh

[Lloyd]

Here is the link to the topic with the free gates drive design software.

http://www.microcogen.info/index.php?topic=2815.msg31861#msg31861

Lloyd

And if you want to watch a video first.

http://www.youtube.com/user/GatesPT?blend=23&ob=5#p/u/1/wcdHKfOa9iQ

[mike90045]

Ahh. I forgotten Mike that you got one of the later groove machined flywheel engines. Try a hand held wire brush for cleaning instead with the engine runnong. Wear a face shield and expect to get bristle peppered. 

Was able to do this by hand, and a screwdriver, most of the crud was yack pucky used to fill voids.   Yucch.

Read back and take the advice to put the tensioner on the slack side of the DRIVING pulley (your flywheel) instead of at the gen head.

What is the "slack side" of the driving pulley (flywheel) ?  is it where the belt leaves (departs) the pulley as it travels to the alternator pulley, or is it the other side, where after leaving the alternator, it meets the flywheel.  Neither side is "slack" as I see it.


I did get a batch of fuel line fittings, and replaced the factory ball valve, with a valve that does not leak.  took about 3 hours to prime and get all the bubbles out, and then it fired up.   The new mounting system seems to be OK so far, there is some flex in the the steel members, and the rocker arm cover does show some motion after the engine settles down,  I'll let things settle in overnight, and re-torque in the AM.  I don't want to torque too much, and pull the epoxy out from the concrete, but it's got to be tight enough to not build enough momentum to start walking away.

The big muffler and 3" pipe really makes it quiet, can still hear the injector clink as it's running.

[Lloyd]

picture= 1000 words

an explanation=5 X's that

I'll try to be succinct, without a picture.


CC...........drive pulley w/driven to the left...slack=top

CW...........drive pulley w/driven to the left...slack=bottom

CC...........drive pulley w/driven to the right...slack= bottom

CW...........drive pulley w/driven to the right...slack=top

as close to the drive pulley as possible W/ spring tension towards the driven pulley, yes they make tenioners with a right and a left.

Slack=the opposite of the pull/tension side.

This is all for a backside tensioner, it's just the opposite for an inside tensioner.

BDP=backside

lloyd

[Tom Reed]

Tom - what does "I can see how your mount in the bottom photo will be a problem with engine to generator belt alignment." mean ? 
I can do fore-aft to adjust tension, and I hope that the side-side alignment will be good enough to not need any adjustments.  I got the square taper washers from Mc-Master Carr, to get better bolt pressure to the tapered I beams, so locking the engine to the frame slots should be OK.

Mike ( now full time in Willits, in a shack by the Skunk Train tracks )

Mike, the way your engine is mounted it can rotate on the mount when adjusting which will cause the belt to walk off the wheel. I see an idler as an extra cost and failure point. The generator mount in the photo will only allow the generator to move straight back and forth and there is an adjustment bolt for the belt tension.

Welcome to the woods. I've yet to get the fire wood in, sigh life is busy!

[XYZER]

The tensioner when needed well of course is nessary. I HAD to use one mounting a 110-555 and a generator head on my lets get by cheap off grid camp genorator. I had to tack weld and leave adjument options all of the way. My tensioner was used as an fixed mount idler to increase the belt contact on the 110-555 and the AC head. The tension was done with the alternator. As Tom mentioned it is another fly in the ointment unless it is absolutly nessary. It will highly affect how the belt will behave and all of the stars must align.

[mike90045]

Mike, the way your engine is mounted it can rotate on the mount when adjusting which will cause the belt to walk off the wheel. I see an idler as an extra cost and failure point. The generator mount in the photo will only allow the generator to move straight back and forth and there is an adjustment bolt for the belt tension.

Welcome to the woods. I've yet to get the fire wood in, sigh life is busy! 

Yep, the belt walks off after about 90 seconds.   And the alternator, doesn't alternate. Just loads the engine down.

So, I have to figure out the geometry, of which way to pivot the engine, to keep the belt in place.  And then it's back to the pages to get the info on re-flashing the residual magnetism in the alternator, and see if that wakes it up.