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Old 07-02-2010, 09:18   #16
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The reason that all new cars use a serpentine belt is - it's better!
More drive, less tension, longer life.

Hinckley has built a serpentine pully kit for the 440 hp Yanmars they use. My boat (not a Hinckley) has the same engines 6LY-STE (420hp) and this winter I am swapping to serpentine. On one engine I do have a Balmar that is derated by the charge controller. Next summer we will crank it up.

So far I have seen the parts they use and a picture of the CEO's boat that has been in charter with the pulleys installed for testing.

Getting the parts for your engine is the problem. Hinckley just went to a CNC shop and had them made. I am in manufacturing and was surprised what they paid but the volume is low...
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Old 07-02-2010, 12:25   #17
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any suggestions about material choice for the pulley i have pictured on the previous page? i was automaticaly thinking alloy however i wonder if nylon might also be a good choice??
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Old 07-02-2010, 12:28   #18
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Any reason you wouldn't go Aluminum?

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Old 07-02-2010, 13:07   #19
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Nylon is a bad choice.
Anodized aluminum much better.
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Old 07-02-2010, 14:46   #20
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weight and cost made me think nylon.
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Old 10-02-2010, 10:11   #21
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Nylon is a bad choice.
Anodized aluminum much better.
I'm with highlander- nylon wouldn't be a good choice for this application.
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Old 10-02-2010, 14:50   #22
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I'm with highlander- nylon wouldn't be a good choice for this application.
Doubt it would be anodized.
More likely just mill finish.

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Old 10-02-2010, 18:10   #23
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The new poly-V pulleys that are going on my boat this winter are anodized.
Not just for good looks but for the hard surface. Plain aluminum will work fine but have a shorter life. Anodizing is cheap and the surface hardness is probly better than cast iron.
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Old 10-02-2010, 18:24   #24
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Don't confuse serpentine belts with ribbed belts. Every serpentine belt I' ve seen has been a ribbed belt, but that doesn't mean you need a serpentine blet with automatic belt tensioning devices, etc. if you are just connecting two pulleys, i.e. the engine and an alternator. A simple ribbed belt is all you need.

One ribbed belt can carry more power than one v-belt, and dual v-belts inevitably fail because one carries more tension than the other, so one slips and the other bursts. They're obsolete, plain and simple. As are v-belts in cars, because one serpentine belt, running in one pulley system with one tensioner, is cheaper and more effective than multiple v-belts.

If you are still running any belt without an automatic tensioner (i.e. us fossils with v-belts) then invest $40-100 in a belt tension gauge and set the tension on that belt correctly. That is going to be way cheaper than replacing your alternator or water pump because you over-tightened the belt and burned out the bearings with excess side load!

Sure, you can measure pulley distances and belt deflection and set tension by using rulers...but I've never seen anyone do that, they just use a thumb and say "that's ok" and inevitably, half of those are too tight because who cares if the alternator and water pump burn out next year? The customer will just come back for more work, meanwhile they're happy. Right?

Aluminum pulleys are nice--but plain aluminum alloys will quickly oxidize in salt air, and if you anodize the pulley the belt may wear it off. Bronze or steel may be a better bet if you can't get a corrosion-resistant aluminum alloy in the right thickness, and the machine shop can lighten that by drilling lightening holes in the body of the pulley. I had one fabbed up from aluminum to get a custom diameter (and cut charging time in half) and had to settle for alu and no lightening holes in order to get it done on time and on budget. So...we ignore a little white powder and spray it with Boeshield once in a while.<G>
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Old 10-02-2010, 21:19   #25
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One ribbed belt can carry more power than one v-belt, and dual v-belts inevitably fail because one carries more tension than the other, so one slips and the other bursts.
Does the ribbed belt carry the more power with less tension?

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Old 10-02-2010, 21:31   #26
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I think the amount of power carried relies on both the tension, and the surface contact area between the belt and pulley. So having the wider ribbed belt, with greater surface contact, should allow it to transfer more power at the same tension. I think.

Anyway...taxi/police/hd packages that used to be equipped with dual belts, are now using ribbed belts along with everyone else. Putting "too much" side load on any bearing (alternator, water pump, whatever) still could be an issue and at some point, you'd want to start checking specs on the engine versus the extra loads on the shaft.
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Old 11-02-2010, 07:36   #27
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Typical power ratings

The power ratings below are based on the smaller pulley with 180o of belt wrap !!. The ratings are based on a light duty application for a transmission working for less than 10 hours per day i.e a service factor K= 1. At the other extreme of a extra heavy duty drive e.g.direct on line AC motor with frequent stops and starts, working for 24 hours /day a service factor K = 1,8 would be necessary. The basic power ratings shown below are used to establish the drive power capacity of a belt drive system using a formula.

Belt
Section Pulley Dia mm Power(kW) at motor speed
................................2880(RPM)..1440(RP M)..960(RPM)
SPZ ...............67...........1,75.........1,05..... ....0,77
....................140...........6,97.........4,0 2.........2,84
SPA ..............100...........4,12.........2,61..... ....1,92
.....................200.........15,1...........9, 4..........6,72
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Old 11-02-2010, 08:17   #28
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"Vee belt drives replaced flat belt drives for many applications because higher power drives could be transmitted with more compact drive arrangements. With a flat belt drive only one belt is used. With a vee belt drive a number of belts are used. Flat belts and vee belts may, and do,slip as the loading increases. For belt drives which drive without slip timing belts should be used. Vee belts on higher power duties generally have to be matched to ensure the drive power is shared."
Vee belts / V belts

I seem to be under the wrong impression about v-vs-ribbed. And while a "timing belt" (toothed belt?) keeping them in lockstep might seem like a good idea, I've seen the way a belt literally jumps when a heavy load cuts in/out of the elctric system, so I think allowing for slippage on the alternator belt is probably a good idea too.
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Old 11-02-2010, 10:07   #29
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Timing belts are very noisy in high speed aplications.
We use them in slow speed drives because the belt tension is not an issue. Anything over 500 RPM and you don't want to be nearby.

The whole idea behind the poly-v belt (looks flat on one side and ribbed for pleasure on the other) is to have more power and less tension.
Those little V's have a ton of surface area, as well as the wedging effect of a regular V belt.

Boaters are just a little bit slow to adapt new things, unless it's shiney or can be clearly seen by the neighbors.
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Old 11-02-2010, 16:58   #30
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I would say that ribbed, double-ribbed allow the use of smaller diameter pulley.
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